Abstract: Objective To investigate the expression levels of somatostatin (SST) gene in endometrial adenocarcinoma tissues and cell lines, and the effects of over-expression of SST gene on the proliferation and invasion of endometrial cancer cell line Ishikawa in vitro. Methods Tissue sections of normal endometrium, endometrioid adenocarcinoma and uterine papillary serous carcinoma were selected to detect the expressions of SST by immunohistochemical method. The total RNA was extracted from fresh specimens that were confirmed as endometrioid adenocarcinoma. According to FIGO staging,samples included G1 (7 cases), G2 (6 cases) and G3 (5 cases) of endometrioid adenocarcinoma. The SST expression levels were detected by real-time PCR. Three endometrial cancer cell lines, Ishikawa, HEC-1A and KLE, were selected and the expression levels of SST were detected by real-time PCR and Western blot assay. Transfection was performed with pLVXSST and pLVX. The transfection efficiency was observed by fluorescence confocal microscopy. The protein levels of SST were detected by Western blot assay. The assays of CCK- 8 and transwell were applied to examine variations in cell proliferation and invasion. Results Immunohistochemical results showed that SST expression was increased in endometrioid adenocarcinoma and uterine papillary serous carcinoma compared with that of normal endometrium. Real-time PCR showed that SST expression was significantly increased in G3 compared with that of G1 and G2 in endometrioid adenocarcinoma (P＜0.05). No matter mRNA or protein, SST levels were significantly increased in endometrial cancer cell line KLE compared with those of Ishikawa and HEC- 1A, and the expression levels of SST mRNA and protein were significantly increased in HEC- 1A group than those of Ishikawa group (P＜0.05). The expression of SST protein was significantly higher in the group of Ish- SST after 2 generations compared with that of Ish- ctr group. There were no significant differences in cell proliferation and invasive ability after over-expression of SST between Ishikawa cell group and control group (P＞0.05). Conclusion SST is highly expressed in poorly differentiated endometrial cancer cells. The proliferation and invasion are not increased after the over-expression of SST in Ishikawa cell line of endometrial cancer.

Key words: endometrial neoplasms, somatostatin, cell proliferation, neoplasm invasiveness