Andrographolide enhances cisplatin-mediated anticancer effects in lung cancer cells through blockade of autophagy

Lung cancer is the most common cause of cancer-related death worldwide and the platinum-based drugs such as cisplatin have been used as the first line of the treatment. However, the clinical effectiveness of such chemotherapy is limited by intrinsic or acquired resistance. In this study, we found that cisplatin induced autophagy that attenuated the sensitivity of both A549 and Lewis lung cancer (LLC) cells to cisplatin. In contrast, the clinical drug andrographolide (Andro) suppressed autophagy and enhanced cisplatin-mediated apoptosis in these cells. Using two murine lung cancer models, including a subcutaneously inoculated LLC model and an orthotopic LLC implantation model, we investigated the therapeutic efficacy of the combined treatment of cisplatin and Andro. Compared with the sole cisplatin treatment, combining cisplatin with Andro potentially inhibited tumor growth, reduced the incidence of lung metastases, and relieved renal tubular damage. Moreover, the combined treatment prolonged the life span of tumor-bearing mice. TUNEL and immunohistochemistry assays showed the increase in apoptotic cells and the decrease in both conversion of LC3B-I to LC3B-II and Atg5 protein expression in the tumor tissues from mice with the combined treatment. These results suggest that Andro offers an ideal candidate of autophagy inhibitors in clinical application, and combination of cisplatin with Andro could be a promising strategy for the treatment of lung cancer.