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In this study we have interrogated the DNA methylome of myelofibrosis patients using high-density DNA methylation arrays. We detected 35,215 differentially methylated CpGs corresponding to 10,253 genes between myelofibrosis patients and healthy controls. These changes were present both in primary and secondary myelofibrosis, which showed no differences between them. Remarkably, the majorities of differentially methylated CpGs were located outside gene promoter regions and showed a significant association with enhancer regions. This enhancer aberrant hypermethylation showed a negative correlation with the expression of 27 genes in the myelofibrosis cohort. Of these, we focused on ZFP36L1 gene and validated its decreased expression and enhancer DNA hypermethylation in an independent cohort of patients and myeloid cell-lines. In vitro reporter assay and 5' azacitidine treatment confirmed the functional relevance of the enhancer hypermethylation of ZFP36L1. Furthermore, in vitro rescue of ZFP36L1 expression had an impact in cell proliferation and induced apoptosis in SET-2 cell line indicating a possible role of ZFP36L1 as a tumor suppressor gene in myelofibrosis. We describe the DNA methylation profile of myelofibrosis, identifying extensive changes in enhancer elements and revealing ZFP36L1 as a novel candidate tumor suppressor gene.

Gene regulation through DNA methylation is a well described phenomenon that has a prominent role in physiological and pathological cell-states. This epigenetic modification is usually grouped in regions denominated CpG islands, which frequently co-localize with gene promoters, silencing the transcription of those genes. Recent genome-wide DNA methylation studies have challenged this paradigm, demonstrating that DNA methylation of regulatory regions outside promoters is able to influence cell-type specific gene expression programs under physiologic or pathologic conditions. Coupling genome-wide DNA methylation assays with histone mark annotation has allowed for the identification of specific epigenomic changes that affect enhancer regulatory regions, revealing an additional layer of complexity to the epigenetic regulation of gene expression. In this review, we summarize the novel evidence for the molecular and biological regulation of DNA methylation in enhancer regions and the dynamism of these changes contributing to the fine-tuning of gene expression. We also analyze the contribution of enhancer DNA methylation on the expression of relevant genes in acute myeloid leukemia and chronic myeloproliferative neoplasms. The characterization of the aberrant enhancer DNA methylation provides not only a novel pathogenic mechanism for different tumors but also highlights novel potential therapeutic targets for myeloid derived neoplasms.

In this study we interrogated the DNA methylome of myelofibrosis patients using high-density DNA methylation arrays. We detected 35,215 differentially methylated CpG, corresponding to 10,253 genes, between myelofibrosis patients and healthy controls. These changes were present both in primary and secondary myelofibrosis, which showed no differences between them. Remarkably, most differentially methylated CpG were located outside gene promoter regions and showed significant association with enhancer regions. This aberrant enhancer hypermethylation was negatively correlated with the expression of 27 genes in the myelofibrosis cohort. Of these, we focused on the ZFP36L1 gene and validated its decreased expression and enhancer DNA hypermethylation in an independent cohort of patients and myeloid cell-lines. In vitro reporter assay and 5’-azacitidine treatment confirmed the functional relevance of hyper-methylation of ZFP36L1 enhancer. Furthermore, in vitro rescue of ZFP36L1 expression had an impact on cell proliferation and induced apoptosis in SET-2 cell line indicating a possible role of ZFP36L1 as a tumor suppressor gene in myelofibrosis. Collectively, we describe the DNA methylation profile of myelofibrosis, identifying extensive changes in enhancer elements and revealing ZFP36L1 as a novel candidate tumor suppressor gene.

The biological role of extracellular vesicles (EVs) in diffuse large B-cell lymphoma (DLBCL) initiation and progression remains largely unknown. We characterized EVs secreted by 5 DLBCL cell lines, a primary DLBCL tumor, and a normal control B-cell sample, optimized their purification, and analyzed their content. We found that DLBCLs secreted large quantities of CD63, Alix, TSG101, and CD81 EVs, which can be extracted using an ultracentrifugation-based method and traced by their cell of origin surface markers. We also showed that tumor-derived EVs can be exchanged between lymphoma cells, normal tonsillar cells, and HK stromal cells. We then examined the content of EVs, focusing on isolation of high-quality total RNA. We sequenced the total RNA and analyzed the nature of RNA species, including coding and noncoding RNAs. We compared whole-cell and EV-derived RNA composition in benign and malignant B cells and discovered that transcripts from EVs were involved in many critical cellular functions. Finally, we performed mutational analysis and found that mutations detected in EVs exquisitely represented mutations in the cell of origin. These results enhance our understanding and enable future studies of the role that EVs may play in the pathogenesis of DLBCL, particularly with regards to the exchange of genomic information. Current findings open a new strategy for liquid biopsy approaches in disease monitoring.

Using knowledge- and structure-based approaches, we designed and synthesized reversible chemical probes that simultaneously inhibit the activity of two epigenetic targets, histone 3 lysine 9 methyltransferase (G9a) and DNA methyltransferases (DNMT), at nanomolar ranges. Enzymatic competition assays confirmed our design strategy: substrate competitive inhibitors. Next, an initial exploration around our hit 11 was pursued to identify an adequate tool compound for in vivo testing. In vitro treatment of different hematological neoplasia cell lines led to the identification of molecules with clear antiproliferative efficacies (GI50 values in the nanomolar range). On the basis of epigenetic functional cellular responses (levels of lysine 9 methylation and 5-methylcytosine), an acceptable therapeutic window (around 1 log unit) and a suitable pharmacokinetic profile, 12 was selected for in vivo proof-of-concept ( Nat. Commun. 2017, 8, 15424). Herein, 12 achieved a significant in vivo efficacy: 70% overall tumor g...

Epigenetic regulators that exhibit aberrant enzymatic activities or expression profiles are potential therapeutic targets for cancers. Specifically, enzymes responsible for methylation at histone-3 lysine-9 (like G9a) and aberrant DNA hypermethylation (DNMTs) have been implicated in a number of cancers. Recently, molecules bearing a 4-aminoquinoline scaffold were reported as dual inhibitors of these targets and showed a significant in vivo efficacy in animal models of hematological malignancies. Here, we report a detailed exploration around three growing vectors born by this chemotype. Exploring this chemical space led to the identification of features to navigate G9a and DNMT1 biological spaces: not only their corresponding exclusive areas, selective compounds, but also common spaces. Thus, we identified from selective G9a and first-in-class DNMT1 inhibitors, >1 log unit between their IC50 values, with IC50 < 25 nM (e.g., 43 and 26, respectively) to equipotent inhibitors with IC50 < 50 nM for both target...

Epigenetic modifications such as DNA and histone methylation functionally cooperate in fostering tumor growth, including that of hepatocellular carcinoma (HCC). Pharmacological targeting of these mechanisms may open new therapeutic avenues. We aimed to determine the therapeutic efficacy and potential mechanism of action of our dual G9a histone-methyltransferase and DNA-methyltransferase 1 (DNMT1) inhibitor in human HCC cells and their crosstalk with fibrogenic cells. The expression of G9a and DNMT1, along with that of their molecular adaptor ubiquitin-like with PHD and RING finger domains-1 (UHRF1), was measured in human HCCs (n = 268), peritumoral tissues (n = 154), and HCC cell lines (n = 32). We evaluated the effect of individual and combined inhibition of G9a and DNMT1 on HCC cell growth by pharmacological and genetic approaches. The activity of our lead compound, CM-272, was examined in HCC cells under normoxia and hypoxia, human hepatic stellate cells and LX2 cells, and xenograft tumors formed by HCC or combined HCC+LX2 cells. We found a significant and correlative overexpression of G9a, DNMT1, and UHRF1 in HCCs in association with poor prognosis. Independent G9a and DNMT1 pharmacological targeting synergistically inhibited HCC cell growth. CM-272 potently reduced HCC and LX2 cells proliferation and quelled tumor growth, particularly in HCC+LX2 xenografts. Mechanistically, CM-272 inhibited the metabolic adaptation of HCC cells to hypoxia and induced a differentiated phenotype in HCC and fibrogenic cells. The expression of the metabolic tumor suppressor gene fructose-1,6-bisphosphatase (FBP1), epigenetically repressed in HCC, was restored by CM-272. Conclusion: Combined targeting of G9a/DNMT1 with compounds such as CM-272 is a promising strategy for HCC treatment. Our findings also underscore the potential of differentiation therapy in HCC.

Next-generation sequencing has substantially improved our understanding of the genomic landscape of multiple myeloma; however, the application of this technology has been confined mostly to research studies. Here, we report on a customized panel to characterize the mutational profile of 79 newly diagnosed patients with multiple myeloma, older than 65 years and who were not transplant candidates, applying the highest read depth to date that has been used for equivalent studies in multiple myeloma. Overall, we identified 53 genes mutated in 85% of patients, including KRAS, NRAS, BRAF, DIS3 and TP53, and found a complex subclonal structure. In addition, the total number of mutations, as well as mutations in TP53 and the Cereblon pathway, were negatively associated with survival. The latter result is particularly noteworthy as patients enrolled in this phase II clinical trial were treated with lenalidomide, which targets this pathway. Our next-generation sequencing strategy not only identified a group of patients with poor outcome, but also provided an extensive genetic profile that should prove useful in the search for new biomarkers and therapeutic targets in multiple myeloma, at an affordable price and with a small amount of sample, which are indispensable features for translating personalized medicine protocols to clinical practice.

