The Evolving, Multifaceted Roles of Autophagy in Cancer.

Autophagy is a lysosomal degradation process crucial for adaptation to stress and cellular homeostasis. In cancer, autophagy has been demonstrated to serve multifaceted roles in tumor initiation and progression. Although genetic evidence corroborates a role for autophagy as a tumor suppressor mechanism during tumor initiation, autophagy also sustains metabolic pathways in cancer cells and promotes survival within the harsh tumor microenvironment and in response to diverse anticancer therapies. Moreover, though traditionally viewed as an autodigestive process, more recent work demonstrates that autophagy also facilitates cellular secretion; the importance of these new functions of the autophagy pathway is being increasingly appreciated during cancer progression and treatment. In this review, we discuss how these evolving and diverse roles for autophagy both impede and promote tumorigenesis.