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Uveal melanomas (UMs) represent rare malignant tumors associated with grim prognosis for the majority of patients. DAXX (Death Domain-Associated Protein), HJURP (Holliday Junction Recognition Protein) and CENPA (Centromere Protein A) proteins are implicated in epigenetic mechanisms, now in the spotlight of cancer research to better understand the molecular background of tumorigenesis. Herein, we investigated their expression in UM tissues using immunohistochemistry and explored possible correlations with a multitude of clinicopathological and survival parameters. The Cancer Genome Atlas Program (TCGA) was used for the investigation of their mRNA levels in UM cases. Nuclear DAXX expression correlated with an advanced T-stage (p = 0.004), while cytoplasmic expression marginally with decreased disease-free survival (DFS) (p = 0.084). HJURP nuclear positivity also correlated with advanced T-status (p = 0.054), chromosome 3 loss (p = 0.042) and increased tumor size (p = 0.03). More importantly, both nuclear and cytoplasmic HJURP immunopositivity correlated with decreased overall survival (OS) (p = 0.011 and 0.072, respectively) and worse DFS (p = 0.071 and 0.019, respectively). Lastly, nuclear CENPA overexpression was correlated with presence of irido-corneal angle involvement (p = 0.015) and loss of chromosome 3 (p = 0.041). Nuclear and cytoplasmic CENPA immunopositivity associated with decreased OS (p = 0.028) and DFS (p = 0.018), respectively. HJURP and CENPA mRNA overexpression exhibited strong association with tumor epithelioid histology and was linked to worse prognosis. Our results show the compounding role of DAXX, HJURP and CENPA in UM carcinogenesis, designating them as potential biomarkers for assessing prognosis and possible targets for novel therapeutic interventions. [ABSTRACT FROM AUTHOR]

During fertilization, DAXX (death domain‐associated protein) mediates histone variant H3.3 incorporation into heterochromatin, which plays an important role in the maintenance of genomic integrity. rDNA, the ribosomal gene, is included in the first wave of gene activation after fertilization. Our and other studies indicated that loss of Daxx disturbs rDNA heterochromatinization and promotes rDNA transcription without change in protein expression of H3.3. However, maternal and zygotic deletion of Daxx impairs blastocyst development. Whether Daxx knockdown affects H3.3 expression and improves the rDNA transcription in preimplantation development has not been reported. In the present study, we injected HA‐labelled H3.3 (H3.3‐HA) into oocytes during ICSI procedure, and detected H3.3 and DAXX by immunofluorescent staining. Then, we knockdowned Daxx and detected the gene expression levels of Daxx, H3.3, 18s and 47s rRNA. We also performed immunofluorescent staining of B23, γH2A and EdU incorporation to demonstrate nuclear structure, DNA damage and replication. We found injection of H3.3‐HA did not impair preimplantation development. Daxx siRNA did not change expression of H3.3 mRNA, and the development of two‐cell embryos and blastocysts, but the overall replication and expression levels of rRNA were increased compared with that in the control group. Finally, knockdown of DAXX did not aggravate the DNA damage but loosened the nucleolus. We concluded that Daxx knockdown promoted DNA replication and rDNA transcription, but did not affect H3.3 expression and subsequent preimplantation development. [ABSTRACT FROM AUTHOR]

Background: The Alternative Lengthening of Telomeres (ALT) pathway represents a non-canonical mechanism of telomere maintenance that operates independently of the conventional telomerase activity. The three biologically significant proteins, designated as SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A-like protein 1), DAXX (Death domain-associated protein 6) and ATRX (alpha-thalassemia/mental retardation, X-linked) are associated with ALT in certain cancer types. The purpose of this study was to identify the most high-risk nsSNPs (non-synonymous Single Nucleotide Polymorphisms) within these three genes and assess their impacts on the structure and function of the proteins they encode. Methods: The reported genetic polymorphisms of SMARCAL1, DAXX and ATRX genes were retrieved from the Ensembl database. Later, various computational tools like PROVEAN, PolyPhen2, SNPs and GO, SNAP2, Predict-SNP, Panther and PMut were used to predict the most deleterious nsSNPs. MutPred was used to understand the underlying molecular reasons of those nsSNPs being deleterious, followed by prediction of Post Translational Modification Sites (PTMs) using ModPred. I-Mutant and MUpro were used to predict the effect of SNP on energy stability. Later, 3D clustering analysis was done using Mutation 3D server. Moreover, ConSurf was utilized to identify the conservation scores of wild-type amino acids. Additionally, the NCBI conserved domain search tool was employed to pinpoint conserved domains within these three proteins. Project-Hope helped for biophysical validation, followed by prediction of these genes’ interaction and function by using GeneMANIA. Result: Analysis on SMARCAL1 protein revealed that among 665 nsSNPs, four were identified as the most deleterious: L578S, T581S, P582A, and P582S. Similarly, within the DAXX protein, among a pool of 480 nsSNPs, P284S, R230C, and R230S were found out to be the most deleterious variants. In case of ATRX protein, V178D, R246C, and V277G, from the total of 1009 nsSNPs, were predicted to be the most deleterious. All these nsSNPs were found to occur at residue positions that are 100 % conserved within protein domains and were predicted to be most damaging from both structural and functional perspectives and highly destabilizing to their corresponding proteins. Conclusion: Computational investigation on the 3 proteins-SMARCAL1, DAXX and ATRX through different bioinformatics analysis tools concludes that the identified high risk nsSNPs of these proteins are pathogenic SNPs. These variants potentially exert functional and structural influences, thus making them valuable candidates for future genetic studies.

Uveal melanomas (UMs) represent rare malignant tumors associated with grim prognosis for the majority of patients. DAXX (Death Domain-Associated Protein), HJURP (Holliday Junction Recognition Protein) and CENPA (Centromere Protein A) proteins are implicated in epigenetic mechanisms, now in the spotlight of cancer research to better understand the molecular background of tumorigenesis. Herein, we investigated their expression in UM tissues using immunohistochemistry and explored possible correlations with a multitude of clinicopathological and survival parameters. The Cancer Genome Atlas Program (TCGA) was used for the investigation of their mRNA levels in UM cases. Nuclear DAXX expression correlated with an advanced T-stage (p = 0.004), while cytoplasmic expression marginally with decreased disease-free survival (DFS) (p = 0.084). HJURP nuclear positivity also correlated with advanced T-status (p = 0.054), chromosome 3 loss (p = 0.042) and increased tumor size (p = 0.03). More importantly, both nuclear and cytoplasmic HJURP immunopositivity correlated with decreased overall survival (OS) (p = 0.011 and 0.072, respectively) and worse DFS (p = 0.071 and 0.019, respectively). Lastly, nuclear CENPA overexpression was correlated with presence of irido-corneal angle involvement (p = 0.015) and loss of chromosome 3 (p = 0.041). Nuclear and cytoplasmic CENPA immunopositivity associated with decreased OS (p = 0.028) and DFS (p = 0.018), respectively. HJURP and CENPA mRNA overexpression exhibited strong association with tumor epithelioid histology and was linked to worse prognosis. Our results show the compounding role of DAXX, HJURP and CENPA in UM carcinogenesis, designating them as potential biomarkers for assessing prognosis and possible targets for novel therapeutic interventions.

