Autophagy is a stress regulatory mechanism that generally exists in eukaryotic cells. This process promotes tumor development and inhibits tumor proliferation. Autophagy is activated by increasing hypoxia inducible factor-1α level, suppressing the mammalian target of the rapamycin signal pathway, and inducing endoplasmic reticulum stress in the tumor hypoxia microenvironment. Autophagy is stimulated through enhancement of glucose metabolism, increase in reactive oxygen species level, downregulation of caveolin 1 expression, and activation of epithelial–mesenchymal transition in tumor during rapid cell proliferation and invasion. Autophagy promotes tumor invasion, metastasis, and drug resistance. Therefore, novel strategies for inhibiting autophagy may serve as promising therapeutic approach for tumor treatment.
