Figure 1.

Multifaceted roles of autophagy in cancer. Autophagy is a catabolic process by which cells degrade large cellular cargoes, such as organelles, ribosomes and intracellular pathogens that are captured inside double-membraned autophagosomes before fusing with the lysosome and resultant constituent metabolites (amino acids, nucleotides, fatty acids) released to the cytsosol for reuse in biosynthetic processes and cell growth. This fuel function of autophagy is important in terms of promoting tumor cell survival at many stages in tumorigenesis. Autophagy also performs an organelle quality control function as part of cellular homeostasis that is important in both normal and tumor cells. As cells progress to becoming invasive, autophagy plays a role in promoting cell migration through focal adhesion disassembly and secretion of pro-migratory cytokines, such as IL-6. Autophagy also plays a role in the tumor microenvironment in modulating recruitment and response of T cells to the tumor and providing tumor cells with nutrients via amino acid transfer from cancer-associated fibroblasts to the tumor. Finally, emerging data have identified a role for autophagy in maintaining CSCs and tumor dormancy, both of which may play into drug resistance of cancers, minimal residual disease and metastatic latency.