Increased expression of androgen receptor coregulator MAGE-11 in prostate cancer by DNA hypomethylation and cyclic AMP

RNA-binding protein 14 promotes phase separation to sustain prostate specific antigen expression under androgen deprivation in human prostate cancer

Castration-resistant prostate cancer (CRPC) is a big challenge in managing prostate cancer patients. The androgen receptor (AR) pathway is a major driver even in CRPC under androgen deprivation. The mechanism in maintaining of the AR pathway under androgen deprivation remains elusive. The recent discovery of biomolecular condensate, a membrane-less intracellular construct formed by liquid-liquid phase separation (LLPS), that facilitate molecular assembly, encouraged the re-screening of our previous microarray data list. We selected Rbm14 as a target molecule for further analysis because it works as a coactivator of nuclear receptors as well as it facilitates formation of biomolecular condensates via its intrinsically disordered region. GFP-tagged Rbm14 transfected into HEK293T cells formed droplet-like puncta, which diminished following treatment with 1,6-hexanediol. Droplet-like structures were also observed in immunofluorescence for endogenous RBM14 of PC-3 and DU145 cells. Luciferase assay revealed that Rbm14 enhanced androgen-responsive element (ARE)-mediated reporter activity in all conditions with or without testosterone and AR. Co-immunoprecipitation confirmed the Rbm14-AR interaction. Long non-coding RNAs, including NEAT1, SRA1, and HOTAIR, were also interacted with Rbm14. Small interfering RNAs of NEAT1 reduced ARE-mediated reporter activity, while transfection of SRA1 and HOTAIR enhance the reporter activity. Treatment with 1,6-hexanediol as well as transfection with a dominant-negative splice variant of Rbm14 reduced expression of prostate specific antigen (PSA), a prototype of androgen-regulated gene, in LNCaP, PC-3, and DU145 cells under androgen deprivation. Immunohistochemically, RBM14 expression was substantially upregulated in prostate cancer tissues after androgen deprivation therapy than in untreated tumors. In conclusion, RBM14 is a novel factor involved in maintenance of PSA expression via phase separation under androgen deprivation in prostate cancer.

Emerging frontiers in nanomedicine targeted therapy for prostate cancer

Prostate cancer is a prevalent cancer in men, often treated with chemotherapy. However, it tumor cells are clinically grows slowly and is heterogeneous, leading to treatment resistance and recurrence. Nanomedicines, through targeted delivery using nanocarriers, can enhance drug accumulation at the tumor site, sustain drug release, and counteract drug resistance. In addition, combination therapy using nanomedicines can target multiple cancer pathways, improving effectiveness and addressing tumor heterogeneity. The application of nanomedicine in prostate cancer treatment would be an important strategy in controlling tumor dynamic process as well as improve survival. Thus, this review highlights therapeutic nanoparticles as a solution for prostate cancer chemotherapy, exploring targeting strategies and approaches to combat drug resistance.

Genome instability-derived genes as a novel prognostic signature for lung adenocarcinoma

Background: An increasing number of patients are being diagnosed with lung adenocarcinoma, but there remains limited progress in enhancing prognostic outcomes and improving survival rates for these patients. Genome instability is considered a contributing factor, as it enables other hallmarks of cancer to acquire functional capabilities, thus allowing cancer cells to survive, proliferate, and disseminate. Despite the importance of genome instability in cancer development, few studies have explored the prognostic signature associated with genome instability for lung adenocarcinoma. Methods: In the study, we randomly divided 397 lung adenocarcinoma patients from The Cancer Genome Atlas database into a training group (n = 199) and a testing group (n = 198). By calculating the cumulative counts of genomic alterations for each patient in the training group, we distinguished the top 25% and bottom 25% of patients. We then compared their gene expressions to identify genome instability-related genes. Next, we used univariate and multivariate Cox regression analyses to identify the prognostic signature. We also performed the Kaplan-Meier survival analysis and the log-rank test to evaluate the performance of the identified prognostic signature. The performance of the signature was further validated in the testing group, in The Cancer Genome Atlas dataset, and in external datasets. We also conducted a time-dependent receiver operating characteristic analysis to compare our signature with established prognostic signatures to demonstrate its potential clinical value. Results: We identified GULPsig, which includes IGF2BP1, IGF2BP3, SMC1B, CLDN6, and LY6K, as a prognostic signature for lung adenocarcinoma patients from 42 genome instability-related genes. Based on the risk score of the risk model with GULPsig, we successfully stratified the patients into high- and low-risk groups according to the results of the Kaplan-Meier survival analysis and the log-rank test. We further validated the performance of GULPsig as an independent prognostic signature and observed that it outperformed established prognostic signatures. Conclusion: We provided new insights to explore the clinical application of genome instability and identified GULPsig as a potential prognostic signature for lung adenocarcinoma patients.

Development of novel self-assembled vaccines based on tumour-specific antigenic peptide and TLR2 agonist for effective breast cancer immunotherapy via activating CD8+ T cells and enhancing their function

Vaccines based on tumour-specific antigens are a promising approach for immunotherapy. However, the clinical efficacy of tumour-specific antigens is still challenging. Twelve conjugates with self-assembly properties were designed and synthesized using MAGE-A1 peptide and TLR2 agonist, combined with different covalent bonds. All the developed conjugates formed spherical nanoparticles with a diameter of approximately 150 nm, and enhanced the efficacy of the peptide vaccines with the better targeting of lymph nodes. All the conjugates could well bind to serum albumin and improve the plasma stability of the individual antigenic peptides. In particular, conjugate 6 (N-Ac PamCS-M-6) had a more significant ability to promote dendritic cell maturation, CD8⁺ T cell activation, and subsequent killing of tumour cells, with an in vivo tumour inhibition rate of 70 ± 2.9%. The interaction between specific response and the different conjugation modes was further explored, thereby providing a fundamental basis for novel immune anti-tumour molecular platforms.

Biology of Cancer-Testis Antigens and Their Therapeutic Implications in Cancer

Tumour-specific antigens have been an area of interest in cancer therapy since their discovery in the middle of the 20th century. In the era of immune-based cancer therapeutics, redirecting our immune cells to target these tumour-specific antigens has become even more relevant. Cancer-testis antigens (CTAs) are a class of antigens with an expression specific to the testis and cancer cells. CTAs have also been demonstrated to be expressed in a wide variety of cancers. Due to their frequency and specificity of expression in a multitude of cancers, CTAs have been particularly attractive as cancer-specific therapeutic targets. There is now a rapid expansion of CTAs being identified and many studies have been conducted to correlate CTA expression with cancer and therapy-resistant phenotypes. Furthermore, there is an increasing number of clinical trials involving using some of these CTAs as molecular targets in pharmacological and immune-targeted therapeutics for various cancers. This review will summarise the current knowledge of the biology of known CTAs in tumorigenesis and the regulation of CTA genes. CTAs as molecular targets and the therapeutic implications of these CTA-targeted anticancer strategies will also be discussed.