Simple Summary: DAXX and HJURP are two proteins implicated in many physiologic processes and are considered important players contributing to the pathogenesis of a multitude of tumors. The aim of the present review of the literature is to retrieve and concisely present the data from studies conducted on human tissues that explored the expression of the aforementioned molecules in various tumor types. The researchers reported the tumor-promoting or tumor-suppressing properties of the two proteins, depending on the organ of origin, and correlated their expression with clinicopathological parameters. We report that enough data currently exist designating DAXX and HJURP as important factors in many tumors' carcinogenesis and that both represent potential biomarkers for diagnosis, estimation of patients' prognosis, therapy monitoring as well as targets for new therapeutic interventions. Death domain-associated protein (DAXX) and Holliday junction recognition protein (HJURP) act as chaperones of H3 histone variants H3.3 and centromere protein A (CENPA), respectively, and are implicated in many physiological processes, including aging and epigenetic regulation, by controlling various genes' transcription and subsequently protein expression. Research has highlighted both these biomolecules as participants in key procedures of tumorigenesis, including cell proliferation, chromosome instability, and oncogene expression. As cancer continues to exert a heavy impact on patients' well-being and bears substantial socioeconomic ramifications, the discovery of novel biomarkers for timely disease detection, estimation of prognosis, and therapy monitoring remains of utmost importance. In the present review, we present data reported from studies investigating DAXX and HJURP expression, either on mRNA or protein level, in human tissue samples from various types of neoplasia. Of note, the expression of DAXX and HJURP has been associated with a multitude of clinicopathological parameters, including disease stage, tumor grade, patients' overall and disease-free survival, as well as lymphovascular invasion. The data reveal the tumor-promoting properties of DAXX and HJURP in a number of organs as well as their potential use as diagnostic biomarkers and underline the important association between aberrations in their expression and patients' prognosis, rendering them as possible targets of future, personalized and precise therapeutic interventions. [ABSTRACT FROM AUTHOR]

Genomes comprise a large fraction of repetitive sequences folded into constitutive heterochromatin, which protect genome integrity and cell identity. De novo formation of heterochromatin during preimplantation development is an essential step for preserving the ground-state of pluripotency and the self-renewal capacity of embryonic stem cells (ESCs). However, the molecular mechanisms responsible for the remodeling of constitutive heterochromatin are largely unknown. Here, we identify that DAXX, an H3.3 chaperone essential for the maintenance of mouse ESCs in the ground state, accumulates in pericentromeric regions independently of DNA methylation. DAXX recruits PML and SETDB1 to promote the formation of heterochromatin, forming foci that are hallmarks of ground-state ESCs. In the absence of DAXX or PML, the threedimensional (3D) architecture and physical properties of pericentric and peripheral heterochromatin are disrupted, resulting in derepression of major satellite DNA, transposable elements and genes associated with the nuclear lamina. Using epigenome editing tools, we observe that H3.3, and specifically H3.3K9 modification, directly contribute to maintaining pericentromeric chromatin conformation. Altogether, our data reveal that DAXX is crucial for the maintenance and 3D organization of the heterochromatin compartment and protects ESC viability. [ABSTRACT FROM AUTHOR]

Abstract Promyelocytic leukemia nuclear bodies (PM NBs), often referred to as membraneless organelles, are dynamic macromolecular protein complexes composed of a PML protein core and other transient or permanent components. PML NBs have been shown to play a role in a wide variety of cellular processes. This review describes in detail the diverse and complex interactions between small and medium size DNA viruses and PML NBs that have been described to date. The PML NB components that interact with small and medium size DNA viruses include PML protein isoforms, ATRX/Daxx, Sp100, Sp110, HP1, and p53, among others. Interaction between viruses and components of these NBs can result in different outcomes, such as influencing viral genome expression and/or replication or impacting IFN-mediated or apoptotic cell responses to viral infection. We discuss how PML NB components abrogate the ability of adenoviruses or Hepatitis B virus to transcribe and/or replicate their genomes and how papillomaviruses use PML NBs and their components to promote their propagation. Interactions between polyomaviruses and PML NBs that are poorly understood but nevertheless suggest that the NBs can serve as scaffolds for viral replication or assembly are also presented. Furthermore, complex interactions between the HBx protein of hepadnaviruses and several PML NBs-associated proteins are also described. Finally, current but scarce information regarding the interactions of VP3/apoptin of the avian anellovirus with PML NBs is provided. Despite the considerable number of studies that have investigated the functions of the PML NBs in the context of viral infection, gaps in our understanding of the fine interactions between viruses and the very dynamic PML NBs remain. The complexity of the bodies is undoubtedly a great challenge that needs to be further addressed.

Purpose: To evaluate the role of 68Ga-DOTATOC PET parameters in predicting DAXX/ATRX loss of expression in patients with Pancreatic neuroendocrine tumors (PanNET) candidate to surgery. Methods: This retrospective study included 72 consecutive patients with PanNET (January 2018–March 2022) who underwent to 68Ga-DOTATOC PET for preoperative staging. Image analysis: qualitative assessment and extraction of SUVmax, SUV mean, somatostatin receptor density (SRD), and total lesion somatostatin receptor density (TLSRD) from primary PanNET. Radiological diameter and biopsy information (grade, Ki67) were collected. Loss of expression (LoE) of DAXX/ATRX was assessed by immunohistochemistry on surgical specimen. Student t-test, univariate and multivariate logistic regression and ROC curves have been used to investigate the predictive value of PET parameters on DAXX/ATRX LoE. Results: Forty-two/72 patients had a G1, 28/72 a G2, and 2/72 a G3 PanNET. Seven/72 patients had DAXX LoE, 10/72 ATRX LoE, and 2/72 DAXX/ATRX LoE. SRD and TLSRD could predict DAXX LoE (p = 0.002, p = 0.018, respectively). By evaluating SRD in combination with radiological diameter, only SRD maintained statistical significance (multivariate logistic regression: p = 0.020, OR = 1.05), providing the best prediction (AUC-ROC = 79.01%; cut-off = 46.96; sensitivity = 77.78%; specificity = 88.89%). In the sub-analysis performed on 55 patients with biopsy availability, SRD demonstrated its role in providing useful and additional information (multivariate logistic regression: SRD p = 0.007; grade p = 0.040). Conclusion: SRD has a predictive role on DAXX LoE in PanNETs, with higher probability of LoE at increasing SRD values. SRD provides complementary/additional information to grade assessed on biopsy material, and the combined use of these approaches might support patients' management by preoperatively identifying subjects with more aggressive diseases. [ABSTRACT FROM AUTHOR]

Restricting the localization of the evolutionarily conserved centromeric histone H3 variant CENP-A to centromeres prevents chromosomal instability (CIN). The mislocalization of CENP-A to noncentromeric regions contributes to CIN in yeasts, flies and human cells. Even though overexpression and mislocalization of CENP-A have been reported in cancers, the mechanisms responsible for its mislocalization remain poorly understood. Here, we used an imagingbased high-throughput RNAi screen to identify factors that prevent mislocalization of overexpressed YFP-tagged CENP-A (YFP--CENPA) in HeLa cells. Among the top five candidates in the screen -- the depletion of which showed increased nuclear YFP--CENP-A fluorescence -- were the histone chaperones CHAF1B (or p60) and CHAF1A (or p150). Follow-up validation and characterization experiments showed that CHAF1B-depleted cells exhibited CENPA mislocalization, CIN phenotypes and increased enrichment of CENP-A in chromatin fractions. The depletion of DAXX, a histone H3.3 chaperone, suppressed CENP-A mislocalization and CIN in CHAF1B-depleted cells. We propose that in CHAF1B-depleted cells, DAXX promotes mislocalization of the overexpressed CENP-A to non-centromeric regions, resulting in CIN. In summary, we identified regulators of CENP-A localization and defined a role for CHAF1B in preventing DAXX-dependent CENP-A mislocalization and CIN. [ABSTRACT FROM AUTHOR]

Background: Grade 3 gastro-entero-pancreatic neuroendocrine tumors (G3 GEP-NET) are poorly characterized in terms of molecular features and response to treatments. Methods: Patients with G3 GEP-NET were included if they received capecitabine and temozolomide (CAPTEM) or oxaliplatin with either 5-fluorouracile (FOLFOX) or capecitabine (XELOX) as first-line treatment (chemotherapy cohort). G3 NET which successfully undergone next-generation sequencing (NGS) were included in the NGS cohort. Results: In total, 49 patients were included in the chemotherapy cohort: 15 received CAPTEM and 34 received FOLFOX/XELOX. Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were 42.9%, 9.0 months, and 33.6 months, respectively. Calculating a Ki67 cutoff using ROC curve analysis, tumors with Ki67 ≥ 40% had lower ORR (51.2% vs. 0%; p = 0.007) and shorter PFS (10.6 months vs. 4.4 months; p < 0.001) and OS (49.4 months vs. 10.0 months; p = 0.023). In patients who received FOLFOX/XELOX as a first-line treatment, ORR, PFS, and OS were 38.2%, 7.9 months, and 30.0 months, respectively. In the NGS cohort (N = 13), the most mutated genes were DAXX/ATRX (N = 5, 38%), MEN1 (N = 4, 31%), TP53 (N = 4, 31%), AKT1 (N = 2, 15%), and PIK3CA (N = 1, 8%). Conclusions: FOLFOX/XELOX chemotherapy is active as the first-line treatment of patients with G3 GEP-NET. The mutational landscape of G3 NET is more similar to well-differentiated NETs than NECs. [ABSTRACT FROM AUTHOR]

