Hormone therapy, a common treatment for men with advanced prostate cancer, generally keeps the cancer at bay for a year or two, but later fails in patients whose disease has spread.
The team led by Chawnshang Chang, Ph.D., director of the George Whipple Laboratory for Cancer Research at the University of Rochester Medical Center showed that androgen receptor, through which male hormones like testosterone work under certain conditions spurs growth, and at other times inhibits growth- just like the same molecule does to hair in different locations on a man's head.
The researchers said that these findings raise the possibility that under some conditions, certain treatments designed to treat prostate cancer could instead remove one of the body's natural brakes on the spread of the disease in the body.
The research in the laboratory involved tracking the disease in mice and also analysing human prostate cancer cells in culture.
"When a man receives hormone therapy, initially the treatment works well, and his PSA (prostate specific antigen) level goes down," said Edward Messing, M.D., a urologist and an author of the paper.
"But inevitably, the PSA will start climbing again, and that is usually the first sign that the treatment is beginning to fail. It's a sign that the cancer in the prostate is making a comeback," he added.
The research team found that blocking the receptor indeed prevents some cells in the prostate from growing, but unexpectedly blocking the receptor can actually spurs other prostate cells to grow.
The androgen receptor in prostate support cells known as stromal cells stimulates growth of cells. After turning off the molecule in stromal cells, growth of cancer cells in the prostate slowed down.
"The effects of the androgen receptor on hair growth in men vary dramatically depending on where in the body the receptor is working," said Chang.
"When the receptor is very active in the mustache area, more hair grows. When it's very active on the top of the skull, toward the front, hair falls out and men become bald. And the hair on the back of the head is insensitive to the receptor. The effects of hormones depend on the location.
"We found that the same is true within the cells of the prostate itself," he added.