Intimate communications within the tumor microenvironment: stromal factors function as an orchestra

Extensive studies of the tumor microenvironment (TME) in the last decade have reformed the view of cancer as a tumor cell-centric disease. The tumor microenvironment, especially termed the "seed and soil" theory, has emerged as the key determinant in cancer development and therapeutic resistance. The TME mainly consists of tumor cells, stromal cells such as fibroblasts, immune cells, and other noncellular components. Within the TME, intimate communications among these components largely determine the fate of the tumor. The pivotal roles of the stroma, especially cancer-associated fibroblasts (CAFs), the most common component within the TME, have been revealed in tumorigenesis, tumor progression, therapeutic response, and tumor immunity. A better understanding of the function of the TME sheds light on tumor therapy. In this review, we summarize the emerging understanding of stromal factors, especially CAFs, in cancer progression, drug resistance, and tumor immunity with an emphasis on their functions in epigenetic regulation. Moreover, the importance of epigenetic regulation in reshaping the TME and the basic biological principles underpinning the synergy between epigenetic therapy and immunotherapy will be further discussed.

Virtual Screening and Quantitative Structure-Activity Relationship of Moringa oleifera with Melanoma Antigen A (MAGE-A) Genes against the Therapeutics of Non-Small Cell Lung Cancers (NSCLCs)

In the last decade, there have been significant advancements in the treatment of non-small cell lung cancer, including remarkable gains in detection, diagnosis, and therapy. The emergence of molecular targeted therapies, immunotherapeutic inhibitors, and antiangiogenesis medicines has largely fueled improvements in combination therapy and systemic treatments, all of which have dramatically ameliorated patient outcomes. The Moringa oleifera bioactive compounds have been effective in the suppression of cancers, making them the therapeutic agents of choice for the current investigation to treat MAGE-A presented in NSCLC. The ligand entrants were screened for their pharmacological properties, and 2,2-diphenyl-1,3-benzodioxole was stipulated as the lead candidate. 2,2-Diphenyl-1,3-benzodioxole exhibited better pharmacological properties and superior binding with branched-chain amino acids, making it an ideal candidate to address MAGE-A. The study concluded that addressing MAGE-A to impede their activity and antigenicity can be exploited as immunotarget(s).

Mechanisms Controlling MicroRNA Expression in Tumor

MicroRNAs (miRNAs) are widely present in many organisms and regulate the expression of genes in various biological processes such as cell differentiation, metabolism, and development. Numerous studies have shown that miRNAs are abnormally expressed in tumor tissues and are closely associated with tumorigenesis. MiRNA-based cancer gene therapy has consistently shown promising anti-tumor effects and is recognized as a new field in cancer treatment. So far, some clinical trials involving the treatment of malignancies have been carried out; however, studies of miRNA-based cancer gene therapy are still proceeding slowly. Therefore, furthering our understanding of the regulatory mechanisms of miRNA can bring substantial benefits to the development of miRNA-based gene therapy or other combination therapies and the clinical outcome of patients with cancer. Recent studies have revealed that the aberrant expression of miRNA in tumors is associated with promoter sequence mutation, epigenetic alteration, aberrant RNA modification, etc., showing the complexity of aberrant expression mechanisms of miRNA in tumors. In this paper, we systematically summarized the regulation mechanisms of miRNA expression in tumors, with the aim of providing assistance in the subsequent elucidation of the role of miRNA in tumorigenesis and the development of new strategies for tumor prevention and treatment.

High expression of MAGE-C1 gene in colorectal cancer is associated with its poor prognosis

BACKGROUND

The aim of this study was to explore the relationship between melanoma antigen gene C1 (MAGE-C1) expression and the prognosis for colorectal cancer (CRC), and to establish a mathematical model to comprehensively evaluate the prognosis of patients with CRC.

METHODS

MAGE-C1 was selected by bioinformatics for its greater expression differences in CRC patients. Immunohistochemistry (IHC) was used to detect the expression level of MAGE-C1 in tissue samples of 156 patients with CRC. Kaplan-Meier analysis was employed to assess the relationship between MAGE-C1 and the prognosis of patients with CRC. Univariate and multivariate Cox regression models analyzed the factors affecting the prognosis of CRC patients. Also, the clinicopathological characteristics of patients and genes with clinical concern were integrated to establish a model to comprehensively predict the prognosis of patients with CRC.

RESULTS

MAGE-C1 was found to be highly expressed in 28.8% of CRC patients. MAGE-C1 expression was associated with tumor size, number, and metastasis. Survival analysis showed that CRC patients with high expression of MAGE-C1 had a poor prognosis. Regression analysis demonstrated that MAGE-C1 protein status, T stage, differentiation, Kirsten rat sarcoma (KRAS) status, and v-RAF murine sarcoma viral oncogene homolog B1 (BRAF) status were the independent factors influencing the overall survival of patients with CRC. Meanwhile, MAGE-C1 combined with clinicopathological characteristics and hotspot gene mutations could be used to evaluate the prognosis of CRC.

CONCLUSIONS

Our study shows that MAGE-C1 is differentially expressed in patients with CRC and affects the prognosis of patients. The combination of MAGE-C1, clinicopathological characteristics, and genes with clinical concern can be used to assess the prognosis of CRC.

Pathogenicity of the MAGE family

The melanoma antigen gene (MAGE) protein family is a group of highly conserved proteins that share a common homology domain. Under normal circumstances, numerous MAGE proteins are only expressed in reproduction-related tissues; however, abnormal expression levels are observed in a variety of tumor tissues. The MAGE family consists of type I and II proteins, several of which are cancer-testis antigens that are highly expressed in cancer and serve a critical role in tumorigenesis. Therefore, this review will use the relationship between MAGEs and tumors as a starting point, focusing on the latest developments regarding the function of MAGEs as oncogenes, and preliminarily reveal their possible mechanisms.

Targeted immune epitope prediction to HHLA2 and MAGEB5 protein variants as therapeutic approach to related viral diseases

Background

Targeted immunotherapy is mostly associated with cancer treatment wherein designed molecules engage signaling pathways and mutant proteins critical to the survival of the cell. One of several genetic approaches is the use of in silico methods to develop immune epitopes targeting specific antigenic regions on related mutant proteins. In a recent study we showed a functional association between the gamma retrovirus HERV-H Long Terminal Associating (HHLA1, HHLA2 and HHLA3) proteins and melanoma associated antigen of the B class proteins (MAGEB5), with a resultant decrease in expression of HLA class I and II immune variants. HLA-C and HLA-DRB5 were the main HLA class I and II Immune variants, respectively, that showed expression changes across viral samples of interest. Specific immune variants for HLA-C and HLA-DRB5 were filtered for the top ten based on their relative frequency of counts across the samples.

Results

Protein variants for HHLA1, HHLA2, HHLA3 and MAGEB5 were used to predict antigenic epitope peptides to immune peptide-MHC class I and II binding using artificial neural networks. For IC50 peptide scores (PS) ≥ 0.5 with a transformed binding ability between 0 and 1, the top 5 epitopes identified for all targeted genes HHLA1,2 & 3 and MAGEB5 were qualified as strong or weak binders according to the threshold. Domain analysis using NCBI Conserved Domain Database (CDD) identified HHLA2 with immunoglobulin-like domains (Ig_C1-set) and MAGEB5 with the MAGE Homology Domain (MHD). Linear regression showed a statistical correlation (P < 0.001) for HHLA2 and MAGEB5 predicted epitope peptides to HLA-C but not HLA-DRB5. The prediction model identified HLA-C variant 9 (HLA-C9, BAA08825.1 HLA-B*1511) at 1.1% as the most valuable immune target for clinical considerations. Identification of the 9-mer epitope peptide within the domain showed for HHLA2: YANRTSLFY (PS = 0.5837) and VLAYYLSSSQNTIIN (PS = 0.77) for HLA-C and HLA-DRB5, respectively and for MAGEB5, peptides: FVRLTYLEY (PS = 0.5293) and YPAHYQFLWGPRAYT (PS = 0.62) for HLA-C and HLA-DRB5, respectively.