Insulinomas are rare functional pancreatic neuroendocrine tumors. While most insulinomas are indolent and cured after surgery, 10--15% of cases show aggressive or malignant tumor behavior and metastasize locally or to distant organs. Patients with metastatic insulinoma survive significantly shorter. Recognizing aggressive insulinomas can help to predict prognosis, guide therapy and determine follow-up intensity after surgery. This review offers a summary of the literature on the significant clinical, pathological, genetic and epigenetic differences between indolent and aggressive insulinomas. Aggressive insulinomas are characterized by rapid onset of symptoms, larger size, expression of ARX and alpha-1-antitrypsin and decreased or absent immunohistochemical expression of insulin, PDX1 and GLP-1R. Moreover, aggressive insulinomas often harbor ATRX or DAXX mutations, the alternative lengthening of telomeres phenotype and chromosomal instability. Tumor grade and MEN1 and YY1 mutations are less useful for predicting behavior. Aggressive insulinomas have similarities to normal alpha-cells and non-functional pancreatic neuroendocrine tumors, while indolent insulinomas remain closely related to normal beta-cells. In conclusion, indolent and aggressive insulinoma are different entities, and distinguishing these will have future clinical value in determining prognosis and treatment. [ABSTRACT FROM AUTHOR]

Promyelocytic leukemia nuclear bodies (PM NBs), often referred to as membraneless organelles, are dynamic macromolecular protein complexes composed of a PML protein core and other transient or permanent components. PML NBs have been shown to play a role in a wide variety of cellular processes. This review describes in detail the diverse and complex interactions between small and medium size DNA viruses and PML NBs that have been described to date. The PML NB components that interact with small and medium size DNA viruses include PML protein isoforms, ATRX/Daxx, Sp100, Sp110, HP1, and p53, among others. Interaction between viruses and components of these NBs can result in different outcomes, such as influencing viral genome expression and/or replication or impacting IFN-mediated or apoptotic cell responses to viral infection. We discuss how PML NB components abrogate the ability of adenoviruses or Hepatitis B virus to transcribe and/or replicate their genomes and how papillomaviruses use PML NBs and their components to promote their propagation. Interactions between polyomaviruses and PML NBs that are poorly understood but nevertheless suggest that the NBs can serve as scaffolds for viral replication or assembly are also presented. Furthermore, complex interactions between the HBx protein of hepadnaviruses and several PML NBs-associated proteins are also described. Finally, current but scarce information regarding the interactions of VP3/apoptin of the avian anellovirus with PML NBs is provided. Despite the considerable number of studies that have investigated the functions of the PML NBs in the context of viral infection, gaps in our understanding of the fine interactions between viruses and the very dynamic PML NBs remain. The complexity of the bodies is undoubtedly a great challenge that needs to be further addressed. [ABSTRACT FROM AUTHOR]

Proliferating cells must enact a telomere maintenance mechanism to ensure genomic stability. In a subset of tumors, telomeres are maintained not by telomerase, but through a homologous recombination-based mechanism termed Alternative Lengthening of Telomeres or ALT. The ALT process is linked to mutations in the ATRX/DAXX/H3.3 histone chaperone complex. This complex is responsible for depositing non-replicative histone variant H3.3 at pericentric and telomeric heterochromatin but has also been found to have roles in ameliorating replication in repeat sequences and in promoting DNA repair. In this review, we will discuss ways in which ATRX/DAXX helps to protect the genome, and how loss of this complex allows ALT to take hold. [ABSTRACT FROM AUTHOR]

The presence and characteristics of HMTV in Iraqi breast cancer women are still unknown. Furthermore, the identification of HMTV in human breast carcinoma tissue of patients differs by country, and the factors that influence it are still unknown. In many epithelial tumor types, the EGFR and its signaling pathways outcomes are necessary for the behavior of cells and regulating their proliferation, and it has been discovered that DAXX has strong carcinogenic characteristics and could be a new treatment target. This case-control retrospective study investigated the presence of HMTV in paraffin-embedded blocks (FFPT) of tumor samples from 60 Iraqi women patients diagnosed with primary breast cancer and 20 cases of benign tumors as a control group. HMTV env sequences were identified by Real-time PCR. EGFR and DAXX expression were immun0-detected by the immuno-histochemistry technique. HMTV sequences were detected in 15 (25%) samples of malignant breast tumors and 8 (40%) samples of benign breast tumors. There was no statistically significant association between the detection of env sequences of HMTV and age, grade, hormone receptors, EGFR, or DAXX expression compared to clinicopathological characteristics. However, statistically, the data showed a highly significant difference in the Expression of EGFR between study groups, age, and histological types (P=0.0001), and a significant negative association was observed between EGFR and both Her2 and TNBC. There was a statistically significant difference between DAXX (+) and DAXX (−) in study groups (P=0.002), and it was significantly associated with age and histological types of breast cancer (P=0.031 and 0.007, respectively). No significant association was found between DAXX and EGFR, grade, Her2. TNBC of breast cancer. The current study found HMTV env sequences in breast tumors of Iraqi women, suggesting that a larger sample size is needed to illustrate the potential causative role of HMTV in the development of human breast malignancy. Moreover, a negative association was found between HMTV and DAXX and EGFR Expression. [ABSTRACT FROM AUTHOR]

Uterine leiomyosarcoma (uLMS) is a rare, highly aggressive malignancy. Recent data suggest 50% of uLMS may harbor alterations in the ATRX gene and such mutations may confer sensitivity to ataxia-telangiectasia-and-Rad3-related (ATR) kinase inhibitors. We sought to investigate the in vivo activity of Elimusertib (BAY1895344), a novel ATR-inhibitor, against ATRX-mutated uLMS patient-derived xenografts (PDXs). Two fully characterized uLMS (i.e., LEY-11 and LEY-16) were grafted into female CB-17/SCID mice. Treatments with control vehicle or BAY1895344 (20 mg/kg dosed twice daily 3 days on 4 days off) were given via oral gavage and tumor measurements as well as weights obtained twice weekly. Tumor volume differences were calculated with a two-way ANOVA. Mechanistic studies were performed ex vivo using BAY1895344 treated uLMS tumor samples by western blot analysis. Both PDX LEY-11 and PDX LEY-16 harboring ATRX gene mutations demonstrated an aggressive behavior in vivo (i.e., control mice were euthanized on average at day 12.5 for PDX LEY-11 and at day 33 for PDX LEY-16). In both tumor models BAY1895344 20 mg/kg dosed with an intermittent oral schedule was able to induce significant growth inhibition compared to vehicle control treatment (p < 0.001 for both LEY-11 and LEY-16) and prolong median overall survival [PDX LEY-11 (12.5 vs. 42 days, p < 0.001) and PDX LEY-16 (33 vs. 60 days, p < 0.001)]. There were not significant changes in weight between treatment and controls. By western blot assays BAY1895344 exposure decreased phosphorylated-ATR and increased expression of apoptotic molecules in LMS PDXs. BAY1895344 demonstrates promising in vivo activity against biologically aggressive PDX models of uLMS harboring ATRX mutations, with no significant toxicity. Clinical trials of BAY1895344 in uLMS patients are warranted. • Elimusertib (BAY1895344) is a novel ATR kinase inhibitor effective against uterine leiomyosarcoma. • Elimusertib decreased tumor growth in uterine leiomyosarcoma PDX mouse models with ATRX mutations. • Elimusertib prolonged overall survival in PDX mouse models of uterine leiomyosarcoma. • Tumor cells exposed to Elimusertib showed decreased phosphorylated-ATR and increased apoptotic molecules on western blot. [ABSTRACT FROM AUTHOR]

Death domain-associated protein (DAXX) and Holliday junction recognition protein (HJURP) act as chaperones of H3 histone variants H3.3 and centromere protein A (CENPA), respectively, and are implicated in many physiological processes, including aging and epigenetic regulation, by controlling various genes’ transcription and subsequently protein expression. Research has highlighted both these biomolecules as participants in key procedures of tumorigenesis, including cell proliferation, chromosome instability, and oncogene expression. As cancer continues to exert a heavy impact on patients’ well-being and bears substantial socioeconomic ramifications, the discovery of novel biomarkers for timely disease detection, estimation of prognosis, and therapy monitoring remains of utmost importance. In the present review, we present data reported from studies investigating DAXX and HJURP expression, either on mRNA or protein level, in human tissue samples from various types of neoplasia. Of note, the expression of DAXX and HJURP has been associated with a multitude of clinicopathological parameters, including disease stage, tumor grade, patients’ overall and disease-free survival, as well as lymphovascular invasion. The data reveal the tumor-promoting properties of DAXX and HJURP in a number of organs as well as their potential use as diagnostic biomarkers and underline the important association between aberrations in their expression and patients’ prognosis, rendering them as possible targets of future, personalized and precise therapeutic interventions.

