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Small guanosine triphosphatase RhoA has been known to re-organize cytoskeletons and regulate cell migration. The present authors have previously reported that expression of RhoA is significantly increased in advanced ovarian carcinomas and also in the peritoneal disseminated lesions. The present study investigated whether overexpression of RhoA could alter the progressive behavior of ovarian cancer cells. The effect of various Rho inhibitors on the biological behavior of ovarian cancer cells in vitro and in vivo was also examined. A stable RhoA-transfectant of an ovarian cancer cell line SKOV3 was generated and examined in vitro for alterations of proliferative activity and invasiveness, and also in the nude mice model for peritoneal dissemination. In addition, the effect of a specific Rho inhibitor (C3 exoenzyme), Rho kinase inhibitor (Y27632) and hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor (Lovastatin and Pravastatin) were studied in vitro and in vivo. Forced overexpression of RhoA did not alter proliferative activity but significantly increased the invasiveness in vitro, which was suppressed by addition of C3 exoenzyme, Y27834, Lovastatin and Pravastatin. In the nude mice model, the frequency of dissemination and the number of disseminated lesions were significantly increased in the RhoA transfectant than in the control. In addition, oral administration of Lovastatin significantly decreased the number of metastatic sites compared with the control. These findings suggest that upregulation and/or activation of RhoA play an important role in the peritoneal dissemination of ovarian carcinoma, and that Lovastatin might be a candidate for the possible, novel treatment for ovarian carcinoma patients with peritoneal dissemination.

The hedgehog (Hh) signal pathway has recently been shown to be activated in human malignancies. However, little is known about its role in the development or patient prognosis of epithelial ovarian carcinoma. In the present study, we examined in vivo and in vitro the expression and functional role of Hh signal molecules in epithelial ovarian tumors and normal ovarian surface epithelial (OSE) cells. The expression of Shh, Dhh, Ptch, Smo and Gli1 proteins was not observed in normal OSE, but was increased stepwise in benign, borderline and malignant neoplasms. In addition, immunoreactivity for Shh, Dhh, Ptch, Smo and Gli1 was highly correlated with cell proliferation assessed by Ki-67. Blocking the Hh signal using either the Hh pathway inhibitor cyclopamine or Gli1 siRNA led to remarkably decreased cell proliferation in ovarian carcinoma cells. Treatment with cyclopamine induced not only G, arrest but also apoptosis along with the downregulation of cyclin A and cyclin D1, and the upregulation of p21 and p27. Among the Hh signal molecules, Dhh expression was correlated with poor prognosis of ovarian carcinoma patients. These findings suggest that the Hh signal pathway plays an important role in ovarian tumorigenesis as well as in the activation of cell proliferation in ovarian carcinomas. Thus, the Hh signal pathway is a possible molecular target of new treatment strategies for ovarian carcinoma.

Although S100A4 expression has reportedly been associated with metastasis of various malignancies, little is known about its biological significance in ovarian carcinomas. In this study, we investigated expression and secretion of S100A4 and its extracellular function in ovarian carcinoma cells. We first used immunohistochemistry to examine the expression and localization of S100A4 in 113 epithelial ovarian neoplasms (24 benign, 20 borderline, and 69 malignant tumors) and analyzed its prognostic significance in patients with ovarian carcinoma. Then we investigated the expression, subcellular localization, and secretion of S100A4 in four ovarian carcinoma cell lines. Finally, we examined the effect of S100A4 treatment on the cell proliferation and invasiveness of ovarian carcinoma cells, along with activation of small GTPase, RhoA. Both cytoplasmic and nuclear expressions of S100A4 were significantly stronger in carcinomas than those in benign and borderline tumors. Ovarian carcinoma patients with strong nuclear S100A4 expression showed a significantly shorter survival than those without (P = 0.0045). This was not the case for cytoplasmic S100A4 expression. Ovarian carcinoma cell lines were shown to express S100A4, and secrete S100A4 into the culture media. Treatment with recombinant S100A4 resulted in the upregulation of S100A4 expression, translocation of S100A4 into the nucleus, and enhancement of invasiveness, which was associated with the upregulation of small GTPase, RhoA. These findings suggest that the nuclear expression of S100A4 is involved in the aggressive behavior of ovarian carcinoma and S100A4 is an autocrine/paracrine factor that plays an important role in the aggressiveness of ovarian carcinoma cells.