Conclusion

Specific immune responses to targeted epitope peptides and their prediction models, suggested co-expression and co-evolution for HHLA2 and MAGEB5 in viral related diseases. HHLA2 and MAGEB5 could be considered markers for virus related tumors and targeted therapy for oncogenic diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00440-w.

Epigenetic Upregulation of MAGE-A Isoforms Promotes Breast Cancer Cell Aggressiveness

Simple Summary

Breast cancer is a heterogeneous disease that has complex causes and mechanisms of development. Currently, patient treatment options depend on the breast cancer molecular subtype, which is classified based on the presence or absence of hormone receptors and HER2. However, this classification system has limitations in terms of predicting responsiveness to anticancer drugs and patient outcomes. In this study, we present a new approach to classifying molecular breast cancer subtypes: it is based on changes in histone modifications in the promoter region of the MAGEA12 locus, which we found related closely to MAGEA12 expression and MAGEA12-associated malignancy of breast cancer cells.

Abstract

After decades-long efforts to diagnose and treat breast cancer, the management strategy that has proved most successful to date is molecular-subtype-specific inhibition of the hormone receptors and HER2 that are expressed by individual cancers. Melanoma-associated antigen (MAGE) proteins comprise >40 highly conserved members that contain the MAGE homology domain. They are often overexpressed in multiple cancers and contribute to cancer progression and metastasis. However, it remains unclear whether the biological activity arising from MAGE gene expression is associated with breast cancer subtypes. In this study, we analyzed the RNA-sequencing (RNA-seq) data of 70 breast cancer cell lines and found that MAGEA12 and MAGEA3 were highly expressed in a subset of these lines. Significantly, MAGEA12 and MAGEA3 expression levels were independent of hormone receptor expression levels but were closely associated with markers of active histone modifications. This indicates that overexpression of these genes is attributable to epigenetic deregulation. RNA-seq of MAGEA12-depleted cells was then used to identify 382 candidate targets of MAGEA12 that were downregulated by MAGEA12 depletion. Furthermore, our gain-of-function experiments showed that MAGEA12 overexpression promoted aggressive behaviors of malignant breast cancer cells, including enhancing their cell migration and invasion. These changes were associated with increased epigenetic deregulation of the MAGEA12 signature genes. Thus, MAGEA12 may play an important role in breast cancer malignancy. Taken together, our findings suggest that MAGEA12 could be a promising therapeutic target in breast cancer, and its overexpression and epigenetic changes could serve as subtype classification biomarkers.

Leveraging epigenetics to enhance the efficacy of immunotherapy

Background

Epigenetic mechanisms regulate chromatin accessibility patterns that govern interaction of transcription machinery with genes and their cis-regulatory elements. Mutations that affect epigenetic mechanisms are common in cancer. Because epigenetic modifications are reversible many anticancer strategies targeting these mechanisms are currently under development and in clinical trials.

Main body

Here we review evidence suggesting that epigenetic therapeutics can deactivate immunosuppressive gene expression or reprogram tumor cells to activate antigen presentation mechanisms. In addition, the dysregulation of epigenetic mechanisms commonly observed in cancer may alter the immunogenicity of tumor cells and effectiveness of immunotherapies.

Conclusions

Therapeutics targeting epigenetic mechanisms may be helpful to counter immune evasion and improve the effectiveness of immunotherapies.

Dissecting the Hormonal Signaling Landscape in Castration-Resistant Prostate Cancer

Understanding the molecular mechanisms underlying prostate cancer (PCa) progression towards its most aggressive, castration-resistant (CRPC) stage is urgently needed to improve the therapeutic options for this almost incurable pathology. Interestingly, CRPC is known to be characterized by a peculiar hormonal landscape. It is now well established that the androgen/androgen receptor (AR) axis is still active in CRPC cells. The persistent activity of this axis in PCa progression has been shown to be related to different mechanisms, such as intratumoral androgen synthesis, AR amplification and mutations, AR mRNA alternative splicing, increased expression/activity of AR-related transcription factors and coregulators. The hypothalamic gonadotropin-releasing hormone (GnRH), by binding to its specific receptors (GnRH-Rs) at the pituitary level, plays a pivotal role in the regulation of the reproductive functions. GnRH and GnRH-R are also expressed in different types of tumors, including PCa. Specifically, it has been demonstrated that, in CRPC cells, the activation of GnRH-Rs is associated with a significant antiproliferative/proapoptotic, antimetastatic and antiangiogenic activity. This antitumor activity is mainly mediated by the GnRH-R-associated Gαi/cAMP signaling pathway. In this review, we dissect the molecular mechanisms underlying the role of the androgen/AR and GnRH/GnRH-R axes in CRPC progression and the possible therapeutic implications.

Epigenetic modulation combined with PD-1/PD-L1 blockade enhances immunotherapy based on MAGE-A11 antigen-specific CD8+T cells against esophageal carcinoma

Cancer testis antigens (CTAs) are promising targets for T cell-based immunotherapy and studies have shown that certain CT genes are epigenetically depressed in cancer cells through DNA demethylation. Melanoma-associated antigen A11 (MAGE-A11) is a CTA that is frequently expressed in esophageal cancer and is correlated with a poor esophageal cancer prognosis. Consequently, MAGE-A11 is a potential immunotherapy target. In this study, we evaluated MAGE-A11 expression in esophageal cancer cells and found that it was downregulated in several tumor cell lines, which restricted the effect of immunotherapy. Additionally, the specific recognition and lytic potential of cytotoxic T lymphocytes (CTLs) derived from the MAGE-A11 was determined. Specific CTLs could kill esophageal cancer cells expressing MAGE-A11 but rarely lysed MAGE-A11-negative tumor cells. Therefore, induction of MAGE-A11 expression is critical for CTLs recognition and lysis of esophageal cancer cells. Treatment with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine increased MAGE-A11 expression in esophageal cancer cells and subsequently enhanced the cytotoxicity of MAGE-A11-specific CD8+T cells against cancer cell lines. Furthermore, we found that PD-L1 expression in esophageal cancer cells affected the antitumor function of CTLs. programmed death-1 (PD-1)/PD-L1 blockade could increase the specific CTL-induced lysis of HLA-A2+/MAGE-A11+ tumor cell lines treated with 5-aza-2'-deoxycytidine. These findings indicate that the treatment of tumor cells with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine augments MAGE-A11 expression in esophageal cancer cells. The combination of epigenetic modulation by 5-aza-2'-deoxycytidine and PD-1/PD-L1 blockade may be useful for T cell-based immunotherapy against esophageal cancer.

Emerging roles of the MAGE protein family in stress response pathways

The melanoma antigen (MAGE) proteins all contain a MAGE homology domain. MAGE genes are conserved in all eukaryotes and have expanded from a single gene in lower eukaryotes to ∼40 genes in humans and mice. Whereas some MAGEs are ubiquitously expressed in tissues, others are expressed in only germ cells with aberrant reactivation in multiple cancers. Much of the initial research on MAGEs focused on exploiting their antigenicity and restricted expression pattern to target them with cancer immunotherapy. Beyond their potential clinical application and role in tumorigenesis, recent studies have shown that MAGE proteins regulate diverse cellular and developmental pathways, implicating them in many diseases besides cancer, including lung, renal, and neurodevelopmental disorders. At the molecular level, many MAGEs bind to E3 RING ubiquitin ligases and, thus, regulate their substrate specificity, ligase activity, and subcellular localization. On a broader scale, the MAGE genes likely expanded in eutherian mammals to protect the germline from environmental stress and aid in stress adaptation, and this stress tolerance may explain why many cancers aberrantly express MAGEs Here, we present an updated, comprehensive review on the MAGE family that highlights general characteristics, emphasizes recent comparative studies in mice, and describes the diverse functions exerted by individual MAGEs.

