Gene may help cancer cells to thrive
WEDNESDAY 23 MAY 2007
The p53 'tumour suppressor' gene, which researchers believe is essential in helping chemotherapy to kill cancer cells, may actually help them to survive, a study has found.
Researchers from the Georgia Institute of Technology and the Ovarian Cancer Institute found that just 30 per cent of chemotherapy patients whose tumours had a normal p53 gene were alive after five years, compared to 70 per cent of patients with a faulty p53 gene, regardless of the stage of cancer at the time the tumours were surgically removed.
For some time, researchers have believed that p53 is essential to successful chemotherapy, as it is responsible for starting the process of cell death if a cell is damaged beyond repair.
The gene is therefore thought to assist in cancer treatment by killing cancerous cells which have been damaged by chemotherapy.
However, before it initiates cell death, p53 attempts to repair the cell and researchers now believe that it may help some damaged cancer cells to survive.
John McDonald, chairman of Georgia Tech's school of biology and chief researcher at the Ovarian Cancer Institute, said: "p53 has long been recognised as a key player in directing chemotherapy-damaged cancer cells to self annihilate, but less attention has been paid to p53's role in repairing damaged cells."
Mr McDonald said that p53 may actually help some cancer cells to make a "comeback".
"Based on our results, we propose that p53 may help repair some of the cancer cells damaged by chemotherapy leading to tumour recurrence and explaining the higher mortality rate of patients whose tumours had a functioning p53," he explained.
"If we are correct, inhibiting p53 in tumours being treated with chemotherapy may substantially improve patients' long-term survival."
Professor Karen Vousden, Director of Cancer Research UK's Beatson Institute in Glasgow, said: "We know p53 protects cells from the type of damage that can lead to cancer, and can also destroy cancer cells that have been damaged by chemotherapy.
"Although this study is small and doesn't directly implicate p53 in the poor response of some ovarian cancer patients to chemotherapy, it certainly gives us food for thought.
"The results suggest that p53 actually continues to protect some cancer cells from the effects of chemotherapy. This will be a very important finding if it is confirmed in other experiments - and it might help in developing better ways to treat ovarian cancers."
The team are now testing their latest theory in cell cultures and mice and propose that, if the theory turns out to be correct, new drugs could be developed to disable p53 in the tumours of patients undergoing chemotherapy and therefore improve survival rates.
P53 is known to be defective in a large majority of human cancers.
The study is published in the journal PLoS ONE.
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