Abstract 1070: Role of FOXO1 in Response of Ovarian Carcinoma Cells to the XPO1/CRM1 Inhibitor KPT-330/selinexor in Combination with Cisplatin

Ovarian carcinoma is a major cause of cancer-related death in women. Besides late diagnosis, treatment often fails to produce a persistent disease control. The efficacy of the platinum drug-based therapy is limited by drug resistance. Thus, an ideal therapy for women with ovarian carcinoma is still missing. Because the karyopherin XPO1/CRM1 contributes to the regulation of the cellular localization of the transcription factor FOXO1 which participates in apoptosis regulation, the aim of this study was to examine if interference with XPO1 to improve FOXO1 nuclear localization may be exploited to kill efficiently ovarian carcinoma cells and to improve cisplatin efficacy. Here, we employed preclinical pharmacology approaches including growth inhibition assays, western blot analyses, gene knockdown by siRNA, quantitative Real-time PCR, immunofluorescence analyses and tests in in vivo models. The drug interaction was analyzed using the Chou and Talalay method. When cell sensitivity to KPT-330 of a panel of ovarian carcinoma cell lines was examined a marked sensitivity to the XPO1 inhibitor was found. The effect of the combination of cisplatin and KPT-330 was investigated in the IGROV-1 cells, using simultaneous or sequential schedules. According to the combination index values, when KPT-330 exposure followed cisplatin exposure the most favourable drug interaction was observed. In IGROV-1 cells, a modulation of proteins involved in apoptosis (p53, Bax) and in cell cycle progression (p21) was found, besides G1 and G2/M accumulation after exposure to KPT-330 and to the cisplatin/KPT-330 combination, respectively. KPT-330-treated cells exhibited FOXO1 nuclear staining, in keeping with the capability of the compound to inhibit FOXO1 nuclear export. Knock-down experiments by RNA interference indicated that FOXO1-silenced cells displayed a reduced sensitivity to KPT-330, but no significant changes in cisplatin sensitivity. FOXO1 silencing tended to reduce the efficacy of the drug combination at selected cisplatin concentrations. An analysis of the antitumor efficacy of KPT-330, indicated the capability of KPT-330 to significantly inhibit tumor growth when IGROV-1 cells were subcutaneously injected in immunodeficient mice or growth intraperitoneally. Our findings support that the XPO1 inhibitor KPT-330 is a promising agent for the treatment of ovarian carcinoma. The effect of the KPT-330-cisplatin combination appears to be dependent on the treatment schedule, as a synergistic interaction occurs when cells are treated with cisplatin followed by KPT-330. Such an interaction can be modulated by silencing of FOXO1, which results in reduced sensitivity to KPT-330. Our results suggest that therapeutic regimens selected on the basis of the molecular tumor features should be used to achieve a personalized therapy tailored to the specific characteristics of each patient. Citation Format: Simone Stucchi, Michelandrea De Cesare, Cristina Corno, Nives Carenini, Emilio Ciusani, Nadia Zaffaroni, Laura Gatti, Paola Perego. Role of FOXO1 in response of ovarian carcinoma cells to the XPO1/CRM1 inhibitor KPT-330/selinexor in combination with cisplatin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1070. doi:10.1158/1538-7445.AM2017-1070