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PURPOSE: Glioblastoma (GBM) carries a dismal prognosis despite standard multimodal treatment with surgery, chemotherapy and radiation. Immune checkpoint inhibitors, such as PD1 blockade, for treatment of GBM failed to show clinical benefit. Rational combination strategies to overcome resistance of GBM to checkpoint monotherapy are needed to extend the promise of immunotherapy to GBM management. Emerging evidence suggests that protein phosphatase 2A (PP2A) plays a critical role in the signal transduction pathways of both adaptive and innate immune cells and that inhibition of PP2A could enhance cancer immunity. We investigated the use of a PP2A inhibitor, LB-100, to enhance antitumor efficacy of PD1 blockade in a syngeneic glioma model. METHODS: C57BL/6 mice were implanted with murine glioma cell line GL261-luc or GL261-WT and randomized into 4 treatment arms: (i) control, (ii) LB-100, (iii) PD1 blockade and (iv) combination. Survival was assessed and detailed profiling of tumor infiltrating leukocytes was performed. RESULTS: Dual PP2A and PD1 blockade significantly improved survival compared with monotherapy alone. Combination therapy resulted in complete regression of tumors in about 25% of mice. This effect was dependent on CD4 and CD8 T cells and cured mice established antigen-specific secondary protective immunity. Analysis of tumor lymphocytes demonstrated enhanced CD8 infiltration and effector function. CONCLUSION: This is the first preclinical investigation of the effect of combining PP2A inhibition with PD1 blockade for GBM. This novel combination provided effective tumor immunotherapy and long-term survival in our animal GBM model.

Triple-negative breast cancer (TNBC) does not respond to widely used targeted/endocrine therapies because of the absence of progesterone and estrogen receptors and HER2 amplification. It has been shown that the majority of TNBC cells are highly sensitive to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis, but the development of TRAIL resistance limits its efficacy. We previously found that protein phosphatase 2A (PP2A) plays an important role in TRAIL resistance. In this study, we evaluated the effects of PP2A inhibition on cell death in TRAIL-resistant TNBC cells. We found that the PP2A inhibitor LB-100 effectively inhibits the growth of a panel of TNBC cell lines including lines that are intrinsically resistant to TRAIL. Using two TRAIL-resistant cell lines generated from TRAIL-sensitive parental cells (MDA231 and SUM159), we found that both TRAIL-sensitive and -resistant cell lines are equally sensitive to LB-100. We also found that LB-100 sensitizes TNBC cells to clinically used chemotherapeutical agents, including paclitaxel and cisplatin. Importantly, we found that LB-100 effectively inhibits the growth of MDA468 tumors in mice in vivo without apparent toxicity. Collectively, these data suggest that pharmacological inhibition of PP2A activity could be a novel therapeutic strategy for treating patients with TNBC in a clinical setting.

Acute‐on‐chronic liver failure (ACLF) has a high mortality rate. Metabolic reprogramming is an important mechanism for cell survival. Herein, the metabolic patterns of ACLF patients are analyzed. An in vitro model of ACLF is established using Chang liver cells under hyperammonemia and hypoxia. A randomized clinical trial (ChiCTR‐OPC‐15006839) is performed with patients receiving L‐ornithine and L‐aspartate (LOLA) daily intravenously (LOLA group) and trimetazidine (TMZ) tid orally (TMZ group) based on conventional treatment (control group). The primary end point is 90‐day overall survival, and overall survival is the secondary end point. By analyzing metabolic profiles in liver tissue samples from hepatitis B virus (HBV)‐related ACLF patients and the controls, the metabolic characteristics of HBV‐related ACLF patients are identified: inhibited glycolysis, tricarboxylic acid cycle and urea cycle, and enhanced fatty acid oxidation (FAO) and glutamine anaplerosis. These effects are mainly attributed to hyperammonemia and hypoxia. Further in vitro study reveals that switching from FAO to glycolysis could improve hepatocyte survival in the hyperammonemic and hypoxic microenvironment. Importantly, this randomized clinical trial confirms that inhibiting FAO using TMZ improves the prognosis of patients with HBV‐related ACLF. In conclusion, this study provides a practical strategy for targeting metabolic reprogramming using TMZ to improve the survival of patients with HBV‐related ACLF., Metabolic characteristics are identified in patients with acute‐on‐chronic liver failure: inhibited glycolysis, tricarboxylic acid cycle (TAC) and urea cycle, and enhanced fatty acid oxidation (FAO) and glutamine anaplerosis. These effects are mainly attributed to hyperammonemia and hypoxia. Trimetazidine that is used to inhibit FAO could enhance glycolysis, TAC and urea cycle, but inhibit glutamine anaplerosis, thereby improving patients' survival.

Chimeric antigen receptor (CAR)-engineered T cells represent a promising modality for treating glioblastoma. Recently, we demonstrated that CAR-T cells targeting carbonic anhydrase IX (CAIX), a protein involved in HIF-1a hypoxic signaling, is a promising CAR-T cell target in an intracranial murine glioblastoma model. Anti-CAIX CAR-T cell therapy is limited by its suboptimal activation within the tumor microenvironment. LB-100, a small molecular inhibitor of protein phosphatase 2A (PP2A), has been shown to enhance T cell anti-tumor activity through activation of the mTOR signaling pathway. Herein, we investigated if a treatment strategy consisting of a combination of LB-100 and anti-CAIX CAR-T cell therapy produced a synergistic anti-tumor effect. Our studies demonstrate that LB-100 enhanced anti-CAIX CAR-T cell treatment efficacy in vitro and in vivo. Our findings demonstrate the role of LB-100 in augmenting the cytotoxic activity of anti-CAIX CAR-T cells and underscore the synergistic therapeutic potential of applying combination LB-100 and CAR-T Cell therapy to other solid tumors.

Contains fulltext : 225895.pdf (Publisher’s version ) (Open Access) Phaeochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumours with a hereditary background in over one-third of patients. Mutations in succinate dehydrogenase (SDH) genes increase the risk for PPGLs and several other tumours. Mutations in subunit B (SDHB) in particular are a risk factor for metastatic disease, further highlighting the importance of identifying SDHx mutations for patient management. Genetic variants of unknown significance, where implications for the patient and family members are unclear, are a problem for interpretation. For such cases, reliable methods for evaluating protein functionality are required. Immunohistochemistry for SDHB (SDHB-IHC) is the method of choice but does not assess functionality at the enzymatic level. Liquid chromatography-mass spectrometry-based measurements of metabolite precursors and products of enzymatic reactions provide an alternative method. Here, we compare SDHB-IHC with metabolite profiling in 189 tumours from 187 PPGL patients. Besides evaluating succinate:fumarate ratios (SFRs), machine learning algorithms were developed to establish predictive models for interpreting metabolite data. Metabolite profiling showed higher diagnostic specificity compared to SDHB-IHC (99.2% versus 92.5%, p = 0.021), whereas sensitivity was comparable. Application of machine learning algorithms to metabolite profiles improved predictive ability over that of the SFR, in particular for hard-to-interpret cases of head and neck paragangliomas (AUC 0.9821 versus 0.9613, p = 0.044). Importantly, the combination of metabolite profiling with SDHB-IHC has complementary utility, as SDHB-IHC correctly classified all but one of the false negatives from metabolite profiling strategies, while metabolite profiling correctly classified all but one of the false negatives/positives from SDHB-IHC. From 186 tumours with confirmed status of SDHx variant pathogenicity, the combination of the two methods resulted in 185 correct predictions, highlighting the benefits of both strategies for patient management. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Background/Aims: Protein phosphatase 2A (PP2A) is a ubiquitous serine/threonine phosphatase that mediates cell cycle regulation and metabolism. Mounting evidence has indicated that PP2A inhibition exhibits considerable anticancer potency in multiple types of human cancers. However, the efficacy of PP2A inhibition remains unexplored in mucoepidermoid carcinoma (MEC), especially in locally advanced and metastatic cases with limited systemic treatment. In this study, we demonstrated the therapeutic potency of LB100 in mucoepidermoid carcinoma. Methods: In this study, the expression of PP2A was evaluated using immunohistochemical (IHC) staining. The effects associated with LB100 alone and in combination with cisplatin for the treatment of mucoepidermoid carcinoma were investigated both in vitro, regarding metabolism, proliferation, and migration, and in vivo in a mucoepidermoid carcinoma xenograft model. In addition, with LB100 treatment and in response to an insulin stimulus, the expression levels and phosphorylation levels of targets in the PI3K-AKT pathway were determined using western blot analysis and immunoblotting. Results: The expression of protein phosphatase 2A was significantly upregulated in the clinical specimens of high-grade MECs compared with those of low-/medium-grade MECs and normal controls. In this article, we report that a small molecule PP2A inhibitor, LB100, decreased cellular viability and glycolytic activity and induced G2/M cell cycle arrest. Importantly, LB100 enhanced the efficacy of cisplatin in mucoepidermoid carcinoma cells both in vitro and in vivo. PP2A inhibition by LB100 increased the phosphorylation of insulin receptor substrate 1(IRS-1) on serine residues, downregulated the expression of phosphatidylinositol 3-kinase (PI3K) p110 alpha subunit and dephosphorylated AKT at Ser473 and Thr308 in mucoepidermoid carcinoma cells in response to insulin stimulus. Conclusion: These results highlight the translational potential of PP2A inhibition to synergize with cisplatin in mucoepidermoid carcinoma treatment.