Purpose: Gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN) form a rare and remarkably heterogeneous group of tumors. Therefore, establishing personalized therapies is eminently challenging. To achieve progress in preclinical drug development, there is an urgent need for relevant tumor models. Methods: We successfully established three gastroenteropancreatic neuroendocrine tumor (GEP-NET) cell lines (NT-18P, NT-18LM, NT-36) and two gastroenteropancreatic neuroendocrine carcinoma (GEP-NEC) cell lines (NT-32 and NT-38). We performed a comprehensive characterization of morphology, NET differentiation, proliferation and intracellular signaling pathways of these five cell lines and, in addition, of the NT-3 GEP-NET cell line. Additionally, we conducted panel sequencing to identify genomic alterations suitable for mutation-based targeted therapy. Results: We found that the GEP-NEN cell lines exhibit a stable neuroendocrine phenotype. Functional kinome profiling revealed a higher activity of serine/threonine kinases (STK) as well as protein tyrosine kinases (PTK) in the GEP-NET cell lines NT-3 and NT-18LM compared to the GEP-NEC cell lines NT-32 and NT-38. Panel sequencing revealed a mutation in Death Domain Associated Protein (DAXX), sensitizing NT-18LM to the Ataxia telangiectasia and Rad3 related (ATR) inhibitor Berzosertib, and a mutation in AT-Rich Interaction Domain 1A (ARID1A), sensitizing NT-38 to the Aurora kinase A inhibitor Alisertib. Small interfering RNA-mediated knock down of DAXX in the DAXX wild type cell line NT-3 sensitized these cells to Berzosertib. Conclusions: The newly established GEP-NET and GEP-NEC cell lines represent comprehensive preclinical in vitro models suitable to decipher GEP-NEN biology and pathogenesis. Additionally, we present the first results of a GEP-NEN-specific mutation-based targeted therapy. These findings open up new potentialities for personalized therapies in GEP-NEN. [ABSTRACT FROM AUTHOR]

Pancreatic neuroendocrine neoplasms (PanNENs) are rare and clinically challenging entities. At the molecular level, PanNENs' genetic profile is well characterized, but there is limited knowledge regarding the contribution of the newly identified genes to tumor initiation and progression. Genetically engineered mouse models (GEMMs) are the most versatile tool for studying the plethora of genetic variations influencing PanNENs' etiopathogenesis and behavior over time. In this review, we present the state of the art of the most relevant PanNEN GEMMs available and correlate their findings with the human neoplasms' counterparts. We discuss the historic GEMMs as the most used and with higher translational utility models. GEMMs with Men1 and glucagon receptor gene germline alterations stand out as the most faithful models in recapitulating human disease; RIP-Tag models are unique models of early-onset, highly vascularized, invasive carcinomas. We also include a section of the most recent GEMMs that evaluate pathways related to cell cycle and apoptosis, Pi3k/Akt/mTOR, and Atrx/Daxx. For the latter, their tumorigenic effect is heterogeneous. In particular, for Atrx/Daxx, we will require more in-depth studies to evaluate their contribution; even though they are prevalent genetic events in PanNENs, they have low/inexistent tumorigenic capacity per se in GEMMs. Researchers planning to use GEMMs can find a road map of the main clinical features in this review, presented as a guide that summarizes the chief milestones achieved. We identify pitfalls to overcome, concerning the novel designs and standardization of results, so that future models can replicate human disease more closely. [ABSTRACT FROM AUTHOR]

PML nuclear bodies (PML-NBs) are dynamic macromolecular complexes that mediate intrinsic immunity against viruses of different families, including human cytomegalovirus (HCMV). Upon HCMV infection, PML-NBs target viral genomes entering the nucleus and restrict viral immediate–early gene expression by epigenetic silencing. Studies from several groups performed in human fibroblast cells have shown that the major PML-NB components PML, Daxx, Sp100 and ATRX contribute to this repression in a cooperative manner. Their role for HCMV restriction in endothelial cells, however, has not yet been characterized although infected endothelium is thought to play a crucial role for HCMV dissemination and development of vascular disease in vivo. Here, we use conditionally immortalized umbilical vein endothelial cells (HEC-LTT) as a cell culture model to elucidate the impact of PML-NB proteins on lytic HCMV infection. Depletion of individual PML-NB proteins by lentiviral transduction showed a particularly strong antiviral effect of PML in HEC-LTT, compared to human fibroblasts. A closer characterization of this antiviral function revealed that PML may not only effectively inhibit HCMV immediate-early gene expression but also act at later steps of the viral replication cycle. At contrast, we surprisingly noted an antiviral behavior of Daxx in complementary approaches: Depletion of Daxx resulted in decreased viral gene expression, while overexpression of Daxx promoted HCMV infection. In summary, our data demonstrate a cell type-specific effect of PML-NB components on lytic HCMV infection and suggest an important role of PML in the inhibition of HCMV dissemination through infected endothelial cells. [ABSTRACT FROM AUTHOR]

Background: Recent advances demonstrate the role of chromatin regulators, including histone variants and histone chaperones, in cancer initiation and progression. Methods: Histone H3K4me3, histone variant centromere protein (CENP-A) and histone chaperones Holliday junction recognition protein (HJURP) as well as DAXX expression were examined immunohistochemically in 95 thymic epithelial tumor (TET) specimens. Our results were compared with the expression profile of DAXX, HJURP and CENP-A in gene expression profiling interactive analysis (GEPIA2). Results: The lymphocyte-poor B3- and C-type TETs were more frequently DAXX negative (p = 0.043). B3 and C-Type TETs showed higher cytoplasmic and nuclear CENP-A (p = 0.007 and p = 0.002) and higher cytoplasmic HJURP H-score (p < 0.001). Higher nuclear CENP-A and cytoplasmic HJURP expression was associated with advanced Masaoka–Koga stage (p = 0.048 and p < 0.001). A positive correlation between HJURP and CENP-A was also observed. The presence of cytoplasmic CENP-A expression was correlated with a favorable overall survival (p = 0.03). CENP-A overexpression in survival analysis of TCGA TETs showed similar results. H3K4me3 expression was not associated with any clinicopathological parameters. Conclusions: Our results suggest a significant interaction between CENP-A and HJURP in TETs. Moreover, we confirmed the presence of a cytoplasmic CENP-A immunolocalization, suggesting also a possible favorable prognostic value of this specific immunostaining pattern. [ABSTRACT FROM AUTHOR]

Herpesviruses are ubiquitous pathogens that cause a wide range of disease. Upon nuclear entry, their genomes associate with histones and chromatin modifying enzymes that regulate the progression of viral transcription and outcome of infection. While the composition and modification of viral chromatin has been extensively studied on bulk populations of infected cells by chromatin immunoprecipitation, this key regulatory process remains poorly defined at single-genome resolution. Here we use high-resolution quantitative imaging to investigate the spatial proximity of canonical and variant histones at individual Herpes Simplex Virus 1 (HSV-1) genomes within the first 90 minutes of infection. We identify significant population heterogeneity in the stable enrichment and spatial proximity of canonical histones (H2A, H2B, H3.1) at viral DNA (vDNA) relative to established promyelocytic leukaemia nuclear body (PML-NB) host factors that are actively recruited to viral genomes upon nuclear entry. We show the replication-independent histone H3.3/H4 chaperone Daxx to cooperate with PML to mediate the enrichment and spatial localization of variant histone H3.3 at vDNA that limits the rate of HSV-1 genome decompaction to restrict the progress of immediate-early (IE) transcription. This host response is counteracted by the viral ubiquitin ligase ICP0, which degrades PML to disperse Daxx and variant histone H3.3 from vDNA to stimulate the progression of viral genome expansion, IE transcription, and onset of HSV-1 replication. Our data support a model of intermediate and sequential histone assembly initiated by Daxx that limits the rate of HSV-1 genome decompaction independently of the stable enrichment of histones H2A and H2B at vDNA required to facilitate canonical nucleosome assembly. We identify HSV-1 genome decompaction upon nuclear infection to play a key role in the initiation and functional outcome of HSV-1 lytic infection, findings pertinent to the transcriptional regulation of many nuclear replicating herpesvirus pathogens., Competing Interests: Conflicts of Interest The authors declare no conflict of interest.

