The role of interaction between autophagy and apoptosis in tumorigenesis (Review).

Autophagy is a highly conserved process that maintains cellular homeostasis during evolution. Autophagy can occur in the form of macroautophagy, microautophagy or molecular chaperone autophagy, among which macroautophagy is the most common. Apoptosis exists in all kinds of cell organisms, and is a kind of programmed cell death which is regulated by pro‑apoptotic factors and anti‑apoptotic signals. The main biological feature of apoptosis is the activation of caspase. Apoptosis is induced by a variety of cell signals, such as endoplasmic reticulum stress, induction of toxic substances, stimulation of pathogenic microorganisms and DNA damage. Inextricable links are found between autophagy and apoptosis. Studies have found that numerous of the autophagy molecules and autophagy signaling pathways involved in the process of autophagy are related to apoptosis. In addition to regulating autophagy, the autophagy signaling pathway also regulates apoptosis. The interaction between the two can achieve a dynamic balance to certain extent, which maintains the basic physiological functions of cells and reduces the damage to the body under stress. Disease occurs when the balance between autophagy and apoptosis is disrupted. Tumors form due to the ability of cells to avoid apoptosis. Autophagy is closely related to apoptosis, there must be a close connection between the three. In the present review, the mechanism between autophagy and apoptosis and the impact of their interaction on tumorigenesis shall be discussed.