A comprehensive analysis of the MAGE family as prognostic and diagnostic markers for hepatocellular carcinoma

The Melanoma Antigen Gene (MAGE) family is a large, highly conserved group of proteins which was reported to participate in the progression of multiple cancers in humans. However, the function of distinct MAGE genes in hepatocellular carcinoma (HCC) is largely unclear. In this study, we comprehensively evaluated the expression, clinical significance, genetic alteration, interaction network and functional enrichment of MAGEs in HCC. Our research showed that many MAGE genes were dysregulated in HCC. Among them, MAGEA1, MAGEC2, MAGED1, MAGED2, MAGEF1 and MAGEL2 were significantly associated with clinical stage and differentiation of HCC. MAGED1, MAGED2, MAGEA6, MAGEA12, MAGEA10, MAGEB4, MAGEL2 and MAGEC3 significantly correlated with HCC prognosis. Further functional enrichment analysis suggested the dysregulated MAGEs may play important roles in signal transduction. These results indicate that multiple dysregulated MAGEs might play important roles in the development of HCC and can be exploited as useful biomarkers for diagnosis and treatment in HCC.

Exosomes-Mediated Transfer of Itga2 Promotes Migration and Invasion of Prostate Cancer Cells by Inducing Epithelial-Mesenchymal Transition

Although integrin alpha 2 subunit (ITGA2) mediates cancer progression and metastasis, its transfer by exosomes has not been investigated in prostate cancer (PCa). We aimed to determine the role of exosomal ITGA2 derived from castration-resistant PCa (CRPC) cells in promoting aggressive phenotypes in androgen receptor (AR)-positive cells. Exosomes were co-incubated with recipient cells and tested for different cellular assays. ITGA2 was enriched in exosomes derived from CRPC cells. Co-culture of AR-positive cells with CRPC-derived exosomes increased their proliferation, migration, and invasion by promoting epithelial-mesenchymal transition, which was reversed via ITGA2 knockdown or inhibition of exosomal uptake by methyl-β-cyclodextrin (MβCD). Ectopic expression of ITGA2 reproduced the effect of exosomal ITGA2 in PCa cells. ITGA2 transferred by exosomes exerted its effect within a shorter time compared to that triggered by its endogenous expression. The difference of ITGA2 protein expression in localized tumors and those with lymph node metastatic tissues was indistinguishable. Nevertheless, its abundance was higher in circulating exosomes collected from PCa patients when compared with normal subjects. Our findings indicate the possible role of the exosomal-ITGA2 transfer in altering the phenotype of AR-positive cells towards more aggressive phenotype. Thus, interfering with exosomal cargo transfer may inhibit the development of aggressive phenotype in PCa cells.

Reduced cytoplasmic expression of MAGE-A2 predicts tumor aggressiveness and survival: an immunohistochemical analysis

BACKGROUND

Melanoma antigen gene A2 (MAGE-A2) is one of the most cancer-testis antigens overexpressed in various types of cancers. Silencing the MAGE-A2 expression inhibited the proliferation of prostate cancer (PCa) cells and increased the chemosensitivity. However, the expression pattern of MAGE-A2 in PCa tissue samples and its prognostic and therapeutic values for PCa patients is still unclear.

METHODS

In this study, for the first time, the staining pattern and clinical significance of MAGE-A2 were evaluated in 166 paraffin-embedded prostate tissues, including 148 cases of PCa and 18 cases of high-grade prostatic intraepithelial neoplasia (HPIN), by immunohistochemical analysis.

RESULTS

The simultaneous expression of both nuclear and cytoplasmic patterns of MAGE-A2 with different staining intensities was observed among studied cases. Increased expression of MAGE-A2 was significantly found in PCa tissues compared to HPIN cases (P < 0.0001). Among PCa samples, the strong staining intensity of nuclear expression was predominantly observed in comparison with cytoplasmic expression in PCa tissues (P < 0.0001). A significant and inverse correlation was found between the cytoplasmic expression of MAGE-A2 and increased Gleason score (P = 0.002). Increased cytoplasmic expression of MAGE-A2 was associated with longer biochemical recurrence-free survival (BCR-FS) and disease-free survival (DFS) of patients (P = 0.002, P = 0.001, respectively). In multivariate analysis, Gleason score and cytoplasmic expression of MAGE-A2 were independent predictors of the BCR-FS (P = 0.014; P = 0.028, respectively).

CONCLUSIONS

Taken together, cytoplasmic expression of MAGE-A2 was inversely proportional to the malignant grade and duration of recurrence of the disease in patients with PCa.

Sexual partner preference in animals and humans

Sex differences in brain and behavior of animals including humans result from an interaction between biological and environmental influences. This is also true for the differences between men and women concerning sexual orientation. Sexual differentiation is mediated by three groups of biological mechanisms: early actions of sex steroids, more direct actions of sex-specific genes not mediated by gonadal sex steroids and epigenetic mechanisms. Differential interactions with parents and conspecifics have additionally long-term influences on behavior. This presentation reviews available evidence indicating that these different mechanisms play a significant role in the control of sexual partner preference in animals and humans, in other words the homosexual versus heterosexual orientation. Clinical and epidemiological studies of phenotypically selected populations indicate that early actions of hormones and genetic factors clearly contribute to the determination of sexual orientation. The maternal embryonic environment also modifies the incidence of male homosexuality via immunological mechanisms. The relative contribution of each of these mechanisms remains however to be determined.

Neoantigen-based EpiGVAX vaccine initiates antitumor immunity in colorectal cancer

Metastatic colorectal cancer (CRC) is poorly immunogenic, with limited neoantigens that can be targeted by cancer vaccine. Previous approaches to upregulate neoantigen have had limited success. In this study, we investigated the role of a DNA methyltransferase inhibitor (DNMTi), 5-aza-2'-deoxycytidine (DAC), in inducing cancer testis antigen (CTA) expression and evaluated the antitumor efficacy of a combinatorial approach with an epigenetically regulated cancer vaccine EpiGVAX and DAC. A murine model of metastatic CRC treated with combination therapy with an irradiated whole-cell CRC vaccine (GVAX) and DAC was used to assess the antitumor efficacy. DAC significantly induced expression of CTAs in CRC, including a new CTA Tra-P1A with a known neoepitope, P1A. Epigenetically modified EpiGVAX with DAC improved survival outcomes of GVAX. Using the epigenetically regulated antigen Tra-P1A as an example, our study suggests that the improved efficacy of EpiGVAX with DAC may due in part to the enhanced antigen-specific antitumor immune responses. This study shows that epigenetic therapy with DNMTi can not only induce new CTA expression but may also sensitize tumor cells for immunotherapy. Neoantigen-based EpiGVAX combined with DAC can improve the antitumor efficacy of GVAX by inducing antigen-specific antitumor T cell responses to epigenetically regulated proteins.