The combination of defined factors with small molecules targeting epigenetic factors is a strategy that has been shown to enhance optimal derivation of iPSCs and could be used for disease modelling, high throughput screenings and/or regenerative medicine applications. In this study, we showed that a new first-in-class reversible dual G9a/DNMT1 inhibitor compound (CM272) improves the efficiency of human cell reprogramming and iPSC generation from primary cells of healthy donors and patient samples, using both integrative and non-integrative methods. Moreover, CM272 facilitates the generation of human iPSC with only two factors allowing the removal of the most potent oncogenic factor cMYC. Furthermore, we demonstrated that mechanistically, treatment with CM272 induces heterochromatin relaxation, facilitates the engagement of OCT4 and SOX2 transcription factors to OSKM refractory binding regions that are required for iPSC establishment, and enhances mesenchymal to epithelial transition during the early phase of cell reprogramming. Thus, the use of this new G9a/DNMT reversible dual inhibitor compound may represent an interesting alternative for improving cell reprogramming and human iPSC derivation for many different applications while providing interesting insights into reprogramming mechanisms.

Analyzing the DNA methylome of multiple myeloma (MM), a plasma cell neoplasm, by whole-genome bisulfite sequencing and high-density arrays, we observed regional DNA hypermethylation embedded in extensive global hypomethylation. In contrast to the widely reported DNA hypermethylation of promoter-associated CpG islands (CGIs) in cancer, hypermethylated sites in MM as compared to normal plasma cells were located outside CpG islands and were unexpectedly associated with intronic enhancer regions active in normal B cells. Both RNA-seq and in vitro reporter assays indicated that enhancer hypermethylation is globally associated with downregulation of its host genes. ChIP-seq and DNAseI-seq further revealed that DNA hypermethylation in these regions was related to enhancer decommissioning. Hypermethylated enhancer regions overlap with binding sites of B-cell specific transcription factors (TFs) and the degree of enhancer methylation inversely correlated with expression levels of these TFs in MM. Furthermore, hypermethylated regions in MM were methylated in stem cells and gradually became demethylated during normal B-cell differentiation suggesting that MM cells reacquire epigenetic features of undifferentiated cells upon loss of expression of B-cell specific TFs. Overall, we have identified DNA hypermethylation of developmentally-regulated enhancers as a new type of epigenetic modification associated with the pathogenesis of MM. Disclosures No relevant conflicts of interest to declare.

The identification of therapeutic strategies exploiting the metabolic alterations of malignant cells is a relevant area in cancer research. Here, we discuss a novel computational method, based on the COBRA (COnstraint-Based Reconstruction and Analysis) framework for metabolic networks, to perform this task. Current and future steps are presented.

Synthetic lethality is a promising concept in cancer research, potentially opening new possibilities for the development of more effective and selective treatments. Here, we present a computational method to predict and exploit synthetic lethality in cancer metabolism. Our approach relies on the concept of genetic minimal cut sets and gene expression data, demonstrating a superior performance to previous approaches predicting metabolic vulnerabilities in cancer. Our genetic minimal cut set computational framework is applied to evaluate the lethality of ribonucleotide reductase catalytic subunit M1 (RRM1) inhibition in multiple myeloma. We present a computational and experimental study of the effect of RRM1 inhibition in four multiple myeloma cell lines. In addition, using publicly available genome-scale loss-of-function screens, a possible mechanism by which the inhibition of RRM1 is effective in cancer is established. Overall, our approach shows promising results and lays the foundation to build a novel family of algorithms to target metabolism in cancer., Exploiting synthetic lethality is a promising approach for cancer therapy. Here, the authors present an approach to identifying such interactions by finding genetic minimal cut sets (gMCSs) that block cancer proliferation, and apply it to study the lethality of RRM1 inhibition in multiple myeloma.

Epigenetic drug discovery is an emerging strategy for the treatment of cancer and other pathologies. Here, we discuss our recent discovery of first-in-class dual reversible inhibitors of the histone methyltransferase activity of G9a/EHMT2 and DNA methyltransferases showing in vivo efficacy in human tumors. Current and future investigation lines are presented.

The indisputable role of epigenetics in cancer and the fact that epigenetic alterations can be reversed have favoured development of epigenetic drugs. In this study, we design and synthesize potent novel, selective and reversible chemical probes that simultaneously inhibit the G9a and DNMTs methyltransferase activity. In vitro treatment of haematological neoplasia (acute myeloid leukaemia-AML, acute lymphoblastic leukaemia-ALL and diffuse large B-cell lymphoma-DLBCL) with the lead compound CM-272, inhibits cell proliferation and promotes apoptosis, inducing interferon-stimulated genes and immunogenic cell death. CM-272 significantly prolongs survival of AML, ALL and DLBCL xenogeneic models. Our results represent the discovery of first-in-class dual inhibitors of G9a/DNMTs and establish this chemical series as a promising therapeutic tool for unmet needs in haematological tumours., Epigenetic drugs are emerging as a powerful therapeutic option for cancer treatment. Here, the authors synthesized selective chemical probes that simultaneously inhibit the G9a and DNMTs methyltransferase activity and demonstrate their anti-tumour activity using in vitro and in vivo models of haematological neoplasia.

Although the BCL6 transcriptional repressor is frequently expressed in human follicular lymphomas (FL), its biological role in this disease remains unknown. Herein, we comprehensively identify the set of gene promoters directly targeted by BCL6 in primary human FLs. We noted that BCL6 binds and represses NOTCH2 and NOTCH pathway genes. Moreover, BCL6 and NOTCH2 pathway gene expression is inversely correlated in FL. Notably, BCL6 upregulation is associated with repression of NOTCH2 and its target genes in primary human and murine germinal center (GC) cells. Repression of NOTCH2 is an essential function of BCL6 in FL and GC B cells because inducible expression of Notch2 abrogated GC formation in mice and killed FL cells. Indeed, BCL6-targeting compounds or gene silencing leads to the induction of NOTCH2 activity and compromises survival of FL cells, whereas NOTCH2 depletion or pathway antagonists rescue FL cells from such effects. Moreover, BCL6 inhibitors induced NOTCH2 expression and suppressed growth of human FL xenografts in vivo and primary human FL specimens ex vivo. These studies suggest that established FLs are thus dependent on BCL6 through its suppression of NOTCH2. Significance: We show that human FLs are dependent on BCL6, and primary human FLs can be killed using specific BCL6 inhibitors. Integrative genomics and functional studies of BCL6 in primary FL cells point toward a novel mechanism whereby BCL6 repression of NOTCH2 drives the survival and growth of FL cells as well as GC B cells, which are the FL cell of origin. Cancer Discov; 7(5); 506–21. ©2017 AACR. This article is highlighted in the In This Issue feature, p. 443

Long Non-Coding RNAs (lncRNAs) are functional RNAs longer than 200 nucleotides in length. Several lncRNAs are involved in cell proliferation and are deregulated in several human tumors. Few lncRNAs have been described to play a role in Acute Lymphoblastic Leukemia (ALL). In this study, we carried out a genome wide lncRNA expression profiling in ALL samples and peripheral blood samples obtained from healthy donors. We detected 43 lncRNAs that were aberrantly expressed in ALL. Interestingly, among them, linc-PINT showed a significant downregulation in T and B-ALL. Re-expression of linc-PINT in ALL cells induced inhibition of leukemic cell growth that was associated with apoptosis induction and cell cycle arrest in G2/M phase. linc-PINT induced the transcription of HMOX1 which reduced the viability of ALL cells. Intriguingly, we observed that treatment with anti-tumoral epigenetic drugs like LBH-589 (Panobinostat) and Curcumin induced the expression of linc-PINT and HMOX1 in ALL. These results indicate that the downregulation of linc-PINT plays a relevant role in the pathogenesis of ALL, and linc-PINT re-expression may be one of the mechanisms exerted by epigenetic drugs to reduce cell proliferation in ALL.

