Autophagy is a highly conservative biological behavior in eukaryotic cells. This dynamic process involves“wrapping” cytoplasmic components and combining with lysosomes in cells for catabolism. The catabolic effect of autophagy can eliminate toxic substances in cells, maintain homeostasis in the intracellular environment, and produce small molecules, such as amino acids, which nourish cells, thereby allowing them to survive. Autophagy can inhibit the occurrence of tumors by maintaining homeostasis in the intracellular environment. However, it can promote the proliferation, invasion, and metastasis of malignant tumor cells. Autophagy can regulate the microenvironment of tumor cells and has an important role in a series of processes, such as anoikis, tumor dormancy, and epithelial–mesenchymal transition.