Posttranslational modifications of mammalian c-Src N-terminal and C-terminal domains regulate distinct functions. Myristoylation of G2 controls its cell membrane association and phosphorylation of Y419/Y527 controls its activation or inactivation, respectively. We provide evidence that Src–cell membrane association–dissociation and catalytic activation–inactivation are both regulated by acetylation. In EGF-treated cells, CREB binding protein (CBP) acetylates an N-terminal lysine cluster (K5, K7, and K9) of c-Src to promote dissociation from the cell membrane. CBP also acetylates the C-terminal K401, K423, and K427 of c-Src to activate intrinsic kinase activity for STAT3 recruitment and activation. N-terminal domain phosphorylation (Y14, Y45, and Y68) of STAT3 by c-Src activates transcriptionally active dimers of STAT3. Moreover, acetyl-Src translocates into nuclei, where it forms the Src-STAT3 enhanceosome for gene regulation and cancer cell proliferation. Thus, c-Src acetylation in the N-terminal and C-terminal domains play distinct roles in Src activity and regulation. Significance: CBP-mediated acetylation of lysine clusters in both the N-terminal and C-terminal regions of c-Src provides additional levels of control over STAT3 transcriptional activity. Cancer Res; 78(11); 2825–38. ©2018 AACR.

PURPOSE: Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors of neural crest origin. Germline or somatic mutations of numerous genes have been implicated in the pathogenesis of PPGLs, including the isocitrate dehydrogenase 1 (IDH1) gene and alpha thalassemia/mental retardation syndrome X-linked (ATRX) gene. Although concurrent IDH1 and ATRX mutations are frequently seen in gliomas, they have never been reported together in PPGLs. The aim of this study was to characterize one paraganglioma with concurrent IDH1 and ATRX mutations identified by whole exome sequencing. METHODS: Leukocyte and tumor DNA were used for whole exome sequencing and Sanger sequencing. 2-hydroxyglurarate level and the global DNA methylation status in the tumor were measured. ATRX’s cDNA transcripts were analyzed. Tyrosine hydroxylase (TH), HIF1α and ATRX staining, as well as telomere-specific FISH was also performed. RESULTS: The presence of a somatic IDH1 (c.394C>T, p.R132C) mutation and a concurrent somatic ATRX splicing mutation (c.4318–2A>G) in the current case was confirmed. Dramatic accumulation of 2-hydroxyglutarate was detected in the paraganglioma without the global DNA hypermethylation, and pseudohypoxia was also activated. Importantly, immunohistochemistry revealed negative TH staining in the tumor and the first exon region of TH gene was hypermethylated resulting in normal plasma metanephrines. The splicing ATRX mutation resulted in two transcripts, causing frameshifts. Immunohistochemistry revealed scarce ATRX staining in the tumor. Alternative lengthening of telomeres (ALT) was detected by FISH. CONCLUSIONS: This case represents the first concurrence of IDH1 and ATRX mutations in PPGLs. Although relatively rare, a somatic R132C mutation of IDH1 might play a role in a small subset of sporadic PPGLs.

Oncocytomas represent a subset of benign pituitary adenomas that are characterized by significant mitochondrial hyperplasia. Mitochondria are key organelles for energy generation and metabolic intermediate production for biosynthesis in tumour cells, so understanding the mechanism underlying mitochondrial biogenesis and its impact on cellular metabolism in oncocytoma is vital. Here, we studied surgically resected pituitary oncocytomas by using multi-omic analyses. Whole-exome sequencing did not reveal any nuclear mutations, but identified several somatic mutations of mitochondrial DNA, and dysfunctional respiratory complex I. Metabolomic analysis suggested that oxidative phosphorylation was reduced within individual mitochondria, and that there was no reciprocal increase in glycolytic activity. Interestingly, we found a reduction in the cellular lactate level and reduced expression of lactate dehydrogenase A (LDHA), which contributed to mitochondrial biogenesis in an in vitro cell model. It is of note that the hypoxia-response signalling pathway was not upregulated in pituitary oncocytomas, thereby failing to enhance glycolysis. Proteomic analysis showed that 14-3-3η was exclusively overexpressed in oncocytomas, and that 14-3-3η was capable of inhibiting glycolysis, leading to mitochondrial biogenesis in the presence of rotenone. In particular, 14-3-3η inhibited LDHA by direct interaction in the setting of complex I dysfunction, highlighting the role of 14-3-3η overexpression and inefficient oxidative phosphorylation in oncocytoma mitochondrial biogenesis. These findings deepen our understanding of the metabolic changes that occur within oncocytomas, and shine a light on the mechanism of mitochondrial biogenesis, providing a novel perspective on metabolic adaptation in tumour cells. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The myelodysplastic syndromes (MDS) are a group of hematologic disorders characterized by the presence of somatically mutated hematopoietic stem cells (HSCs) that increase the risk of progression to secondary acute myeloid leukemia (sAML). Mutations in isocitrate dehydrogenase (IDHmut) are thought to correlate with the increased production of the oncogenic protein 2-hydroxyglutarate (2-HG) in AML. The aim of this study was to examine whether serum 2-HG has utility as a prognostic biomarker, and whether elevated 2-HG levels are predictive of IDH mutations in patients with MDS. Genetic profiling was utilized to determine the genetic composition of a large cohort of MDS patients, including the presence or absence of IDH1 or IDH2 mutations (n = 281). Serum 2-HG levels were detected by liquid chromatography–tandem mass spectrometry. In the current study of MDS patients, elevated serum 2-HG levels were predictive of inferior overall- and leukemia-free survival irrespective of IPSS risk grouping. Higher serum 2-HG levels predicted the presence of IDH mutations. IDH2mut patients had a higher risk of leukemic transformation. The co-occurrence of DNMT3A or SRSF2 mutations was found to be increased in IDH2mut patients. IDH2 mutations were associated with significantly worse OS and LFS amongst patients with low-risk MDS by IPSS grouping. The noted predictive value of serum 2-HG levels and IDH2 mutations on OS and LFS support the use of biomarkers and/or underlying cytogenetics in novel prognostic scoring systems for MDS.

Oral mucosal melanoma (OMM) is a rare and aggressive subtype of melanoma with little known about its pathogenesis or carcinogenesis. We therefore performed whole-exome sequencing (WES) on 19 matched OMM tumor/normal pairs in order to gain insight into potential genetic drivers of tumor formation. For the first time, we describe the comprehensive mutational profile of OMM. Our data suggest that the genetic background of OMM differs from those of other melanoma subtypes. We identified recurrent mutations involving KIT, POLE, PTPRD, PTCHD2, and DMXL2. Notably, copy number analysis revealed recurrently amplified regions of 12q14 (57.9%, containing CDK4) and 5p15 (47.4%, containing TERT). CNV analysis in a separate cohort of 15 samples validated the frequent CNV in CDK4 and TERT. We also observed that the melanocyte development and pigmentation signaling pathway is frequently altered in OMM. Furthermore, our data suggest several altered genes that may be amenable for targeted therapy. We identified one patient with metastatic OMM in our cohort who was identified to harbor a targetable KIT mutation using our WES results. This patient was able to achieve complete remission following implementation of KIT-targeted therapy. These findings provide further insight into the genetic underpinnings of OMM development and suggest that patients with OMM may benefit from WES analysis to identify potential targetable genetic mutations. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Tumor-associated macrophages (TAMs) are predominantly M2 phenotype in solid cancers including hepatocellular carcinoma (HCC). Though differentiation of M2 macrophages has been recently linked to fatty acid oxidation (FAO), whether FAO plays a role in functional maintenance of M2 macrophages is still unclear. Here, we used an in vitro model to mimic TAM-HCC interaction in tumor microenvironment. We found that M2 monocyte-derived macrophages (MDMs) enhanced the proliferation, migration, and invasion of HCC cells through an FAO-dependent way. Further investigations identified that IL-1β mediated the pro-migratory effect of M2 MDM. Using etomoxir and siRNA to inhibit FAO and palmitate to enhance FAO, we showed that FAO was responsible for the up-regulated secretion of IL-1β and, thus, the pro-migratory effect in M2 MDMs. In addition, we proved that IL-1β induction was reactive oxygen species and NLRP3-dependent. Our study demonstrates that FAO plays a key role in functional human M2 macrophages by enhancing IL-1β secretion to promote HCC cell migration. These findings provide evidence for different dependency of energy sources in macrophages with distinct phenotypes and functions, and suggest a novel strategy to treat HCC by reprogramming cell metabolism or modulating tumor microenvironment.

