Contact inhibition is a fundamental cellular process where cells stop moving and dividing when they come into contact with each other. It consists of two closely related phenomena:
- Contact inhibition of locomotion (CIL): When two motile cells collide, they change direction to avoid each other, reducing their movement to prevent overcrowding. This involves cell-cell adhesion, tension buildup, and eventual repolarization to move away from the contact site
- Contact inhibition of proliferation (CIP): When cells grow to fill available space and make contact with neighbors, they stop dividing, preventing overgrowth and maintaining a single-cell layer thickness (a monolayer). This cell cycle arrest is reversible and regulated by mechanical tension and signaling pathways such as mTOR. Normal cells exhibit this behavior to control tissue growth and development, but cancer cells often lose this inhibition, leading to uncontrolled proliferation
Contact inhibition is essential for proper tissue structure, differentiation, wound healing, and preventing tumor formation. It is characterized by reduced cell migration and proliferation in high-density areas, and its loss is associated with cancer progression
. In summary, contact inhibition helps maintain organized tissue architecture by halting cell movement and division upon cell-cell contact, a property that is disrupted in many cancers.
