Androgen Receptor Methylation Research Articles

Combined effects of organochlorine pesticides on type 2 diabetes mellitus: Insights from endocrine disrupting effects of hormones

Association between organochlorine pesticides (OCPs) exposure and type 2 diabetes mellitus (T2DM) remains contradictory, and the evidence is mostly focused on a single exposure. Here, we assessed the associations between individual and combined OCPs exposure and T2DM, and explored the underlying mechanism of sex hormones and the methylation levels of sex hormone receptors in above associations. A case-control study with 1812 participants was performed. Gas chromatography mass spectrometry, liquid chromatography-tandem mass spectrometry, and pyrosequencing were used to measure plasma OCPs, serum sex hormones, and whole blood methylation levels of sex hormone receptors, respectively. Generalized linear models were used to analyze the relationships between OCPs, sex hormones, the methylation levels of sex hormone receptors, and T2DM. Quantile based g-computation (QGC) and Bayesian Kernel Machine Regression (BKMR) were employed to assess the combined OCPs exposure. The roles of sex hormones and the methylation levels of their receptors were evaluated by moderating mediation models. After adjusting for covariates, each unit (2.718 ng/ml) increase in p,p’-DDE was associated with a higher risk of T2DM in males (odds ratio (OR) and 95% confidence interval (CI): 1.066 (1.023, 1.112)). QGC and BKMR showed a positive combined effect in the associations of OCPs mixtures on T2DM among premenopausal females, and positive effects but not statistically significant among males and postmenopausal females. p,p'-DDE was the largest contributor for the positive associations. Furthermore, testosterone mediated 21.149% of the associations of p,p’-DDE with T2DM moderated by the androgen receptor methylation (ARm) located in CpG island 1. Individual and mixtures of OCPs exposure were positively linked to elevated risk of T2DM. Testosterone and ARm may participate in the related processes of OCPs with T2DM, providing new insights into the adverse endocrine effects caused by OCPs and specific pathways for the etiology and control of diabetes.

Explore the mechanism of ursolic acid acting on atherosclerosis through network pharmacological and bioinformatics methods.

To explore the deep mechanisms of ursolic acid (UA) for treating atherosclerosis based on network pharmacology and bioinformatics. UA target genes were derived from traditional Chinese medicine system pharmacology, BATMAN-TCM, and SwissTargetPrediction databases. Atherosclerosis-related genes were derived from genecards, NCBI genes, and OMIM databases. The protein interaction network was constructed through the STRING database, and the hub network was extracted by using the Cytoscape software MCODE app. The enrichment analysis of gene ontology and Kyoto encyclopedia of genes and genomes was performed by the R software clusterProfiler package, and the expression and prognostic value of the hub genes were verified on the data set. Screen the genes for expression and prognosis conclusions, conduct methylation analysis, and ceRNA construction. UA had 145 targets in the treatment of atherosclerosis. The top 7 gene ontology (biological process, molecular function, and cellular component) and pathways related to atherosclerosis were screened out. It is principally involved in biological processes, including response to lipopolysaccharide and regulation of inflammatory response. The main signaling pathways incorporated the TNF signaling pathway and the AGE-RAGE signaling pathway. Androgen receptor (AR) and interleukin-1 beta gene (IL1B) were further screened as core target genes. Methylation analysis demonstrated that the AR methylation level was elevated in the atherosclerotic group. On the contrary, the IL1B methylation level was lower in the atherosclerotic group. The results of the ceRNA analysis indicated that there were 43 targeted miRNAs in AR and 3 miRNAs in IL1B. We speculate that the target genes of UA regulating atherosclerosis are AR and IL1B. The mechanism may be that UA regulates the expression of target genes by regulating the methylation of target genes.

