Abstract 2081: Evaluation of Src as a therapeutic target in biliary tract cancer using bosutinib, a c-Src/Abl kinase inhibitor.

Abstract

Abstract Background: Src is a nonreceptor tyrosine kinase involved in the crosstalk and mediation of many signaling pathways that promote cell proliferation, invasion and angiogenesis. Elevation of Src activity has been reported in many types of cancers including biliary tract cancer (BTC). In BTC, no molecular therapeutic target has been validated so far. Therefore, the prognosis of advanced BTC is limited and there is a huge unmet medical need in this area. The purpose of this study is to evaluate of Src as a therapeutic target in BTC and to elucidate the therapeutic potential and action mechanism of bosutinib, an orally active small molecule c-Src/Abl kinase inhibitor, alone or in combination with chemotherapy for the treatment of BTC. Methods: Experiments were conducted using 8 human biliary tract cancer cell lines (SNU-245, 308, 478, 869, 1079, 1196, HuCCT1, TFK1). MTT assay, colony formation assay and 3D culture were done for determining growth inhibitory effect of bosutinib, alone or in combination with chemotherapeutic agents (gemcitabine, cisplatin). Cell cycle distribution was analyzed by FACS Calibur flow cytometer. Matrigel invasion assay and wound healing assay were done. The methods described by Chou and Talalay were used to determine whether a synergistic effect existed between drug combination. Results: pSrc was highly expressed in most BTC cells. Bosutinib inhibited the growth of BTC cells, especially SNU308, SNU478 and HuCCT1 (IC50, 0.6-0.8 μmol/L). Bosutinib induced G1 arrest (decrease of cyclin D, cyclin E, cyclin A, cyclin B and increase of p27) in SNU308 and SNU478. It decreased pSrc, pFAK, pAKT and pERK in these cells. Bosutinib also inhibited the cell migration and invasion in parallel with decrease of snail, not only in SNU308, SNU478 cells but also in several other cells. Interestingly, bosutinib showed synergistic antiproliferative effects (Combination Index value <1) with gemcitabine in 4 out of 8 BTC cells. Bosutinib was downregulated TS (thymidine synthase) expression, one of resistance mechanisms to gemcitabine. Bosutinib also showed synergistic anti-invasion activity in combination of gemcitabine or cisplatin. Conclusion: Taken together, these preclinical evaluations reveal that Src could be a potential therapeutic target in biliary tract cancer and support clinical development of bosutinib alone or in combination with chemotherapy in biliary tract cancer. Citation Format: Ah-Rong Nam, Ahrum Min, Sae-Won Han, Sang-hyun Song, Do-Youn Oh, Seock-Ah Im, Tae-You Kim, Youg-Jue Bang. Evaluation of Src as a therapeutic target in biliary tract cancer using bosutinib, a c-Src/Abl kinase inhibitor. [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 2081. doi:10.1158/1538-7445.AM2013-2081