Pancreatic neuroendocrine tumors (PanNETs) comprise a heterogeneous group of neoplasms in terms of biological behavior. This study aims to develop a practical algorithm based on emerging biomarkers, including chromatin-remodeling molecules DAXX/ATRX/H3K36me3, in conjunction with established prognostic factors, such as WHO grade and size. In immunohistochemical analyses, 18 of the 111 (16.2%) primary PanNETs showed DAXX or ATRX loss in a mutually exclusive manner. DAXX/ATRX loss was significantly correlated with higher recurrence risk and better predicted postoperative recurrence than WHO grade. We proposed a novel algorithm for stratifying patients with resectable PanNET into three groups according to recurrence risk: (A) WHO Grade 1 and ≤2 cm (very low-risk); for the others, (B) retained DAXX/ATRX (low-risk) and (C) DAXX/ATRX complete/heterogeneous loss (high-risk). Furthermore, we elucidated the intratumoral heterogeneities of PanNETs. Among cases with DAXX or ATRX loss, nine cases demonstrated heterogeneous loss of expression of DAXX/ATRX/H3K36me3. The majority of cases with DAXX/ATRX loss, either homogeneous or heterogeneous loss, showed uniform α-cell-like phenotype (ARX1+/PDX1-). In cases of metastatic or recurrent tumors, the expression pattern was identical to that observed in at least part of the primary tumor. In some instances, the expression pattern differed among different metastatic or recurrent tumors of the same patient. In summary, we propose a clinically useful and practical algorithm for postoperative recurrence risk stratification in PanNETs, by combining DAXX/ATRX status with WHO grade and size. Moreover, our findings highlighted the frequent spatiotemporal heterogeneity of chromatin-remodeling molecule expression in PanNETs with an α-cell phenotype, offering insights into tumorigenesis., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Genome sequencing has revealed the importance of epigenetic regulators in tumorigenesis. The genes encoding the chromatin remodeling complex DAXX:ATRX are frequently mutated in pancreatic neuroendocrine tumors; however, the underlying mechanisms of how mutations contribute to tumorigenesis are only partially understood, in part because of the lack of relevant preclinical models. Here, we used genetically engineered mouse models combined with environmental stress to evaluate the tumor suppressor functions of Daxx and Atrx in the mouse pancreas. Daxx or Atrx loss, alone or in combination with Men1 loss, did not drive or accelerate pancreatic neuroendocrine tumorigenesis. Moreover, Daxx loss did not cooperate with environmental stresses (ionizing radiation or pancreatitis) or with the loss of other tumor suppressors (Pten or p53) to promote pancreatic neuroendocrine tumorigenesis. However, owing to promiscuity of the Cre promoter used, hepatocellular carcinomas and osteosarcomas were observed in some instances. Overall, our findings suggest that Daxx and Atrx are not robust tumor suppressors in the endocrine pancreas of mice and indicate that the context of a human genome is essential for tumorigenesis. This article has an associated First Person interview with the first author of the paper.

Background: Abdominal aortic aneurysm (AAA) is a potentially life-threatening vascular abnormality, that, if ruptured, is almost universally fatal without repair, and is associated with up to 50% mortality even if repaired in hospital. To date, there is no drug therapy that has clinically proven benefit to reduce or prevent expansion of AAA. The aim of this study was to investigate whether Daxx could affect AAA through inhibiting the PI3K/AKT/ID2 signaling pathway mediated by transforming growth factor β-1 (TGFβ1). Methods: The AAA model was constructed by injecting angiotensin Ⅱ (Ang-Ⅱ) into rats, and the Daxx lentivirus vector was constructed. Hematoxylin and eosin (HE) staining was used to detect the wall thickness of the abdominal aorta in rats. The gene and protein expressions in abdominal aortic tissues were detected utilizing western blot, immunohistochemistry (IHC) and fluorescence quantitative real-time polymerase chain reaction (qRT-PCR). Finally, the concentration of TGF-β1 in abdominal aortic tissue was determined by ELISA. Results: The abdominal aortic wall thickness was decreased in the Daxx expression group (by HE staining), and Daxx overexpression markedly reduced the protein expression levels of MMP2 and MMP9. Proteins related to the PI3K/AKT/ID2 signaling pathway were highly enhanced in the aneurysm wall of rats, but were reduced following Daxx addition. Moreover, Daxx reduced the damage to elastin (by IHC), and the expression levels of α-SMA and SM22α were up-regulated by Daxx (by qRT-PCR). The concentration of TGF-β1 was correlated with the activation of the PI3K/AKT/ID2 signaling pathway (by ELISA), whereas AKT overexpression weakened the inhibitory effect of Daxx. Conclusion: Daxx ameliorated several mechanisms that contributed to expansion of AAA suppressing the tissue concentration of TGF-β1, thereby inhibiting the activation of the PI3K/AKT/ID2 signaling pathway. This evidence might form the basis to develop a therapeutic target for AAA. [ABSTRACT FROM AUTHOR]

Genetic profiling is an increasingly useful tool for sub-classification of gliomas in adults and children. Specific gene mutations, structural rearrangements, DNA methylation patterns, and gene expression profiles are now recognized to define molecular subgroups of gliomas that arise in distinct anatomic locations and patient age groups, and also provide a better prediction of clinical outcomes for glioma patients compared to histologic assessment alone. Understanding the role of these distinctive genetic alterations in gliomagenesis is also important for the development of potential targeted therapeutic interventions. Mutations including K27M and G34R/V that affect critical amino acids within the N-terminal tail of the histone H3 variants, H3.3 and H3.1 (encoded by H3F3A and HIST1H3B genes), are prime examples of mutations in diffuse gliomas with characteristic clinical associations that can help diagnostic classification and guide effective patient management. These histone H3 mutations frequently co-occur with inactivating mutations in ATRX in association with alternative lengthening of telomeres. Telomere length can also be maintained through upregulation of telomerase reverse transcriptase (TERT) expression driven by mutation within the TERT gene promoter region, an alteration most commonly found in oligodendrogliomas and primary glioblastomas arising in adults. Interestingly, the genetic alterations perturbing histone and telomere function in pediatric gliomas tend to be different from those present in adult tumors. We present a review of these mutations affecting the histone code and telomere length, highlighting their importance in prognosis and as targets for novel therapeutics in the treatment of diffuse gliomas.

Phenotypic switching is the main cause of the abnormal proliferation and migration of vascular smooth muscle cells (VSMCs). We previously showed that Daxx exerted negative regulatory effect on AngII-induced VSMC proliferation and migration. However, the function of Daxx in VSMC phenotype switching remained unknown. Nicotinate-curcumin (NC) is an esterification derivative of niacin and curcumin that can prevent the formation of atherosclerosis. We found that NC significantly decreased AngII-induced VSMC phenotype switching. Furthermore, NC significantly inhibited AngII-induced cell proliferation and migration. Moreover, NC upregulated Daxx expression and regulated the PTEN/Akt signaling pathway. We concluded that NC inhibited AngII-induced VSMC phenotype switching by regulating the PTEN/Akt pathway, and through a mechanism that might be associated with the upregulation of Daxx expression.

Proliferating cells must enact a telomere maintenance mechanism to ensure genomic stability. In a subset of tumors, telomeres are maintained not by telomerase, but through a homologous recombination-based mechanism termed Alternative Lengthening of Telomeres or ALT. The ALT process is linked to mutations in the ATRX/DAXX/H3.3 histone chaperone complex. This complex is responsible for depositing non-replicative histone variant H3.3 at pericentric and telomeric heterochromatin but has also been found to have roles in ameliorating replication in repeat sequences and in promoting DNA repair. In this review, we will discuss ways in which ATRX/DAXX helps to protect the genome, and how loss of this complex allows ALT to take hold.

