Effects of Src kinase inhibition induced by dasatinib in non–small cell lung cancer cell lines treated with cisplatin

c-Src is a tyrosine kinase involved in tumor proliferation, migration, and angiogenesis and has been shown to modulate the cytotoxicity following cisplatin-induced DNA damages. c-Src is frequently activated in non-small cell lung cancer (NSCLC) tissues and cell lines, but no preclinical data regarding the effects of the novel potent Src inhibitor, dasatinib (BMS-354825), in the modulation of cisplatin resistance are currently available. The present study reports that treatment with dasatinib completely abrogated Src phosphorylation in the majority of the NSCLC cell lines tested (n = 7), with modest effects on cell proliferation and survival. In five cell lines, a higher cytotoxicity was observed delivering cisplatin in combination with dasatinib: the most evident effects were found in the squamous H520 cells due to the effective block of cisplatin-induced Src phosphorylation. Moreover, dasatinib treatment significantly blocked cisplatin-induced transcription of a panel of DNA repair and synthesis genes. In addition, a real-time PCR analysis done on tumor and matched normal lung specimens from 44 surgically resected NSCLC patients showed that Src transcripts are significantly upregulated in 23% of cases. In conclusion, Src-directed therapeutic strategies could interfere with cisplatin resistance, possibly allowing to reduce cisplatin doses, thus improving its efficacy. The data of this study support further clinical studies aimed to evaluate the efficacy of Src-inhibiting agents in combination with cisplatin in the treatment of NSCLC.