Promoter hypermethylation patterns in fallopian tube epithelium of BRCA1 and BRCA2 germ line mutation carriers.

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, intra-epithelial 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 (n=13) 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 non-malignant 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.

The role of hypoxia inducible factor-1alpha in gynecological cancer.

Understanding the mechanisms of carcinogenesis and progression of gynecological tumors is important as these insights might lead to improved diagnostic tools for the pathologist, improved prediction of prognosis, response to therapy, and eventually better biology-based disease management, thereby improving prognosis and quality of life for the individual patient. Hypoxia is an important event in carcinogenesis because it renders a more aggressive phenotype with increased invasiveness and proliferation, formation of metastases and poorer survival. Although selecting patients with hypoxic tumors may therefore be clinically important, there is no consensus as to the method best suited for routine assessment of hypoxia. One of the potential tumor hypoxia markers is hypoxia inducible factor 1 (HIF-1). HIF-1 is the key cellular survival protein under hypoxia, and is associated with tumor progression and metastasis in various solid tumors. In this review, we show that in gynecological cancers, HIF-1A is emerging as an important factor in carcinogenesis, and that overexpression of HIF-1A and its target genes CA9 and SLC2A1 seems associated with shorter progression free- and overall survival. Since hypoxia and HIF-1A expression are associated with treatment failure, targeting HIF-1A could be an attractive therapeutic strategy with the potential for disrupting multiple pathways crucial for tumor growth. Currently, HIF-1A inhibitors are being studied in clinical trials in recurrent ovarian- and cervical cancer, and trials in other gynecological cancers are expected.

Necrosis related HIF-1alpha expression predicts prognosis in patients with endometrioid endometrial carcinoma.

BACKGROUND: Hypoxia inducible factor 1alpha (HIF-1alpha) 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-1alpha and p27kip expression in patients with endometrioid endometrial cancer. METHODS: Expression levels of HIF-1alpha, 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. RESULTS: Necrosis was correlated with shortened disease free survival (DFS) (p = 0.008) and overall survival (OS) (p = 0.045). For DFS, perinecrotic HIF-1alpha expression was also prognostic (p = 0.044). Moreover, high p27kip1 expression was an additional prognostic factor for these patients with perinecrotic HIF-1alpha expression. In multivariate Cox regression, perinecrotic HIF-expression emerged as an independent prognostic factor. Perinecrotic HIF-1alpha expression was significantly associated with CAIX and Glut-1 expression, pointing towards functional HIF-1. CONCLUSIONS: In patients with endometrioid endometrial cancer, necrosis and necrosis-related expression of HIF-1alpha are important prognostic factors. More aggressive adjuvant treatment might be necessary to improve the outcome of patients with these characteristics.

Methylation profiles of endometrioid and serous endometrial cancers.

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; P=0.005). In a multivariate model, MLH1 methylation emerged as an additional prognostic factor to stage for DFS (P=0.002). 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.

Hypoxia-inducible factor-1 as a therapeutic target in endometrial cancer management.

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-1alpha (HIF-1alpha) 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-1alpha 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.