( consider whether the patients actually ...)Gene thought to assist chemo may help cancer thrive

consider whether the patients actually had malignant tumors or had been treated with chemotherapy. However, they found that the gene expression profiles of the tumors clustered the chemotherapy-treated patients into two groups: those whose profiles were similar to cancer patients who had not been treated with chemo and those whose profiles were similar to patients with benign tumors.

As they continued their analysis, they found that the main difference between the groups' genetic profiles was the gene p53. While both groups had roughly the same amount of the protein encoded by p53, the cancer group had mutations in their p53 that caused the gene’s corresponding protein not to function.The benign group's p53 was normal.

Five years later, only 30 percent of the chemotherapy cancer patients clustering in the benign group were alive, while 70 percent of those clustering in the cancer group were still alive. The stage of cancer at the time of surgery had no correlation to who survived and who didn't. What did seem to have an effect was whether p53 was working or not in the chemotherapy-treated tumors.

A standard belief in cancer research is that a working p53 is essential in helping chemo patients because it turns on the killing mechanism for the cells that were damaged by chemo. But McDonald points out that p53 can also help repair damaged cells. If p53 is repairing cancer cells, that may lead to cancer recurrence.

"We think p53 may actually help some cancer cells make a comeback,?he said. "Based on our results, we propose that p53 may help repair some of the cancer cells damaged by chemotherapy leading to tumor recurrence and explaining the higher mortality rate of patients whose tumors had a functioning p53. If we are correct, inhibiting p53 in tumors being treated with chemotherapy may substantially improve patients' long-term survival."

McDonald and colleagues are continuing to test their theory by conducting stud
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Source:Georgia Institute of Technology

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