Homeobox genes encode transcription factors that control cell differentiation and play essential roles in developmental patterning. Increasing evidence indicates that many homeobox genes are aberrantly expressed in cancers, and that their deregulation significantly contributes to tumor progression. The homeobox gene HOXA10 controls uterine organogenesis during embryonic development and functional endometrial differentiation in the adult. We investigated whether HOXA10 expression is deregulated in endometrial carcinomas, and how counteracting this aberrant expression modifies tumor behavior. We found that down-regulation of HOXA10 expression in endometrial carcinomas strongly correlates with increased tumor grade and is associated with methylation of the HOXA10 promoter. Enforced expression of HOXA10 in endometrial carcinoma cells inhibited invasive behavior in vitro and tumor dissemination in nude mice. The inhibitory effect of HOXA10 on invasive behavior was attributable at least in part to the ability of HOXA10 to induce expression of the epithelial cell adhesion molecule E-cadherin by downregulating expression of Snail, a repressor of E-cadherin gene transcription. These findings reveal a novel role for HOXA10 deregulation in the progression of endometrial carcinoma by promoting epithelial-mesenchymal transition. (Cancer Res 2006; 66(2): 889-97)

Well-differentiated neuroendocrine tumors including pancreatic endocrine tumors and carcinoid tumors are uncommon neoplasms that have site-specific differences in clinicopathological features, clinical course and genetic alterations. The epigenetic alterations in these tumors are not well characterized. We therefore compared methylation of the RAS-association domain family 1, isoform A (RASSF1A), p14, p16 and O 6 -methylguanine methyltransferase genes in neuroendocrine tumors from 47 patients including 16 pancreatic, 15 nonileal and 16 ileal neuroendocrine tumors. Methylation of the RASSF1A gene was present in 57% of tumors, p14 in 49%, p16 in 26% and O 6 -methyl-guanine methyltransferase in 13% of tumors. Ileal neuroendocrine tumors lacked methylation of O 6 -methyl-guanine methyltransferase gene (P ¼ 0.04). RASSF1A methylation was associated with histopathologic type of tumors (P ¼ 0.03) and lymph node metastasis (P ¼ 0.004), and p16 methylation with older patient age (P ¼ 0.002) and liver metastasis (P ¼ 0.04). Two or more genes were methylated in 53% of tumors, one gene was methylated in 30% of tumors, and all four genes were unmethylated in 17% of tumors. Methylation of one or more gene was associated with older age of patients (P ¼ 0.01), and methylation of two or more genes was associated with liver metastasis (P ¼ 0.044). Our study shows that in neuroendocrine tumors epigenetic alterations vary by tumor subsite and clinicopathologic features, including age of onset, histopatholoic type and metastasis status.

Expression of various S100 genes has been associated with clinically aggressive subtypes in a variety of different cancers. We hypothesized that S100A4 would be overexpressed in endometrial carcinoma compared to benign endometrium. Quantitative real-time RT-PCR (qRT-PCR) was used to quantify the mRNA level of S100A4 in benign endometrium (n ¼ 19), endometrioid adenocarcinoma (n ¼ 87), and non-endometrioid tumors (n ¼ 21). Immunohistochemistry was used to verify the results of qRT-PCR and to assess protein localization. Possible mechanisms of S100A4 gene regulation were also examined. S100A4 was overexpressed in the grade 3 endometrioid tumors, uterine papillary serous carcinoma, and uterine malignant mixed mü llerian tumor. Expression in grade 1 and grade 2 endometrioid tumors was comparable to that of normal endometrium, which was quite low. Expression was significantly higher in stage III and IV tumors compared with stage I. By immunohistochemistry, S100A4 was expressed in the tumor cell cytoplasm of poorly differentiated tumors, but was not detected in normal endometrial glandular epithelium. In benign endometrium, S100A4 expression was confined to stromal cells. S100A4 was not regulated by estrogen or progesterone, and its expression in tumors was not significantly correlated to estrogen receptor or progesterone receptor content. However, methylation of the S100A4 gene was detected in benign endometrium and grade 1 tumors with low S100A4 expression. In contrast, grade 3 endometrioid tumors with high S100A4 mRNA and protein expression showed no methylation of the gene. These methylation results were verified in endometrial cancer cell lines with differential baseline levels of S100A4 protein. These results suggest that hypomethylation is an important mechanism of regulating the expression of the S100A4 gene. These results support the emerging concept that hypomethylation may play a role in the upregulation of genes during later stages of tumorigenesis. Keywords: endometrial cancer; S100A gene family; S100A4; methylation Endometrial carcinoma is the most common malignant neoplasm of the female genital tract and the fourth most frequently diagnosed cancer in women, following cancers of the breast, lung, and colon. 1 On the basis of histological and clinical features, endometrial carcinoma has been classified into two types. 2-4 Type I tumors (approximately 80% of all endometrial carcinomas) are typically low-grade (grade 1 or grade 2) endometrioid adenocarcinoma, most of which are confined to the uterus and have a favorable prognosis. Type II tumors (approximately 20%) are comprised of uterine papillary serous carcinoma, malignant mixed mü llerian tumors, and clear cell carcinoma. The nature of high-grade (grade 3) endometrioid adenocarcinoma is more controversial, as a subset may behave more like the Type II tumors. Type II cancers are associated with extrauterine spread and carry a high mortality rate. Previous studies have documented interesting molecular differences between endometrioid and nonendometrioid ...

The molecular mechanisms of endometrial cancer invasion are poorly understood. S100A4, also known as FSP1 (fibroblast specific protein 1), has long been known to be a molecular marker of fibrosis in a variety of different fibrotic diseases of the lungs, liver, kidney, and heart. We demonstrate here that increased expression of S100A4 is associated with advanced stage endometrial cancer and decreased recurrence free survival. To verify the essential role of S100A4 in invasiveness of endometrial cancer, S100A4 expression was down-regulated by RNAi in HEC-1A cells, which resulted in undetectable S100A4 protein and significantly decreased migration and invasion. Due to the established connection between TGF-β1 and S100A4 induction in experimental models of kidney and liver fibrosis, we next examined whether TGF-β1 could also regulate S100A4 in endometrial cancer cells. TGF-β1 stimulated endometrial cancer cell migration and invasion with a concomitant increase in S100A4 protein. Induction of S100A4 was associated with the activation of Smads. TGF -β1 mediated endometrial cancer cell motility was inhibited by S100A4 siRNA. In aggregate, these results suggest that S100A4 is a critical mediator of invasion in endometrial cancer and is upregulated by the TGF-β1 signaling pathway. These results also suggest that endometrial cancer cell invasion and fibrosis share common molecular mechanisms.

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