MM patients are living longer with increasingly effective therapies, but long-term complications including second primary malignancies (SPMs) are becoming new challenges in designing optimal patient care. It has been demonstrated in large studies that amongst others, risk is particularly high for SPMs such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Importantly, such increased risk of MDS/AML has also been observed in MGUS patients, suggesting that increased risk for MDS/AML may not only be treatment related but inheritably high in MGUS/MM. Thus, there is need to investigate for biomarkers that uncover cellular alterations predisposing for higher risk of MDS/AML in MM. Here, we started by investigating in 312 newly diagnosed MM patients the presence of MDS-like phenotypic abnormalities (MDS-PA) in bone marrow (BM) neutrophil, monocytic, and erythroid lineages, using multidimensional flow cytometry 8 color combinations (CD138, CD27, CD38, CD56, CD45, CD19, CD117, CD81; and HLADR, CD45, CD36, CD13, CD34, CD117, CD11b, CD71). Up to 33/312 (11%) patients showed MDS-PA at diagnosis, which were more frequently observed in the neutrophil lineage (6%), followed by monocytic (4%) and erythroid (4%) lineages. Four cases had multilineage MDS-PA. Afterwards, we investigated if the presence of MDS-PA was associated with underlying somatic mutations by performing targeted sequencing of 54 MDS/AML related genes (depth ≥500x) in 44 patients from the previous series (10 with MDS-PA and 34 without). Next generation sequencing was performed, at diagnosis and after HDT/ASCT in FACS sorted CD34+ hematopoietic stem cells (HSCs) and dysplastic cell lineages from patients with MDS-PA, as well as in HSC from cases without MDS-PA. CD138+ BM plasma cells (PCs) from both cohorts were also sequenced using the same panel. Six out of the 10 cases with MDS-PA showed somatic mutations. Namely, HSCs from one patient had two mutations in TET2 [allele fraction (AF): 18%, ≥ 26017x] one in CALR (AF: 14%, 1158x) and another in ASXL1 (AF: 7%, 1339x). None of these mutations were present in myeloid/erythroid cells. A second patient had NPM1 mutated in HSCs (AF: 7%, 12825x), which was absent in neutrophils. A third case had TET2 mutated in HSCs (AF: 16%, 1233x) as well as in dysplastic monocytes (AF: 27%, 16647x) and neutrophils (AF: 23%, 21719x). In the fourth case, a mutation in BCORL1 was noted in dysplastic erythroid cells (AF: 10%, 796x). The fifth patient had TET2 mutated in both HSCs and dysplastic monocytes (AF: 45%-63%; ≥21799x). The sixth case had PHF6 mutated in HSCs (AF: 8%; 800x). In none of the patients were the mutations found in HSCs and/or dysplastic lineages, present in PCs. Within the control cohort of the 34 patients without MDS-PA, only two of them displayed somatic mutations in HSCs; one case had DNMT3A mutated (AF: 26%, 1900x) and the other TET2 (AF: 13%, 3400x). After demonstrating a correlation between MDS-PA and MDS/AML-related somatic mutations, we sought to analyze the prognostic significance of such alterations in MM. Since the follow-up of the present series of 312 cases is relatively short, we focused on a large series of 965 patients with longer follow up (median of 6.5 years) enrolled in GEM clinical trials, and for which the presence of CD56+ aberrant monocytes could be readily investigated. Noteworthy, this particular MDS-PA was again observed in a similar frequency as noted above (n=63; 6.5%) and as compared to the overall MM population, patients with MDS-PA showed significantly higher age, lower hemoglobin values and higher BMPC infiltration at diagnosis. Furthermore, they experienced more frequently hematological toxicity including anemia and neutropenia during treatment. Most interestingly, as compared to the overall MM population, patients with MDS-PA had significantly inferior progression-free (medians of 24 vs 37 months; P=.006) and overall survival (medians of 47 vs 73 months; P=.01). In conclusion, we showed for the first time that a fraction of newly diagnosed MM patients harbors MDS/AML-related somatic mutations in HSCs and myeloid/erythroid lineages, and that such patients could be predicted through flow-based screening for MDS-PA. The presence of MDS-PA identifies a subset of patients that experience more frequently hematological toxicity and display inferior survival; accordingly, screening for MDS-PA could become an important biomarker to tailor treatment in MM. Disclosures Paiva:Celgene: Honoraria, Research Funding; Janssen: Honoraria; Takeda: Honoraria, Research Funding; Sanofi: Consultancy, Research Funding; EngMab: Research Funding; Amgen: Honoraria; Binding Site: Research Funding. Oriol:Amgen: Honoraria, Other: Expert board committee; Janssen: Honoraria, Other: Expert board committee. Mateos:Amgen: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Janssen: Honoraria.

Somatic mutations in CREBBP occur frequently in B-cell lymphoma. Here, we show that loss of CREBBP facilitates the development of germinal center (GC)–derived lymphomas in mice. In both human and murine lymphomas, CREBBP loss-of-function resulted in focal depletion of enhancer H3K27 acetylation and aberrant transcriptional silencing of genes that regulate B-cell signaling and immune responses, including class II MHC. Mechanistically, CREBBP-regulated enhancers are counter-regulated by the BCL6 transcriptional repressor in a complex with SMRT and HDAC3, which we found to bind extensively to MHC class II loci. HDAC3 loss-of-function rescued repression of these enhancers and corresponding genes, including MHC class II, and more profoundly suppressed CREBBP-mutant lymphomas in vitro and in vivo. Hence, CREBBP loss-of-function contributes to lymphomagenesis by enabling unopposed suppression of enhancers by BCL6/SMRT/HDAC3 complexes, suggesting HDAC3-targeted therapy as a precision approach for CREBBP-mutant lymphomas. Significance: Our findings establish the tumor suppressor function of CREBBP in GC lymphomas in which CREBBP mutations disable acetylation and result in unopposed deacetylation by BCL6/SMRT/HDAC3 complexes at enhancers of B-cell signaling and immune response genes. Hence, inhibition of HDAC3 can restore the enhancer histone acetylation and may serve as a targeted therapy for CREBBP-mutant lymphomas. Cancer Discov; 7(1); 38–53. ©2016 AACR. See related commentary by Höpken, p. 14. This article is highlighted in the In This Issue feature, p. 1

Background: Genetic characterization is becoming relevant to predict risk of progression in smoldering MM and is fundamental to estimate survival in active MM. Thus, patients undergo multiple bone marrow (BM) aspirates for genetic screening that beyond painful, may not be fully representative due to patchy BM involvement, spatial genomic heterogeneity, or extramedullary disease. Accordingly, cell-free DNA has been investigated and showed high concordance with BM aspirates, but information is typically restricted to a few recurrent mutations since comprehensive genetic characterization (eg. whole-exome sequencing, WES) is applicable to Aim: To compare the genetic landscape of CTCs vs matched BM clonal plasma cells (PCs) and extramedullary (EM) plasmacytomas, and validate standardized assays for CTCs' detection, isolation and genetic characterization. Methods: We used EuroFlow next-generation flow (NGF) cytometry to detect and isolate peripheral blood (PB) CTCs and matched BM clonal PCs from 38 MM patients (25 at diagnosis and 13 at relapse). In 8 cases, clonal PCs from EM plasmacytomas were also FACSorted. PB T cells were always used as matched germline control. In the training set, we performed custom WES (preceded by triplicates of whole-genome amplification) in matched CTCs, BM and EM clonal PCs from the 8 patients with all three spatially distributed clones. Only those mutations present in 2/3 libraries analyzed per sample were considered positive. In the validation set, we compared mutations, copy number alterations (CNA) and translocations present in CTCs and BM clonal PCs using the Chromium Exome Solution for low DNA-input (n=8), and solely CNA using the Affymetrix CytoScan HD platform (n=22). Read mapping, variant and structural calling were performed with the Multisample Exome (Dreamgenics) and LongRanger (10XGenomics) pipelines. The Chromosome Analysis Suite software (Affymetrix) was used to analyze CNA. Only those mutations with ≥10% variant allele frequency (VAF) and CNA larger than 1Mb were considered. Results: In the training set, 193/226 (85%) and 231/269 (86%) of total mutations present in BM and EM clonal PCs, respectively, were detectable on CTCs. All MM recurrent mutations (eg. BRAF) found in BM or EM clonal PCs were present in CTCs. Of note, there were 39 mutations in EM plasmacytomas that were detectable in CTCs but absent in BM clonal PCs. Furthermore, up to 50 mutations were present in CTCs while undetectable in BM clonal PCs (n=44) or EM plasmacytomas (n=6). After showing that CTCs harbor most mutations present in both medullary and extramedullary disease and even unveil mutations undetectable in single BM aspirates or individual EM plasmacytomas, we sought to evaluate the performance of standardized assays suitable to screen mutations and/or CNA from low cell numbers (ie. CTCs). Using 10XGenomics, 250/266 (94%) of total mutations and 17/17 (100%) of MM recurrent mutations present in BM clonal PCs were detectable on CTCs (eg. KRAS, BRAF, TP53 or FAM46C). The VAF of private mutations ranged between 0.1 and 0.3, suggesting these were subclonal in their respective spatial regions. Using 10XGenomics, 101/119 (85%) CNA and 2/2 (100%) IgH Tx present in BM clonal PCs were detectable in CTCs. Using the Cytoscan HD, there was 100% concordance between CNA in CTCs and BM clonal PCs, both at the chromosomal arm and interstitial levels. All mutations in TP53 were detectable in CTCs. Furthermore, +1q, del(1p), del(17p) or t(4;14) were always detected in CTCs whenever present in BM clonal PCs, and confirmed by FISH. Conversely, such comprehensive genetic characterization unveiled innumerous CNA and translocations not tested by routine FISH panels [eg. MYC amplification or t(6;14)]. Conclusions: Using two different standardized methods, we showed in the largest series in which CTCs were genetically characterized, that these are a reliable surrogate of MM patients' genetic landscape inside and outside the BM. Because NGF is broadly used, quantification, isolation and genetic characterization of CTCs may emerge as an optimal and standardized approach for non-invasive risk-stratification of MM patients. Disclosures Rios: Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria. Paiva:Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche and Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene, Janssen, Sanofi and Takeda: Consultancy.