METTL3 boosts glycolysis and cardiac fibroblast proliferation by increasing AR methylation

Dysregulated glycolysis has been noted in several pathological processes characterized by supporting cell proliferation. Nonetheless, the role of glycolysis reprogramming is not well appreciated in cardiac fibrosis which is accompanied by increased fibroblasts proliferation. In this study, we investigated the cause and consequence of glycolysis reprogramming in cardiac fibrosis, using clinical samples, animal models, and cultured cells. Herein, we report that methyltransferase-like 3 (METTL3) facilitates glycolysis and cardiac fibroblasts proliferation, leading to cardiac fibrosis. The augmentation of glycolysis, an essential event during cardiac fibroblasts proliferation, is dependent on an increased expression of METTL3. A knockdown of METTL3 suppressed glycolysis, and inhibited cardiac fibroblast proliferation and cardiac fibrosis. Mechanistically, METTL3 epigenetically repressed androgen receptor (AR) expression in an m6A-YTHDF2- dependent manner, by targeting the specific AR m6A site. AR could interact with the glycolysis marker HIF-1α, and down-regulation of AR activates HIF-1α signaling, resulting in enhanced glycolysis and cardiac fibroblast proliferation. In contrast, the overexpression of AR significantly reduced the HIF-1α axis, decreased expression of glycolytic enzymes HK3, inhibited glycolysis, and repressed cardiac fibroblasts proliferation. Notably, increased METTL3 and YTHDF2 levels, decreased AR expression, increased HIF-1α and Postn expression and augmented glycolysis, and increased cardiac fibrosis were detected in human atrial fibrillation heart tissues. Our results found a novel mechanism by which METTL3-catalyzed m6A modification in cardiac fibrosis, wherein it facilitated glycolysis and cardiac fibroblasts proliferation by increasing AR methylation in an m6A-YTHDF2- dependent manner and provided new insights strategies to intervene cardiac fibrosis.

Aberrant X chromosome skewing and acquired clonal hematopoiesis in adult-onset common variable immunodeficiency.

Advances in genomic medicine have elucidated an increasing number of genetic etiologies for patients with common variable immunodeficiency (CVID). However, there is heterogeneity in clinical and immunophenotypic presentations and a limited understanding of the underlying pathophysiology of many cases. The primary defects in CVID may extend beyond the adaptive immune system, and the combined defect in both the myeloid and lymphoid compartments suggests the mechanism may involve bone marrow output and earlier progenitors. Using the methylation profile of the human androgen receptor (AR) gene as a surrogate epigenetic marker for bone marrow clonality, we examined the hematopoietic compartments of patients with CVID. Our data show that clonal hematopoiesis is common among patients with adult-onset CVID who do not have associated noninfectious complications. Nonblood tissues did not show a skewed AR methylation status, supporting a model of an acquired clonal hematopoietic event. Attenuation of memory B cell differentiation into long-lived plasma cells (CD20–CD27+CD38+CD138+) was associated with marked changes in the postdifferentiation methylation profile, demonstrating the functional consequence of clonal hematopoiesis on humoral immunity in these patients. This study sheds light on a potential etiology of a subset of patients with CVID, and the findings suggest that it is a stage of an acquired lymphocyte maturation disorder.

Androgen receptor gene methylation related to colorectal cancer risk.

According to its incidence patterns, colorectal cancer (CRC) tends to occur more frequently in males than in females, and the evidence shows that CRC is a hormone-related tumor. These findings indicate that androgen receptor (AR) gene methylation might be important for the regulation of the CRC risk in the different sexes. We used a case–control study to investigate the association between AR methylation in peripheral blood (PBL) and CRC risk. A cohort study was conducted to analyze the effect of AR methylation levels in both PBL and tissue on the prognosis of CRC. AR methylation levels were detected using methylation-sensitive high-resolution melting (MS-HRM). The results indicate that the hypomethylation of AR was significantly associated with the risk of CRC (OR = 1.869, 95% CI: 1.629–2.141, P < 0.001), and the results remained similar after adjusting for the propensity score (PS) (OR = 1.344, 95% CI: 1.147–1.575, P < 0.001) and PS matching (OR = 1.138, 95% CI: 1.000–1.292 P = 0.049). The hypomethylation of AR was significantly associated with CRC in males (OR = 2.309, 95% CI: 1.200–4.245; P = 0.012) but not females (OR = 1.000, 95% CI: 0.567–1.765; P = 0.999). The methylation status of AR in PBL and tissue does not seem to be associated with prognosis in colorectal cancer (OR = 1.425, 95% CI: 0.895–2.269, P = 0.135; OR = 0.930, 95% CI: 0.674–1.285, P = 0.661). We conclude that AR hypomethylation in PBL is associated with a high risk of CRC and may serve as a biomarker. Further studies involving large sample sizes are needed to validate the results of this study.

