Abstract 5512: Dual inhibition of AXL and FN14 reverses cisplatin resistance in non-small cell lung carcinoma by inducing higher caspase 3 cleavage

Abstract

Abstract Background and Objectives: NSCLC patients undergoing Cisplatin therapy often develop resistance within 9-12 months that decreases treatment efficacy and is the major reason for the low median survival of 10-14 months among stage IV patients. Therefore, resistance is the main therapeutic limitation in the later part of the progressive disease. It has been suggested that suppressed Caspase-3 is one of the major reasons for failure to induce apoptosis by the cell during cisplatin resistance. We hypothesized this resistance to be related to EMT and other survival pathways. Recently, AXL and TWEAK/FN14 pathways have been shown to be upregulated in cisplatin resistant cells causing activation of EMT and survival pathways. Therefore, we examined whether dual inhibition of AXL and TWEAK/FN14 successfully reverses the cisplatin resistance in NSCLC. Materials and Methods: Drug resistant EGFR mutant H1975 and KRAS mutant A549 cells were tested for cisplatin desensitization following knock down of AXL and FN14 inhibition. We studied resensitization by determining the IC50 values in the drug resistant cell lines by treatment with both AXL and FN14 siRNA. We investigated detailed cellular mechanisms imparting resistance by detecting relative levels of Caspase 3, cleaved Caspase 3, PARP, cleaved PARP, p-SRC, p-EGFR, AXL and FN14 by western blotting. Cytochrome-C induced apoptosis was detected by monitoring cytochrome-c released from mitochondria using fluorescence microscopy. Results: Suppression of AXL and FN14 by siRNA treatment resensitized NSCLC to cisplatin and induced apoptosis. IC50 values were decreased significantly following dual inhibition (by more than 200%). A marked increase in cleaved caspase 3 levels was also observed in both mutant cell lines. A subsequent increase in PARP and cleaved PARP levels verified the fact that caspase 3 is indeed responsible for the apoptosis in these cells. Upregulation of p-SRC and eventually p-EGFR failed to suppress the apoptosis through PI3K/AKT pathway. Cytochrome c release from mitochondria further confirmed cellular apoptosis. Conclusion: Our results show that dual inhibition of AXL and TWEAK/FN14 can reverse cisplatin resistance by inducing higher caspase 3 cleavage that can enhance survival of NSCLC patients undergoing chemotherapy. Citation Format: Soumavo Mukherjee, Dhananjay Suresh, Ajit P. Zambre, Anandhi Upendran, Raghuraman Kannan. Dual inhibition of AXL and FN14 reverses cisplatin resistance in non-small cell lung carcinoma by inducing higher caspase 3 cleavage [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5512.