New Evidence Suggests Protein Kinase C (PKC) Proteins Suppress Rather Than Promote Cancer

Researchers from Manchester, UK, working with scientists in California, have found that certain molecules long thought to promote cancer growth, actually suppress tumors, suggesting that therapeutic approaches should aim to restore, rather than block, their activity. The protein kinase C (PKC) family of molecules are enzymes that facilitate a range of cellular processes, including cell survival, proliferation, migration, and death. In the 1980s, it was found that PKCs were activated by cancer-causing phorbol esters, and that led to the conclusion that PKCs themselves induced the development of tumors. However, attempts to develop new treatments that prevent tumor cell growth by blocking the activity of PKCs have had little success. A recent study involving Manchester scientists, the findings of which have been published in the January 29, 2015 issue of Cell, has explored the effect of mutations in PKC on tumor growth. The article is titled “Cancer-Associated Protein Kinase C Mutations Reveal Kinase’s Role as Tumor Suppressor.” Dr. John Brognard, from the Cancer Research UK Manchester Institute at The University of Manchester – part of the Manchester Cancer Research Centre – said: “Despite phorbol esters being known to cause cancers, we’ve seen frustratingly little progress when targeting PKCs to stop tumor growth.” The Manchester group collaborated with a team from the University of California, San Diego, to analyze PKC mutations in human cancer cells. They found that most were ‘loss of function’ mutations, meaning that the genetic changes stopped PKC from working. When they corrected these mutations in bowel cancer cells, they saw a reduction in tumor growth, meaning that contrary to the previous understanding, PKC normally acts to block cancer.
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