X chromosome gain is related to increased androgen receptor expression in male breast cancer.

X chromosome gain has been previously described in male breast cancer (MBC). Androgen receptor (AR) gene is located on X chromosome. The aim of this study was to investigate the role of the X chromosome gain in the development of MBC and its relation with AR gene copy number and expression.The X chromosome status was assessed in 66 cases of male invasive and in situ duct breast carcinoma, in 34 cases of gynecomastia associated with cancer, and in 11 cases of tumor-free gynecomastia. Cases were tested by fluorescence in situ hybridization (FISH) to assess the X chromosome status and AR amplification. AR expression was studied by immunohistochemistry (IHC). In addition, AR methylation status was assessed.X chromosome gain was observed in 74.7% of invasive duct carcinoma, in 20.6% of in situ duct carcinoma, and in 14.6% of gynecomastia when associated with cancer, while all cases of tumor-free gynecomastia showed wild X chromosome asset. AR gene copy number when increased paralleled the number of X chromosomes. AR IHC expression was observed in 100% of MBC tested. AR gene methylation status revealed low level or absence of methylation.These data suggest that X chromosome can play a role in the neoplastic transformation of male breast epithelium. X chromosome gain is paralleled by AR gene polysomy. Polysomic AR genes show low methylation levels and high AR protein expression on IHC. These data should be taken into consideration for MBC treatment planning.

Abstract 4356: Methylation and expression of androgen receptor in Papillary Thyroid Cancer

Abstract Papillary Thyroid Cancer (PTC) accounts for the vast majority of thyroid cancers and comprises more than 90% of neoplasms in the endocrine system. In the last 30 years, the incidence and prevalence of PTC has dramatically risen in developed countries, with a three-fold higher incidence in women than in men. With an overall five-year survival rate of 98.1%, early stage PTC has a favorable prognosis. However, PTC exhibits increased aggressiveness with poor prognosis in men diagnosed with the disease. These striking observations led us to explore the role of androgen and androgen receptor (AR) in this disease. We found an approximately 70% decrease in median AR RNA expression (p&amp;lt;0.0001) in 24 PTC patient tissue samples (from New York Eye and Ear Infirmary), compared to matched, normal thyroid tissue. A similar trend was also observed in about 500 PTC samples in the TCGA database, compared with 60 normal thyroid samples. Methylation was explored as a cause for the down-regulation of the AR mRNA in disease pathogenesis, using in-silico methods such as Wanderer, a Maplab tool for TCGA RNA data visualization, and MethylPlotter. A methylation pattern of the AR gene, spanning 7 exons, was generated with 30 methylation sites and, AR in PTC was found to be predominantly methylated at ten sites, compared to matched normal thyroid tissue samples, in the TCGA. Patients with ten or more hypermethylated sites on the AR gene in tumor tissue exhibited a significant decrease in the AR RNA expression in the tumor, versus matched normal thyroid tissue. Methylation of AR (10 or more sites) was accompanied by a nine-fold reduction in AR expression in male PTC, and a five-fold decrease in female PTC. This reduction was not observed in hyper- or equally-methylated normal thyroid tissue. We selected eleven methylation sites in the CpG islands that we predict are essential for AR silencing, with four sites in the AR promoter region. Additionally, we found AR gene-specific and global transcription activators to be downregulated, and repressors up-regulated in the PTC samples. The data adds importance to our previous studies showing induction of senescence in AR-transfected PTC cells in culture, when AR is stimulated with 5α-dihydrotestosterone. In conclusion, our study demonstrates a fine regulation and differential expression of AR associated with methylation, and highlights the significance of epigenetic modifications in thyroid cancer progression. Citation Format: Anvita Gupta, Timmy O'Connell, Melanie Jones, Karnika Singh, Monica Schwarcz, JK Rasamny, Dorota Halicka, Jiangwei Li, Codrin Iacob, Nina Suslina, Stimson Schantz, Edward Shin, Zbigniew Darzynkiewicz, Raj Tiwari, Jan Geliebter. Methylation and expression of androgen receptor in Papillary Thyroid Cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4356. doi:10.1158/1538-7445.AM2017-4356

ERG signaling in prostate cancer is driven through PRMT5-dependent methylation of the Androgen Receptor

