Cancer and Autophagy
In 1992, Ashford and Porter observed in human liver cells that the cytoplasm,
organelles and proteins that need to be degraded are encapsulated by a bilayer
membrane to form autophagosomes, which fuse with lysosomes to form
autophagosomes and degrade them. This phenomenon is called autophagy.
Autophagy is widely present in eukaryotic cells and is a self-protective mechanism of
cells. Under normal conditions, the level of autophagy in the cells is low, and the
level of autophagy in the cells is rapidly increased under stress conditions. This is
beneficial to maintaining the metabolic balance of the protein and alleviating the
metabolic pressure, thereby maintaining the stability of the intracellular
environment.
The autophagy process is mainly made up of four stages: initiation and extension of
autophagic membranes, maturation and degradation of autophagosomes. First,
autophagosome-associated proteins recognize parts of cytoplasm, organelles,
proteins, and other molecules. Next, the cell membrane of part of the rough
endoplasmic reticulum that has not been detached from the ribosome attachment
region begins to form an autophagic membrane, also called a barrier membrane. The
autophagic membrane gradually extends to encapsulate the components to be
degraded to form a closed spherical vesicle, called an autophagosome.
Autophagosomes fuse with lysosomes to form autolysosome, which lead to
degradation of the membrane and contents of the autophagy, thereby providing
energy for intracellular chemical reactions. According to previous studies,
researchers have shown that autophagy is closely related to cancer.
