Amino Acid in Meat and Dairy Foods May Fuel Prostate Cancer

A new study by researchers at the Centenary Institute in Sydney, Australia has demonstrated a potential future treatment for prostate cancer, by starving the tumor cells of leucine, an essential nutrient that prostate cancer cells need to grow rapidly.

Each year about 3,300 Australian men die of prostate cancer, compared to about 34,000 men in the USA. It’s Australia’s second worst cancer killer for men.

The current treatments for prostate cancer include surgical removal of the prostate (prostatectomy), radiation therapy, freezing the tumor (cryosurgery) or cutting off the supply of the hormone testosterone (hormone therapy for prostate cancer) — but all of these have side-effects including incontinence and erectile dysfunction.

Leucine is an essential amino acid that is not produced within the human body and, therefore, must be supplied through dietary intake. While it’s a nutrient of particular interest to bodybuilders because of its role in building muscle and maintaining lean tissue, leucine also helps protect muscle tissue during recovery from illness, injury and extreme stress. Dietary sources of leucine include seafood, meat and dairy.

Growing prostate cancer cells need leucine, which is pumped into the cell by specialized proteins. 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 which allow the cancer cells to take in more leucine and outgrow normal cells.

“This information allows 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 tumor growth in both the early and late stages of prostate cancer. “In some of the experiments, we were able to slow tumor 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 also commented on the connection between diets high in leucine and prostate cancer. “Diets high in red meat and dairy are correlated with prostate cancer but still no one really understands why”. However numerous other studies have also shown the impact of dairy, calcium and red meat on prostate cancer risk so the discover of the role of leucine, which is high in meats and dairy foods, just adds more weight to the potential preventative role in prostate cancer in reducing intake of these foods.

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