Primary non‐functional pancreatic neuroendocrine tumors (NF‐PanNETs) are a heterogeneous group of neuroendocrine neoplasms that display highly variable clinical behavior. Therefore, NF‐PanNETs often present clinical teams with a dilemma: the uncertain metastatic potential of the tumor has to be weighed against the morbidity associated with surgical resection. Thus, rather than utilizing current radiologic thresholds, there is an urgent need for improved prognostic biomarkers. Recent studies aimed at understanding the epigenetic underpinnings of NF‐PanNETs have led to the identification of tumor subgroups based on histone modification and DNA methylation patterns. These molecular profiles tend to resemble the cellular origins of PanNETs. Subsequent retrospective analyses have demonstrated that these molecular signatures are of prognostic value and, importantly, may be useful in the preoperative setting. These studies have highlighted that sporadic NF‐PanNETs displaying biomarkers associated with disease progression and poor prognosis, such as alternative lengthening of telomeres, inactivating alpha thalassemia/mental retardation X‐linked (ATRX) or death domain‐associated protein (DAXX) gene mutations, or copy number variations, more often display alpha cell characteristics. Conversely, NF‐PanNETs with beta cell characteristics often lack these unfavorable biomarkers. Alternative lengthening of telomeres, transcription factor protein expression, and possibly DNA methylation can be assessed in endoscopic ultrasound‐guided tumor biopsies. Prospective studies focusing on cell‐of‐origin and epigenetic profile‐driven decision making prior to surgery are likely to be routinely implemented into clinical practice in the near future. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland. [ABSTRACT FROM AUTHOR]

Background: Abdominal aortic aneurysm (AAA) is a potentially life-threatening vascular abnormality, that, if ruptured, is almost universally fatal without repair, and is associated with up to 50% mortality even if repaired in hospital. To date, there is no drug therapy that has clinically proven benefit to reduce or prevent expansion of AAA. The aim of this study was to investigate whether Daxx could affect AAA through inhibiting the PI3K/AKT/ID2 signaling pathway mediated by transforming growth factor β-1 (TGFβ1). Methods: The AAA model was constructed by injecting angiotensinⅡ(Ang-Ⅱ) into rats, and the Daxx lentivirus vector was constructed. Hematoxylin and eosin (HE) staining was used to detect the wall thickness of the abdominal aorta in rats. The gene and protein expressions in abdominal aortic tissues were detected utilizing western blot, immunohistochemistry (IHC) and fluorescence quantitative real-time polymerase chain reaction (qRT-PCR). Finally, the concentration of TGF-β1 in abdominal aortic tissue was determined by ELISA. Results: The abdominal aortic wall thickness was decreased in the Daxx expression group (by HE staining), and Daxx overexpression markedly reduced the protein expression levels of MMP2 and MMP9. Proteins related to the PI3K/AKT/ID2 signaling pathway were highly enhanced in the aneurysm wall of rats, but were reduced following Daxx addition. Moreover, Daxx reduced the damage to elastin (by IHC), and the expression levels of a-SMA and SM22a were up-regulated by Daxx (by qRT-PCR). The concentration of TGF-β1 was correlated with the activation of the PI3K/AKT/ID2 signaling pathway (by ELISA), whereas AKT overexpression weakened the inhibitory effect of Daxx. Conclusion: Daxx ameliorated several mechanisms that contributed to expansion of AAA suppressing the tissue concentration of TGF-β1, thereby inhibiting the activation of the PI3K/AKT/ID2 signaling pathway. This evidence might form the basis to develop a therapeutic target for AAA. [ABSTRACT FROM AUTHOR]

Abstract Background Telomere stability is one of the hallmarks of cancer that promotes cellular longevity, the accumulation of genetic alterations, and tumorigenesis. The loss of death domain-associated protein (DAXX) and α-thalassemia/mental retardation X-linked protein (ATRX) plays a role in telomere lengthening and stability. This study aims to evaluate the prognostic significance of telomere length (TL) and its association with DAXX and ATRX proteins in breast cancer (BC). Our study used the FISH technique to detect peptide nucleic acid (PNA) in the peripheral blood cells of a cohort of BC patients (n = 220) and a control group of apparently healthy individuals (n = 100). Expression of DAXX and ATRX proteins was evaluated using immunohistochemistry (IHC) in all BC tissues. Results Patients with a shorter TL had worse disease-free survival (DFS) and overall survival (OS). There were significant associations between shorter TL and advanced disease stages, lymph node metastasis, and positive HER2/neu expression. DAXX protein expression was significantly correlated with TL. Lower DAXX expression was significantly with shorter DFS. Conclusion Assessing TL can be used as a worthy prognostic indicator in BC patients. Specifically, short TL had a poor impact on the prognosis of BC patients. Low DAXX expression is associated with poor outcomes in BC. Further mechanistic studies are warranted to reveal the underlying mechanisms of these associations.

Background: The Alternative Lengthening of Telomeres (ALT) pathway represents a non-canonical mechanism of telomere maintenance that operates independently of the conventional telomerase activity. The three biologically significant proteins, designated as SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A-like protein 1), DAXX (Death domain-associated protein 6) and ATRX (alpha-thalassemia/mental retardation, X-linked) are associated with ALT in certain cancer types. The purpose of this study was to identify the most high-risk nsSNPs (non-synonymous Single Nucleotide Polymorphisms) within these three genes and assess their impacts on the structure and function of the proteins they encode., Methods: The reported genetic polymorphisms of SMARCAL1, DAXX and ATRX genes were retrieved from the Ensembl database. Later, various computational tools like PROVEAN, PolyPhen2, SNPs and GO, SNAP2, Predict-SNP, Panther and PMut were used to predict the most deleterious nsSNPs. MutPred was used to understand the underlying molecular reasons of those nsSNPs being deleterious, followed by prediction of Post Translational Modification Sites (PTMs) using ModPred. I-Mutant and MUpro were used to predict the effect of SNP on energy stability. Later, 3D clustering analysis was done using Mutation 3D server. Moreover, ConSurf was utilized to identify the conservation scores of wild-type amino acids. Additionally, the NCBI conserved domain search tool was employed to pinpoint conserved domains within these three proteins. Project-Hope helped for biophysical validation, followed by prediction of these genes' interaction and function by using GeneMANIA., Result: Analysis on SMARCAL1 protein revealed that among 665 nsSNPs, four were identified as the most deleterious: L578S, T581S, P582A, and P582S. Similarly, within the DAXX protein, among a pool of 480 nsSNPs, P284S, R230C, and R230S were found out to be the most deleterious variants. In case of ATRX protein, V178D, R246C, and V277G, from the total of 1009 nsSNPs, were predicted to be the most deleterious. All these nsSNPs were found to occur at residue positions that are 100 % conserved within protein domains and were predicted to be most damaging from both structural and functional perspectives and highly destabilizing to their corresponding proteins., Conclusion: Computational investigation on the 3 proteins-SMARCAL1, DAXX and ATRX through different bioinformatics analysis tools concludes that the identified high risk nsSNPs of these proteins are pathogenic SNPs. These variants potentially exert functional and structural influences, thus making them valuable candidates for future genetic studies., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author(s).)

