Hypomethylation-induced expression of S100A4 in endometrial carcinoma

Abstract

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 ...

Immunohistochemical Expressionof S100a4 and Cd24 in Colorectal Adenoma and Carcinoma.

“…The role of S100A4 in tumor progression and metastasis via induction of epithelial to mesenchymal transition (EMT) has been confirmed in many types of cancer including CRC (21).The positive relationship between S100A4 expression and aggressiveness was also observed in advanced-stage endometrial cancer (22) and bladder cancer (23). These findings suggest that S100A4 overexpression is involved in the growth, invasion, and metastasis of CRC and may serve as an indicator of the aggressiveness of CRC in the clinicopathological practice.…”

Local Depletion of DNA Methylation Identifies a Repressive p53 Regulatory Region in the NEK2 Promoter

“…The 18 S rRNA, ␤-actin, and Ki67 assay details have been published previously (22). Additional RT-qPCR primer sequences are listed in supplemental Table 1.…”

DNA methylation inhibits p53-mediated survivin repression

“…Alternatively, hypomethylation has been described as a contributing factor for oncogene overexpression in EC. The oncogene, PAX2, (Wu et al, 2005;Shang, 2006) and the metastasis promoting gene, S100A4, (Xie et al, 2007) were shown to be hypomethylated in aggressive endometrial cancer. As survivin levels progressively increased in EC tumors, we hypothesized that progressive DNA hypomethylation could explain this expression pattern.…”