Background Standard therapy for chordoma consists of surgical resection followed by high-dose irradiation. Protein phosphatase 2A (PP2A) is a ubiquitously expressed serine/threonine phosphatase involved in signal transduction, cell cycle progression, cell differentiation, and DNA repair. LB100 is a small-molecule inhibitor of PP2A designed to sensitize cancer cells to DNA damage from irradiation and chemotherapy. A recently completed phase I trial of LB100 in solid tumors demonstrated its safety. Here, we show the therapeutic potential of LB100 in chordoma. Methods Three patient-derived chordoma cell lines were used: U-CH1, JHC7, and UM-Chor1. Cell proliferation was determined with LB100 alone and in combination with irradiation. Cell cycle progression was assessed by flow cytometry. Quantitative γ-H2AX immunofluorescence and immunoblot evaluated the effect of LB100 on radiation-induced DNA damage. Ultrastructural evidence for nuclear damage was investigated using Raman imaging and transmission electron microscopy. A xenograft model was established to determine potential clinical utility of adding LB100 to irradiation. Results PP2A inhibition in concert with irradiation demonstrated in vitro growth inhibition. The combination of LB100 and radiation also induced accumulation at the G2/M phase of the cell cycle, the stage most sensitive to radiation-induced damage. LB100 enhanced radiation-induced DNA double-strand breaks. Animals implanted with chordoma cells and treated with the combination of LB100 and radiation demonstrated tumor growth delay. Conclusions Combining LB100 and radiation enhanced DNA damage-induced cell death and delayed tumor growth in an animal model of chordoma. PP2A inhibition by LB100 treatment may improve the effectiveness of radiation therapy for chordoma.

Immunotherapy has become an essential component of cancer treatment, however, a majority of patients with solid metastatic cancers, such as pheochromocytoma (PHEO), do not respond to this type of therapy. Recently, we developed an intratumoral (i.t.) immunotherapy based on the unique combination of TLR ligands, anti-CD40 antibodies, and mannan, which is artificially bound to tumor cells via an anchor (MBTA therapy). This therapy resulted in the complete eradication of aggressive subcutaneous PHEO in 67% of mice and demonstrated a systemic antitumor immune response and regression of non-treated lesions in the metastatic model (1). To further evaluate this systemic effect generated during MBTA therapy, we established a murine bilateral PHEO model, where MBTA therapy was i.t. injected into one tumor, and the distant (non-treated) tumor was monitored for changes in size and immune cell infiltration. The growth of both MBTA-treated and distant tumors was reduced compared to that of the control. Interestingly, survival of the MBTA-treated mice was twice as long compared to the control mice. Moreover, we have made several unique observations during the experiments which were focused on the tumor microenvironment. Flow cytometry analysis revealed the ability of MBTA therapy to significantly increase the infiltration of innate immune cells (monocytes, DCs, macrophages, NK cells) not only in MBTA-treated tumors, but also in distal tumors, despite the fact that MBTA therapy was designed to elicit only local inflammation. An analysis of the macrophage phenotype revealed a switch from protumor M2 to antitumor M1 macrophages in both tumors during the entire MBTA therapy treatment. Analysis of splenic adaptive immune cells revealed that naïve CD4+ or CD8+ T cells differentiated into central memory cells and effector memory cells. CD4+ and CD8+ T cells were elevated in MBTA-treated and distant tumors with a significantly higher frequency of CD8+ effector memory T cells. Moreover, the adoptive transfer of CD4+ and CD8+ T cells revealed that immune memory, after tumor rechallenging, was driven by CD4+ T cells. Collectively, these results illustrate the ability of MBTA therapy to activate both parts of the immune system and render a systemic antitumor response against non-treated metastases. We believe that our results could lead to the use of MBTA therapy in patients with aggressive, metastatic lesions. Reference: Caisova et al., Cancers (Basel), 2019. 11(5).

Atypical teratoid rhabdoid tumor (ATRT) is a pediatric brain tumor with a high mortality rate characterized by mutations in/ deletions of SWI/SNF matrix-associated actin-dependent regulator of chromatin sub-family B member 1 (SMARCB1). We previously showed that loss of SMARCB1 causes up-regulation and release of HML-2 subfamily of human endogenous retrovirus K envelope protein (HML-2 ENV), resulting in maintenance of pluripotency. Here, we investigated intracellular trafficking and release of HML-2 ENV. Further, we demonstrate two potential therapeutic strategies to decrease intracellular HML-2 ENV: 1) inhibition of calcium influx by ouabain, a cardiac glycoside toxic to neural stem cells, and 2) targeted inhibition of cyclin-dependent kinase 5 (CDK5), which is restricted to neurons by p35, its activator protein, by TP5. ATRT cell lines and tumor tissue obtained from patients were confirmed for SMARCB1 loss and increased HML-2 ENV. Cell viability and intracellular HML-2 ENV concentration were measured after treatment with ouabain and TP5 (CDK5 antagonist). We evaluated the calcium-mediated effect of ouabain on HML-2 intracellular concentration by treating the cells with ouabain, the calcium chelators calcimycin and EGTA, and calpeptin, a calpain inhibitor, which activates CDK5, and measuring HML-2 ENV and p35. We evaluated HML-2 ENV for a CDK5 consensus phosphorylation site and performed co-immunoprecipitation to evaluate direct interaction. We evaluated activity of CDK5 in ATRT cell lines by autoradiography. Both Ouabain and TP5 caused a decrease in cell viability in a dose-dependent manner. Further, ouabain treatment decreased HML-2 ENV intracellular concentration. We found that HML-2 ENV contains a consensus phosphorylation site for CDK5. We discovered that HML-2 ENV was bound to CDK5. We established that ATRT cell lines had hyperactive CDK5. Finally, we established that the effect of ouabain on HML-2 ENV was due to indirect inhibition of calcium-mediated activation of calpain and thus CDK5.

// Jian He 1, * , Mingju Sun 1, * , Enyou Li 2, * , Yingyong Hou 5, * , Matthew J. Shepard 3, 6 , Di Chen 1 , Karel Pacak 7 , Changsong Wang 4 , Lei Guo 2 , Zhengping Zhuang 3 and Yang Liu 1 1 Scientific Research Center for Translational Medicine, Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China 2 Department of Anesthesiology, First Affiliated Hospital of Harbin Medical University, Harbin, China 3 Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 4 Department of Critical Care Medicine, The Third Affiliated Hospital of Harbin Medical University, Nangang District, Harbin, China 5 Department of Pathology, School of Basic Medical Sciences & Zhongshan Hospital, Fudan University, Shanghai, China 6 Department of Neurologic Surgery, University of Virginia Health System, Charlottesville, Virginia, USA 7 Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA * These authors have contributed equally to this work Correspondence to: Zhengping Zhuang, email: zhuangp@ninds.nih.gov Yang Liu, email: yliuqq@dicp.ac.cn Keywords: cardiac myxomas; PRKAR1A; somatic mutation Received: July 14, 2017 Accepted: September 20, 2017 Published: October 19, 2017 ABSTRACT Background: Cardiac myxomas are benign tumors that commonly arise within the left atria. Familial cardiac myxomas are a part of Carney Complex (CNC), an autosomal dominant multiple neoplasia syndrome caused by germline mutations in PRKAR1A . Seven percent of cardiac myxomas are associated with CNC. To date, the genetic basis of isolated cardiac myxomas (ICM), however, has not been fully elucidated. Methods: We investigated the genetic profile of ICM using whole exome sequencing (WES). Suspected mutations were confirmed using targeted sanger sequencing. To further examine the presence of PRKAR1A mutations in ICM, we performed targeted sequencing in an additional 61 ICM specimens. Results: 87.5% (7/8) of ICM harbored mutations in PRKAR1A . Three of the 8 ICM harbored biallelic somatic mutations of PRKAR1A , including c.607_610del:p.Leu203fs (pathogenic) + c.C896G:p.Ser299X (pathogenic), c.952delT:p.Leu318fs (pathogenic) + c.769-2 A>G (pathogenic) and c.178-1 G>C (pathogenic) + c. 550+1 G>C (pathogenic). Four of 8 tumors harbored monoallelic PRKAR1A mutations, including c.523_524insG:p.Tyr175_Val176delinsX (pathogenic), c.C920A:p.Ser307X (pathogenic), c.30delG:p.Glu10fs (pathogenic) and c.C289T:p.Arg97X (pathogenic). No identical variants were observed across the 8 ICM samples. Interestingly, none of these variants have been previously described in familial cardiac myxomas. In order to confirm our findings, directed sequencing of 61 ICM specimens was subsequently performed. Sixty-four percent (39/61) of ICMs tumors contained inactivating PRKAR1A mutations. Conclusion: Our findings suggest that loss-of-function mutations of PRKAR1A may play a vital role in the formation of isolated cardiac myxomas.