The TMPRSS2:ERG gene fusion is common in androgen receptor (AR) positive prostate cancers, yet its function remains poorly understood. From a screen for functionally relevant ERG interactors, we identify the arginine methyltransferase PRMT5. ERG recruits PRMT5 to AR-target genes, where PRMT5 methylates AR on arginine 761. This attenuates AR recruitment and transcription of genes expressed in differentiated prostate epithelium. The AR-inhibitory function of PRMT5 is restricted to TMPRSS2:ERG-positive prostate cancer cells. Mutation of this methylation site on AR results in a transcriptionally hyperactive AR, suggesting that the proliferative effects of ERG and PRMT5 are mediated through attenuating AR's ability to induce genes normally involved in lineage differentiation. This provides a rationale for targeting PRMT5 in TMPRSS2:ERG positive prostate cancers. Moreover, methylation of AR at arginine 761 highlights a mechanism for how the ERG oncogene may coax AR towards inducing proliferation versus differentiation.

Abstract 2986: Mechanism of androgen receptor (AR) silencing in small cell prostate carcinoma.

Abstract Small cell prostate cancer (SCPC) is an androgen receptor (AR) negative variant that often emerges in the castration-resistant progression of typical AR-positive prostate adenocarcinomas. Its presence predicts for an aggressive clinical course with poor response to hormonal therapies and a short median survival. Evidence suggests that the emergence of (SCPC) occurs through cellular transdifferentiation. Therefore, we hypothesized that loss of AR gene transcription may depend on epigenetic events. Given the central role of AR in prostate cancer, we reasoned that identifying the mechanisms involved in its downregulation could improve our understanding of how the lethal SCPC subtype arises. Here we investigated the DNA methylation and histone modifications of AR in a group of six prostate tumor xenografts developed from men with CRPC (two AR-positive [MDA PCa 170.4 and MDA PCa 180.30] and four AR-negative SCPC [MDA PCa 144.13, MDA PCa 144.4, MDA PCa 155 and MDA PCa 146.10]) and three established prostate cancer cell lines (one AR-positive [LNCaP] and two AR-negative [PC3 and DU145]). We first evaluated the methylation status of selected CpG sites in the AR promoter-associated CpG island using bisulfite-sequencing followed by pyrosequencing analysis. Except for the cancer cell lines PC-3 and DU145, all other cell lines and xenografts were unmethylated regardless of the AR expression status. Next, we used chromatin immunoprecipitation (ChIP) to evaluate marking of the AR promoter and a putative proximal enhancer by active (H3K4me3 and H3K9ac) and repressive (H3K9me2 and H3K27me3) histone modifications. Marking of the constitutively expressed genes (ACTB and GAPDH) and a repressed gene (HBB) served as control for these experiments. As expected, the only samples with AR marking by H3K4me3 and H3K9ac were the two AR-positive xenografts and LNCaP. Marking by repressive histone modifications was more variable: H3K27me3 was a universal finding in AR-negative samples except for Du-145, and was accompanied by H3K9me2 in two out of four xenografts. H3K27me3 and H3K9me2 also marked the putative enhancer region when AR was repressed. Altogether, these data indicate that promoter DNA methylation of AR is an infrequent finding in prostate cancer, while polycomb protein-based silencing is nearly universal in AR-negative variants. Also, it shows that H3K9me2 promotes reinforcement of silencing. Thus, we propose that reactivation of AR may by achieved in selected cases by inhibiting H3K27me3 alone, while concomitant inhibition of both polycomb and SET domain proteins may be necessary for double-positive H3K27/K9 methylation cases. Given the purported differentiating and tumor suppressor effects of AR, its reactivation in SCPC may be of therapeutic benefit. Citation Format: Brittany N. Kleb, Marcos RH Estecio, Guanglin Wu, Jing-Fang Lu, Christopher J. Logothetis, Sankar Maity, Ana M. Aparicio. Mechanism of androgen receptor (AR) silencing in small cell prostate carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2986. doi:10.1158/1538-7445.AM2013-2986

Evidence for Epigenetic Abnormalities of the Androgen Receptor Gene in Foreskin from Children with Hypospadias