Global DNA Hypomethylation in Epithelial Ovarian Cancer: Passive Demethylation and Association with Genomic Instability

A hallmark of human cancer is global DNA hypomethylation (GDHO), but the mechanisms accounting for this defect and its pathological consequences have not been investigated in human epithelial ovarian cancer (EOC). In EOC, GDHO was associated with advanced disease and reduced overall and disease-free survival. GDHO (+) EOC tumors displayed a proliferative gene expression signature, including FOXM1 and CCNE1 overexpression. Furthermore, DNA hypomethylation in these tumors was enriched within genomic blocks (hypomethylated blocks) that overlapped late-replicating regions, lamina-associated domains, PRC2 binding sites, and the H3K27me3 histone mark. Increased proliferation coupled with hypomethylated blocks at late-replicating regions suggests a passive hypomethylation mechanism. This hypothesis was further supported by our observation that cytosine DNA methyltransferases (DNMTs) and UHRF1 showed significantly reduced expression in GDHO (+) EOC after normalization to canonical proliferation markers, including MKI67. Finally, GDHO (+) EOC tumors had elevated chromosomal instability (CIN), and copy number alterations (CNA) were enriched at the DNA hypomethylated blocks. Together, these findings implicate a passive DNA demethylation mechanism in ovarian cancer that is associated with genomic instability and poor prognosis.

The role of DNA-demethylating agents in cancer therapy

DNA methylation patterns are frequently altered in cancer cells as compared to normal cells. A large body of research associates these DNA methylation aberrations with cancer initiation and progression. Moreover, cancer cells seem to depend upon these aberrant DNA methylation profiles to thrive. Finally, DNA methylation modifications are reversible, highlighting the potential to target the global methylation patterns for cancer therapy. In this review, we will discuss the scientific and clinical aspects of DNA methylation in cancer. We will review the limited success of targeting DNA methylation in the clinic, the associated clinical challenges, the impact of novel DNA methylation inhibitors and how combination therapies are improving patient outcomes.

Demethylation-mediated upregulation of melanoma-associated antigen-A11 correlates with malignant progression of esophageal squamous cell carcinoma

BACKGROUND

The expression and methylation status of oncogenes are closely related to the onset and progression of cancer.

AIMS

To explore the role and methylation status of melanoma-associated antigen-A11 in the pathogenesis of esophageal squamous cell carcinoma.

METHODS

116 esophageal squamous cell carcinoma patients with tumor tissues and corresponding adjacent normal tissues were obtained. The expression level and methylation status of melanoma-associated antigen-A11 in esophageal cancer cell lines and esophageal squamous cell carcinoma tissues were determined respectively.

RESULTS

Significant up-regulation of melanoma-associated antigen-A11 was detected in esophageal cancer cell lines and esophageal squamous cell carcinoma tissues. Up-regulation of melanoma-associated antigen-A11 contributed to proliferation and invasion in cancer cells. Hypomethylation of the CpG site was associated with pathological differentiation, clinical stage, tumor size, lymph node metastasis and distant metastasis. Esophageal squamous cell carcinoma patients in stage III and IV, with high expression of melanoma-associated antigen-A11 or hypomethylation of the CpG site within the promoter demonstrated poor survival.

CONCLUSION

Melanoma-associated antigen-A11 is up-regulated in esophageal squamous cell carcinoma at least partly by hypomethylation of the CpG site within the promoter and this hypomethylation may affect the prognosis of esophageal squamous cell carcinoma patients.

Androgen Receptor Signaling in the Development of Castration-Resistant Prostate Cancer

Most prostate cancers are androgen-sensitive malignancies whose growths depend on the transcriptional activity of the androgen receptor (AR). In the 1940s, Charles Huggins demonstrated that the surgical removal of testes in men can result in a dramatic improvement in symptoms and can induce prostate cancer regression. Since then, androgen deprivation therapies have been the standard first-line treatment for advanced prostate cancer, including: surgical castration, medical castration, antiandrogens, and androgen biosynthesis inhibitors. These therapies relieve symptoms, reduce tumor burden, and prolong patient survival, while having relatively modest side effects. Unfortunately, hormone deprivation therapy rarely cures the cancer itself. Prostate cancer almost always recurs, resulting in deadly castration-resistant prostate cancer. The underlying escape mechanisms include androgen receptor gene/enhancer amplification, androgen receptor mutations, androgen receptor variants, coactivator overexpression, intratumoral de novo androgen synthesis, etc. Whereas, the majority of the castration-resistant prostate cancers continuously rely on the androgen axis, a subset of recurrent cancers have completely lost androgen receptor expression, undergone divergent clonal evolution or de-differentiation, and become truly androgen receptor-independent small-cell prostate cancers. There is an urgent need for the development of novel targeted and immune therapies for this subtype of prostate cancer, when more deadly small-cell prostate cancers are induced by thorough androgen deprivation and androgen receptor ablation.

Genetic variations in MAGE-A11 predict the risk and survival of renal cell cancer

Melanoma antigen-A11 (MAGE-A11) is a low-abundance, primate-specific steroid receptor coregulator in normal tissues of the human reproductive tract, which plays an important role in tumorigenesis. Single-nucleotide polymorphisms (SNPs) have been shown to contribute to cancer risk and prognosis. However, the role of SNPs of MAGE-A11 in renal cell carcinoma (RCC) has not been established. Two intronic SNPs (rs6641352 and rs6540341) of MAGE-A11 have been screened to assess their associations with RCC risk and prognosis in a case control study. We found that rs6641352 was associated with RCC susceptibility in the dominant model (TC/CC vs. TT, adjusted odds ratio = 1.315, 95% confidence interval [CI] = 1.089-1.588) and with survival of RCC in the recessive model (CC vs. TT/TC, adjusted hazard ratio = 3.526, 95% CI = 1.072-11.595). For the SNP rs6540341, individuals with the T allele could have a critically increased risk of RCC (adjusted odds ratio = 1.301, 95% CI = 1.081-1.564, P = 0.005 in the dominant model). However, there was no significant association between rs6540341 and RCC survival. Hence, rs6641352 in MAGE-A11 may contribute to the genetic susceptibility and prognosis for RCC and act as a biomarker for RCC occurrence and prognosis.

Epigenetic activation of POTE genes in ovarian cancer

The POTE gene family consists of 14 homologous genes localized to autosomal pericentromeres, and a sub-set of POTEs are cancer-testis antigen (CTA) genes. POTEs are over-expressed in epithelial ovarian cancer (EOC), including the high-grade serous subtype (HGSC), and expression of individual POTEs correlates with chemoresistance and reduced survival in HGSC. The mechanisms driving POTE overexpression in EOC and other cancers is unknown. Here, we investigated the role of epigenetics in regulating POTE expression, with a focus on DNA hypomethylation. Consistent with their pericentromeric localization, Pan-POTE expression in EOC correlated with expression of the pericentromeric repeat NBL2, which was not the case for non-pericentromeric CTAs. POTE genomic regions contain LINE-1 (L1) sequences, and Pan-POTE expression correlated with both global and POTE-specific L1 hypomethylation in EOC. Analysis of individual POTEs using RNA-seq and DNA methylome data from fallopian tube epithelia (FTE) and HGSC revealed that POTEs C, E, and F have increased expression in HGSC in conjunction with DNA hypomethylation at 5' promoter or enhancer regions. Moreover, POTEs C/E/F showed additional increased expression in recurrent HGSC in conjunction with 5' hypomethylation, using patient-matched samples. Experiments using decitabine treatment and DNMT knockout cell lines verified a functional contribution of DNA methylation to POTE repression, and epigenetic drug combinations targeting histone deacetylases (HDACs) and histone methyltransferases (HMTs) in combination with decitabine further increased POTE expression. In summary, several alterations of the cancer epigenome, including pericentromeric activation, global and locus-specific L1 hypomethylation, and locus-specific 5' CpG hypomethylation, converge to promote POTE expression in ovarian cancer.

