The role of protein kinase C and novel phorbol ester receptors in tumor cell invasion and metastasis (Review)

Phorbol ester tumor promoters activate protein kinase C (PKC isozymes and n ovel non-kinase receptors, suggesting a high degree of complexity in the si gnaling mechanisms of tumorigenesis. Many studies have shown that PKC isozy mes contribute to the progression of malignant phenotype, We review the eme rging understanding of the roles of PKC isozymes in the three sequential ce llular processes of tumor invasion and metastasis: attachment to extracellu lar matrix or basement membrane components, matrix degradation by proteolyt ic enzymes, and migration through the digested matrix. In addition, we disc uss the potential role of chimaerins, novel non-kinase phorbol ester recept ors, in carcinogenesis.