Topotecan as a molecular targeting agent which blocks the Akt and VEGF cascade in platinum-resistant ovarian cancers.

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Tsunetoh S, Terai Y, Sasaki H, Tanabe A, Tanaka Y, Sekijima T, Fujioka S, Kawaguchi H, Kanemura M, Yamashita Y, Ohmichi M

Topotecan as a molecular targeting agent which blocks the Akt and VEGF cascade in platinum-resistant ovarian cancers.

Cancer Biol Ther. 2010 Dec 1;10(11):1137-46. doi: 10.4161/cbt.10.11.13443. Epub 2010 Dec 1.

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20935474 [ View in PubMed

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Abstract

OBJECTIVE: Topotecan, a novel topoisomerase-1 inhibitor, is a drug that appears to be effective against platinum-resistant ovarian cancers. However, the molecular mechanisms by which Topotecan treatment inhibits cancer cell proliferation are unclear. We investigated whether Topotecan increases the efficacy of Cisplatin in platinum-resistant ovarian cancer models in vitro and in vivo. METHODS: We used Cisplatin-resistant Caov-3 cells and Cisplatin-sensitive A2780 cells. We examined the effect of Cisplatin and Topotecan on the cell viability of Caov-3 and A2780 cells by MTS assay. We examined the Akt kinase activity, VEGF and HIF-1alpha expression after Cisplatin and Topotecan by a Western blot analysis. Moreover, we also evaluated the effects of Cisplatin and Topotecan on the intraabdominal dissemination of ovarian cancer in vivo. RESULTS: Topotecan significantly inhibited Cisplatin-induced Akt activation in Caov-3 cells, but not in A2780 cells. In the presence of Topotecan, Cisplatin-induced growth inhibition and apoptosis were significantly enhanced in Caov-3 cells. Topotecan inhibited not only Cisplatin-induced Akt activation but also VEGF and HIF-1alpha expression. Moreover, treatment with Topotecan increased the efficacy of Cisplatin-induced growth inhibition in the intraabdominal dissemination and production of ascites in athymic nude mice inoculated with Caov-3 cells. CONCLUSION: We herein demonstrated that Topotecan inhibits Akt kinase activity and VEGF transcriptional activation after Cisplatin treatment in platinum-resistant ovarian cancers. We clarified how Topotecan enhanced the clinical activity in the platinum-resistant ovarian cancer. These results provide a rationale for using Topotecan in clinical regimens aimed at molecular targeting agents in platinum-resistant ovarian cancers.