Supplementary Figures S1-5, Tables S1-5. Figure S1 The Cytotoxic Effect of KPT-185 is Tumor Suppressor-independent. Figure S2 Combination Index of KPT-185 with Chemotherapeutic Agents. Figure S3 1D Gel Analysis of Cytoplasmic Protein. Figure S4 Effects of Selinexor (KPT-330) in an Ovarian Cancer Mouse Model. Figure S5 The Efficacy of Selinexor (KPT-330) on Tumor Regression and Metastasis Table S1 p53 status and IC50 concentration of KPT-185 after 72 hours of incubation in human cancer cell lines Table S2 Combination index (CI) of KPT-185 with cytotoxic agents Table S3 Proteins showing altered mitochondrial localization after treatment with KPT-185 Table S4 1D Proteomic analysis of cytoplasmic proteins immunoprecipitated with eIF5A Table S5 siRNA Sequences
ARTICLE ABSTRACT
Purpose: XPO1 inhibitors have shown promise for cancer treatment, and yet the underlying mechanisms for the antitumor effects are not well understood. In this study, we explored the usefulness of selective inhibitors of nuclear export (SINE) compounds that are specific inhibitors of XPO1.Experimental Design: We used proteomic analysis in XPO1 inhibitor–treated ovarian cancer cell lines and examined antitumor effects in ovarian and breast cancer mouse models. We also studied the effects of XPO1 inhibitor in combination with chemotherapeutic agents.Results: XPO1 inhibitor treatment substantially increased the percentage of apoptotic cells (60%) after 72 hours of incubation. XPO1 inhibitor promoted the accumulation of eIF5A in mitochondria, leading to cancer cell death. Topotecan showed the greatest synergistic effect with XPO1 inhibitor. XPO1 inhibitors prevented the translocation of IGF2BP1 from the nucleus to the cytoplasm, thereby permitting the localization of eIF5A in the mitochondria. This process was p53, RB, and FOXO independent. Significant antitumor effects were observed with XPO1 inhibitor monotherapy in orthotopic ovarian (P < 0.001) and breast (P < 0.001) cancer mouse models, with a further decrease in tumor burden observed in combination with topotecan or paclitaxel (P < 0.05). This mitochondrial accumulation of eIF5A was highly dependent on the cytoplasmic IGF2BP1 levels.Conclusions: We have unveiled a new understanding of the role of eIF5A and IGF2BP1 in XPO1 inhibitor–mediated cell death and support their clinical development for the treatment of ovarian and other cancers. Our data also ascertain the combinations of XPO1 inhibitors with specific chemotherapy drugs for therapeutic trials. Clin Cancer Res; 21(14); 3286–97. ©2015 AACR.
