UPDATE - Issue 31 - Autumn 2007
Research into diagnostic tools
Dr. Hayley Whitaker at the Department of Oncology, University of Cambridge is investigating the role of proteins in diagnosing prostate cancer and, in particular, progression to advanced prostate cancer. This research is partially funded by Prostate UK and is due to finish in 2008. However, Dr. Whitaker has already obtained some exciting results.
Prostate cancer is currently diagnosed using a test which detects a protein called prostate specific antigen (PSA). This protein can be measured in blood, and can determine whether a patient's treatment is working. However, the PSA test is not 100% accurate and the Prostate UK-funded research is looking for another protein, also referred to as a biomarker, to diagnose prostate cancer. To find new biomarkers, the levels of a particular protein in the urine, blood or tissue of people with cancer are compared to people without cancer.
Dr Hayley Whitaker in her Cambridge laboratory
The biomarkers currently being investigated belong to a family of proteins called peroxiredoxins (Prxs). Prxs act like a molecular sponge in cells, mopping up free radicals which can cause cancer by damaging DNA. If cells don't have enough Prxs they may be more likely to become cancerous.
The research has already found that the level of Prxs are very low in normal prostate tissue but twice as much was present in cancerous prostate tissue. This suggests Prxs may be a good biomarker to identify prostate cancer. There are also more Prxs found in very aggressive cancers compared to less aggressive cancers. This indicates that it may be possible to use these proteins to show how far a patient's cancer has developed or how they are responding to treatment.
The researchers are also interested in why hormone therapy that is used to treat prostate cancer often stops working. Hormones, called androgens, are required for cancer growth and act on other proteins in the cells instructing the cells to grow, divide or spread to other organs in the body. Such proteins are said to be androgen-regulated and the hormone therapy that is used is termed anti-androgen. It is difficult to investigate anti-androgens in patients; so the researchers grow a type of prostate cancer cell that has been modified to grow continuously in a culture dish. These cell lines are then manipulated and anti-androgens added to them to mimic prostate cancer growth and its treatment in the body. While the majority of cells die, a small number survive and continue to grow. It is believed that this is similar to what happens in patients with advanced prostate cancer after hormone therapy. Dr Whitaker has measured the levels of Prxs in surviving cells compared to cells that haven't been treated with drugs. She found that three times more Prxs are found in the surviving cells which suggests that Prxs could be used to indicate when prostate cancer is progressing in patients.
Her research is now focusing on what happens to cells when the levels of Prxs increase and whether it has a direct effect on how cancer cells grow and spread to other parts of the body.