Multiple myeloma (MM) is a hematological malignancy characterized by an abnormal accumulation of clonal plasma cells in the bone marrow. MM heterogeneity is associated to the presence of different genomic and transcriptomic profiles that have a clear impact on the prognosis of the disease. Metabolism has been deeply studied in cancer research, unveiling several vulnerabilities in different tumors. However, information regarding the role of metabolism in the pathogenesis of MM has not been explored in detail. Previous studies from our group using Systems Biology approach, explained the essentiality of metabolic gene RRM1 in several MM cell lines. The aim of our current study was to identify metabolic vulnerabilities in MM based on the application of a system biology approach focus on metabolic networks and trascriptomic data from MM patients. Our hypothesis being that changes in the metabolic landscape of MM could be exploited to uncover novel targets for prognosis and treatment in MM patients. We have analyzed the strand specific RNA-seq data from 35 samples from different subpopulations of B cells (Naïve, Centroblast, Centrocyte, Memory, Tonsilar and Bone Marrow Plasma cells (PCs)) and PCs of 37 MM patient samples. Using only the expression of 3287 metabolic genes included in Recon3D, the latest human metabolic reconstruction, we identified metabolic transcription patterns that clearly differentiate the different B cells from MM plasma cells (Figure 1A). MM samples were more similar to the normal PCs than to other B cells, which suggest that they maintain part of the metabolic pattern of the PCs, but in turn showed significant differences in the expression of metabolic genes. Interestingly, differential expression analysis of metabolic genes in MM PCs revealed a decrease in the expression of genes involved in mitochondrial activity and an increase in those that participate in metabolic proliferation, indicating that these alterations could probably play an important role in the development of this tumor. Using our novel systems biology approach, based on Recon3D and transcriptomic profiles, we predicted essential genes and synthetic lethals (involving two or more genes) that were specific for MM patients and not for the rest of the B cell subpopulations. Our approach makes use of the concept of genetic Minimal Cut Sets, previously introduced by our group in cancer research, which defines subsets of genes that if knocked out at the same time, induce a blockage of cellular proliferation. A metabolic vulnerability is found when only one gene is highly expressed in one of these gMCSs. We also analyzed the essentiality of these genes in more than 500 MM patients samples included in CoMMpass project and MM cell lines analyzed in Cancer Cell Line encyclopedia (CCLE). Using this computational strategy, we detected 8 essential genes involved in 42 gMCS specific for MM patients. From those candidates, GNPAT was our most promising target gene, as it was predicted to be essential for more than 40% of MM patients in our group, approximately 10% of patients of CoMMpass and in the majority of MM cell lines (Figure 1B). Validation of GNPAT expression and other 18 genes involved in the GNPAT gMCS was carried out by RT-qPCR showing similar results that were obtained with our RNA-seq data. Interestingly, the expression of the partner genes included in the GNPAT gMCS, such as DGK gene family, could also be indicators of the effectiveness of knocking-out, where their high expression is an indicator of resistance and their low expression an indicator of sensitivity. In conclusion, our findings suggest that our systems biology computational approach, driven by RNA-seq data, identifies metabolic vulnerabilities (defined as essential genes or synthetic lethal genes) providing pairs of new targets (essential gene) and their associated biomarkers (gMCS) in patients with MM. Figure 1: Metabolic genes expression analysis in human humoral immune response and MM patient samples. A) Standardized PCA result using the expression of metabolic genes included in Recon3D, in distinct subpopulations of B cells and MM samples. B) GNPAT gMCS showing the expression (in TPM) of GNPAT and associated 18 genes in MM cell lines. Figure 1 Disclosures Paiva: Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche, and Sanofi; unrestricted grants from Celgene, EngMab, Sanofi, and Takeda; and consultancy for Celgene, Janssen, and Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau. Melnick:Epizyme: Consultancy; KDAc Therapeutics: Membership on an entity's Board of Directors or advisory committees; Constellation Pharmaceuticals: Consultancy; Janssenn: Research Funding. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria.

Deregulation of long non-coding RNAs (lncRNAs) is emerging as a common feature of different human tumors and their investigation may uncover novel biomarkers and oncogenic mechanisms. Previous studies have suggested that the alteration of some lncRNAs may play an important role in the pathogenesis of multiple myeloma (MM); however, the complete expression landscape of lncRNAs has not been elucidated. In the present work we characterized the lncRNAs transcriptome of MM and determined the potential involvement of lncRNAs in the pathogenesis and clinical behavior of MM. To characterize the MM transcriptome, we performed paired-end strand-specific RNA sequencing (ssRNA-seq) in 38 purified plasma cell (PC) samples from MM patients and in 3 bone marrow PCs (BMPCs) of healthy donors, as well as in distinct normal B-cell populations (Naïve, Centroblasts, Centrocytes, Memory and Tonsilar PCs). We identified 40,511 novel lncRNAs that were expressed, accounting for more than half of MM transcriptome (56%). This group of novel lncRNAs together with previously annotated lncRNAs comprised most (82%) of the MM transcriptome. We studied the transcriptional heterogeneity in MM samples and observed that lncRNAs showed a much more heterogeneous expression than coding genes, suggesting that these elements could contribute to the biological heterogeneity of the disease. Moreover, to determine differentially expressed genes, each MM patient was compared to normal BMPCs, detecting 19,886 lncRNAs deregulated (10,351 overexpressed and 9,535 downregulated) in more than 50% of patients. We then analyzed the transcriptional dynamics of MM considering the different stages of B-cell differentiation and focused on a group of 989 lncRNAs that were upregulated specifically in plasma cells from MM in comparison with the rest of B-cell stages (MM-specific lncRNAs). Next, we aimed to determine whether upregulation of MM-specific lncRNAs in MM was under epigenetic control so we analyzed the distribution of six histone modifications with non-overlapping functions (H3K4me3, H3K4me1, H3K27ac, H3K36me3, H3K27me3, and H3K9me3) of within the lncRNAs of interest by ChIP-seq in MM cases as compared to normal B cell subtypes. We detected 89 lncRNAs with de novo epigenomic activation. These data suggest an epigenetic rewiring in MM where the loci of most MM-specific lncRNAs are in an inactive state in normal cells and become active in MM. We focused on a specific lncRNA, LINC-SMILO, de novo epigenetically active and expressed in MM cells to determine whether upregulation of this lncRNA could play a role in the pathogenesis of the disease. Knockdown of LINC-SMILO in 3 different MM cell lines (MM.1S, MM.1R and KMS-11) using two different shRNAs, resulted in reduced proliferation and induction of apoptosis of myeloma cells. Using low input RNA-seq (MARS-seq), we found that inhibition of LINC-SMILO was associated with activation of ERVs (Endogenous retroviruses) and increase in interferon (IFN) induced genes and activation of IFN pathways, essential for MM cells survival. Finally, we aimed to determine whether the use of specific lncRNAs could improve the current prognostic stratification of MM patients using the IA11 release of CoMMpass data. We analyzed the prognostic value of lncRNAs using COX regression analysis and Backward elimination of Stepwise regression analysis, obtaining that the overexpression of the lncRNA PDLIM1P4 together with 1q amplification and 17p deletion stratified MM patients in three different risk groups (Figure 1). In summary, our study shows that the lncRNA transcriptome is widely altered in MM and suggests that some of the identified lncRNAs have marked prognostic influence and can be used as potential therapeutic targets for MM. Disclosures Paiva: Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche, and Sanofi; unrestricted grants from Celgene, EngMab, Sanofi, and Takeda; and consultancy for Celgene, Janssen, and Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria. Melnick:KDAc Therapeutics: Membership on an entity's Board of Directors or advisory committees; Constellation Pharmaceuticals: Consultancy; Epizyme: Consultancy; Janssenn: Research Funding.

Deregulation of long non-coding RNAs (lncRNAs) is a common feature of cancer, including Multiple Myeloma (MM). In our previous studies, we detected 11,495 and 40,511 previously non-annotated lncRNAs during normal humoral immune response and MM patient samples, respectively. These results support an important role for the lncRNAs transcriptome in this hematological malignancy. lncRNAs are genes that differ from coding genes in that they do not give rise to a protein. Nevertheless, lncRNA could undergo the same genetic alterations as coding genes. In this study, we hypothesize that lncRNAs can be involved in the principal genetic alterations occurring in MM such as chromosomal translocations, affecting the Immunoglobulin loci (IG) and in the majority of which the fusion partner still remains unknown. In order to unveil the role of lncRNAs in fusion transcripts occurring in MM, we analyzed the strand specific RNA-seq (ssRNA-seq) data obtained from 35 samples from different subpopulations of B cells (Naïve, Centroblast, Centrocyte, Memory and Plasma cells (PCs)), purified PCs from 32 MM patients and 3 MM cell lines. Chimeric transcripts were detected with the STAR-Fusion software, identifying 1,347 novel fusion transcripts ranging from 1 to 142 chimeric transcripts per sample. Strikingly, healthy PC samples (from tonsils and bone marrow) yielded the highest number of fusion transcripts, while other B cell subpopulations showed overall low numbers and MM samples turned out highly variable. 96% of all fusion transcripts detected in healthy PCs occurred with IG genes and harbored few reads per transcript, suggesting that the hyperactive transcription of the IG loci in PCs may be the cause for their formation and are probably not involved in the pathogenesis of the disease. We also found that HLA fusion transcripts were abundant in Naïve B cells, disappearing progressively during the humoral immune response (Figure 1). Interestingly, fusion transcripts identified in different B cell subpopulations were not detected in MM samples. Next, we focus on myeloma samples and identified 362 chimeric transcripts (312 unique) expressed specifically in MM (ranging from 2 to 24 chimeric transcripts per sample), most of them (84%) identified for the first time. 69% of these transcripts partnered with the IG genes, while the other fusions involved two non-IG genes. Interestingly, as we hypothesized, 26,5% of the chimeric transcripts in MM occurred with lncRNA as a partner, increasing the relevance of lncRNAs in this disease. Furthermore, using the read distribution per chimeric transcript, we identified a prevalent reciprocal transcript or a prevalent transcript expressed with >1 FFPM in 47% of MM samples, suggesting that they could derived from underlying genomic rearrangements. Besides these prevalent transcripts, we observed that 40% of the non-IG fusion transcripts occurred between adjacent genes, defining novel MM-transcriptional read-throughs, possibly caused by the oncogenic stress suffered by MM cells. Some of these chimeric transcripts were validated in different cell lines of MM by conventional PCR and sequencing. In summary, our findings show that ssRNA-seq data is an adequate strategy for the detection of chimeric transcripts in MM, being able to detect highly expressed chimeric transcripts that probably were derived from an underlying genomic rearrangements and also new categories of chimeric transcripts. In addition, our study reveals a complex landscape of fusion transcripts in the MM, many of them including a lncRNA, which could be potential therapeutic targets for the development of new treatment strategies for MM. Disclosures Paiva: Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche, and Sanofi; unrestricted grants from Celgene, EngMab, Sanofi, and Takeda; and consultancy for Celgene, Janssen, and Sanofi: Consultancy, Honoraria, Research Funding, Speakers Bureau. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria.

