Abstract 3444: Novel SINE CRM1 antagonists for non-small cell lung cancer (NSCLC) in vitro and in vivo.
Authors: Han Xiaohong , Wang Shuai , Shi Yuankai , Wang Michael , Zhang Liang , Fang Bingliang , McCauley Dilara , Kauffman Michael , Shacham Sharon 
Published: August 2014

Background: Chromosome Region Maintenance 1 (CRM1, XPO1) is a nuclear export receptor which transports certain proteins from the nucleus to the cytoplasm, including tumor suppressor proteins (TSPs) and other modulators of proliferative responses.Overexpression of CRM1 correlates with cancer progression in several human cancers, suggesting that CRM1 could serve as a novel target for the treatment of cancers. NSCLC is an aggressive carcinoma which is not yet curable. The aim of our study was to explore the therapeutic efficiency of novel drug-like CRM1 inhibitors in NSCLC in vitro and in vivo, and to investigate the cytotoxic mechanisms of CRM1 inhibitors in NSCLC cell lines.

Methods: KPT-185 and KPT-276 are selective inhibitors of nuclear export (SINE) that block CRM1. Cell viability, apoptosis and cell cycle were evaluated in 6 NSCLC cell lines (1975,H1650,A431,A549,H2228,HCC827) which were treated with KPT-185; TSPs were detected by western blot to explore the possible mechanisms of KPT-185 inducing NSCLC cells growth inhibition and apoptosis. BALB/c nude mice bearing H1975 tumors were treated orally with KPT-276 (similar structure to KPT-185, but improved animal pharmacokinetics) to examine the efficacy and side-effects of KPT-276.

Results: In 6 NSCLC cell lines, growth inhibition showed in a dose-dependent way when inhibiting CRM1 by KPT185, with IC50 values range between 50nM to 1500nM. The epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor(TKI) resistant cell line H1975 was significantly more sensitive to KPT-185 than the EGFR-TKI sensitive cell line H1650. Cell apoptosis analysis showed that KPT-185 induced NSCLC cells apoptosis in both time- and dose-dependent manners. KPT-185 induced cell cycle arrest at the G1/S checkpoint in KPT-185 sensitive cell lines by cell cycle analysis. CRM1 protein expression in both the cytoplasm and nuclei of 6 NSCLC cell lines was down regulated when treated with KPT-185 for 48h. CRM1 inhibition by KPT-185 up-regulated the protein expression of p53 in some cell lines, and down-regulated the expression of EGFR and caspase8. In the xenograft H1975 model, tumor growth was significantly inhibited in KPT-276 oral treatment group compared with vehicle control group (P&lt;0.01) with good tolerability.

Conclusions: We investigated the anti-NSCLC activity of SINE (KPT-185 and -276) in vitro and in vivo. SINE CRM1 inhibitors inhibited growth of NSCLC both in vitro and in vivo. SINE inhibited and reduced CRM1 protein, retained TSPs and apoptosis-related proteins in the nucleus, inhibited cell growth and induced apoptosis. Novel SINE CRM1 antagonists may be effective oral therapies for NSCLC.

Citation Format: Xiaohong Han, Shuai Wang, Yuankai Shi, Michael Wang, Liang Zhang, Bingliang Fang, Dilara McCauley, Michael Kauffman, Sharon Shacham. Novel SINE CRM1 antagonists for non-small cell lung cancer (NSCLC) in vitro and in vivo. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3444. doi:10.1158/1538-7445.AM2013-3444

Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.