Attenuation of Protein Kinase C Activity by Estrogen: A possible Role in Heart Disease Prevention
Fowler, Brian E.
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Atherosclerosis, or heart disease, is the number one cause of death in western society. It is for this reason that treatments are being developed that will prevent or treat heart disease. The disease is caused by a proliferation of smooth muscle cells into the arteries which eventually causes a blockage of blood flow. This proliferation may, in some cases, be caused by the over-activation of the enzyme Protein Kinase C. Estrogen therapy has been shown to reduce the risk of heart disease when administered to post-menopausal women. For this reason, the present study sought to determine the effects of estrogen on Protein Kinase C. The hypothesis was that estrogen attenuates the over-activation of Protein Kinase C thus reducing the possibility of human coronary smooth muscle cell proliferation. By treating cultured human coronary smooth muscle cells with estrogen and Phorbol esters (a compound that mimics the over-activation of Protein Kinase C), it was determined that estrogen decreases over-activation of Protein Kinase C by 33% (±18) in 1 nM concentrations. An estrogen concentration of 500 nM, however, does not decrease Protein Kinase C activity. This discovery partially explains why estrogen therapy prevents heart disease. However, it should be noted that further study is needed to find the ideal estrogen concentration that effectively decreases the risk for heart disease and has the fewest side-effects.