The activity of trabectedin as a single agent or in combination with everolimus for clear cell carcinoma of the ovary.

PURPOSE: The objective of this study was to evaluate the antitumor efficacy of trabectedin in clear cell carcinoma (CCC) of the ovary, which is regarded as an aggressive, chemoresistant, histologic subtype. EXPERIMENTAL DESIGN: Using 6 human ovarian cancer cell lines (3 CCC and 3 serous adenocarcinomas), the antitumor effects of trabectedin were examined in vitro, and we compared its activity according to histology. We next examined the antitumor activity of trabectedin in both cisplatin-resistant and paclitaxel-resistant CCC cells in vitro. Then, the in vivo effects of trabectedin were evaluated using mice inoculated with CCC cell lines. Using 2 pairs of trabectedin-sensitive parental and trabectedin-resistant CCC sublines, we investigated the role of mTOR in the mechanism of acquired resistance to trabectedin. Finally, we determined the effect of mTOR inhibition by everolimus on the antitumor efficacy of trabectedin in vitro and in vivo. RESULTS: Trabectedin showed significant antitumor activity toward chemosensitive and chemoresistant CCC cells in vitro. Mouse xenografts of CCC cells revealed that trabectedin significantly inhibits tumor growth. Greater activation of mTOR was observed in trabectedin-resistant CCC cells than in their respective parental cells. The continuous inhibition of mTOR significantly enhanced the therapeutic efficacy of trabectedin and prevented CCC cells from acquiring resistance to trabectedin. CONCLUSION: Trabectedin is a promising agent for CCC as a first-line chemotherapy and as a second-line treatment of recurrent CCC that had previously been treated with cisplatin or paclitaxel. Moreover, trabectedin combined with everolimus may be more efficacious for the management of CCC.

Vascular endothelial growth factor is a promising therapeutic target for the treatment of clear cell carcinoma of the ovary.

This study examines the role of vascular endothelial growth factor (VEGF) as a therapeutic target in clear cell carcinoma (CCC) of the ovary, which has been regarded as a chemoresistant histologic subtype. Immunohistochemical analysis using tissue microarrays of 98 primary ovarian cancers revealed that VEGF was strongly expressed both in early-stage and advanced-stage CCC of the ovary. In early-stage CCCs, patients who had tumors with high levels of VEGF had significantly shorter survival than those with low levels of VEGF. In vitro experiments revealed that VEGF expression was significantly higher in cisplatin-refractory human CCC cells (RMG1-CR and KOC7C-CR), compared with the respective parental cells (RMG1 and KOC7C) in the presence of cisplatin. In vivo treatment with bevacizumab markedly inhibited the growth of both parental CCC cell-derived (RMG1 and KOC7C) and cisplatin-refractory CCC cell-derived (RMG1-CR and KOC7C-CR) tumors as a result of inhibition of tumor angiogenesis. The results of the current study indicate that VEGF is frequently expressed and can be a promising therapeutic target in the management of CCC. Bevacizumab may be efficacious not only as a first-line treatment but also as a second-line treatment of recurrent disease in patients previously treated with cisplatin.

Fasudil inhibits lysophosphatidic acid-induced invasiveness of human ovarian cancer cells.

Ovarian cancer is known to be highly invasive. The poor prognosis of advanced ovarian cancer comes from increased invasiveness of human ovarian cancer cells. The lysophosphatidic acid (LPA)/Rho/Rho-associated kinase (ROCK) pathway is intimately involved in the course of ovarian cancer progression, and the inhibition of this pathway attenuates ovarian cancer invasiveness. Fasudil (1-[5-isoquinolinesulfonyl]-homopiperazine; HA-1077) is a drug that has been in clinical use in Japan for the prevention of vasospasm after subarachnoid hemorrhage and is known to be a potent ROCK-specific inhibitor. In this study, we examined the effect of fasudil on LPA-induced invasiveness of human ovarian cancer cells to explore the potential of fasudil as an anticancer agent against ovarian cancer. Fasudil induced changes in cell morphology but not in cell viability. Fasudil significantly inhibited LPA-induced invasion and motility of human ovarian cancer cells in a dose-dependent manner. Furthermore, fasudil caused the loss of intracellular cytoskeletal rearrangement, which is necessary for cell motility, such as stress fiber formation and focal adhesion assembly. Fasudil suppressed LPA-induced tyrosine phosphorylation of paxillin, a representative focal adhesion protein, and serine phosphorylation of myosin light chain, which are essential for the process for cell migration. These findings showed that fasudil attenuated the invasiveness of human ovarian cancer cells via inhibition of the LPA/Rho/ROCK pathway. In SKOV-3ip1 ovarian cancer xenografts, intraperitoneal treatment with fasudil significantly reduced tumor burden and ascites formation. Our findings suggest that fasudil might be useful to prevent the progression of ovarian cancer in clinical settings.

mTOR is a promising therapeutic target both in cisplatin-sensitive and cisplatin-resistant clear cell carcinoma of the ovary.

PURPOSE: Mammalian target of rapamycin (mTOR) plays a central role in cell proliferation and is regarded as a promising target in cancer therapy, including for ovarian cancer. This study aimed to examine the role of mTOR as a therapeutic target in clear cell carcinoma of the ovary, which is regarded as an aggressive, chemoresistant histologic subtype. EXPERIMENTAL DESIGN: Using tissue microarrays of 98 primary ovarian cancers (52 clear cell carcinomas and 46 serous adenocarcinomas), the expression of phospho-mTOR was assessed by immunohistochemistry. Then, the growth-inhibitory effect of mTOR inhibition by RAD001 (everolimus) was examined using two pairs of cisplatin-sensitive parental (RMG1 and KOC7C) and cisplatin-resistant human clear cell carcinoma cell lines (RMG1-CR and KOC7C-CR) both in vitro and in vivo. RESULTS: Immunohistochemical analysis showed that mTOR was more frequently activated in clear cell carcinomas than in serous adenocarcinomas (86.6% versus 50%). Treatment with RAD001 markedly inhibited the growth of both RMG1 and KOC7C cells both in vitro and in vivo. Increased expression of phospho-mTOR was observed in cisplatin-resistant RMG1-CR and KOC7C-CR cells, compared with the respective parental cells. This increased expression of phospho-mTOR in cisplatin-resistant cells was associated with increased activation of AKT. RMG1-CR and KOC7C-CR cells showed greater sensitivity to RAD001 than did parental RMG1 and KOC7C cells, respectively, in vitro and in vivo. CONCLUSION: mTOR is frequently activated in clear cell carcinoma and can be a promising therapeutic target in the management of clear cell carcinoma. Moreover, mTOR inhibition by RAD001 may be efficacious as a second-line treatment of recurrent disease in patients previously treated with cisplatin.

In vitro and in vivo assays to analyze the contribution of Rho kinase in angiogenesis.

Therapeutic targeting of angiogenesis has become a novel approach to cancer therapy. The recent discovery of specific molecular targets that modulate the endothelial cell response and the development of suitable methods for assessing the contribution of these targets have given further impetus for the development and therapeutic application of an angiogenesis-targeted therapy. The small GTPase Rho and the major downstream effector, Rho kinase, is well established to regulate cell migration by the formation of stress fibers and the turnover of focal adhesions and plays a pivotal role in endothelial cell organization in angiogenesis. Several approaches have been developed to analyze the contribution of Rho kinase so far, and this chapter describes the in vitro and in vivo protocols used routinely in our laboratory to analyze the contribution in angiogenesis and shows the possibility of Rho kinase inhibitors in the clinical setting.