These proteins include tumor suppressors and regulators of cell apoptosis, nuclear localization of which is required for their proper function . 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 Butabindide oxalate 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 exhibited 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. Introduction Lung cancer is the leading cause of cancer death in the world, accounting for 1.3 million worldwide cancer-related deaths each year . Histologically, approximately 85% of patients with lung cancers are non-small cell lung cancers (NSCLC) , most of which are diagnosed at an advanced stages of the disease and ineligible for curative surgery. Palliative treatment includes chemo- and radiotherapy and more recently, targeting therapy, such as epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKI) gefitinib, erlotinib, and icotinib. These therapies have improved the survival of patients with NSCLC ; however, patients who initially respond to EGFR-TKI treatments eventually develop acquired resistance. Thus, novel therapeutic brokers with low toxicity and better outcomes are urgently needed for patients with NSCLC. During human carcinogenesis or cancer progression, malignant cells acquire the ability to export key nuclear proteins that can influence treatment efficacy. These proteins include tumor suppressors and regulators of cell apoptosis, nuclear localization of which is required for their proper function . Chromosome region maintenance 1 protein (CRM1 or called XPO1) is a member of the importin superfamily of nuclear export receptors (karyopherins). Furthermore, CRM1 is the chief mediator of nuclear export, can interact with leucine-rich nuclear export signals (NESs), and transport proteins through nuclear pore complexes to the cytoplasm C, including EGFR, p53 and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IB-) C. If the activity of CRM1-mediated export is usually blocked, protein function can be altered. Therefore, CRM1 inhibitors could be utilized as a novel class of targeting therapy against human cancer. Indeed, to date, many small molecule CRM1 inhibitors have been developed and with high anti-tumor activity, such as leptomycin B (LMB), ratjadone, goniothalamin, N-azolylacrylates, and CBS9106 C. These small molecule inhibitors covalently bind to the cysteine residue (Cys528) in the NES-binding groove of CRM1 protein C. A phase I clinical trial of LMB was conducted, but LMB was not recommended for further clinical development because of the high toxicity and lack of efficacy . Thereafter, a number of LMB analogues have been reported with Butabindide oxalate reduced toxicity . More recently, another class of CRM1 inhibitor has been identified, including KPT-185 and KPT-276 (Karyopharm Therapeutics Inc.; Boston, MA, USA). These inhibitors are selectively inhibitors of nuclear export (SINE), and have been showed to be effective for treating certain types of cancers, including pancreatic cancer, acute myeloid leukemia, mantle cell lymphoma, resulting in significant growth inhibition and apoptosis of tumor cells without severe toxicity C. Meanwhile, the levels of CRM1 protein are elevated in lung cancer tissues Butabindide oxalate when compared to normal lung tissues. Thus, in this study, we Rabbit Polyclonal to OR2T2 explored the therapeutic efficiency of these novel drug-like CRM1 inhibitors (i.e., KPT-185 and KPT-276) in NSCLC cells and to hopefully provide novel insight into these drugs for future target therapy of NSCLC. Materials and Methods Cell lines and reagents The human NSCLC cell.