Mechanisms Involved in Focal Adhesion Signaling Regulating Tumor Anoikis Resistance

Among the numerous malignant behaviors of tumors, metastasis plays a critical role in contributing to poor prognosis. Anoikis is a distinct form of apoptosis induced when cells detach from the extracellular matrix (ECM) or adhere to an improper ECM. It is a physiological obstacle to tumor cell metastasis. Anoikis resistance is considered to be a critical initial step in cancer cell metastasis. However, the mechanism by which tumor cells develop anoikis resistance is still unclear, in which the focal adhesion signaling pathway plays an important role. This review first outlines the composition of focal adhesion (FAs) multi-protein signaling complexes and then discusses the following three aspects: integrin expression changes of tumor cells, intracellular oxidative stress response, and FAs multi-protein signaling complex members activating downstream survival signaling pathways. The specific mechanisms of focal adhesion signaling pathways in tumor cell anoikis resistance and molecular characteristics of the anoikis resistance state are reviewed.