The switch/sucrose non-fermentable (SWI/SNF) subunit ARID1A (AT-rich interactive domain 1A gene) has been recently postulated as a novel tumor suppressor of gynecologic cancer and one of the driver genes in endometrial carcinogenesis. However, specific relationships with established molecular alterations in endometrioid endometrial cancer (EEC) are currently unknown. We analyzed the expression of ARID1A in 146 endometrial cancers (130 EECs and 16 non-EECs) in relation to alterations in the PI3K-Akt pathway (PTEN expression/KRAS/PIK3CA mutations), TP53 status (TP53 immunohistochemistry) and microsatellite instability. To discriminate between microsatellite instability due to somatic MLH1 promoter hypermethylation or germline mutations in one of the mismatch repair genes (Lynch syndrome), we included a 'Lynch syndrome set'. This set included 21 cases with confirmed germline mutations and 15 cases that were suspected to have a germline mutation. Loss of ARID1A expression was exclusively found in EECs in 31% (40/130) of the EEC cases. No loss of expression of the other subunits of the SWI/SNF complex, SMARCD3 and SMARCB1, was detected. Alterations in the PI3K-Akt pathway were more frequent when ARID1A expression was lost. Loss of ARID1A and mutant-like TP53 expression was nearly mutually exclusive (P ¼ 0.0004). In contrast to Lynch-associated tumors, a strong association between ARID1A loss and sporadic microsatellite instability was found. Only five cases (14%) of the 'Lynch syndrome set' as compared with 24 cases (75%, Po0.0001) of the sporadic microsatellite-unstable tumors showed loss of ARID1A. These observations suggest that ARID1A is a causative gene, instead of a target gene, of microsatellite instability by having a role in epigenetic silencing of the MLH1 gene in endometrial cancer. Keywords: ARID1A; endometrial cancer; Lynch syndrome; microsatellite instability Recent genome-wide sequencing studies have demonstrated that the AT-rich interactive domain 1A (ARID1A) gene is frequently mutated in a wide variety of cancer types 1 including a subset of gynecological cancers. 2 In ovarian cancer, near half of the clear-cell subtype and 30% of the endometrioid subtype showed ARID1A mutations, 3 particularly those that are related to endometriosis. 4,5 In endometrial cancer, mutations in the ARID1A gene have been reported in approximately 30% of both low-and high-grade endometrioid endometrial cancers (EECs) but not in serous endometrial carcinomas. [6][7][8] ARID1A encodes a large nuclear protein involved in chromatin remodeling and interacts with several other proteins, including the core protein

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BackgroundHypoxia inducible factor 1α (HIF-1α) plays an essential role in the adaptive response of cells to hypoxia and is associated with aggressive tumour behaviour. We have shown p27kip1, which is generally reduced in endometrial cancer, to be re-expressed in hypoxic regions. This possibly contributes to survival of cancer cells. The aim of this study was to evaluate the prognostic value of HIF-1α and p27kip expression in patients with endometrioid endometrial cancer.MethodsExpression levels of HIF-1α, CAIX, Glut-1, and p27kip1 were analyzed by immunohistochemistry. Percentage of positive cells, staining pattern (perinecrotic, diffuse, or mixed) and presence of necrosis were noted.ResultsNecrosis was correlated with shortened disease free survival (DFS) (p = 0.008) and overall survival (OS) (p = 0.045). For DFS, perinecrotic HIF-1α expression was also prognostic (p = 0.044). Moreover, high p27kip1 expression was an additional prognostic factor for these patients with perinecrotic HIF-1α expression. In multivariate Cox regression, perinecrotic HIF-expression emerged as an independent prognostic factor. Perinecrotic HIF-1α expression was significantly associated with CAIX and Glut-1 expression, pointing towards functional HIF-1.ConclusionsIn patients with endometrioid endometrial cancer, necrosis and necrosis-related expression of HIF-1α are important prognostic factors. More aggressive adjuvant treatment might be necessary to improve the outcome of patients with these characteristics.

Ovarian cancer is the most lethal gynecological cancer. Due to few early symptoms and a lack of early detection strategies, most patients are diagnosed with advanced-stage disease. Most of these patients, although initially responsive, eventually develop drug resistance. In this chapter, epigenetic changes in ovarian cancer are described. Various epigenetic changes including CpG island methylation and histone modification have been identified in ovarian cancer. These aberrations are associated with distinct disease subtypes and present in circulating serum of ovarian cancer patients. Several epigenetic changes have shown promise for their diagnostic, prognostic, and predictive capacity but still need further validation.In contrast to DNA mutations and deletions, epigenetic modifications are potentially reversible by epigenetic therapies. Promising preclinical studies show epigenetic drugs to enhance gene re-expression and drug sensitivity in ovarian cancer cell lines and animal models.