// Chao Zhang 1,2,* , Chunzhang Yang 3,* , Michael J. Feldman 4 , Herui Wang 4 , Ying Pang 2 , Dominic M. Maggio 4 , Dongwang Zhu 4 , Cody L. Nesvick 4 , Pauline Dmitriev 4 , Petra Bullova 2,5 , Prashant Chittiboina 4 , Roscoe O. Brady 4 , Karel Pacak 2 and Zhengping Zhuang 4 1 Department of Orthopedics, Xinqiao Hospital, The Third Military Medical University, Chongqing, China 2 Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, USA 3 Neuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA 4 Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA 5 Department of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, Bratislava, Slovakia * These authors have contributed equally to this work Correspondence to: Karel Pacak, email: // Zhengping Zhuang, email: // Keywords : HDACi, Hsp90, SAHA, HIF, hypoxia Received : December 14, 2016 Accepted : April 10, 2017 Published : May 23, 2017 Abstract Histone deacetylase inhibitors (HDACis) are a potent class of tumor-suppressive agents traditionally believed to exert their effects through loosening tightly-wound chromatin resulting in de-inhibition of various tumor suppressive genes. Recent literature however has shown altered intratumoral hypoxia signaling with HDACi administration not attributable to changes in chromatin structure. We sought to determine the precise mechanism of HDACi-mediated hypoxia signaling attenuation using vorinostat (SAHA), an FDA-approved class I/IIb/IV HDACi. Through an in-vitro and in-vivo approach utilizing cell lines for hepatocellular carcinoma (HCC), osteosarcoma (OS), and glioblastoma (GBM), we demonstrate that SAHA potently inhibits HIF-a nuclear translocation via direct acetylation of its associated chaperone, heat shock protein 90 (Hsp90). In the presence of SAHA we found elevated levels of acetyl-Hsp90, decreased interaction between acetyl-Hsp90 and HIF-a, decreased nuclear/cytoplasmic HIF-α expression, absent HIF-α association with its nuclear karyopharyin Importin, and markedly decreased HIF-a transcriptional activity. These changes were associated with downregulation of downstream hypoxia molecules such as endothelin 1, erythropoietin, glucose transporter 1, and vascular endothelial growth factor. Findings were replicated in an in-vivo Hep3B HRE-Luc expressing xenograft, and were associated with significant decreases in xenograft tumor size. Altogether, this study highlights a novel mechanism of action of an important class of chemotherapeutic.

INTRODUCTION Glioblastoma (GBM) is the most common malignant primary brain tumor and has a heterogeneous tumor cell population. The median survival of GBM patients is less than two years with current multi-model therapy of maximal surgical resection followed by chemotherapy, radiation and tumor treating fields. Protein Arginine Methyltransferase 5 (PRMT5) regulates cellular functions through symmetric di-methylation of arginine residues of histone and non-histone proteins. Our recent findings show that PRMT5 is overexpressed in GBM; its inhibition causes apoptosis and senescence of mature and immature GBM tumor cells respectively. Protein Phosphatase 2A (PP2A), a serine-threonine phosphatase, is associated with senescent tumor cells that contribute to therapy resistance; LB100 is a first-in-class small molecule inhibitor of PP2A that can sensitize tumor cells that are chemo- and radiation-therapy resistant. In this study, using patient-derived primary GBM neurospheres (GBMNS), we tested the anti-GBM effect of concurrent PRMT5 and PP2A inhibition. METHODS Patient-derived primary GBM neurospheres transfected with PRMT5 target-specific siRNA were treated with LB100 and subjected to in vitro assays such as proliferation assay, cell cycle analysis, cytotoxicity assay, PP2A activity and western blot. RESULTS LB100 treatment significantly reduced the viability of PRMT5-depleted GBM cells as compared to PRMT5 intact cells. LB100 caused G1 cell cycle arrest through inactivation of Rb protein; this effect is further enhanced in combination with PRMT5-depletion. Combination therapy also increased the expression of phospho-MLKL; Necrostatin-1 rescued PRMT5-depleted cells from the cytotoxic effects of LB100 indicating that necroptosis caused the enhanced cytotoxicity in combination therapy. We also found that PRMT5-depletion increased the PP2A activity in GBM neurospheres. CONCLUSION Combining the PRMT5 inhibition and PP2A inhibition produced greater antitumor effects than with PRMT5 inhibition alone.

We report an index case of a male patient who presented with all clinical manifestations of Pacak-Zhuang syndrome, including early-age polycythemia, multiple pheochromocytomas/paragangliomas, duodenal somatostatinoma, and ocular findings. Sequencing analysis detected an EPAS1 mutation in all tumors tested, but not in the germline.

Advances in the understanding of growth hormone-producing adenomas (GHomas) are ongoing, but current therapy is limited by moderate and variable efficacy and in need of life-long treatment. In this study, the molecular signaling pathway related to GHoma was investigated by proteomics and transcriptomics. The differentially expressed proteins and genes were significantly enriched in Extracellular Matrix-Receptor Interactions, Notch Signaling, Basal Cell Carcinoma Signaling, JAK-STAT3, Wnt Signaling, and Glioblastoma Multiforme Signaling by Ingenuity Pathway Analysis. Furthermore, the Notch2/Delta-like canonical Notch ligand (DLL) signaling pathway was identified to be associated with tumorigenesis and invasiveness of GHoma. In 76 patients, Notch2 and DLL3 were upregulated in invasive compared to those in non-invasive GHoma (p < 0.05). Disease-free survival was significantly longer in patients with low, compared with high, DLL3 expression (p = 0.027). Notch 2 knockdown inhibited cell migration in both GH3 cells and primary GHoma cells, along with downregulation of the mRNA expression of related genes. DAPT, a γ-secretase inhibitor, inhibited tumor growth and invasion in vivo and in vitro and suppressed the release of growth hormone in primary GHoma cells. The involvement of Notch2/DLL3 signaling in GHoma progression warrants additional study of Notch inhibitor, DAPT, as a potential GHoma treatment. Importance of the Study Current treatments of GH adenomas (GHomas) are limited by their moderate and variable efficacy and in need of life-long treatment. We found that the Notch2/Delta-like Notch ligand 3 (DLL3) signaling pathway was active in GHoma tumorigenesis, progression, and invasion. The γ-secretase inhibitor DAPT is of potential use in GHoma treatment targeting Notch signaling.

The posterior fossa of the cranium contains the cerebellum and brainstem. Processes that reduce the volume of the posterior fossa squeeze the cerebellum and brainstem caudally, resulting in Chiari I malformation (CM1). CM1 causes neck pain, balance issues, decreased motor skills and headaches in those affected. We have posterior fossa measurements and whole exome sequence data on individuals from 7 extended families from Russia that have a family history of CM1. We performed parametric linkage analyses using an autosomal dominant inheritance model with a disease allele frequency of 0.01 and a penetrance of 0.8 for carriers and 0.0 for non-carriers. Variant-based two-point linkage analysis and gene-based linkage analysis was performed. Our results found a genome-wide significant signal on chromosome 1q43-44 (max HLOD = 3.3) in the variant-based analysis and 12q23 (max HLOD = 4.2) in the gene-based analysis. In both cases, the signal was driven by a single (different) family that contained a long, linked haplotype across the region in question. Using functional annotation, we were able to identify several rare nonsynonymous variants that were enriched in each family. The best candidate genes were rs765865412:G>A in MYBPC1 for the 12q haplotype and rs61749963:A>G in COX20 for the 1q haplotype. Good candidate variants in the 1q haplotype were also identified in CEP170 and AKT. Further laboratory work is planned to verify the causality of these genes.