Epigenetic regulation of MAGE family in human cancer progression-DNA methylation, histone modification, and non-coding RNAs

The melanoma antigen gene (MAGE) proteins are a group of highly conserved family members that contain a common MAGE homology domain. Type I MAGEs are relevant cancer-testis antigens (CTAs), and originally considered as attractive targets for cancer immunotherapy due to their typically high expression in tumor tissues but restricted expression in normal adult tissues. Here, we reviewed the recent discoveries and ideas that illustrate the biological functions of MAGE family in cancer progression. Furthermore, we also highlighted the current understanding of the epigenetic mechanism of MAGE family expression in human cancers.

Behavioral evidence for sex steroids hypersensitivity in castrated male canaries

In seasonally breeding songbirds such as canaries, singing behavior is predominantly under the control of testosterone and its metabolites. Short daylengths in the fall that break photorefractoriness are followed by increasing daylengths in spring that activate singing via both photoperiodic and hormonal mechanisms. However, we observed in a group of castrated male Fife fancy canaries maintained for a long duration under a short day photoperiod a large proportion of subjects that sang at high rates. This singing rate was not correlated with variation in the low circulating concentrations of testosterone. Treatment of these actively singing castrated male canaries with a combination of an aromatase inhibitor (ATD) and an androgen receptor blocker (flutamide) only marginally decreased this singing activity as compared to control untreated birds and did not affect various measures of song quality. The volumes of HVC and of the medial preoptic nucleus (POM) were also unaffected by these treatments but were relatively large and similar to volumes in testosterone-treated males. In contrast, peripheral androgen-sensitive structures such as the cloacal protuberance and syrinx mass were small, similar to what is observed in castrates. Together these data suggest that after a long-term steroid deprivation singing behavior can be activated by very low concentrations of testosterone. Singing normally depends on the activation by testosterone and its metabolites of multiple downstream neurochemical systems such as catecholamines, nonapeptides or opioids. These transmitter systems might become hypersensitive to steroid action after long term castration as they probably are at the end of winter during the annual cycle in seasonally breeding temperate zone species.

Evolution of Melanoma Antigen-A11 (MAGEA11) During Primate Phylogeny

Melanoma antigen-A11 (MAGE-A11) is an X-linked and primate-specific steroid hormone receptor transcriptional coregulator and proto-oncogenic protein whose increased expression promotes the growth of prostate cancer. The MAGEA11 gene is expressed at low levels in normal human testis, ovary, and endometrium, and at highest levels in castration-resistant prostate cancer. Annotated genome predictions throughout the surviving primate lineage show that MAGEA11 acquired three 5' coding exons unique within the MAGEA subfamily during the evolution of New World monkeys (NWM), Old World monkeys (OWM), and apes. MAGE-A11 in all primates has a conserved FXXIF coactivator-binding motif that suggests interaction with p160 coactivators contributed to its early evolution as a transcriptional coregulator. An ancestral form of MAGE-A11 in the more distantly related lemur has significant amino acid sequence identity with human MAGE-A11, but lacks coregulator activity based on the absence of the three 5' coding exons that include a nuclear localization signal (NLS). NWM MAGE-A11 has greater amino acid sequence identity than lemur to human MAGE-A11, but inframe premature stop codons suggest that MAGEA11 is a pseudogene in NWM. MAGE-A11 in OWM and apes has nearly identical 5' coding exon amino acid sequence and conserved interaction sites for p300 acetyltransferase and cyclin A. We conclude that the evolution of MAGEA11 within the lineage leading to OWM and apes resulted in steroid hormone receptor transcriptional coregulator activity through the acquisition of three 5' coding exons that include a NLS sequence and nonsynonymous substitutions required to interact with cell cycle regulatory proteins and transcription factors.

MAGE-A11 is activated through TFCP2/ZEB1 binding sites de-methylation as well as histone modification and facilitates ESCC tumor growth

Recently, we have reported that the product of Melanoma Antigens Genes (MAGE) family member MAGE-A11 is an independent poor prognostic marker for esophageal squamous cell carcinoma (ESCC). However, the reason how MAGE-A11 is activated in ESCC progression still remains unclear. In the current study, we demonstrated that DNA methylation and the subsequent histone posttranslational modifications play crucial roles in the regulation of MAGE-A11 in ESCC progression. We found that the methylation rate of TFCP2/ZEB1 binding site on MAGE-A11 promoter in ESCC tissues and cells is higher than the normal esophageal epithelial tissues and cells. Transcription factors TFCP2 and ZEB1 directly bind MAGE-A11 promoter and regulate the endogenous MAGE-A11 expression in a methylation-dependent manner in ESCC cells. Following MAGE-A11 promoter methylation, the methyl-CpG-binding protein MeCP2 was found to bind the methylated MAGE-A11 promoter to mediate histone deactylation by recruiting HDAC1 and HDAC2. Simultaneously, histone inactivation marks including H3K27me3 as well as H3K9me3 were increased, whereas histone activation mark H3K4me3 was decreased. HDAC inhibitor Trichostatin A (TSA) increased DNA methylase inhibitor Decitabine (DAC)-induced MAGE-A11 expression. siRNA-mediated knockdown of histone methltransferase EZH2 or DZNep (a EZH2 inhibitor) treatment increased DAC-induced MAGE-A11 expression. Our results indicate that MAGE-A11 is activated through DNA demethylation, histone acetylation and histone methylation in ESCC, and its activation promotes ESCC tumor growth.

Rationale for the development of alternative forms of androgen deprivation therapy

With few exceptions, the almost 30,000 prostate cancer deaths annually in the United States are due to failure of androgen deprivation therapy. Androgen deprivation therapy prevents ligand-activation of the androgen receptor. Despite initial remission after androgen deprivation therapy, prostate cancer almost invariably progresses while continuing to rely on androgen receptor action. Androgen receptor's transcriptional output, which ultimately controls prostate cancer behavior, is an alternative therapeutic target, but its molecular regulation is poorly understood. Recent insights in the molecular mechanisms by which the androgen receptor controls transcription of its target genes are uncovering gene specificity as well as context-dependency. Heterogeneity in the androgen receptor's transcriptional output is reflected both in its recruitment to diverse cognate DNA binding motifs and in its preferential interaction with associated pioneering factors, other secondary transcription factors and coregulators at those sites. This variability suggests that multiple, distinct modes of androgen receptor action that regulate diverse aspects of prostate cancer biology and contribute differentially to prostate cancer's clinical progression are active simultaneously in prostate cancer cells. Recent progress in the development of peptidomimetics and small molecules, and application of Chem-Seq approaches indicate the feasibility for selective disruption of critical protein-protein and protein-DNA interactions in transcriptional complexes. Here, we review the recent literature on the different molecular mechanisms by which the androgen receptor transcriptionally controls prostate cancer progression, and we explore the potential to translate these insights into novel, more selective forms of therapies that may bypass prostate cancer's resistance to conventional androgen deprivation therapy.

