Researchers now know why hormone deprivation therapy is not so successful in prostate cancer patients.
Prostate cancer cells rely on androgens, male hormones that include testosterone, to survive and grow.
This hormone deprivation therapy causes tumours to shrink, however, it's never a cure. They tumours eventually regrow into a stronger form, becoming resistant to treatment.
To understand why this therapy eventually fails, Luo and his colleagues looked at a key player: the androgen receptors on prostate cancer cells.
The researchers searched for variations of the nucleic acid RNA that prostate cells use to create androgen receptors, eventually identifying seven RNA sequences different from the "normal" androgen receptor already known.
When they looked for these sequences in cells isolated from 124 prostate cancer patients, they found over-production of these outlaw variants in prostate cancer cells taken from patients whose disease had become resistant to hormone deprivation therapy.
The researchers also found a variation known as AR-V7 that was prevalent in a select group of patients who had never taken hormone therapy, but whose cancer aggressively regrew after surgery to remove their tumours.
The results suggest that hormone therapy might encourage prostate cancer cells to overproduce the AR-V7 receptors over time, leading them to survive and grow aggressively even without androgens,
"We may eventually be able to develop an assay to test for this androgen receptor variant, giving us a way to test which patients are good candidates for hormone deprivation therapy and providing a way to monitor disease progression in patients already on this therapy," said Luo.
The researchers believe that the new findings could lead to a way to track disease progression, as well as new targets to fight prostate cancer.
The findings are reported in the Jan. 1 issue of Cancer Research.