Hypospadias is a malformation of the penis due to an incomplete development of the male urethra, the exact etiology of which in the majority of cases remains unknown. The objective of the study was to assess whether defects of the androgen receptor (AR) gene (CAG repeats and methylation pattern) and DNA methyltransferases (DNMT) family are present in hypospadic patients. CAG repeats length, methylation status, and expression of the AR gene were analyzed. The DNMT family was studied at the protein level and the DNMT3A sequenced. The study was performed at a pediatric endocrinology referral clinic. Twenty boys with isolated glandular hypospadias and 20 age-matched control children undergoing a surgical procedure for circumcision were studied. CAG repeats length and AR methylation pattern in PBLs and foreskin tissue, DNMT expression and sequencing in patients and controls, and in vitro studies in cultured fibroblasts were measured. AR gene methylation in foreskin tissues from patients with hypospadias was higher than in normal children. AR expression in foreskin tissue of hypospadic patients was lower than in controls, whereas the DNMT3A protein level was significantly higher in patients than controls. In cultured fibroblasts, both dihydrotestosterone and testosterone significantly reduced AR gene methylation and DNMT3A expression in a dose-dependent fashion and increased AR expression. The AR gene in target tissues from patients with hypospadias is more methylated than in control children, resulting in a decreased expression of the AR. The mechanism underlying the modulation of the AR gene expression seems to be mediated by DNMT3A. This epigenetic alteration of the AR gene might be involved in the pathogenesis of hypospadias.

X inactivation testing for identifying a non-syndromic X-linked mental retardation gene

The purpose of this study was to identify a gene causing non-syndromic X-linked mental retardation in an extended family, taking advantage of the X chromosome inactivation status of the females in order to determine their carrier state. X inactivation in the females was determined with the androgen receptor methylation assay; thereafter, the X chromosome was screened with evenly spaced polymorphic markers. Once initial linkage was identified, the region of interest was saturated with additional markers and the males were added to the analysis. Candidate genes were sequenced. Ten females showed skewed inactivation, while six revealed a normal inactivation pattern. A maximal lod score of 5.54 at θ = 0.00 was obtained with the marker DXS10151. Recombination events mapped the disease gene to a 17.4-Mb interval between the markers DXS10153 and DXS10157. Three candidate genes in the region were sequenced and a previously described missense mutation (P375L) was identified in the ACSL4/FACL4 gene. On the basis of the female X inactivation status, we have mapped and identified the causative mutation in a gene causing non-syndromic X-linked mental retardation.

Lysine Methylation and Functional Modulation of Androgen Receptor by Set9 Methyltransferase

Lysine methyltransferases modulate activities of transcription factors and transcription coregulators by methylating specific lysine residue(s). We report that the androgen receptor (AR) is methylated at lysine-630 by Set9, which was originally identified as a histone H3K4 monomethyltransferase. Alanine substitution of lysine-630 prevented AR methylation in vitro and in vivo. Set9 methylated the nuclear and cytoplasmic AR utilizing the cofactor S-adenosyl-methionine. A pan-methyllysine antibody recognized endogenous AR, and Set9 coimmunoprecipitated with nuclear and cytoplasmic AR. Set9 overexpression potentiated AR-mediated transactivation of the probasin promoter, whereas Set9 depletion inhibited AR activity and target gene expression. Similar to AR, chromatin occupancy of Set9 at androgen response elements (AREs) was androgen dependent, and associated with methylated histone H3K4 chromatin activation marks and p300/CBP associated factor acetyltransferase recruitment. Set9 depletion increased the histone H3K9-dimethyl repressive mark at AREs and reduced histone activation marks and occupancy of p300/CBP associated factor. K630A mutation reduced amino- and carboxy-terminal (N-C) interaction in Set9-intact cells, whereas N-C interaction for wild-type AR was reduced upon Set9 depletion. The K630A mutant was resistant to loss of activity from Set9 silencing and to increase of activity from Set9 overexpression. The K630 dependence of Set9-regulated N-C interaction and AR activity suggests that Set9 directly acts on AR at the amino acid level. Chromatin recruitment of Set9 to AREs is suggestive of its additional role as a transcriptional coactivator. Because the cellular metabolic state determines the level of S-adenosylmethionine and consequently the activity of Set9, the enhanced activity of methylated AR may have special significance in certain metabolic contexts.

Decreased Androgen Receptor Gene Methylation in Premature Pubarche: A Novel Pathogenetic Mechanism?

