Inhibiting glucosylceramide synthase facilitates the radiosensitizing effects of vinorelbine in lung adenocarcinoma cells

The standard treatment regimen for patients diagnosed with non-small cell lung cancer (NSCLC) with locally advanced stage III disease is concurrent chemoradiotherapy (CCRT). This study investigated the molecular effects of vinca alkaloid vinorelbine (VNR)-based CCRT. We reviewed the records of 68 patients with stage III NSCLC: 42 patients received VNR-based CCRT, and 26 were treated with radiation alone. Human lung adenocarcinoma cells were used in this study to investigate the molecular effects of glucosylceramide synthase inhibition on VNR-based CCRT. There was response rate of 66.7% with CCRT, which was better than the response rate observed with radiation alone (30.8%; P < 0.001). CCRT caused an increase in cell cycle arrest at G2/M phase accompanied by apoptosis. Oxidative c-Jun N-terminal kinase (JNK) activation was involved in the increased apoptosis levels but not the cell cycle arrest. CCRT also induced an increase in ceramide accompanied by a decrease in glucosylceramide that was positively correlated with the cytotoxic effects. Pharmacologically inhibiting glucosylceramide synthase facilitated VNR- and CCRT-induced apoptosis by promoting the JNK pathway. Inhibiting glucosylceramide synthase facilitates the radiosensitizing effects of VNR by promoting JNK-mediated apoptosis in lung adenocarcinoma cells.