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POLYPHENOLS AS PROSTATE CANCER PREVENTION AGENTS.
Mr J.F. Thorpe, Professor J.K. Mellon Cancer Biomarkers and Prevention Group, Department of Cancer Studies and Molecular Medicine, University of Leicester |
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Summary of Final Report – March 2007
Prostate cancer represents an excellent target for prevention strategies; the late age of onset and slow development, means a modest delay would reduce the frequency of the disease. If the average onset were delayed to 80-90 years of age, relatively few men would develop the condition. There are a number of nutritional supplements with possible prostate cancer preventive effects that are being investigated. They cannot all be tested in large, lengthy human trials, so before such an investment can be made the most promising agents must be identified in animal trials. Once agents have been selected for investigation in humans, short trials must be performed that cannot measure the frequency of prostate cancer directly, because of the short time involved. Instead, these trials would use a molecular marker (biomarker) that can be measured in the laboratory to indicate that the agent is having a desirable effect.
The project reported here has investigated chemicals from tea called polyphenols; those from green tea are called catechins, those from black tea are theaflavins. Both agents have been shown, in this work, to reduce the size of prostate tumours in mice. In addition, oxidative damage in DNA was shown to be reduced in the tumours of the mice that received catechins. In fact the levels of oxidative damage were found to be related to tumour size. The levels of this oxidative DNA damage in prostate tissue can therefore be used as a biomarker of prostate cancer prevention in human trials. This work has also provided evidence that the catechins reach the mouse prostate in the form of epicatechin. Of the range of catechins which are found in green tea, this may mean that epicatechin is the particular agent responsible for the prostate cancer inhibition that is seen.
This project is continuing with a human trial, prostate tissue is being collected following taking one month of tea capsules. This will enable us to examine oxidative damage in the tissue to try to demonstrate evidence of cancer prevention in men.
I would like to gratefully acknowledge the support of the Prostate Research Campaign UK.
Progress report dated 15 September 2006
Project 2004/11