Acute myeloid leukemia (AML) is a hematologic neoplasm characterized by a remarkable phenotypic and genomic heterogeneity. The recent characterization of genomic subtypes of AML based on large sequencing studies has provided the rationale for the development of targeted therapies based on the presence of specific genomic abnormalities. However, long term survival particularly in older patients remains a unmet medicalneed. Additionally, recent studies using RNA interference (RNAi) libraries have determined the existence of genes that are essential for the survival of multiple cancer cells. Understanding the effect of genomic alterations (mutations, deletions, translocations) on gene essentiality could favor the development of targeted therapies for specific subgroups of AML patients. However, current statistical methods such as the Benjamini-Hochberg (BH) procedure have shown limitations for controlling the false discovery rate (FDR) and have suboptimal sensitivity (recall of true positives) because the P-value correction does not include any prior information of individual tests. For this reason, in this study we developed a new large-scale statistical algorithm, which combine the RNAi libraries (more than 17.000 genes) data with mutational profiles, to identify gene essentialities associated with specific genomic mutations in order to explore this approach in AML. We adapted the Independent Hypothesis Weighting (IHW) procedure to the problem of identifying mutations as surrogate markers of gene essentiality, by using the gene mutation state in each cell line as prior information of a IHW problem. This approach was tested in 19 tumor subtypes, of the Cancer Cell Line Encyclopedia (CCLE) showing that it recalls new discoveries that cannot be identified with standard procedures in 17 out of 19 tumors, including the identification of up to 1,000 discoveries in tumor types in which BH recalls no discovery. These results demonstrated the accuracy of the IHW-based approach to identify gene mutations as surrogate markers of gene essentiality in the future. Once validated, we applied this computational model to the15 AMLcell lines of CCLE. The number of discoveries with an FDR of 20% increases from 2 (using the traditional BH correction), to 38 using our procedure, showing NRAS as the top mutation biomarker in the ranking. Interestingly, the algorithm identified one essential gene (NRAS) for NRAS mutated (NRAS-mut) and another essential gene (PTPN11) for NRAS wild type (NRAS-wt) AML cells, covering all samples of AMLs. To validate this hypothesis, we examined the effect of two different specific siRNAs for each gene (siPTPN11 and siNRAS) on cell proliferation of four AML cell lines: two lines with NRAS-mut (HL-60 and OCIAML3) and two with NRAS-wt (MV4-11 and HEL). Downregulation of NRAS expression significantly decreases the cell proliferation only in the 2 NRAS-mutated AML cell lines. Whereas the inhibition of PTPN11expression produced an equivalent effect, but specifically in the 2 NRAS-wt AML cell lines (Figure 1). These results confirmed our predictions and showed the essential role of NRAS or PTNPN11 in AML cell lines either with NRAS mutated or wild type, respectively. These results demonstrate that the application of our algorithm in the context of specific gene mutation not only may allow identification of directed therapies based on the mutation but can also define new gene essentialities amenable for targeted therapies providing new therapeutic strategies in patients with AML and potentially in other tumors. Disclosures Paiva: Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche and Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene, Janssen, Sanofi and Takeda: Consultancy. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria.

Acute myeloid leukemia (AML) is a malignant disease characterized by uncontrolled proliferation, differentiation arrest and accumulation of immature myeloid progenitors. Despite recent developments and the approval of new therapeutic agents in the last few years, long term survival of AML, particularly in elderly patients remains an unmet medical need.The use of all-trans retinoic acid (ATRA) in Acute Promyelocytic Leukemia has proven that differentiation therapy may significantly change the survival of AML patients, however the success in APL has not been translated to other groups of AML. Therefore, the identification of new therapeutic agents that may induce the differentiation of AML blasts represents an attractive new target. Furthermore, it is well known that epigenetic alterations have an important role in the development and maintenance of cancer and AML in particular. Thus, our aim was to develop new small molecules targeting epigenetic modifying enzymes like DNA methyltransferases (DNMT), histone methyltransferases or histone deacetylase (HDAC) with the aim of inducing differentiation in AML. We performed a screening of over 50 small molecules synthesized by our group. The design was performed in-house using a knowledge and structure based strategy and the read out of the screening was based on changes in expression of CD11b (a well described marker of myeloid differentiation) after in vitro treatment of AML cells lines. Interestingly, we found several compounds with high capacity to promote the differentiation of leukemic cells in AML cells lines at low non-cytotoxic doses, selecting CM-444 and CM-1758 as our lead compounds (Figure 1a).A complete biochemical characterization showed that both compounds are specific pan-HDACs inhibitors (HDACi). CM-444 and CM-1758 induced in vitro cell differentiation in all subtypes of AML, independently of the AML genetic subgroups or the presence of mutations, which was significantly more pronounced that differentiation induced by reference compounds such as Panobinostat, Vorinostat, Entinostat, Tubastatin or Quisinostat, previously described HDACi. CM-444 and CM-1758 also induced in vivo differentiation in xenogeneic models of AML. AML differentiation was associated with induction of CD11b, downregulation of c-MYC, overexpression of transcription factors that govern the myeloid differentiation and morphologic changes. In addition, these compounds promoted in vitro differentiation of patient-derived AML blasts. The complete transcriptome analysis by RNA-Seq carried out in AML cell lines after CM-444, CM-1758, Panobinostat or Vorinostat treatment showed changes in genes implicated in differentiation, but without explaining the differences among the different HDACi. Analysis of the complete acetylome and proteome before and after treatment with CM-444 and CM-1758 in comparison with other HDACi showed differential acetylation of non-histone proteins included in the GO categories of Zn binding proteins and nucleic acid binding proteins (Figure 1b). Most of these proteins are epigenetic enzymes and have been related to AML and myeloid differentiation, such as MLL2, EP300 or BRD4. In summary, we have developed and characterized novel epigenetic small molecules with a high in vitro and in vivo capacity of differentiating AML cells. These compounds might be an effective differentiation-based therapy to be tested in AML. Besides, the mechanism of differentiation of these compounds is due, at least in part, to the acetylation of non-histone epigenetic proteins, which are key in the myeloid differentiation. Disclosures Paiva: Celgene, Janssen, Sanofi and Takeda: Consultancy; Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, Novartis, Roche and Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria.

Multiple myeloma (MM) is a plasma cell neoplasm associated with a broad variety of genetic lesions. In spite of this genetic heterogeneity, MMs share a characteristic malignant phenotype whose underlying molecular basis remains poorly characterized. In the present study, we examined plasma cells from MM using a multi-epigenomics approach and demonstrated that when compared to normal B cells, malignant plasma cells showed an extensive activation of regulatory elements, in part affecting co-regulated adjacent genes. Among target genes upregulated by this process, we found members of the NOTCH, NFkB, mTOR1 signaling and p53 signaling pathways. Other activated genes included sets involved in osteoblast differentiation and response to oxidative stress, all of which have been shown to be associated with the MM phenotype and clinical behavior. We functionally characterized MM specific active distant enhancers controlling the expression of thioredoxin (TXN), a major regulator of cellular redox status, and in addition identified PRDM5 as a novel essential gene for MM. Collectively our data indicates that aberrant chromatin activation is a unifying feature underlying the malignant plasma cell phenotype.

Acute lymphoblastic leukemia (ALL) is a heterogeneous cancer that is characterized by rapid and uncontrolled proliferation of immature B- or T-lymphoid precursors. Although ALL has been regarded as a genetic disease for many years, the crucial importance of epigenetic alterations in leukemogenesis has become increasingly evident. Epigenetic mechanisms, which include DNA methylation and histone modifications, are critical for gene regulation during many key biological processes. Here, we review the cell signaling pathways that are regulated by DNA methylation or histone modifications in ALL. Recent studies have highlighted the fundamental role of these modifications in ALL development, and suggested that future investigation into the specific genes and pathways that are altered by epigenetic mechanisms can contribute to the development of novel drug-based therapies for ALL.

The ASXL1 gene encodes a chromatin-binding protein involved in epigenetic regulation in haematopoietic cells. Loss-of-function ASXL1 mutations occur in patients with a range of myeloid malignancies and are associated with adverse outcome. We have used lentiviral-based shRNA technology to investigate the effects of ASXL1 silencing on cell proliferation, apoptosis, myeloid differentiation and global gene expression in human CD34+ cells differentiated along the myeloid lineage in vitro. ASXL1-deficient cells showed a significant decrease in the generation of CD11b+ and CD15+ cells, implicating impaired granulomonocytic differentiation. Furthermore, colony-forming assays showed a significant increase in the number of multipotent mixed lineage colony-forming unit (CFU-GEMM) colonies and a significant decrease in the numbers of granulocyte-macrophage CFU (CFU-GM) and granulocyte CFU (CFU-G) colonies in ASXL1-deficient cells. Our data suggests that ASXL1 knockdown perturbs human granulomonocytic differentiation. Gene expression profiling identified many deregulated genes in the ASXL1-deficient cells differentiated along the granulomonocytic lineage, and pathway analysis showed that the most significantly deregulated pathway was the LXR/RXR activation pathway. ASXL1 may play a key role in recruiting the polycomb repressor complex 2 (PRC2) to specific loci, and we found over-representation of PRC2 targets among the deregulated genes in ASXL1-deficient cells. These findings shed light on the functional role of ASXL1 in human myeloid differentiation. © 2013 Blackwell Publishing Ltd.