Functional interaction between co-expressed MAGE-A proteins

MAGE-A (Melanoma Antigen Genes-A) are tumor-associated proteins with expression in a broad spectrum of human tumors and normal germ cells. MAGE-A gene expression and function are being increasingly investigated to better understand the mechanisms by which MAGE proteins collaborate in tumorigenesis and whether their detection could be useful for disease prognosis purposes. Alterations in epigenetic mechanisms involved in MAGE gene silencing cause their frequent co-expression in tumor cells. Here, we have analyzed the effect of MAGE-A gene co-expression and our results suggest that MageA6 can potentiate the androgen receptor (AR) co-activation function of MageA11. Database search confirmed that MageA11 and MageA6 are co-expressed in human prostate cancer samples. We demonstrate that MageA6 and MageA11 form a protein complex resulting in the stabilization of MageA11 and consequently the enhancement of AR activity. The mechanism involves association of the Mage A6-MHD domain to MageA11, prevention of MageA11 ubiquitinylation on lysines 240 and 245 and decreased proteasome-dependent degradation. We experimentally demonstrate here for the first time that two MAGE-A proteins can act together in a non-redundant way to potentiate a specific oncogenic function. Overall, our results highlight the complexity of the MAGE gene networking in regulating cancer cell behavior.

Up-Regulation of Follistatin-Like 1 By the Androgen Receptor and Melanoma Antigen-A11 in Prostate Cancer

BACKGROUND

High affinity androgen binding to the androgen receptor (AR) activates genes required for male sex differentiation and promotes the development and progression of prostate cancer. Human AR transcriptional activity involves interactions with coregulatory proteins that include primate-specific melanoma antigen-A11 (MAGE-A11), a coactivator that increases AR transcriptional activity during prostate cancer progression to castration-resistant/recurrent prostate cancer (CRPC).

METHODS

Microarray analysis and quantitative RT-PCR were performed to identify androgen-regulated MAGE-A11-dependent genes in LAPC-4 prostate cancer cells after lentivirus shRNA knockdown of MAGE-A11. Chromatin immunoprecipitation was used to assess androgen-dependent AR recruitment, and immunocytochemistry to localize an androgen-dependent protein in prostate cancer cells and tissue and in the CWR22 human prostate cancer xenograft.

RESULTS

Microarray analysis of androgen-treated LAPC-4 prostate cancer cells indicated follistatin-like 1 (FSTL1) is up-regulated by MAGE-A11. Androgen-dependent up-regulation of FSTL1 was inhibited in LAPC-4 cells by lentivirus shRNA knockdown of AR or MAGE-A11. Chromatin immunoprecipitation demonstrated AR recruitment to intron 10 of the FSTL1 gene that contains a classical consensus androgen response element. Increased levels of FSTL1 protein in LAPC-4 cells correlated with higher levels of MAGE-A11 relative to other prostate cancer cells. FSTL1 mRNA levels increased in CRPC and castration-recurrent CWR22 xenografts in association with predominantly nuclear FSTL1. Increased nuclear localization of FSTL1 in prostate cancer was suggested by predominantly cytoplasmic FSTL1 in benign prostate epithelial cells and predominantly nuclear FSTL1 in epithelial cells in CRPC tissue and the castration-recurrent CWR22 xenograft. AR expression studies showed nuclear colocalization of AR and endogenous FSTL1 in response to androgen.

CONCLUSION

AR and MAGE-A11 cooperate in the up-regulation of FSTL1 to promote growth and progression of CRPC. Prostate 77:505-516, 2017. © 2016 Wiley Periodicals, Inc.

A Comprehensive Guide to the MAGE Family of Ubiquitin Ligases

Melanoma antigen (MAGE) genes are conserved in all eukaryotes and encode for proteins sharing a common MAGE homology domain. Although only a single MAGE gene exists in lower eukaryotes, the MAGE family rapidly expanded in eutherians and consists of more than 50 highly conserved genes in humans. A subset of MAGEs initially garnered interest as cancer biomarkers and immunotherapeutic targets due to their antigenic properties and unique expression pattern that is primary restricted to germ cells and aberrantly reactivated in various cancers. However, further investigation revealed that MAGEs not only drive tumorigenesis but also regulate pathways essential for diverse cellular and developmental processes. Therefore, MAGEs are implicated in a broad range of diseases including neurodevelopmental, renal, and lung disorders, and cancer. Recent biochemical and biophysical studies indicate that MAGEs assemble with E3 RING ubiquitin ligases to form MAGE-RING ligases (MRLs) and act as regulators of ubiquitination by modulating ligase activity, substrate specification, and subcellular localization. Here, we present a comprehensive guide to MAGEs highlighting the molecular mechanisms of MRLs and their physiological roles in germ cell and neural development, oncogenic functions in cancer, and potential as therapeutic targets in disease.

Melanoma antigen-A11 regulates substrate-specificity of Skp2-mediated protein degradation

Melanoma antigen-A11 (MAGE-A11) is a proto-oncogene involved in androgen receptor signaling and androgen-dependent cell growth. In this report we provide evidence that MAGE-A11 interacts with Skp2 (S phase kinase-associated protein), the substrate recognition protein of the Skp1-Cullin1-F-box E3 ubiquitin ligase, and with Skp2 binding protein, cyclin A. A similar cyclin A binding motif in MAGE-A11 and Skp2 was consistent with a competitive relationship between MAGE-A11 and Skp2 in binding cyclin A. Skp2 inhibited MAGE-A11 interaction with cyclin A. Differential effects of MAGE-A11 on Skp2-mediated protein degradation were also revealed. MAGE-A11 increased Skp2-mediated degradation of cyclin A and retinoblastoma-related protein p130. In contrast, MAGE-A11 decreased Skp2-mediated degradation of E2F1 and Skp2 self-ubiquitination. Stabilization of E2F1 by MAGE-A11 was associated with sequestration and inactivation of Skp2 through the formation of an E2F1-MAGE-A11-Skp2 complex. We conclude that direct interactions of MAGE-A11 with Skp2 and cyclin A regulate the substrate-specificity of Skp2-mediated protein degradation.

Prognostic Significance of MAGE-A11 in Esophageal Squamous Cell Carcinoma and Identification of Related Genes Based on DNA Microarray

BACKGROUND AND AIMS

This study aims to investigate the expression pattern of melanoma-associated antigen-A11 (MAGE-A11) in esophageal squamous cell carcinoma (ESCC) specimens and analyze its prognostic significance for ESCC patients. In addition, the purpose of our study was also to explore the biological function of MAGE-A11 in ESCC cells based on DNA microarray.

METHODS

Immunohistochemistry was used to detect the expression of MAGE-A11 in ESCC specimens, and its prognostic significance was analyzed by statistical analysis. DNA microarray and quantitative RT-PCR were used to explore the different expression of MAGE-A11 downstream genes in ESCC cells. Cell invasion assay and MTT assay were used to detect the effect of MAGE-A11 cDNA on the invasion and proliferation of ESCC cells.

RESULTS

Of the ESCC specimens, 59.3% showed positive MAGE-A11 expression. MAGE-A11 expression in ESCC specimens was positively associated with distant lymph node metastasis. Overall survival of ESCC patients with positive MAGE-A11 expression was shorter than in patients with negative MAGE-A11 expression. Multivariate Cox regression analysis showed MAGE-A11 expression is an independent poor prognostic factor for ESCC patients. Overexpression of MAGE-A11 changed a variety of gene expressions, which was associated with various cell functions such as protein ubiquitination, cell proliferation and apoptosis, tumor invasion and metastasis. Overexpression of MAGE-A11 directly increased the invasion and proliferation of ESCC cells.