Several studies found links between DNA methylation and gene expression. In patients with idiopathic hirsutism, a preferential methylation of the of shorter androgen receptor (AR) alleles was hypothesized to be responsible for the abnormal hair growth. The objective of this study was to assess whether abnormalities in the AR function in both peripheral blood leukocytes (PBLs) and androgen target tissues are present in children with premature pubarche (PP). Human DNA was extracted from PBLs and pubic hair and CAG repeats length and methylation status of the AR gene were analyzed. The study was performed at a Pediatric Endocrinology referral clinic. Twenty-five girls with PP, 23 prepubertal children, and 10 girls with Tanner stage II pubertal development were studied. The main outcome measures were CAG repeat length and AR methylation pattern in PBLs and pubic hair. In PBLs from PP patients, AR gene methylation was significantly lower (P < 0.01) than that of prepubertal children and similar to that of girls with Tanner II stage pubertal development. A negative correlation between AR gene methylation in PBLs and the age of normal children was detected. PATIENTS with PP exhibited a hair follicle AR methylation pattern similar to that of Tanner stage II girls. The mean number of CAG repeats was lower in PP patients than in prepubertal and Tanner stage II girls, although it was within the normal range for the general population in both groups. The increased AR gene activity observed in PP patients, as indicated by the reduced AR gene methylation pattern, together with the presence of shorter CAG repeats, might lead to hypersensitivity of the hair follicles to steroid hormones and therefore to the premature development of pubic hair.

Epigenetic Regulation of Androgen Receptor Gene Expression in Human Prostate Cancers

Epigenetic mechanisms including DNA methylation and histone deacetylation are thought to play important roles in gene transcriptional inactivation. Heterogenous expression of androgen receptor (AR), which appears to be related to variable responses to endocrine therapy in prostate cancer (PCa) may also be due to epigenetic factors. The methylation status of the 5′ CpG island of the AR in 3 prostate cancer cell lines and 10 primary and 14 hormone-refractory PCa samples was determined using the bisulfite PCR methods. In DU145, CpG-rich regions of the AR were hypermethylated. By an immunohistochemical analysis, only one PCa sample had no AR expression, the others being heterogenous. Bisulfite sequencing and methylation-specific PCR analysis showed aberrant methylation of AR 5′-regulatory region in 20% of 10 primary and 28% of 14 hormone-refractory PCa samples. To clarify the effect of epigenetic regulation on AR expression, we treated three prostate cancer cell lines with a demethylating agent, 5-aza-2′-deoxycytidine (azaC), and a histone deacetylase inhibitor, Trichostatin A (TSA). In DU145, re-expression of AR mRNA was detected after treatment with azaC and/or TSA. Our results suggest that epigenetic regulations including CpG methylation and histone acetylation may play important roles in the regulation of the AR.

Inactivation of the human androgen receptor gene is associated with CpG hypermethylation in uterine endometrial cancer.

Androgens mediate their effects through the androgen receptor (AR) and have antiproliferative effects on uterine endometrial cells. In this report, we investigated methylation status and the expression of the AR gene in normal endometrium and uterine endometrial cancer (UEC) tissues using methylation-specific polymerase chain reaction (MSP) and immunohistochemical staining. Seventy of 89 cancer samples were AR negative, although 39 of 46 normal samples were AR positive by immunohistochemistry. By MSP, 64 of 89 cancer samples showed only methylated AR alleles, although all normal tissues showed both unmethylated and methylated AR alleles. To determine whether similar changes occurred in methylation status in the UEC carcinogenesis, we studied AR methylation using pairs of cancerous and normal samples from 28 patients. Twenty-three of 28 cancer samples showed only methylated AR alleles, although all normal samples showed both unmethylated and methylated alleles. All of the 23 cancer samples that lost unmethylated alleles were negative for AR by immunohistochemical analysis. Reverse transcription-polymerase chain reaction was performed by using UEC cell lines with and without treatment by the demethylating reagent 5-aza-2'-deoxycytidine. No AR expression was found in any of the UEC cell lines, except for MFE-296 without 5-aza-2'-deoxycytidine. Treatment with 5-aza-2'-deoxycytidine restored AR expression in all of the UEC cell lines that showed no AR expression before treatment. This study is the first to report that the possible mechanism of AR inactivation in endometrial cancer is through hypermethylation of the AR gene CpG islands.