A syndrome of multiple paragangliomas/pheochromocytomas, somatostatinoma, and polycythemia due to somatic mosaic gain-of-function mutation of EPAS1, encoding HIF-2α, was previously described. HIF-2α has been implicated in endochondral and intramembranous ossification. Abnormal bone growth of the skull base may lead to Chiari malformation type I. We report two cases of EPAS1 gain-of-function mutation syndrome with Chiari malformation and developmental skull base anomalies. Patients were referred to the Section on Medical Endocrinology, Eunice Kennedy Shriver NICHD, NIH for evaluation of recurrent and metastatic paragangliomas or pheochromocytoma. The syndrome was confirmed genetically by identification of the functional EPAS1 gain-of-function mutation in the resected tumors and circulating leukocytes. Both patients were confirmed for characteristics of EPAS1 gain-of-function mutation syndrome by complete blood count (CBC), plasma biochemistry, and computed tomography (CT) of the abdomen and pelvis. Chiari malformation type I and abnormal bony development of the posterior fossa was found on MRI and CT of the head. The present study implicates EPAS1 mutations in abnormal posterior fossa development resulting in Chiari malformation type I.

Therapeutic options for metastatic pheochromocytoma/paraganglioma (PHEO/PGL) are limited. Here, we tested an immunotherapeutic approach based on intratumoral injections of mannan-BAM with toll-like receptor ligands into subcutaneous PHEO in a mouse model. This therapy elicited a strong innate immunity-mediated antitumor response and resulted in a significantly lower PHEO volume compared to the phosphate buffered saline (PBS)-treated group and in a significant improvement in mice survival. The cytotoxic effect of neutrophils, as innate immune cells predominantly infiltrating treated tumors, was verified in vitro. Moreover, the combination of mannan-BAM and toll-like receptor ligands with agonistic anti-CD40 was associated with increased mice survival. Subsequent tumor re-challenge also supported adaptive immunity activation, reflected primarily by long-term tumor-specific memory. These results were further verified in metastatic PHEO, where the intratumoral injections of mannan-BAM, toll-like receptor ligands, and anti-CD40 into subcutaneous tumors resulted in significantly less intense bioluminescence signals of liver metastatic lesions induced by tail vein injection compared to the PBS-treated group. Subsequent experiments focusing on the depletion of T cell subpopulations confirmed the crucial role of CD8+ T cells in inhibition of bioluminescence signal intensity of liver metastatic lesions. These data call for a new therapeutic approach in patients with metastatic PHEO/PGL using immunotherapy that initially activates innate immunity followed by an adaptive immune response.

We previously identified a novel syndrome in patients characterized by paraganglioma, somatostatinoma, and polycythemia. In these patients, polycythemia occurs long before any tumor develops, and tumor removal only partially corrects polycythemia, with recurrence occurring shortly after surgery. Genetic mosaicism of gain-of-function mutations of the EPAS1 gene (encoding HIF2&alpha, ) located in the oxygen degradation domain (ODD), typically p.530&ndash, 532, was shown as the etiology of this syndrome. The aim of the present investigation was to demonstrate that these mutations are necessary and sufficient for the development of the symptoms. We developed transgenic mice with a gain-of-function Epas1A529V mutation (corresponding to human EPAS1A530V), which demonstrated elevated levels of erythropoietin and polycythemia, a decreased urinary metanephrine-to-normetanephrine ratio, and increased expression of somatostatin in the ampullary region of duodenum. Further, inhibition of HIF2&alpha, with its specific inhibitor PT2385 significantly reduced erythropoietin levels in the mutant mice. However, polycythemia persisted after PT2385 treatment, suggesting an alternative erythropoietin-independent mechanism of polycythemia. These findings demonstrate the vital roles of EPAS1 mutations in the syndrome development and the great potential of the Epas1A529V animal model for further pathogenesis and therapeutics studies.

Background: Somatic mutations in hypoxia-inducible factor 2α (HIF2A) is associated with polycythemia-paraganglioma syndrome. Specifically, the classic presentation of female patients with recurrent paragangliomas (PGLs), polycythemia (at birth or in early childhood), and duodenal somatostatinomas has been described. Studies have demonstrated that somatic HIF2A mutations occur as postzygotic events and some to be associated with somatic mosaicism affecting hematopoietic and other tissue precursors. This phenomenon could explain the development of early onset of polycythemia in the absence of erythropoietin secreting tumors. Methods: Correlation analysis was performed between mosaicism of HIF2A mutant patients and clinical presentations. Results: Somatic HIF2A mutations (p.A530V, p.P531S and p.D539N) were identified in DNA extracted from PGLs of three patients. No somatic mosaicism was detected through deep sequencing of blood genomic DNA. Compared to classic syndrome, both polycythemia and PGL in all three patients developed at an advanced age with polycythemia at 30, 30, and 17 and PGLs at age 34, 30, and 55 years, respectively. Somatostatinomas were not detected and two patients had ophthalmic findings. The biochemical phenotype in all three patients was noradrenergic with 18F-fluorodopa PET/CT as the most sensitive imaging modality. All patients demonstrated multiplicity and none developed metastatic disease. Conclusions: These findings suggest that newer techniques need to be developed to detect germline or somatic mosaicism in patients with this syndrome. Absence of HIF2A mosaicism in patients with somatic HIF2A mutations supports association with late onset of the disease, milder clinical phenotype and an improved prognosis compared to patients with HIF2A mosaicism.

We previously identified a novel syndrome in patients characterized by paraganglioma, somatostatinoma, and polycythemia. In these patients, polycythemia occurs long before any tumor develops, and tumor removal only partially corrects polycythemia, with recurrence occurring shortly after surgery. Genetic mosaicism of gain-of-function mutations of the EPAS1 gene (encoding HIF2α) located in the oxygen degradation domain (ODD), typically p.530–532, was shown as the etiology of this syndrome. The aim of the present investigation was to demonstrate that these mutations are necessary and sufficient for the development of the symptoms. We developed transgenic mice with a gain-of-function Epas1A529V mutation (corresponding to human EPAS1A530V), which demonstrated elevated levels of erythropoietin and polycythemia, a decreased urinary metanephrine-to-normetanephrine ratio, and increased expression of somatostatin in the ampullary region of duodenum. Further, inhibition of HIF2α with its specific inhibitor PT2385 significantly reduced erythropoietin levels in the mutant mice. However, polycythemia persisted after PT2385 treatment, suggesting an alternative erythropoietin-independent mechanism of polycythemia. These findings demonstrate the vital roles of EPAS1 mutations in the syndrome development and the great potential of the Epas1A529V animal model for further pathogenesis and therapeutics studies.

Background The bromodomain and extra-terminal domain (BET) inhibitor is a type of anti-tumor agent, currently being evaluated in phase I and II clinical trials for cancer therapy. It can decrease MYC expression levels and cause effective anti-tumor effects in diverse human cancers. However, its cytotoxic effect and related mechanisms of drug resistance are poorly understood in hepatocellular carcinomas (HCC). Here, we investigated the anti-tumor effects of BET inhibitor on HCC and the molecular mechanisms involved in its associated drug resistance. Methods We assessed the cytotoxicity of BET inhibitor on HCC cells compared with sorafenib by cell viability assay, metastasis assay and reproduced the anti-tumor effect in xenograft mouse model. In addition, the molecular mechanisms involved in drug resistance on JQ1-resistant HCC cells were revealed by western blotting, qRT-PCR, whole exome-sequencing and gene-editing technology. Finally, with specific inhibition of EGFR or ERK activity by interference RNAs or inhibitors, the efficacy of the synergistic treatment was investigated using cell viability assay, colony formation, apoptosis and xenograft mouse model. Results We found that JQ1, a commonly used BET bromo-domain inhibitor, offered a better anti-tumor response than sorafenib in MYC-positive HCC cells by inducing apoptosis in vitro and in vivo. Unlike sorafenib, JQ1 treatment significantly impaired mitochondrial respiration and glycolysis in HCC cells. Importantly, we revealed that MAPK activation by a previously undescribed activating mutation of EGFR-I645L, was critical for JQ1 sensitivity through stabilizing oncogenic MYC protein in JQ1-resistant HCC cells. Inhibition of either EGFR or ERK activity overcame the JQ1 resistance and significantly decreased MYC protein level in vitro and in vivo. Conclusion Since MYC amplification is frequently identified in HCC, co-occurring with EGFR amplification, our findings suggest that targeting EGFR signaling might be essential for JQ1 therapy in advanced HCC. Electronic supplementary material The online version of this article (10.1186/s13046-019-1082-6) contains supplementary material, which is available to authorized users.

