Autophagic responses to hypoxia and anticancer therapy in head and neck cancer.

Autophagy is a major intracellular pathway involving in the degradation and recycling of cytosolic material, including organelles, proteins, and ribosomes. Autophagy is commonly active in tumor cells and could be induced by stress conditions such as hypoxia, nutrient depletion and anticancer therapy. Increasing evidence supports the role of autophagy in modulating cancer behavior in head and neck squamous cell carcinoma (HNSCC). Despite recent advances in surgery combined with chemotherapy and radiotherapy, the survival rate of patients with HNSCC has not been improved substantially. To adapt to the hostile microenvironment induced by stress condition including hypoxia and anticancer therapy, more biological changes such as autophagy are induced in tumor cells contributing to their malignant and aggressive behavior. In the present review, we summarized recent findings on the molecules involved in the autophagy induced by hypoxia and anticancer therapy and basic mechanisms of autophagy, and focused on elucidating the role of autophagy in tumor progression of HNSCC. Some novel studies on the relationships between mircoRNA and autophagy were also discussed in this review. A better understanding of this knowledge may provide new ideas and targets for effective prevention and treatment in HNSCC.