Autophagy inhibition contributes to Endostar sensitization in esophageal squamous cell carcinoma

Endostar is a novel artificially-synthesized anti-angiogenesis drug, and has been approved for clinical use. Previous studies have indicated that patients with esophageal cancer could benefit from Endostar combined with chemotherapy or chemoradiotherapy. However, the most advantageous use of this drug remains to be elucidated. The role of autophagy in cancer treatment remains controversial. The results of the present study demonstrated that Endostar promotes autophagy activation, which is regulated via phosphorylation inhibition of the downstream signaling molecules of the vascular endothelial growth factor, AKT serine/threonine kinase and mechanistic target of rapamycin signaling pathways. Furthermore, inhibiting autophagy using the pharmacological inhibitor chloroquine facilitated the antiproliferative effect of Endostar and increased the number of apoptotic cells, compared with Endostar monotherapy. Taken together, the results of the present study suggest that autophagy activation induced by Endostar serves a protective role in human esophageal cancer treatment, and that autophagy inhibition promotes the antiproliferative role of Endostar. Therefore, the combination of Endostar with an autophagy inhibitor may be a novel prospective approach to improving the efficacy of Endostar for the treatment of patients with esophageal cancer.