Purpose of Review: Alternative lengthening of telomeres (ALT) is a telomerase-independent mechanism used by some types of malignancies, including pancreatic neuroendocrine tumors, to overcome the issue of telomere shortening, thus supporting tumor growth and cell proliferation. This review is focused on the most important achievements and opportunities deriving from ALT assessment in PanNET onco-pathology, highlighting the most promising fields in which such biomarker could be implemented in clinical practice. Recent Findings: In pancreatic neuroendocrine tumors (PanNET), ALT is strongly correlated with the mutational status of two chromatin remodeling genes, DAXX and ATRX. Recent advances in tumor biology permitted to uncover important roles of ALT in the landscape of PanNET, potentially relevant for introducing this biomarker into clinical practice. Indeed, ALT emerged as a reliable indicator of worse prognosis for PanNET, helping in clinical stratification and identification of "high-risk" patients. Furthermore, it is a very specific marker supporting the pancreatic origin of neuroendocrine neoplasms and can be used for improving the diagnostic workflow of patients presenting with neuroendocrine metastasis from unknown primary. The activation of this process can be determined by specific FISH analysis. Summary: ALT should be introduced in clinical practice for identifying "high-risk" PanNET patients and improving their clinical management, and as a marker of pancreatic origin among neuroendocrine tumors. [ABSTRACT FROM AUTHOR]

While carcinoma of the prostate is the second most common cause of cancer death in the US, current methods and markers used to predict prostate cancer (PCa) outcome are inadequate. This study was aimed at understanding the genome-wide binding and regulatory role of the DAXX transcriptional repressor, recently implicated in PCa. ChIP-Seq analysis of genome-wide distribution of DAXX in PC3 cells revealed over 59,000 DAXX binding sites, found at regulatory enhancers and promoters. ChIP-Seq analysis of DNA methyltransferase 1 (DNMT1), which is a key epigenetic partner for DAXX repression, revealed that DNMT1 binding was restricted to a small number of DAXX sites. DNMT1 and DAXX bound close to transcriptional activator motifs. DNMT1 sites were found to be dependent on DAXX for recruitment by analyzing DNMT1 ChIP-Seq following DAXX knockdown (K/D), corroborating previous findings that DAXX recruits DNMT1 to repress its target genes. Massively parallel RNA sequencing (RNA-Seq) was used to compare the transcriptomes of WT and DAXX K/D PC3 cells. Genes induced by DAXX K/D included those involved in autophagy, and DAXX ChIP-Seq peaks were found close to the transcription start sites (TSS) of autophagy genes, implying they are more likely to be regulated by DAXX. In conclusion, DAXX binds active regulatory elements and co-localizes with DNMT1 in the prostate cancer genome. Given DAXX's putative regulatory role in autophagy, future studies may consider DAXX as a candidate marker and therapeutic target for prostate cancer.

Background: Recent advances demonstrate the role of chromatin regulators, including histone variants and histone chaperones, in cancer initiation and progression. Methods: Histone H3K4me3, histone variant centromere protein (CENP-A) and histone chaperones Holliday junction recognition protein (HJURP) as well as DAXX expression were examined immunohistochemically in 95 thymic epithelial tumor (TET) specimens. Our results were compared with the expression profile of DAXX, HJURP and CENP-A in gene expression profiling interactive analysis (GEPIA2). Results: The lymphocyte-poor B3- and C-type TETs were more frequently DAXX negative (p = 0.043). B3 and C-Type TETs showed higher cytoplasmic and nuclear CENP-A (p = 0.007 and p = 0.002) and higher cytoplasmic HJURP H-score (p < 0.001). Higher nuclear CENP-A and cytoplasmic HJURP expression was associated with advanced Masaoka–Koga stage (p = 0.048 and p < 0.001). A positive correlation between HJURP and CENP-A was also observed. The presence of cytoplasmic CENP-A expression was correlated with a favorable overall survival (p = 0.03). CENP-A overexpression in survival analysis of TCGA TETs showed similar results. H3K4me3 expression was not associated with any clinicopathological parameters. Conclusions: Our results suggest a significant interaction between CENP-A and HJURP in TETs. Moreover, we confirmed the presence of a cytoplasmic CENP-A immunolocalization, suggesting also a possible favorable prognostic value of this specific immunostaining pattern.

BackgroundPancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and unpredictable behavior. Whole-exome sequencing recently has shown very frequent somatic mutations in the alpha-thalassemia/mental retardation X-linked (ATRX) and death domain-associated protein (DAXX) genes in PanNETs. And the prognostic significance of altered ATRX/DAXX genes in PanNETs patients have been revealed in several reports. However, many of these include small sample size and hold controversial opinions. To increase statistical power, we performed a systematic review and meta-analysis to determine a pooled conclusion. We examined the impact of altered ATRX/DAXX genes mainly on overall survival (OS), disease-free survival (DFS) and relapse-free survival (RFS) in PanNETs.MethodsEligible studies were identified and quality was assessed using multiple search strategies (last search May 2021). Data were collected from studies about prognostic significance of altered ATRX/DAXX in PanNETs. Studies were pooled, and combined hazard ratios (HRs) with 95% confidence intervals (CIs) were used to estimate strength of the associations.ResultsFourteen studies involving 2313 patients treated for PanNETs were included. After evaluating for publication bias, disease-free survival and relapse-free survival was significantly shortened in patients with altered ATRX/DAXX gene, with combined HR 5.05 (95% confidence interval (CI): 1.58-16.20, P = 0.01) and 3.21 (95% confidence interval (CI): 1.44-7.16, P < 0.01) respectively. However, the combined data showed there were no difference between patients with altered ATRX/DAXX gene or not in overall survival, with a combined HR 0.71 (95% confidence interval (CI): 0.44-1.15, P = 0.23). We also performed a subgroup analysis with metastatic patients in overall survival, showing a combined HR 0.22 (95% confidence interval (CI): 0.11-0.48, P = 0.96). The small number of studies and paucity of multivariate analyses are the limitations of our study.ConclusionsThis is the first rigorous pooled analysis assessing ATRX/DAXX mutation as prognostic biomarkers in PanNETs. Patients with altered ATRX/DAXX gene would have poor DFS according to the combined data. And altered ATRX/DAXX genes in metastatic patients showed a trend towards improved overall survival, although the difference did not reach statistical significance.

Background: Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous group of neoplasms with increasing incidence and unpredictable behavior. Whole-exome sequencing recently has shown very frequent somatic mutations in the alpha-thalassemia/mental retardation X-linked (ATRX) and death domain-associated protein (DAXX) genes in PanNETs. And the prognostic significance of altered ATRX/DAXX genes in PanNETs patients have been revealed in several reports. However, many of these include small sample size and hold controversial opinions. To increase statistical power, we performed a systematic review and meta-analysis to determine a pooled conclusion. We examined the impact of altered ATRX/DAXX genes mainly on overall survival (OS), disease-free survival (DFS) and relapse-free survival (RFS) in PanNETs. Methods: Eligible studies were identified and quality was assessed using multiple search strategies (last search May 2021). Data were collected from studies about prognostic significance of altered ATRX/DAXX in PanNETs. Studies were pooled, and combined hazard ratios (HRs) with 95% confidence intervals (CIs) were used to estimate strength of the associations. Results: Fourteen studies involving 2313 patients treated for PanNETs were included. After evaluating for publication bias, disease-free survival and relapse-free survival was significantly shortened in patients with altered ATRX/DAXX gene, with combined HR 5.05 (95% confidence interval (CI): 1.58-16.20, P = 0.01) and 3.21 (95% confidence interval (CI): 1.44-7.16, P < 0.01) respectively. However, the combined data showed there were no difference between patients with altered ATRX/DAXX gene or not in overall survival, with a combined HR 0.71 (95% confidence interval (CI): 0.44-1.15, P = 0.23). We also performed a subgroup analysis with metastatic patients in overall survival, showing a combined HR 0.22 (95% confidence interval (CI): 0.11-0.48, P = 0.96). The small number of studies and paucity of multivariate analyses are the limitations of our study. Conclusions: This is the first rigorous pooled analysis assessing ATRX/DAXX mutation as prognostic biomarkers in PanNETs. Patients with altered ATRX/DAXX gene would have poor DFS according to the combined data. And altered ATRX/DAXX genes in metastatic patients showed a trend towards improved overall survival, although the difference did not reach statistical significance. [ABSTRACT FROM AUTHOR]

