Denying Amino Acid Leucine To Stem Prostate Cancer

Denying the amino acid leucine to tumor cells could help stem prostate cancer, Australian researchers say.

Current therapies for prostate cancer include surgical removal of the prostate, radiation, freezing the tumour or cutting off the supply of the hormone testosterone - but there are often side-effects including incontinence and impotence.

Trying a different tack, researchers zeroed in on leucine, which is pumped into the cell by specialised proteins, believing it could be prostate cancer's weak link.

Dr Jeff Holst and his team at the Centenary Institute found, in a study to be published this month in Cancer Research, that prostate cancer cells have more pumps than normal. This allows the cancer cells to take in more leucine and outgrow normal cells.

"This information enables us to target the pumps - and we've tried two routes. We found that we could disrupt the uptake of leucine firstly by reducing the expression amount of the protein pumps, and secondly by introducing a drug that competes with leucine. Both approaches slowed cancer growth, in essence �starving' the cancer cells," Dr Holst says.

First author Dr Qian Wang says by targeting different sets of pumps, the researchers were able to slow tumour growth in both the early and late stages of prostate cancer. "In some of the experiments, we were able to slow tumour growth by as much as 50 per cent. Our hope is that we could develop a treatment that slows the growth of the cancer so that it would not require surgical removal. If animal trials are successful over the next few years then clinical trials could start in as little as five years," he says.

Dr Holst says one of the other spin-offs of the discovery is a better understanding of the links between prostate cancer and eating foods high in leucine. "Diets high in red meat and dairy are correlated with prostate cancer but still no one really understands why. We have already begun examining whether these pumps can explain the links between diet and prostate cancer."

"Given one in nine men in Australia may develop prostate cancer in their lifetime, this discovery could touch thousands of lives."