CONCLUSIONS

MAGE-A11 is an independent poor prognostic marker for ESCC patients. MAGE-A11 regulates various cell functions and directly increases the invasion and proliferation of ESCC cells.

Expression of MAGE-A1-A12 subgroups in the invasive tumor front and tumor center in oral squamous cell carcinoma

MAGE-A proteins are highly expressed in oral squamous cell carcinoma (OSCC) and are promising targets for cancer immunotherapy. This study examined the presence of MAGE-A expression within the tumor center (TC) and tumor invasive front (TIF) and evaluated its relationship to poor prognosis. The expression rate of each MAGE-A subtype, A1-A12, was examined in 68 OSCCs at the TIF and TC. Slides (1-µm) of tissue microarrays (diameter =0.6 mm) were immunohistochemically stained, and the findings were correlated to clinical data. Approximately 95% of the tumors had MAGE-A expression. Higher expression in the TC was shown significantly for MAGE-A1, -A5, -A6, -A9 and -A12 (P<0.05). MAGE-A2 and -A3 exhibited the opposite behavior (not significant, P>0.05). Age, tumor size, grade and survival time were not associated with the expression of certain MAGE-A subgroups. When expression in the whole tumor tissue was considered, only MAGE-A1 was expressed at a significantly higher rate in male patients (P=0.034). At the TIF, MAGE-A9 and the UICC disease stage were significantly correlated (P=0.0263), and MAGE-A6 and the UICC disease stage exhibited a strong trend (P=0.0596). The expression of MAGE-A3, -A4, -A5, -A9 and -A11 was significantly associated with lymph node metastasis, while MAGE-A4 was expressed in all regions of the tumors (TIF and TC). This study showed that higher expression of most MAGE-A antigens occurred at the TC rather than at the TIF. MAGE‑A1, -A3, -A4, -A5, -A9 and -A11 were significantly associated with clinically advanced stages of disease and seem to be of particular interest.

The MAGE protein family and cancer

The Melanoma Antigen Gene (MAGE) protein family is a large, highly conserved group of proteins that share a common MAGE homology domain. Intriguingly, many MAGE proteins are restricted in expression to reproductive tissues, but are aberrantly expressed in a wide variety of cancer types. Originally discovered as antigens on tumor cells and developed as cancer immunotherapy targets, recent literature suggests a more prominent role for MAGEs in driving tumorigenesis. This review will highlight recent developments into the function of MAGEs as oncogenes, their mechanisms of action in regulation of ubiquitin ligases, and outstanding questions in the field.

Post-translational Down-regulation of Melanoma Antigen-A11 (MAGE-A11) by Human p14-ARF Tumor Suppressor

X-linked primate-specific melanoma antigen-A11 (MAGE-A11) is a human androgen receptor (AR) coactivator and proto-oncogene expressed at low levels in normal human reproductive tract tissues and at higher levels in castration-resistant prostate cancer where it is required for androgen-dependent cell growth. In this report, we show that MAGE-A11 is targeted for degradation by human p14-ARF, a tumor suppressor expressed from an alternative reading frame of the p16 cyclin-dependent kinase inhibitor INK4a/ARF gene. MAGE-A11 degradation by the proteasome was mediated by an interaction with p14-ARF and was independent of lysine ubiquitination. A dose-dependent inverse relationship between MAGE-A11 and p14-ARF correlated with p14-ARF inhibition of the MAGE-A11-induced increase in androgen-dependent AR transcriptional activity and constitutive activity of a splice variant-like AR. Reciprocal stabilization between MAGE-A11 and AR did not protect against degradation promoted by p14-ARF. p14-ARF prevented MAGE-A11 interaction with the E2F1 oncoprotein and inhibited the MAGE-A11-induced increase in E2F1 transcriptional activity. Post-translational down-regulation of MAGE-A11 promoted by p14-ARF was independent of HDM2, the human homologue of mouse double minute 2, an E3 ubiquitin ligase inhibited by p14-ARF. However, MAGE-A11 had a stabilizing effect on HDM2 in the absence or presence of p14-ARF and cooperated with HDM2 to increase E2F1 transcriptional activity in the absence of p14-ARF. We conclude that degradation of MAGE-A11 promoted by the human p14-ARF tumor suppressor contributes to low levels of MAGE-A11 in nontransformed cells and that higher levels of MAGE-A11 associated with low p14-ARF increase AR and E2F1 transcriptional activity and promote the development of castration-resistant prostate cancer.

Inhibiting DNA Methylation Causes an Interferon Response in Cancer via dsRNA Including Endogenous Retroviruses

We show that DNA methyltransferase inhibitors (DNMTis) upregulate immune signaling in cancer through the viral defense pathway. In ovarian cancer (OC), DNMTis trigger cytosolic sensing of double-stranded RNA (dsRNA) causing a type I interferon response and apoptosis. Knocking down dsRNA sensors TLR3 and MAVS reduces this response 2-fold and blocking interferon beta or its receptor abrogates it. Upregulation of hypermethylated endogenous retrovirus (ERV) genes accompanies the response and ERV overexpression activates the response. Basal levels of ERV and viral defense gene expression significantly correlate in primary OC and the latter signature separates primary samples for multiple tumor types from The Cancer Genome Atlas into low versus high expression groups. In melanoma patients treated with an immune checkpoint therapy, high viral defense signature expression in tumors significantly associates with durable clinical response and DNMTi treatment sensitizes to anti-CTLA4 therapy in a pre-clinical melanoma model.

Immune regulation by low doses of the DNA methyltransferase inhibitor 5-azacitidine in common human epithelial cancers

Epigenetic therapy is emerging as a potential therapy for solid tumors. To investigate its mechanism of action, we performed integrative expression and methylation analysis of 63 cancer cell lines (breast, colorectal, and ovarian) after treatment with the DNA methyltransferase inhibitor 5-azacitidine (AZA). Gene Set Enrichment Analysis demonstrated significant enrichment for immunomodulatory pathways in all three cancers (14.4-31.3%) including interferon signaling, antigen processing and presentation, and cytokines/chemokines. Strong upregulation of cancer testis antigens was also observed. An AZA IMmune gene set (AIMs) derived from the union of these immunomodulatory pathway genes classified primary tumors from all three types, into "high" and "low" AIM gene expression subsets in tumor expression data from both TCGA and GEO. Samples from selected patient biopsies showed upregulation of AIM genes after treatment with epigenetic therapy. These results point to a broad immune stimulatory role for DNA demethylating drugs in multiple cancers.

Epigenetic therapy as a novel approach in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver malignancy and one with high fatality. Its 5-year survival rate remains low and thus, there is a need for improvement of current treatment strategies as well as development of novel targeted methodologies in order to optimize existing therapeutic protocols. To this end, only recently, it was discovered that its pathophysiology also involves epigenetic alterations in DNA methylation, histone modifications and/or non-coding microRNA patterns. Unlike genetic events, epigenetic alterations are reversible and thus potentially considered to be an alternative option in cancer treatment protocols. In this review, we describe the general characteristics and resulted major alterations of the epigenetic machinery as well as current state of progress of epigenetic therapy (via different single or combinatorial experimental approaches) in HCC.