Promoter methylation is a gene-and cancer type-specific epigenetic event that plays an important role in tumour development. As endometrioid (endometrioid endometrial carcinoma, EEC) and serous endometrial cancers (uterine papillary serous carcinoma, UPSC) exhibit different clinical, histological and molecular genetic characteristics, we hypothesized that these differences may be reflected in epigenetic phenomena as well. Identification of a panel of methylation biomarkers could be helpful in a correct histological classification of these two subtypes, which solely on the basis of morphology is not always easy. Methylation-specific multiplex ligation-dependent probe amplification was used to assess the extent of promoter methylation of different tumour suppressor genes in EEC and UPSC. Methylation results were correlated with histology and survival. The median cumulative methylation index of all genes was significantly higher in EEC (124) than in UPSC (93) (P!0.001). Promoter methylation of CDH13 and MLH1 was more frequently present in EEC, while CDKN2B and TP73 were more frequently methylated in UPSC. Almost 90% of EEC and 70% of UPSC could be predicted by CDH13 and TP73. In EEC, methylation of MLH1 was associated with a shorter disease-free survival (DFS; P!0.0001) and overall survival (OS; PZ0.005). In a multivariate model, MLH1 methylation emerged as an additional prognostic factor to stage for DFS (PZ0.002). In conclusion, promoter methylation is more common in EEC than UPSC. A panel of methylation biomarkers could be useful to distinguish between the two histological subtypes of endometrial cancer. Furthermore, methylation of MLH1 may have prognostic value in EEC.

In the Western world, endometrial cancer (EC) is the most common malignant tumor of the female genital tract. Solid tumors like EC outgrow their vasculature resulting in hypoxia. Tumor hypoxia is important because it renders an aggressive phenotype and leads to radio- and chemo-therapy resistance. Hypoxia-inducible factor-1α (HIF-1α) plays an essential role in the adaptive cellular response to hypoxia and is associated with poor clinical outcome in EC. Therefore, HIF-1 could be an attractive therapeutic target. Selective HIF-1 inhibitors have not been identified. A number of nonselective inhibitors which target signaling pathways upstream or downstream HIF-1 are known to decrease HIF-1α protein levels. In clinical trials for the treatment of advanced and/or recurrent EC are the topoisomerase I inhibitor Topotecan, mTOR-inhibitor Rapamycin, and angiogenesis inhibitor Bevacizumab. Preliminary data shows encouraging results for these agents. Further work is needed to identify selective HIF-1 inhibitors and to translate these into clinical trials.

BRCA1/2 germ line mutation carriers have a high risk of developing fallopian tube carcinoma (FTC), thought to occur through different early (p53 signatures) and later (dysplasia, intraepithelial carcinoma) premalignant stages. Promoter hypermethylation of tumour suppressor genes is known to play a key role in (early) carcinogenesis. However, little is known about methylation in normal and (pre)malignant fallopian tube tissue. We identified 14 areas of p53 accumulation in the fallopian tubes of BRCA mutation carriers. Cells from these areas were harvested together with cells from adjacent benign appearing areas. An age-matched non-BRCA sporadic control group (nZ13) and eight sporadic FTCs were included as negative and positive controls respectively. Methylation-specific multiplex ligation-dependent probe amplification was used to assess promoter methylation of 70 tumour suppressor genes in all samples. We observed a gradual increase in methylation from sporadic control tissue (median cumulative methylation index (CMI) 568.19) through normal tissue and from areas of p53 accumulation in BRCA carriers (median CMI 687.54 and 676.72) to FTC (median CMI 780.97). Furthermore, the methylation percentage of many individual tumour suppressor genes differed significantly between these groups, gradually increasing as for CMI. Between areas with and without p53 accumulation in BRCA mutation carriers no significant differences were found. In this paper, we have shown that BRCA mutation carriers display increased methylation of tumour suppressor genes in their nonmalignant fallopian tube epithelium, closer to methylation levels in FTC than to normal sporadic tissue. Methylation could, therefore, play an important role in the increased risk of gynaecological malignancies in BRCA mutation carriers.

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