On December 2, 2010, researchers with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA announced that they had discovered a key mechanism that regulates stem cell renewal and transforms healthy cells into cancer cells. The finding could result in new ways to control cancer growth. The research was conducted on prostate stem cells and animal models. A protein, called Bm-1, regulates the self-renewal of normal prostate stem cells and is needed to repair injured cells or restore normal cells killed by hormone withdrawal therapy for cancer. The researchers found that Bm-1 also aids the transformation of healthy cells into prostate cancer cells.
Bmi-1, which is often up-regulated (stimulated) in prostate cancer, has been associated with higher grade cancers and is predictive of poor prognosis, according to previous studies. However, its functional roles in prostate stem cell maintenance and prostate cancer have been unclear, said Dr. Owen Witte, who is director of the Broad Stem Cell Research Center and senior author of the study. A study of loss and gain of function in prostate stem cells indicated that Bmi-1 expression was required for self-renewal activity and maintenance of prostate stem cells with high growth potential. Loss of Bmi-1 expression blocks the self-renewal activity, protecting prostate cells from developing abnormal growth changes which can lead to cancer. More importantly, Bmi-1 inhibition slowed the growth of an aggressive form of prostate cancer in animal models, Witte said. “We conclude by these results that Bmi-1 is a crucial regulator of self-renewal in adult prostate cells and plays important roles in prostate cancer initiation and progression,” Witte said. “It was encouraging to see that inhibiting this protein slows the growth of even a very aggressive prostate cancer, because that could give us new ways to attack this disease.” UCLA stem cell researchers have been studying the mechanisms of prostate stem cells for years on the theory that the mechanism that gives the cells their unique ability to self-renew somehow gets high-jacked by cancer cells, allowing the malignant cells to grow and spread. If the mechanism for self-renewal could be understood, researchers could find a way to interrupt it once it is taken over by the cancer cells, Witte said.
This year alone, more than 277,000 men in the United States will be diagnosed with prostate cancer. Of those, 32,000 men will die from the disease
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