Antitumor Effects of a Novel Chromosome Region Maintenance 1 (CRM1) Inhibitor on Non-Small Cell Lung Cancer Cells In Vitro and in Mouse Tumor Xenografts

Background: Chromosome Region Maintenance 1 (CRM1) is a nuclear exporter and its inhibitor has anti-tumor activity in various cancers. This study assessed the therapeutic efficiency of the novel CRM1 inhibitor KPT-185 on non-small cell lung cancer (NSCLC). Methods: NSCLC cell lines were treated with KPT-185 to assess changes in cell viability, cell cycle, apoptosis, and protein expression. NOD-SCID mice carrying NSCLC cell xenografts were orally treated with KPT-276, a clinical analog of KPT-185, to examine the efficacy and side effects of KPT-276 in vivo. Results: KPT-185 significantly reduced the viability of six NSCLC cell lines in a time-and dose-dependent manner, including epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-resistant H1975 and H1650GR cell lines. In addition, KPT-185 induced these NSCLC cells to arrest at G1 phase of the cell cycle and caused apoptosis in a dose-dependent manner. KPT-185 treatment also reduced CRM1 protein levels in six NSCLC cell lines, and the reduction could be completely abolished by the proteasome inhibitor bortezomib. KPT-185 activated caspase 3, 8, and 9, but inhibited survivin expression in NSCLC cells. In a mouse H1975 cell xenograft model, tumor growth was significantly inhibited by oral KPT-276 administration, and there was no significant mouse body weight loss or other side effects. Conclusions: The current study demonstrated the anti-tumor effects of KPT-185 in NSCLC cells, including EGFR-TKI-resistant NSCLC cell lines. Further studies will assess anti-tumor activity of KPT-185 in a clinical trial for NSCLC patients.