Classical PKC isoforms in cancer

Protein kinases C (PKCs) are a family of serine/threonine kinases which are involved in tumor formation and progression. Although PKC over-expression has been shown to contribute to cell transformation, PKCs are not considered to be classical oncogenes which are activated by mutations, but considered as tumor promoters that enhance multiple cellular signaling pathways. Over the last two decades a lot of evidence has emerged demonstrating a role for various PKC isoforms in cancer. Small molecular weight inhibitors and antisense molecules have been developed, specifically targeting the calcium dependent classical isoforms of PKC. This review focuses on the role of classical PKCs in cancer and the results obtained by attempting to inhibit these enzymes to achieve a therapeutic benefit. (C) 2007 Elsevier Ltd. All rights reserved.