Additional file 7: Table S4. The H-Score of IDH2 in different subtypes of pituitary adenomas.

Targeting glutamine metabolism in cancer has become increasingly vibrant area of research. Mutant IDH1 (IDH1mut) gliomas are considered good candidates for targeting this pathway because of the contribution of glutamine to their newly acquired function: synthesis of 2-hydroxyglutarate (2HG). Here, we report the adaptability of IDH1mut cells’ metabolism to the inhibition of glutamine/glutamate pathway. The glutaminase inhibitor CB839 showed decreased production of the downstream metabolites of glutamate, including those involved in the TCA cycle and 2HG. However, this effect on metabolism was not extended to viability; rather, our patient-derived IDH1mut cell lines display a metabolic plasticity that allows them to overcome glutaminase inhibition. The major metabolic adaptation involved pathways that can generate glutamate by using alternative substrates from glutamine, such as alanine or aspartate. Indeed, asparagine synthetase was upregulated both in vivo and in vitro revealing a new potential therapeutic target for a combinatory approach with CB839 against IDH1mut gliomas.

Heat shock protein 90 (HSP-90) has been identified in many disease processes including cancer, neurodegeneration, autoimmune diseases, and cancers. Great effort has been expended in the development of specific inhibitors of the N-terminal and C-terminal domains. Inhibitors of post-translational modification have also been developed. Herein, we explore the available inhibitors and those in development, discuss the relevant disease processes, and examine the pitfalls and promises of targeting HSP-90 for therapeutic intervention.

Metabolomics has shown significant potential in identifying small molecules specific to tumor phenotypes. In this study we analyzed resected tissue metabolites using capillary electrophoresis-mass spectrometry and found that tissue hypotaurine levels strongly and positively correlated with glioma grade. In vitro studies were conducted to show that hypotaurine activates hypoxia signaling through the competitive inhibition of prolyl hydroxylase domain-2. This leads to the activation of hypoxia signaling as well as to the enhancement of glioma cell proliferation and invasion. In contrast, taurine, the oxidation metabolite of hypotaurine, decreased intracellular hypotaurine and resulted in glioma cell growth arrest. Lastly, a glioblastoma xenograft mice model was supplemented with taurine feed and exhibited impaired tumor growth. Taken together, these findings suggest that hypotaurine is an aberrantly produced oncometabolite, mediating tumor molecular pathophysiology and progression. The hypotaurine metabolic pathway may provide a potentially new target for glioblastoma diagnosis and therapy.

The protein phosphatase 2A (PP2A) inhibitor, LB100, has been shown in pre-clinical studies to be an effective chemo- and radio-sensitizer for treatment of various cancers. We investigated effects associated with LB100 treatment alone and in combination with cisplatin for medulloblastoma (MB) in vitro and in vivo in an intracranial xenograft model. We demonstrated that LB100 had a potent effect on MB cells. By itself, LB100 inhibited proliferation and induced significant apoptosis in a range of pediatric MB cell lines. It also attenuated MB cell migration, a pre-requirement for invasion. When used in combination, LB100 enhanced cisplatin-mediated cytotoxic effects. Cell viability in the presence of 1 uM cisplatin alone was 61% (DAOY), 100% (D341), and 58% (D283), but decreased with the addition of 2 μM of LB100 to 26% (DAOY), 67% (D341), and 27% (D283), (p < 0.005). LB100 suppressed phosphorylation of the STAT3 protein and several STAT3 downstream targets. Also, LB100 directly increased cisplatin uptake and overcame cisplatin-resistance in vitro. Finally, LB100 exhibited potent in vivo anti-neoplastic activity in combination with cisplatin in an intracranial xenograft model.

Objective: To report the functional imaging experience with a 29-year-old woman carrying a mutation in the fumarate hydratase (FH)-encoding gene and a history of a pheochromocytoma (PHEO) and retroperitoneal paraganglioma (PGL).Methods: The patient was found to have a splice-site mutation in the FH gene at intron 2, c.268-2A>G. To confirm this, immunohistochemical staining was performed on tumor tissue slides from the patient's previous surgeries. The patient underwent biochemical testing for PHEO/PGL, which included chromogranin A and plasma methoxytyramine. The patient's tumors were also imaged using several imaging modalities, including computed tomography (CT), magnetic resonance imaging, ultrasound, and positron emission tomography (PET)/CT studies using &lsqb;18F]-fluorodeoxyglucose (&lsqb;18F]-FDG), &lsqb;18F]-fluorodopamine (&lsqb;18F]-FDA), &lsqb;18F]-fluorodihydroxyphenylalanine (&lsqb;18F]-FDOPA), and &lsqb;68Ga]-tetraazacyclododecanetetraacetic acid–&lsqb;Tyr3]-octreotate (&lsqb;68Ga]-DOTATATE) as tracers.Results: The patient received a comprehensive evaluation based on her symptoms and medical history. She was found to have 3 noradrenergic-secreting tumors that showed uptake on &lsqb;18F]-FDG-(2/3), &lsqb;68Ga]-DOTATATE-(2/3), &lsqb;18F]-FDOPA-(3/3), and &lsqb;18F]-FDA-(3/3) PET/CT. The patient was recommended to have the tumor sites removed (renal hilum, aortocaval, and periaortic regions) with lympadenectomies to address possible metastases. Pathology confirmed paraganglioma. Immunohistochemical staining from previous surgical slides showed negative staining for FH, consistent with a mutation in the gene.Conclusion: We share, for the first time, functional images for an FH mutation–positive PHEO/PGL patient using various PET radiopharmaceuticals. &lsqb;18F]-FDA- and &lsqb;18F]-FDOPA PET/CT served as the best imaging modalities. This case provides the appropriate selection of imaging studies and further evidence for the importance of screening for FH mutations in patients with noradrenergic PHEOs/PGLs.Abbreviations: CT = computed tomography &lsqb;18F]-FDA = &lsqb;18F]-fluorodopamine &lsqb;18F]-FDG = &lsqb;18F]-fluorodeoxyglucose &lsqb;18F]-FDOPA = &lsqb;18F]-fluorodihydroxyphenylalanine FH = fumarate hydratase &lsqb;68Ga]-DOTATATE = &lsqb;68Ga]-tetraazacyclododecanetetraacetic acid–&lsqb;Tyr3]-octreotate MTY = methoxytyramine NIH = National Institutes of Health PET = positron emission tomography PGL = paraganglioma PHEO = pheochromocytoma SDHB = succinate dehydrogenase complex, subunit B URL = upper reference limit

Objective: The normal blood–brain barrier (BBB) is composed of tight junctions between endothelial cells and surrounding astrocyte foot processes. Breakdown of the physiological astrocyte-endothelial cell relationship occurs in adult metastatic and primary brain tumors. However, the astrocyte-endothelial cell relationship has not been studied in pediatric tumors. Materials and Methods: Utilizing specimens from cases of pilocytic astrocytoma (n = 5), medulloblastoma (n = 5), and low-grade diffuse astrocytoma (n = 1), immunofluorescence were performed using primary antibodies against CD31, glial fibrillary acidic protein (GFAP), and aquaporin 4 (AQ4). Clinical, magnetic resonance imaging, operative, and histopathological findings were analyzed. Results: Strongly-enhancing areas of medulloblastoma exhibited complete BBB breakdown with sparse GFAP and AQ4 staining around CD31-positive vessels. Moderately enhancing regions of pilocytic astrocytomas exhibited regions of intact BBB and vasculature surrounded by dense GFAP staining but reduced and disorganized AQ4 staining, suggesting tumor cells could not fulfill physiological BBB support. Non-enhancing low-grade diffuse astrocytoma demonstrated intact BBB with intense peri-microvasculature GFAP and AQ4 staining. AQ4 stained so strongly that AQ4 visualization alone delineated CD31-positive vessels. Conclusion: Taken together, BBB breakdown in pediatric tumors corresponds to a loss of normal endothelial cell-astrocyte foot process relationships. Further development of pharmaceutical agents capitalizing on this disrupted BBB is warranted in medulloblastoma and pilocytic astrocytoma. However, BBB integrity remains a challenge in treating low-grade diffuse astrocytoma before progression toward secondary glioblastoma.