NKX2 homeobox family proteins have a role in cancer development. Here we show that NKX2-3 is overexpressed in tumour cells from a subset of patients with marginal-zone lymphomas, but not with other B-cell malignancies. While Nkx2-3-deficient mice exhibit the absence of marginal-zone B cells, transgenic mice with expression of NKX2-3 in B cells show marginal-zone expansion that leads to the development of tumours, faithfully recapitulating the principal clinical and biological features of human marginal-zone lymphomas. NKX2-3 induces B-cell receptor signalling by phosphorylating Lyn/Syk kinases, which in turn activate multiple integrins (LFA-1, VLA-4), adhesion molecules (ICAM-1, MadCAM-1) and the chemokine receptor CXCR4. These molecules enhance migration, polarization and homing of B cells to splenic and extranodal tissues, eventually driving malignant transformation through triggering NF-κB and PI3K-AKT pathways. This study implicates oncogenic NKX2-3 in lymphomagenesis, and provides a valid experimental mouse model for studying the biology and therapy of human marginal-zone B-cell lymphomas., Instituto de Salud Carlos III (ISCIII), Spanish Ministry of Economy and Competitiveness, FIS-PI12/00202 (to J.A.M.-C.), RTICC-RD12/0036/0063 (to J.A.M-C.), RTICC-RD12/0036/0068 (to M.J.C and F.P.), RTICC-RD12/0036/0022 (to J.L.F-L.), RTICC-RD12/ 0036/0070 (to J.C.), RTICC-RD12/0036/0010 (to B.B.), RTICC- RD12/0036/0044 (to M.J.B.) and RTICC-RD12/0036/0069 (to J.M.H.R. and M.G.); by Worldwide Cancer Research project grant 15-1322 (to J.A.M.-C., Y.R.C. and M.-Q.D.); by BFU2011-30097 (to Y.R.C); by MINECO SAF2013-45787-R and Marie Curie Programme FP7-PIIF-2012-328177 (to S.R.); by the French-Spanish CITTIL project (to F.P., X.A., J.A.M.-C., C.B. and P. Brousset); by SAF2012-32810, SAF2014-57791-REDC; PIE14/00066, BIO/SA32/ 14 and CSI001U14 (to I.S.G); by FIS-ISCIII projects PI13/00160 and PI14/00025, and Fundación Inocente Inocente (to C.C.); by Deutsche Krebshilfe, Molecular Mechanisms in Malignant Lymphomas Network Project (to R.S.); by the Institut Universitaire de France (to P. Brousset); by the Broad Medical Research Program of The Eli and Edythe Broad Foundation and the Hungarian Scientific Research Fund (OTKA K108429) (to P. Balogh)

The notion that plasma cells (PCs) are terminally differentiated has prevented intensive research in multiple myeloma (MM) about their phenotypic plasticity and differentiation. Here, we demonstrated in healthy individuals (n=20) that the CD19-CD81 expression axis identifies three bone marrow (BM)PC subsets with distinct age-prevalence, proliferation, replication-history, immunoglobulin-production, and phenotype, consistent with progressively increased differentiation from CD19+CD81+ into CD19-CD81+ and CD19-CD81- BMPCs. Afterwards, we demonstrated in 225 newly diagnosed MM patients that, comparing to normal BMPC counterparts, 59% had fully differentiated (CD19-CD81-) clones, 38% intermediate-differentiated (CD19-CD81+) and 3% less-differentiated (CD19+CD81+) clones. The latter patients had dismal outcome, and PC differentiation emerged as an independent prognostic marker for progression-free (HR: 1.7; P=0.005) and overall survival (HR: 2.1; P=0.006). Longitudinal comparison of diagnostic vs minimal-residual-disease samples (n=40) unraveled that in 20% of patients, less-differentiated PCs subclones become enriched after therapy-induced pressure. We also revealed that CD81 expression is epigenetically regulated, that less-differentiated clonal PCs retain high expression of genes related to preceding B-cell stages (for example: PAX5), and show distinct mutation profile vs fully differentiated PC clones within individual patients. Together, we shed new light into PC plasticity and demonstrated that MM patients harbouring less-differentiated PCs have dismal survival, which might be related to higher chemoresistant potential plus different molecular and genomic profiles., This study was supported by the Cooperative Research Thematic Network grants RD12/0036/0048, RD12/0036/0058, RD12/0036/0046, RD12/0036/0068, RD12/0036/0069, and RD12/0036/0061 of the Red de Cancer (Cancer Network of Excellence); Instituto de Salud Carlos III, Spain, Instituto de Salud Carlos III/Subdirección General de Investigación Sanitaria (FIS: PI060339; 06/1354; 02/0905; 01/0089/01-02; PS09-/01897/01370; PI13/01469, PI14/01867, G03/136; Sara Borrell: CD13/00340 and CD12/00540); Fundació La Marató de TV3 (20132130-31-32) and Asociación Española Contra el Cáncer (GCB120981SAN). The study was also supported internationally by the International Myeloma Foundation (IMF) Junior Grant, the Black Swan Research Initiative of the IMF, the Multiple Myeloma Research Foundation research fellow award, the Qatar National Research Fund (QNRF) Award No. 7-916-3-237, Marie Curie (LincMHeM-330598), the AACR-Millennium Fellowship in Multiple Myeloma Research (15-40-38-PAIV), Leukemia Research Foundation and the European Research Council (ERC) 2015 Starting Grant.

Apart from microRNAs, little is known about the regulation of expression of non-coding RNAs in cancer. We investigated whether small nucleolar RNAs (snoRNAs) accumulation displayed specific signatures in acute myeloblastic and acute lymphoblastic leukemias. Using microarrays and high-throughput quantitative PCR (qPCR), we demonstrate here that snoRNA expression patterns are negatively altered in leukemic cells compared with controls. Interestingly, a specific signature was found in acute promyelocytic leukemia (APL) with ectopic expression of SNORD112-114 snoRNAs located at the DLK1-DIO3 locus. In vitro experiments carried out on APL blasts demonstrate that transcription of these snoRNAs was lost under all-trans retinoic acid-mediated differentiation and induced by enforced expression of the PML-RARalpha fusion protein in negative leukemic cell lines. Further experiments revealed that the SNORD114-1 (14q(II-1)) variant promoted cell growth through cell cycle modulation; its expression was implicated in the G0/G1 to S phase transition mediated by the Rb/p16 pathways. This study thus reports three important observations: (1) snoRNA regulation is different in normal cells compared with cancer cells; (2) a relationship exists between a chromosomal translocation and expression of snoRNA loci; and (3) snoRNA expression can affect Rb/p16 cell cycle regulation. Taken together, these data strongly suggest that snoRNAs have a role in cancer development.

An ultra high performance liquid chromatography tandem mass spectrometry method (UHPLC-MS/MS) was developed and validated for the quantitation of LBH589, a novel histone deacetylase inhibitor (HDACi), in mouse plasma and tissues (liver, spleen, kidney and lung). Tobramycin was employed as the internal standard. Separation was performed on an Acquity UPLC™ BEH column, with a mobile phase consisting of 10% water (with 0.1% of trifluoroacetic acid) and 90% methanol (with 0.1% trifluoroacetic acid). LBH589 and tobramycin were determined using an electrospray ionization (ESI) interface. Detection was performed on electrospray positive ionization mass spectrometry by multiple reaction monitoring of the transitions of LBH589 at m/z 349.42→157.95 and of tobramycin at 468.2→163. Calibration curves for the UHPLC method (0.0025-1 μg/mL for plasma and tissue homogenates, equivalent to 0.0357-14.2857 μg/g for tissue samples) showed a linear range of detector responses (r>0.998). Intra-batch and inter-batch precision expressed as coefficient of variation (CV) ranged from 0.92 to 8.40%. Accuracy expressed as bias, ranged from -2.41 to 2.62%. The lower limit of quantitation (LLOQ) was 0.0025 μg/mL for both plasma and tissue homogenate samples, equivalent to 0.0357 μg/g tissue. This method was successfully applied to quantify LBH589 in plasma and tissue samples obtained after the intraperitoneal administration of a single dose of 20 mg/kg of LBH589 in BALB/c mice.

Summary The role of epigenetic mechanisms in the regulation of microRNAs (miRNAs) with a tumour-suppressor function in human neoplasms has recently been established. Several miRNAs have been found to be inappropriately regulated by DNA methylation in patients with acute lymphoblastic leukaemia (ALL). We analysed the methylation status of the three members of the MIR9 family (MIR9-1, MIR9-2 and MIR9-3) in a uniformly treated cohort of 200 newly diagnosed ALLs. MIR9 was methylated in 54% of the patients and was associated with downregulation of MIR9 (P

