Extracellular regulation of cancer invasion: the E-cadherin-catenin and other pathways.
The E-cadherin-catenin complex is pivotal for the regulation of cancer invasion. It not only serves cell-cell adhesion but also transduces signals from the micro-environment to other molecular complexes possibly implicated in invasion. Both functions are disturbed when the extracellular part of E-cadherin is cleaved off. Moreover, upon release into the environment, the E-cadherin fragments may interfere with intact complexes, as indicated by experiments with His-Ala-Val (HAV)-containing peptides that are homologous to parts of the first extracellular domain of E-cadherin. Scatter factor/hepatocyte growth factor (SF/HGF), on binding to its c-met tyrosine kinase receptor, can induce invasion through tyrosine phosphorylation of beta-catenin. SF/HGF-induced invasion is also associated with phosphorylation of pp125FAK, and both invasion and phosphorylation are inhibited by platelet-activating factor (PAF). Activation of the membrane-bound non-receptor tyrosine kinase pp60src can also induce invasion. Signal transduction pathways starting from pp60src include E-cadherin-associated beta-catenin as well as the focal adhesion kinase pp125FAK. Whereas all invasion-inducing pathways implicate phosphoinositide 3-kinase, the PAF pathway seems to be E-cadherin-catenin-independent. We conclude that cancer cell invasion is regulated by paracrine and autocrine factors that are released upon cross-talk with the host cells.
D000595:Amino Acid Sequence; D000818:Animals; D015820:Cadherins / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism*; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D009361:Neoplasm Invasiveness; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D015534:Trans-Activators; D051176:beta Catenin