Emerging evidence is demonstrating the extent of T-cell infiltration within the tumor microenvironment has favorable prognostic and therapeutic implications. Hence, immunotherapeutic strategies that augment the T-cell signature of tumors hold promising therapeutic potential. Recently, immunotherapy based on intratumoral injection of mannan-BAM, toll-like receptor ligands and anti-CD40 antibody (MBTA) demonstrated promising potential to modulate the immune phenotype of injected tumors. The strategy promotes the phagocytosis of tumor cells to facilitate the recognition of tumor antigens and induce a tumor-specific adaptive immune response. Using a syngeneic colon carcinoma model, we demonstrate MBTA’s potential to augment CD8(+) T-cell tumor infiltrate when administered intratumorally or subcutaneously as part of a whole tumor cell vaccine. Both immunotherapeutic strategies proved effective at controlling tumor growth, prolonged survival and induced immunological memory against the parental cell line. Collectively, our investigation demonstrates MBTA’s potential to trigger a potent anti-tumor immune response.

IMPORTANCE: Patients with the EPAS1 gain-of-function mutation syndrome (or Pacak-Zhuang syndrome) present with multiple paragangliomas or pheochromocytomas, duodenal somatostatinoma, polycythemia, headaches, and sometimes diminished visual acuity at an early age. The characteristic phenotype and known genetic cause of the syndrome provide an opportunity to study the role of hypoxia-inducible factor 2α (HIF-2α) in oxygen sensing, development in regions of physiologic hypoxia, and other pathological processes. OBJECTIVES: To describe the ocular lesions in EPAS1 gain-of-function mutation syndrome and to establish whether early-onset diminished visual acuity is developmental or associated with long-term physiologic sequelae of the syndrome. DESIGN, SETTING, AND PARTICIPANTS: This clinical case series with a transgenic murine model study was conducted from July 2013 to June 2019. Participants were 3 patients referred by their primary care physicians to the National Institutes of Health for evaluation of recurrent and metastatic paragangliomas or pheochromocytomas accompanied by polycythemia. The syndrome and somatic mosaicism in patients were confirmed by the identification of gain-of-function mutations in the EPAS1 gene in resected tumors and other tissues. MAIN OUTCOMES AND MEASURES: Ocular findings in patients with EPAS1 gain-of-function mutation syndrome. RESULTS: A total of 3 patients (mean [SD] age, 29 [6.2] years) with confirmed ocular abnormalities were included in the study. Increased contrast accumulation at the posterior aspect of the globe was seen bilaterally on magnetic resonance imaging scans in all patients. Ophthalmoscopy images demonstrated fibrosis overlying the optic disc, tortuous and dilated retinal vessels, and retinal pigment epithelium changes. Optic disc edema and retinal exudates were also seen. Fluorescein angiography images showed leakage of dye from postcapillary venules surrounding the optic disc and highlighted aberrant retinal vascular patterns. Enhanced-depth imaging optical coherence tomography images showed substantial thickening of the choroid and dilation of choroidal vessels. The ocular features of the syndrome were confirmed with a transgenic model of mice with gain-of-function Epas1(A529V) mutation. CONCLUSIONS AND RELEVANCE: In this case series, HIF-2α and hypoxia signaling was found to have a role in vessel development within the choroid and retina, indicating that the marked permanent choroidal thickening and tortuous and dilated veins seen in the choroid and retina in patients with EPAS1 gain-of-function mutation syndrome were suggestive of the persistence of venous elements within the developing mesenchyme. These findings may explain other eye and vascular abnormalities whose pathogenesis remains unclear.

BACKGROUND: Increasing evidence suggests a role of increased expression of CDK5 in cancer progression. Here, we examined the efficacy of selective inhibition of CDK5 in glioblastoma, the most frequent and aggressive primary brain tumor in adults. TP5 is a small peptide developed by National Institutes of Health which selectively inhibits aberrant and hyperactive CDK5/p25 while preserving the physiological CDK5/p35 functions. This peptide was modified to facilitate passage through blood brain barrier. METHODS & RESULTS: We demonstrated that TP5 decreased the activity but not the expression of CDK5 and p35. TP5 alone, but not the scrambled peptide, impacted cell viability and colony formation of glioblastoma cell lines and increased early and late apoptosis. Analyzing the pH2A.X expression by Immunofluorescence and Western Blot, we observed that TP5 increased the DNA damage in a dose dependent manner. TP5 impaired the DNA repair by reducing the G2 phase and decreased the phosphorylation of ATM. Whereas CDK5 activity is increased by DNA-damaging agents such as temozolomide (TMZ) and irradiation (IR), we observed that the addition of TP5 to either TMZ or IR was synergistic on colony formation due to an accumulation of DNA damages. Concomitant use of TP5 and either TMZ or IR increased the pH2A.X foci number and expression, inhibited the G2 arrest induced by these therapies and the phosphorylation of ATM. TP5 alone (300 mg/kg every 2 days) decreased the tumor volume of orthotopic glioblastoma mouse-model in a safety and dose-escalation experiment (4 mice per group: control, scrambled peptide, 100mg/kg, 300mg/kg). The treatment was well tolerated as the mouse weights were stable during the treatment and no hematologic, renal, pancreatic or liver function toxicities were observed (blood test). CONCLUSIONS: TP5 is a promising therapy for glioblastoma patients alone or in association with temozolomide and radiotherapy targeting a unique aspect of tumor biology.

BACKGROUND: Somatic mutations in hypoxia-inducible factor 2α (HIF2A) is associated with polycythemia-paraganglioma syndrome. Specifically, the classic presentation of female patients with recurrent paragangliomas (PGLs), polycythemia (at birth or in early childhood), and duodenal somatostatinomas has been described. Studies have demonstrated that somatic HIF2A mutations occur as postzygotic events and some to be associated with somatic mosaicism affecting hematopoietic and other tissue precursors. This phenomenon could explain the development of early onset of polycythemia in the absence of erythropoietin secreting tumors. METHODS: Correlation analysis was performed between mosaicism of HIF2A mutant patients and clinical presentations. RESULTS: Somatic HIF2A mutations (p.A530V, p.P531S and p.D539N) were identified in DNA extracted from PGLs of three patients. No somatic mosaicism was detected through deep sequencing of blood genomic DNA. Compared to classic syndrome, both polycythemia and PGL in all three patients developed at an advanced age with polycythemia at 30, 30, and 17 and PGLs at age 34, 30, and 55 years, respectively. Somatostatinomas were not detected and two patients had ophthalmic findings. The biochemical phenotype in all three patients was noradrenergic with (18)F-fluorodopa PET/CT as the most sensitive imaging modality. All patients demonstrated multiplicity and none developed metastatic disease. CONCLUSIONS: These findings suggest that newer techniques need to be developed to detect germline or somatic mosaicism in patients with this syndrome. Absence of HIF2A mosaicism in patients with somatic HIF2A mutations supports association with late onset of the disease, milder clinical phenotype and an improved prognosis compared to patients with HIF2A mosaicism.

Hypoxia-inducible factor-1α (HIF-1α) has been identified as an unfavorable prognostic factor in most solid tumors. However, HIF-1α was suggested to predict improved survival in Western patients with diffuse large B-cell lymphoma (DLBCL) under rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) treatment. We studied HIF-1α protein expression by immunohistochemical staining of 155 paraffin-embedded specimens from Chinese patients with DLBCL treated with R-CHOP or CHOP. Results were correlated with patient outcome. HIF-1α expression had no impact on survival for the patients treated with CHOP. In the R-CHOP-treated group, however, HIF-1α expression was significantly correlated with superior OS and EFS (P = 0.048 and 0.040, respectively). Moreover, HIF-1α expression maintained independent prognostic value for OS (RR, 0.41; 95% CI, 0.19-0.92; P = 0.030) and EFS (RR, 0.53; 95% CI, 0.31-0.90; P = 0.020) when it was adjusted by IPI stratification. Therefore, HIF-1α expression benefits from R-CHOP in DLBCL.

Mounting evidence suggests that inhibition of protein phosphatase-2A (PP2A), a serine/threonine phosphatase, could enhance anticancer immunity. However, drugs targeting PP2A are not currently available. Here, we report that a PP2A inhibitor, LB-100, when combined with anti-PD-1 (aPD-1) blockade can synergistically elicit a durable immune-mediated antitumor response in a murine CT26 colon cancer model. This effect is T-cell dependent, leading to regression of a significant proportion of tumors. Analysis of tumor lymphocytes demonstrates enhanced effector T-cell and reduced suppressive regulatory T-cell infiltration. Clearance of tumor establishes antigen-specific secondary protective immunity. A synergistic effect of LB-100 and aPD-1 blockade is also observed in B16 melanoma model. In addition, LB-100 activates the mTORC1 signaling pathway resulting in decreased differentiation of naive CD4 cells into regulatory T cells. There is also increased expression of Th1 and decreased expression of Th2 cytokines. These data highlight the translational potential of PP2A inhibition in combination with checkpoint inhibition., Protein phosphatase 2A (PP2A) has been proposed as a target for cancer immunotherapy. Here the authors show that pharmacological inhibition of PP2A with a clinically-relevant inhibitor enhances response to immune checkpoint blockade in pre-clinical models of cancer, resulting in long lasting immunity.

