Study reveals a reprogrammed role for the androge...( BOSTONThe androgen receptor a prote...)

BOSTONThe androgen receptor a protein ignition switch for prostate cancer cell growth and division is a master of adaptability. When drug therapy deprives the receptor of androgen hormones, thereby halting cell proliferation, the receptor manages to find an alternate growth route. A new study by Dana-Farber Cancer Institute and Ohio State University scientists demonstrates how.

The shift from androgen-dependent to androgen-independent cell growth occurs, in part, because the androgen receptor switches on an entirely different set of genes in the latter group than in the former, the researchers report in the July 24 issue of Cell. In contrast to androgen-dependent prostate tumors, androgen-independent ones experience an uptick in the activity of genes that control cell division, or mitosis. One such gene, called UBE2C, which causes cells to ignore a natural pause in the division process, becomes especially active, the researchers report. This pause, or "checkpoint," ensures that cell division progresses normally; without it, daughter cells may grow even more aggressively and be harder to stop.

"The evolution of prostate cancer from an androgen-dependent state to an androgen-independent one is a key step in its progression," says study senior author Myles Brown, MD, of Dana-Farber. "The discovery that the androgen receptor directs a distinct gene pathway in androgen-independent prostate cancers may lead to the identification of genes in that pathway that can be targeted by future therapies." Prostate cancers whose growth is fed by androgen are commonly treated with androgen-blocking drugs. Such medications can hold the disease in check for a period of time that varies from patient to patient, but the tumor almost invariably gains the ability to grow without external androgen.

One of the ways such cells re-start their growth is by producing their own androgen, scientists have discovered. Another way involves the androgen recept
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