Objective: Because our previous study of microarray suggested that STAT5 and its downstream target, survivin, were up-regulated in complete mole (CM), we clarified the status of STAT-mediated signal transduction in CM and choriocarcinoma (CC).
Study design: Proteins from 4 CM and normal villi and from 3 CC cell lines were subjected to Western blot (WB) analysis to evaluate STAT3 and 5 activation. After STAT and MEK inhibitor were added to these cells, the change in survivin expression was analyzed. Immunohistochemical staining was also done on CM and normal villi.
Results: WB showed that phosphorylated STAT3 and 5, which are active forms of STAT protein, as well as survivin, were significantly up-regulated in CM. Immunohistochemistry showed positive signals of pSTATs in the cytotrophoblast and syncytiotrophoblast layer in CM but not in normal villi. In contrast, the pSTAT signal was hardly detected by WB in CC cells. However, a high level of survivin expression was maintained in CC by activation of the MEK signal pathway.
Conclusion: An activated STAT signal may contribute to hyperplastic cell growth of trophoblasts in CM. CC cells might be obtained independently of cytokine signals for tumor cell growth during the carcinogenic process.