Background The role of the hypoxia signaling pathway in the pathogenesis of pheochromocytoma/paraganglioma (PPGL)-polycythemia syndrome has been elucidated. Novel somatic mutations in hypoxia-inducible factor type 2A (HIF2A) and germline mutations in prolyl hydroxylase type 1 and type 2 (PHD1 and PHD2) have been identified to cause upregulation of the hypoxia signaling pathway and its target genes including erythropoietin (EPO) and its receptor (EPOR). However, in a minority of patients presenting with this syndrome, the genetics and molecular pathogenesis remain unexplained. The aim of the present study was to uncover novel genetic causes of PPGL-polycythemia syndrome. Case presentation A female presented with a history of JAK2 V617F positive PV, diagnosed in 2007, and right adrenal pheochromocytoma diagnosed and resected in 2011. Her polycythemia symptoms and hematocrit levels continued to worsen from 2007 to 2011, with an increased frequency of phlebotomies. Postoperatively, until early 2013, her hematocrit levels remained normalized. Following this, the hematocrit levels ranged between 46.4 and 48.9% [35–45%]. Tumor tissue from the patient was further tested for mutations in genes related to upregulation of the hypoxia signaling pathway including iron regulatory protein 1 (IRP1), which is a known regulator of HIF-2α mRNA translation. Functional studies were performed to investigate the consequences of these mutations, especially their effect on the HIF signaling pathway and EPO. Indel mutations (c.267-1_267delGGinsTA) were discovered at the exon 3 splicing site of IRP1. Minigene construct and splicing site analysis showed that the mutation led to a new splicing site and a frameshift mutation of IRP1, which caused a truncated protein. Fluorescence in situ hybridization analysis demonstrated heterozygous IRP1 deletions in tumor cells. Immunohistochemistry results confirmed the truncated IRP1 and overexpressed HIF-2α, EPO and EPOR in tumor cells. Conclusions This is the first report which provides direct molecular genetic evidence of association between a somatic IRP1 loss-of-function mutation and PHEO and secondary polycythemia. In patients diagnosed with PHEO/PGL and polycythemia with negative genetic testing for mutations in HIF2A, PHD1/2, and VHL, IRP1 should be considered as a candidate gene.

Immunotherapy based on activation of innate immunity has been tested in syngeneic mouse tumor models via intratumoral administration of the following components: phagocytosis-stimulating ligands (Mannan-BAM), toll-like receptor (TLR) agonists, and immunostimulant anti-CD40 antibody (abbreviated as MBTA). In this study, syngeneic colon carcinoma (CT26) and glioma (GL261) models were established to assess MBTA’s efficacy in generating immune responses against distal metastatic lesions and CNS tumors. Additionally, we investigated if therapeutic delivery of MBTA could be optimized beyond intratumoral delivery. In the colon carcinoma model, intratumoral injection of MBTA significantly reduced all metastatic CT26 tumor growth rate and induced complete remission (CR) in 33% (3/9) of treated animals. In the glioma model, subcutaneous injection of GL261 cells incubated with MBTA resulted in the complete regression of intracranial gliomas in 87.5% (7/8) of treated animals. Therapeutic effect of MBTA was abrogated in CD4+ and CD8+ lymphocyte depleted mice. Tumor infiltrating leukocyte analyses demonstrated significantly increased CD8+ cytotoxic T-lymphocytes (CTL) in metastatic tumors with higher percentages of TNFα and IFNγ positive cells. Further assessments with MHC I tetramers revealed significantly increased CT26-associated peptide (AH1) specific CTLs in the blood of MBTA treated animals. All animals that achieved complete remission in the colon carcinoma model resisted subsequent peripheral and intracranial challenges with CT26 cells, confirming the induction of immunological memory against CT26 tumors. Collectively, our investigation demonstrates that MBTA can effectively induce a tumor-specific adaptive immune response that can target tumors located in the periphery and within the CNS.

Purpose: Glioblastoma (GBM) is highly resistant to treatment, largely due to disease heterogeneity and resistance mechanisms. We sought to investigate a promising drug that can inhibit multiple aspects of cancer cell survival mechanisms and become an effective therapeutic for GBM patients. Experimental Design: To investigate TG02, an agent with known penetration of the blood–brain barrier, we examined the effects as single agent and in combination with temozolomide, a commonly used chemotherapy in GBM. We used human GBM cells and a syngeneic mouse orthotopic GBM model, evaluating survival and the pharmacodynamics of TG02. Mechanistic studies included TG02-induced transcriptional regulation, apoptosis, and RNA sequencing in treated GBM cells as well as the investigation of mitochondrial and glycolytic function assays. Results: We demonstrated that TG02 inhibited cell proliferation, induced cell death, and synergized with temozolomide in GBM cells with different genetic background but not in astrocytes. TG02-induced cytotoxicity was blocked by the overexpression of phosphorylated CDK9, suggesting a CDK9-dependent cell killing. TG02 suppressed transcriptional progression of antiapoptotic proteins and induced apoptosis in GBM cells. We further demonstrated that TG02 caused mitochondrial dysfunction and glycolytic suppression and ultimately ATP depletion in GBM. A prolonged survival was observed in GBM mice receiving combined treatment of TG02 and temozolomide. The TG02-induced decrease of CDK9 phosphorylation was confirmed in the brain tumor tissue. Conclusions: TG02 inhibits multiple survival mechanisms and synergistically decreases energy production with temozolomide, representing a promising therapeutic strategy in GBM, currently under investigation in an ongoing clinical trial. Clin Cancer Res; 24(5); 1124–37. ©2017 AACR.

International audience; Central nervous system hemangioblastomas (CNS-HBs) occur sporadically or as a component of von Hippel-Lindau-VHL syndrome. CNS-HBs share some molecular similarities with pheochromocytomas/paragangliomas (PPGLs) and renal cell carcinomas (RCCs). Recently, hypoxia-inducible factors, particularly somatic HIF2A mutations, have been found to play an important role in the pathogenesis of PPGLs. Somatic mutations in HIF2A have been reported in PPGLs associated with polycythemia, which have been reported to also be present in patients with RCCs and HBs. However, whether CNS-HBs is associated with the presence of a HIF2A mutation is currently uknown. We analyzed somatic HIF2A and VHL mutations in a series of 28 sporadic CNS-HBs. We also investigated the expression of HIF target proteins and hypoxia-associated factor (HAF). Two sporadic CNS-HBs were found to have somatic HIF2A mutations. One tumor had 2 HIF2A missense mutations, one of which was previously described in a PPGL (c.1121 T\textgreaterA, F374Y). The second patient had coexistence of somatic truncated mutations (c.1669 C\textgreaterT, Q557*) in HIF2A together with a VHL mutation. Neither of the two patients had polycythemia at the time of diagnosis. We demonstrate that the novel truncated mutation in HIF2A (Q557*) affects HIF-2α prolyl hydroxylation with its reduced ubiquitination but intact transcriptional activity, resulting in an activating effect. Both CNS-HB samples showed positive expression of VEGFR2/CA9/Glut1 and HAF. Our data support the unique central role of the VHL/HIF-2α signaling pathway in the molecular pathogenesis of CNS-HBs and show for the first time the presence of HIF2A mutations in sporadic HB.

There has been increasing evidence that pseudohypoxia--a phenomenon that we refer to as "gasping for air"--along with mitochondrial enzyme dysregulation play a crucial role in tumorigenesis, particularly in several hereditary pheochromocytomas (PHEOs) and paragangliomas (PGLs). Alterations in key tricarboxylic acids (TCA) cycle enzymes (SDH, FH, MDH2) have been shown to induce pseudohypoxia via activation of the hypoxia-inducible transcription factor (HIF) signaling pathway that is involved in tumorigenesis, invasiveness, and metastatic spread, including an association with resistance to various cancer therapies and worse prognosis. This review outlines the ongoing story of the pathogenesis of hereditary PHEOs/PGLs, showing the unique and most updated evidence of TCA cycle dysregulation that is tightly linked to hypoxia signaling.