Inhibition of autophagy by andrographolide resensitizes cisplatin-resistant non-small cell lung carcinoma cells via activation of the Akt/mTOR pathway.

Resistance to cisplatin is a major obstacle for the success of non-small cell lung cancer therapy. The mechanisms underlying cisplatin resistance are not fully understood. In this study, we found that the increase of basal auotophagy accompanied the development of cisplatin resistance. Meanwhile the blockade of the Akt/mTOR pathway occurred in the process. Inhibition of this pathway was induced by cisplatin treatment in the resistant non-small cell lung carcinoma cells. Andrographolide, a natural diterpenoid, promoted the activation of the Akt/mTOR signaling by downregulating PTEN and suppressed autophagy, which subsequently resensitized the resistant cells to cisplatin-mediated apoptosis. Cisplatin treatment in combination with andrographolide significantly prevented the growth of the resistant cells in vivo. These results highlight the involvement of autophagy in cisplatin-resistance development and suggest that inhibition of autophagy via tuning the Akt/mTOR signaling could be a promising strategy in the therapy for cisplatin-resistant non-small cell lung cancer.