Background. The number of CTC predicts risk of transformation in smoldering MM and survival in active MM. Growing evidence suggests that as the tumor progresses and the microenvironment becomes hypoxic, clonal plasma cells (PC) constantly invade new regions of the bone marrow (BM) through induced systemic recirculation. Of note, the frequency of CTCs is typically low and thus, it is conceivable that the dissemination of MM depends on few tumor cells with unique features that induce them to egress the BM and spread the disease through peripheral blood (PB). This hypothesis has not been yet demonstrated because the transcriptional profile of CTCs in MM has not been investigated. Aim. To identify gene regulatory networks related to MM dissemination by comparing the transcriptional profile of CTCs with patient-matched BM clonal PCs. Methods. We used FACS to isolate CTCs and BM clonal PCs of paired PB and BM samples from 34 patients: 24 newly diagnosed MM, 9 relapsed MM and 1 MGUS. Transcriptomes were analyzed using Affymetrix arrays (n =31) and the BD WTA Precise assay was used for single-cell RNA sequencing (scRNAseq, n =3). Data was analyzed using Gene Set Enrichment Analysis (GSEA) and Limma for bulk and Seurat for scRNAseq data. The prognostic value of deregulated genes (FDR 0.5) was investigated using a Cox-regression model in the CoMMpass dataset (n =553, IA11 release). The role of specific deregulated genes was evaluated by shRNA knockdown and blocking using a monoclonal antibody (mAb). Results. Transcriptomic profiling of patient matched CTCs and BM clonal PCs revealed a high correlation in gene expression (r =0.93; p =10-16). Only 45 genes emerged as significantly deregulated in CTCs, and GSEA unveiled biological functions related to inflammatory and interferon response (e.g. CCL5), signaling by IL-6/JAK/STAT3, IL-2/STAT5 and TNF via NFKB (CD44), the epithelial mesenchymal transition (EMP3), mitotic spindle and G2M checkpoints (TOP2A), or E2F targets (BIRC5). A high correlation in gene expression was also observed by scRNAseq (r =0.9; p =10-16), with only 31 genes (e.g. MALAT1, B2M, RHOH, ENAM or DUSP5) differentially expressed (adj.p Conclusions. This is the first study analyzing the transcriptional profile of CTCs in MM. Our results reveal that gene expression of CTCs is almost identical to that of patient-matched BM clonal PCs, except for a few genes that are involved in interferon and inflammatory response, hypoxia, cell cycle and migration. Importantly, some of these genes are related to more aggressive disease and therefore, may represent novel therapeutic targets to overcome disease dissemination. Figure. Figure. Disclosures Rios: Amgen, Celgene, Janssen, and Takeda: Consultancy. Martinez-Lopez:Pfizer: Research Funding; Vivia: Honoraria; Celgene: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; BMS: Research Funding; Novartis: Research Funding. Hajek:Janssen: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding. San-Miguel:Sanofi: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Amgen: Honoraria; Novartis: Honoraria; BMS: Honoraria; Roche: Honoraria.

El éxito de las investigaciones de crímenes internacionales (genocidio, crímenes de guerra y crímenes de lesa humanidad) depende en gran parte de poder establecer el patrón delictivo. El patrón delictivo es el conjunto de características que tienen en común varios incidentes con relación a las víctimas, los perpetradores y el modus operandi. Las pruebas y los análisis con base en patrones han sido utilizados con éxito principalmente en las investigaciones de masacres, destrucciones y desplazamiento, pero su utilización en imputaciones de violencia sexual ha sido notoriamente más limitada. Es necesario cubrir este vacío por medio del establecimiento de métodos apropiados de recolección y análisis de datos. A nivel de la recolección de pruebas, la carencia de denuncias presentadas por las víctimas se debe suplir por medio de encuestas a las víctimas o por medio del análisisde la información secundaria disponible en diferentes fuentes. A nivel de análisis, la evidencia disponible debe ser evaluada de manera imparcial, independientemente de las ideas preconcebidas de las partes en conflicto y de los grupos de defensa de derechos, cumpliendo con los estándares y métodos científicos para el análisis cuantitativo, cualitativo y de sistemas de información geográfica (GIS). Un análisis de varias experiencias investigativas y de la jurisprudencia permitirá establecer la metodología más apropiada y será la manera más eficiente de ayudar a poner fin a la impunidad relacionada con los crímenes sexuales. Establishing the pattern of crime is fundamental for the successful investigation ofinternational crimes (genocide, war crimes, and crimes against humanity). A patternof crime is the aggregate of multiple incidents that share common features related tothe victims, the perpetrators, and the modus operandi. Pattern evidence and analysishave been used successfully, mainly in the investigation of large-scale killings, destruction,and displacement; the use for sexual violence charges has been remarkablymore limited. There is a need to overcome this gap by setting proper methods of datacollection and analysis. At the level of evidence collection, under-reporting should beaddressed through victimization surveys or secondary analysis of data available fromdifferent sources. At the level of analysis, the available evidence needs to be subject toimpartial examination beyond the pre-conceptions of the conflict parties and advocacygroups, in compliance with scientific standards for quantitative, qualitative, andGIS (Geographic Information Systems)methods. Reviewing the different investigativeexperiences and jurisprudence will help to set the right methodology and contribute mostefficiently to putting an end to the impunity regarding sexual crimes. O presente artigo argumenta que se deve e como se pode trazer à justiça aos perpetradoresda violência sexual no quadro dos conflitos armados como um crime internacionalde transcendência e não como algo que surge como um “by product” deguerra. Este artigo analisa as concepções comuns que obstaculizam a judicializaçãode casos, e explica como documentar os patrões do crime, os enlaces com as organizaçõesarmadas, e a responsabilidade dos responsáveis na liderança do grupo. Todoisto a partir da análise das práticas e achados do cpi e da icty, os artigos acadêmicossobre o tema, e também na experiência própria do autor. Além disso, uma análiseoriginal de como provar responsabilidade para crimes de violência sexual, baseadonos casos internacionais, no qual sairão convicções, mas também na extensão daspráticas de pesquisa e provação de outros crimes internacionais.

To measure a combination of novel molecular biomarkers in urine/blood samples of consecutive patients referring lower urinary tract symptoms (LUTS) not previously diagnosed, to improve prostate cancer diagnosis. Serum and urine samples from 113 men who went consecutively to the Department of Urology of our Institution. Biomarkers analyzed were AMACR and MMP-2 levels, and GSTP1/RASSF1A methylation status, in addition to PSA levels. Sensitivity, specificity, area under the ROC (AUROC) curves, and discriminant function analysis were assessed to determine the diagnostic potential of each variable alone or in combination. Of the patients, 30.08% had PCa and the remaining ones were tumor free. Areas under the ROC (AUROC) curves were as follows: 0.476 for PSA, 0.532 for AMACR, and 0.706 for MMP-2. Sensitivity and specificity for methylation status were 53.3 and 45.9%, respectively. The combination of these biomarkers resulted in an AUROC curve of 0.788, which significantly outperformed AUROC curves for PSA (P = 0.0033) and AMACR (P = 0.0375). Sensitivity, specificity, positive and negative predictive values for the combination of biomarkers were 57.1, 96.6, 88.9, and 82.4%, respectively. We conclude that analysis of this biomarker combination in body fluids improves very significantly the diagnosis of PCa compared to the PSA test.

A majority of B-cell lymphomas, including diffuse large B-cell lymphomas (DLBCLs) and follicular lymphomas (FLs), arise from germinal center (GC) B cells. GC B cells are highly proliferative and manifest genomic instability as a byproduct of immunoglobulin affinity maturation. These characteristics make GC B cells particularly prone to malignant transformation such that DLBCLs and FLs inherit and are dependent on mutations in proteins that are also required for normal GC B cells. For example, the BCL6 transcriptional repressor is required to establish the GC phenotype in both normal B-cell development and GC B-cell malignancy through its effect on silencing expression of plasma cell differentiation and checkpoint genes. GC B cells feature a unique transcriptional program featuring upregulation of genes involved in cell proliferation and other growth pathways. Cell context-specific gene expression is largely mediated through gene enhancers. Hence we hypothesized that transcription factors that activate GC specific gene enhancers would play a critical role in formation of these cells, and would likely be required in turn to maintain the survival of GC-derived lymphoma cells. To address this question we first mapped gene enhancers in primary human resting B cells and purified GC B cells by performing ChIP-seq to map the distribution of H3K27Acetyl, H3K4me1, and H3K4me3. This procedure allowed us to identify several thousand GC-specific enhancers. We next examined these enhancers using bioinformatic approaches to identify transcription factor binding sites and identified a list of fifteen putative GC enhancer regulators. Of these potential GC enhancer regulators, only SOX9 was highly induced in GC B cells as compared to resting B cells, pointing to SOX9 as a candidate master enhancer regulator of the GC transcriptome with potential relevance to lymphomas. Indeed, in addition to the well-known role of SOX9 as a stem cell self-renewal and cell-differentiation regulator during development, SOX9 has also been described as playing a role in colon, breast, and prostate carcinogenesis through inhibition of apoptosis, and promoting proliferation, invasion, and metastasis. We confirmed that SOX9 is highly induced in GC cells using QPCR and Western blots. To determine whether SOX9 would indeed bind to these enhancer sites, we next performed SOX9 ChIP-seq in GC B-cell derived lymphoma cell lines. These experiments validated and showed that SOX9 binds to 1,668 upstream distal enhancer regions (-5 to -100 kb upstream from TSS) associated with 963 genes. These target genes were significantly enriched in cell cycle regulation (CCND2, CDC25B, CDK1), transcription regulation (BCOR, NCOR2), epigenetic regulation (BMI1, DNMT3A, MLL2, SUZ12, TET3), and MAPK signaling (MAP2K3, MAP3K7) and also for B-cell activation and BCL6 repressed pathways (p We next wished to determine whether SOX9 was also expressed in GC-derived lymphoma clinical samples. Therefore we next examined RNA-seq gene expression profiles derived from cohorts of FL and DLBCL patients. We found that SOX9 is expressed at higher levels in FL patient samples, but lower levels in most DLBCLs compared to naïve B cells. These data raise the possibility that SOX9 might be differentially relevant to FL more than DLBCLs, perhaps contributing to the biologic distinction between these two GC-derived lymphomas. To determine if SOX9 protein was also expressed in these tumors, we examined protein expression by immunohistochemistry using tissue microarrays (TMAs) containing both FLs and DLBCLs. We found that 88 of the 242 FL TMA samples (36.4%) were positive for SOX9 staining. Eleven of the 114 DLBCL TMA samples (10%) were positive for SOX9 staining, among which 80% (9/11) were GC-type DLBCL and 45% (5/11) had a prior FL history. To determine if any of the currently available GC derived lymphoma cell lines manifest high SOX9 levels, we performed a series of Western blot experiments. These studies show high levels of SOX9 protein in the GC-type DLBCL cell lines HT, Karpas422, DB, and Farage, but not in any of the eight ABC-DLBCLs subtypes. Ongoing studies are assessing the biologic relevance of SOX9 for the GC reaction and possible contribution to lymphomagenesis using gain- and loss-of-function studies in human cells and mouse models. These data will determine whether this apparently key enhancer regulatory protein is a novel lineage factor for follicular lymphoma and potentially suitable as a therapeutic target. Citation Format: Angela A. Fachel, Yanwen Jiang, Wayne Tam, Ashlesha S. Muley, Cem Meydan, Xabier Agirre, Ari M. Melnick, Kristy L. Richards. SOX9 enhancer regulator may play an oncogenic role in B-cell lymphomas [abstract]. In: Proceedings of the Second AACR Conference on Hematologic Malignancies: Translating Discoveries to Novel Therapies; May 6-9, 2017; Boston, MA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(24_Suppl):Abstract nr 30.

