Introduction; Non-small cell lung cancer (NSCLC), which does not have druggable driver oncogene, is treated with cytotoxic chemotherapy, but clinical outcome is suboptimal. Cisplatin is still one of the most commonly used drugs for the treatment of NSCLC, and, however, there are limitations of the therapeutic effect because of the multiple resistance mechanisms. In particular, elevated level of anti-apoptotic proteins (Bcl-2, Bcl-xL, Mcl-1) triggered by cisplatin-induced DNA damage response correlate with the drug resistance. In this study, we investigated synergic effects of combined treatment with cisplatin and dual inhibitor of Bcl-2/Bcl-xL, ABT-737, in NSCLC models.

Materials and Methods; H460 and A549 NSCLC cells, and LSL K-Ras G12D mouse model were used. Protein expression was evaluated by immunoblotting and cytotoxicity was measured by FACS followed by annexin-V and PI staining. LSL Kras G12D mouse were inhaled 5 × 107 PFU AdCre virus at 8 weeks after birth and, in 24 weeks after inhalation, were taken microCT, randomized into 4 groups, and then treated with ABT-737 (50mg/kg, i.p., daily) and/or cisplatin (5 mg/kg, i.p., weekly) for two weeks.

Results; There was a dose dependent phosphorylation of JNK, which is most prominent between 6 to 24hr after cisplatin treatment. Expression of anti-apoptotic molecules, Bcl-2, Bcl-w, Bcl-xL, and Mcl-1 were increased by cisplatin treatment in a dose and time dependent manner. JNK specific activator, anisomycin, increased mRNA level of anti-apoptotic molecules. ABT-737 displaced BCL-xL to the cytoplasm and aggregated Bak. Furthermore, ABT-737 released cytochrome C from mitochondria to the cytoplasm. ABT-737 itself showed cytotoxic effects and combination of ABT-737 potentiates cytotoxic effects of cisplatin with strong synergism. Combination of ABT-737 with cisplatin treatment induced significant tumor regression in 2 weeks in LSL K-ras G12D mouse model when compared those treated with single agents or vehicle.

Conclusion; Combination of ABT-737 with cisplatin showed synergistic cytotoxic effects and anti-tumor activities in NSCLC preclinical models. These findings suggest that clinical trials using combination with ABT-737 and cisplatin may be beneficial in advanced NSCLC patients.

Citation Format: Eun Young KIM, Arum Kim, Yoon Soo Chang. Bcl-2 and Bcl-xL dual inhibitor, ABT-737, circumvents JNK mediated upregulation of anti-apoptotic molecules in cisplatin treated non-small cell lung cancer models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2530. doi:10.1158/1538-7445.AM2015-2530