Genetic factors coordinate with environmental factors to drive the pathogenesis of prostate adenocarcinoma (PRAD). SPOP is one of the most mutated genes and LRP5 mediates lipid metabolism that is abnormally altered in PRAD. Here, we investigated the potential cross-talk between SPOP and LRP5 in PRAD. We find a negative correlation between SPOP and LRP5 proteins in PRAD. SPOP knockdown increased LRP5 protein while SPOP overexpression resulted in LRP5 reduction that was fully rescued by proteasome inhibitors. LRP5 intracellular tail has SPOP binding site and the direct interaction between LRP5 and SPOP was confirmed by Co-IP and GST-pulldown. Moreover, LRP5 competed with Daxx for SPOP-mediated degradation, establishing a dynamic balance among SPOP, LRP5 and Daxx. Overexpression of LRP5 tail could shift this balance to enhance Daxx-mediated transcriptional inhibition, and inhibit T cell activity in a co-culture system. Further, we generated human and mouse prostate cancer cell lines expressing SPOP variants (F133V, A227V, R368H). SPOP-F133V and SPOP-A227V have specific effects in up-regulating the protein levels of PD-1 and PD-L1. Consistently, SPOP-F133V and SPOP-A227V show robust inhibitory effects on T cells compared to WT SPOP in co-culture. This is further supported by the mouse syngeneic model showing that SPOP-F133V and SPOP-A227V enhance tumorigenesis of prostate cancer in in-vivo condition. Taken together, our study provides evidence that SPOP-LRP5 crosstalk plays an essential role, and the genetic variants of SPOP differentially modulate the expression and activity of immune checkpoints in prostate cancer. [ABSTRACT FROM AUTHOR]

Abstract Background The death-domain-associated protein (DAXX) was originally identified as a protein that binds to the transmembrane death receptor FAS and enhances both FAS-induced and transforming growth factor-β-dependent apoptosis. In a previous study, we found that nude mice injected with DAXX-overexpressing cells (ES-2-DAXX) accumulated large concentrations of first-generation ascites cells (I ascites cells). The role of DAXX in the development of ascites is unknown. The aim of this study was to analyze the effect of DAXX on proliferation and migration of ascites cells in ovarian cancer in vitro and in vivo. Methods Nude mice were housed in cages with a 14:10 h light:dark cycle; water and food were provided ad libitum. ES-2-DAXX cells (1×106) were injected intraperitoneally into athymic nude mice (8-week-old female mice). After 4 weeks, I ascites cells were collected. The I ascites cells were injected intraperitoneally into athymic nude mice (8-week-old female mice). After 4 weeks, II ascites cells were collected and cultured. Ascites cell survival, migration, and colony formation were measured using colony formation and cell growth assays. Immunofluorescent staining revealed the co-localization of DAXX and promyelocytic leukemia protein (PML) in ascites cell nuclei. Western blotting and immunohistochemistry showed that extracellular signal-related kinase (p-ERK) 1/2 and CEBP-β were highly expressed in tumor tissues formed by II ascites cells. Through immunoprecipitation, we also found that DAXX can interact with CEBP-β. Results DAXX enhanced ascites cell survival, migration, and colony formation. DAXX and PML nuclear foci dramatically increased in a passage-dependent manner in ascites cells, DAXX promoted the tumor growth of ascites cells in vivo, increased ascites cell proliferation in vivo, and enhanced ascites cell survival and migration by activating the ERK signalling pathway and integrating with CEBP-β. Conclusions DAXX can interact with CEBP-β. DAXX can induce ovarian cancer ascites formation by activating the ERK signal pathway and binding to CEBP-β.

Pancreatic neuroendocrine neoplasms (panNENs) are the second most common epithelial tumors of the pancreas. Despite improvements in prognostic grading and staging systems, it remains a challenge to predict the clinical behavior of panNENs and the response to specific therapies given the high degree of heterogeneity of these tumors. Most panNENs are nonfunctional and present as advanced disease. However, systemic therapies provide modest benefits. Therefore, there is a need for predictive biomarkers to develop personalized treatment and to advance new drug development. The somatostatin receptors remain the only clinically established prognostic and predictive biomarkers in panNENs. Oncogenic drivers are at a very low frequency. Commonly mutated genes in panNENs include MEN1, chromatin remodeling genes (DAXX and ATRX), and mammalian target of rapamycin pathway genes. In contrast, poorly differentiated neuroendocrine carcinomas (panNECs), which carry a very poor prognosis, have distinctive mutations in certain genes (eg, RB1 and p53). Ongoing research to integrate epigenomics will provide tremendous opportunities to improve current understanding of the clinical heterogeneity of pancreatic neuroendocrine tumors and provide invaluable insight into the biology of these tumors, new drug development, and establishing personalized therapies. A wider application of new technologies that will go beyond simple genetic markers and would include epigenetic data will ensure that pancreatic neuroendocrine neoplasms will be managed best by molecularly tailored therapies that are currently not a standard of care. [ABSTRACT FROM AUTHOR]

Introduction: Homeostasis of cholesterol is crucial for cellular function, and dysregulated cholesterol biosynthesis is a metabolic event that can lead to hepatic and cardiovascular abnormalities. Objective: The aim of this study was to investigate the effects and mechanisms of domain-associated protein (Daxx) and androgen receptor (AR) on intracellular cholesterol synthesis. Methods: HepG2 cells were transfected with pCDNA3.1(+)/Daxx plasmid or treated with testosterone propionate to observe the effects of Daxx and AR on intracellular cholesterol levels. Co-immunoprecipitation experiments were performed to identify the interaction between Daxx and AR and to explore the regulatory effects of this interaction on cholesterol synthesis. Results: Our experiments showed that AR promoted cholesterol synthesis and accumulation by activating sterol-regulatory element-binding protein isoform 2. AR-induced cholesterol synthesis was inhibited by Daxx; however, the expression of AR was not affected. Further studies demonstrated the existence of direct binding between Daxx and AR and this interaction was required to suppress AR activity. Conclusions: The Daxx-mediated antagonism of AR depicts a more complete picture as to how Daxx regulates intracellular cholesterol level and provides a new target for treatment of atherosclerosis. [ABSTRACT FROM AUTHOR]

The objective of this study was to analyze the expression and clinical role of mitosis regulators α-thalassemia/mental retardation syndrome X-linked (ATRX) and death-domain-associated protein (DAXX) in metastatic high-grade serous carcinoma (HGSC). ATRX and DAXX protein expression by immunohistochemistry was analyzed in 400 HGSC effusions. DAXX expression was additionally studied in 15 cancer cell lines, including 4 ovarian carcinoma lines, and in 81 of the 400 HGSC effusions using Western blotting. ATRX and DAXX were expressed in HGSC cells in 386/400 (96%) and 348/400 (87%) effusions, respectively. Western blotting showed DAXX expression in all 15 cell lines and in 70/81 (86%) HGSC effusions. DAXX expression by immunohistochemistry was higher in pleural compared to peritoneal effusions (p = 0.006) and in post-chemotherapy compared to pre-chemotherapy effusions (p = 0.004), and its expression was significantly associated with poor overall survival in univariate of the entire cohort (p = 0.014), as well as analysis limited to chemo-naïve effusions tapped at diagnosis (p = 0.038). The former association retained its prognostic role in Cox multivariate survival analysis (p = 0.011). ATRX expression was unrelated to clinicopathologic parameters or survival. In conclusion, DAXX is associated with disease progression and could be a prognostic marker in metastatic HGSC. Silencing this molecule may have therapeutic relevance in this cancer. [ABSTRACT FROM AUTHOR]

Adeno-associated virus (AAV) has proven to be a promising candidate for gene therapy due to its nonpathogenic nature, ease of production, and broad tissue tropism. However, its transduction capabilities are not optimal due to the interaction with various host factors within the cell. In a previous study, we identified members of the small ubiq like modifier (SUMO) pathway as significant restriction factors in AAV gene transduction. In the present study, we explored the scope of this restriction by focusing on the AAV capsid and host cell proteins as targets. We show that during vector production, the capsid protein VP2 becomes SUMOylated, as indicated by deletion and point mutations of VP2 or the obstruction of its N terminus via the addition of a tag. We observed that SUMOylated AAV capsids display higher stability than non-SUMOylated capsids. Prevention of capsid SUMOylation by VP2 mutations did not abolish transduction restriction by SUMOylation; however, it reduced activation of gene transduction by shutdown of the cellular SUMOylation pathway. This indicates a link between capsid SUMOylation and SUMOylation of cellular proteins in restricting gene transduction. Infection with AAV triggers general SUMOylation of cellular proteins. In particular, the DAXX protein, a putative host cell restriction factor that can become SUMOylated, is able to restrict AAV gene transduction by reducing the intracellular accumulation of AAV vectors. We also observe that the coexpression of a SUMOylation inhibitor with an AAV2 reporter gene vector increased gene transduction significantly. [ABSTRACT FROM AUTHOR]