Background Expression of the pro-apoptotic BCL-2-interacting mediator ( BIM ) has recently been implicated in imatinib-induced apoptosis of BCR-ABL1 + cells. However, the mechanisms involved in the regulation of BIM in CML and its role in the clinical setting have not been established. Design and methods We analysed the mRNA expression of BIM in 100 newly diagnosed patients with CML in chronic phase by Q-RT-PCR and the protein levels by Western blot analysis. Methylation status was analysed by bisulphite genomic sequencing and MSP. CML cell lines were treated with imatinib and 5-aza-2’-deoxycytidine, and were transfected with two different siRNAs against BIM and cell proliferation and apoptosis were analysed. Results We demonstrated that down-regulation of BIM expression was present in 36% of the patients and was significantly associated with a lack of optimal response to imatinib as indicated by the decrease in cytogenetic and molecular responses at 6, 12 and 18 months in comparison with patients with normal BIM expression ( p BIM was mediated by promoter hypermethylation as demonstrated by restoration of BIM expression after treatment of CML cells with 5-aza-2′-deoxycytidine. Using CML cell lines with low and normal expression of BIM we further demonstrated that the expression of BIM is required for imatinib-induced CML apoptosis. Conclusion Our data indicate that down-regulation of BIM is epigenetically controlled by methylation in a percentage of CML patients and has an unfavourable prognostic impact, and that the combination of imatinib with a de-methylating agent may result in improved responses in patients with decreased expression of BIM .

Lymphomas are assumed to originate at different stages of lymphocyte development through chromosomal aberrations. Thus, different lymphomas resemble lymphocytes at distinct differentiation stages and show characteristic morphologic, genetic, and transcriptional features. Here, we have performed a microarray-based DNA methylation profiling of 83 mature aggressive B-cell non-Hodgkin lymphomas (maB-NHLs) characterized for their morphologic, genetic, and transcriptional features, including molecular Burkitt lymphomas and diffuse large B-cell lymphomas. Hierarchic clustering indicated that methylation patterns in maB-NHLs were not strictly associated with morphologic, genetic, or transcriptional features. By supervised analyses, we identified 56 genes de novo methylated in all lymphoma subtypes studied and 22 methylated in a lymphoma subtype–specific manner. Remarkably, the group of genes de novo methylated in all lymphoma subtypes was significantly enriched for polycomb targets in embryonic stem cells. De novo methylated genes in all maB-NHLs studied were expressed at low levels in lymphomas and normal hematopoietic tissues but not in nonhematopoietic tissues. These findings, especially the enrichment for polycomb targets in stem cells, indicate that maB-NHLs with different morphologic, genetic, and transcriptional background share a similar stem cell–like epigenetic pattern. This suggests that maB-NHLs originate from cells with stem cell features or that stemness was acquired during lymphomagenesis by epigenetic remodeling.

MicroRNAs (miRNA) are small noncoding, single-stranded RNAs that inhibit gene expression at a posttranscriptional level, whose abnormal expression has been described in different tumors. The aim of our study was to identify miRNAs potentially implicated in chronic myeloid leukemia (CML). We detected an abnormal miRNA expression profile in mononuclear and CD34+ cells from patients with CML compared with healthy controls. Of 157 miRNAs tested, hsa-miR-10a, hsa-miR-150, and hsa-miR-151 were down-regulated, whereas hsa-miR-96 was up-regulated in CML cells. Down-regulation of hsa-miR-10a was not dependent on BCR-ABL1 activity and contributed to the increased cell growth of CML cells. We identified the upstream stimulatory factor 2 (USF2) as a potential target of hsa-miR-10a and showed that overexpression of USF2 also increases cell growth. The clinical relevance of these findings was shown in a group of 85 newly diagnosed patients with CML in which expression of hsa-miR-10a was down-regulated in 71% of the patients, whereas expression of USF2 was up-regulated in 60% of the CML patients, with overexpression of USF2 being significantly associated with decreased expression of hsa-miR-10a (P = 0.004). Our results indicate that down-regulation of hsa-miR-10a may increase USF2 and contribute to the increase in cell proliferation of CML implicating a miRNA in the abnormal behavior of CML. (Mol Cancer Res 2008;6(12):1830–40)

The clinical significance of aberrant promoter methylation of the canonical Wnt pathway antagonist genes (sFRP1, sFRP2, sFRP4, sFRP5, Wif1, Dkk3, and Hdpr1) and also putative tumor-suppressor gene Wnt5a, belonging to the non-canonical Wnt signaling pathway, was investigated in a large series of 75 patients with Philadelphia chromosome-positive acute lymphoblastic leukemia by methylationspecific polymerase chain reaction. At least one methylated gene was observed in cells from 66% (49/75) of patients (methylated group). Disease-free survival and overall survival at 9 years were 51 and 40%, respectively, for the unmethylated group and 3 and 2%, respectively, for the methylated group (both P < 0.0001). Multivariate analysis demonstrated that the Wnt methylation profile was an independent prognostic factor predicting disease-free survival (P = 0.007) and overall survival (P = 0.039). Abnormal DNA methylation of promoter-associated CpG islands in the Wnt signaling pathway is very common in Philadelphia chromosome-positive acute lymphoblastic leukemia and potentially defines subgroups with distinct clinical characteristics.

In order to determine new signal transduction pathways implicated in chronic myeloid leukaemia (CML), we performed a gene expression profile comparison between CD34+ cells from CML patients and healthy donors. Functional studies were performed using the Mo7e and Mo7e-p210 cell lines. Expression of CCND1 (Cyclin D1), as well as the chaperone HSPA8, which is important for regulation of CCND1, were significantly upregulated in CD34+ CML cells. Upregulation of HSPA8 was dependent, at least in part, on STAT5 (signal transducer and activator of transcrition 5)-dependent transcriptional activation, as demonstrated by chromatin immunoprecipitation. The presence of HSPA8 in the nuclear protein fraction as well as its binding to CCND1 suggests that it may contribute to stabilization of the CCND1/CDK4 complex, which, in turn, may participate in proliferation of CML cells. Treatment of CML cells with the specific HSPA8 inhibitor 15-deoxyspergualin induced inhibition of CML cell viability but did not induce apoptosis. In conclusion, our studies suggest that STAT5-mediated activation of HSPA8 induces nuclear translocation and activation of the CCND1/CDK4 complex leading to increased proliferation of CML cells, deciphering a new pathway implicated in CML and supporting a potential role of chaperone inhibitors in the treatment of CML.

The aim of our study was to determine the potential mechanism(s) implicated in Imatinib resistance in patients with Ph + ALL. Resistance of Ph + ALL cells to Imatinib-induced apoptosis was associated with lack of inhibition of Akt phosphorylation. Addition of the PI3K inhibitor LY294002 to Imatinib significantly increased apoptosis of Ph + ALL cells. Interestingly, expression of PTEN was reduced in Ph + ALL cells which was due to PTEN promoter hypermethylation. Treatment of Ph + ALL cells with 5-Aza-2′-deoxycytidine was associated with an increased expression of PTEN and an increase in cell apoptosis. These results suggest that Imatinib resistance in patients with ALL may be dependent at least in part to PTEN down-regulation due to the abnormal promoter hypermethylation and support the potential role of de-methylating agents for the treatment of patients with Ph + ALL.

Recent published data have shown the efficacy of gene therapy treatments of certain monogenic diseases. Risks of insertional oncogenesis, however, indicate the necessity of developing new vectors with weaker or cell-restricted promoters to minimize the trans-activation activity of integrated proviruses. We have inserted the proximal promoter of the vav proto-oncogene into self-inactivating lentiviral vectors (vav-LVs) and investigated the expression pattern and therapeutic efficacy of these vectors. Compared with other LVs frequently used in gene therapy, vav-LVs mediated a weak, though homogeneous and stable, expression in in vitro-cultured cells. Transplantation experiments using transduced mouse bone marrow and human CD34(+) cells confirmed the stable activity of the promoter in vivo. To investigate whether the weak activity of this promoter was compatible with a therapeutic effect, a LV expressing the Fanconi anemia A (FANCA) gene was constructed (vav-FANCA LV). Although this vector induced a low expression of FANCA, compared to the expression induced by a LV harboring the spleen focus-forming virus (SFFV) promoter, the two vectors corrected the phenotype of cells from a patient with FA-A with the same efficacy. We propose that self-inactivating vectors harboring weak promoters, such as the vav promoter, will improve the safety of gene therapy and will be of particular interest for the treatment of diseases where a high expression of the transgene is not required.