What’s good for the heart is good for the prostate

Cholesterol-lowering drug slows the growth of prostate tumors in mice

It’s the medical equivalent of a buy one, get one free offer — for men at least. Take cholesterol-lowering drugs for your heart, and slow the growth of prostate tumors, too. Lower cholesterol levels limit the growth of blood vessels inside prostate tumors, scientists report.

At left is a cross section of a prostate tumor from a mouse fed a no cholesterol diet with Zetia. At right is a cross section of a prostate tumor from a mouse fed a high cholesterol diet without the drug. Green fluorescence shows the blood vessels inside the tumors, with more blood vessels visible in the mice fed the high cholesterol diet. Blue fluorescence shows the nuclei of the prostate tumor cells. Credit: KR Solomon and K Pelton

In a new study, researchers implanted mice with human prostate cancer tumors and fed the mice either a high-cholesterol or a no-cholesterol diet. Half the mice on each diet received the cholesterol-lowering drug Zetia.

Two weeks after implantation, the prostate tumors were largest in mice on the high-cholesterol diet without Zetia and smallest in mice on the no-cholesterol diet with the drug, Keith Solomon of Children’s Hospital Boston at Harvard Medical School and colleagues report in the March issue of The American Journal of Pathology. And as expected, when cholesterol levels were measured, the mice on high-cholesterol diets not receiving the drug had the highest levels, while those on no-cholesterol diets with the drug had the lowest.

Scientists found that as well as being smaller, tumors from the Zetia-treated mice also had dramatically fewer blood vessels. “It was a complete surprise,” Solomon says. “I just noticed that some of the tumors seemed bloodier than others. It was a basic bench-top observation.”

Limited blood vessel development starves the tumor of the blood and oxygen it needs to thrive, slowing the progression of prostate cancer, the researchers suggest.

Prostate cancer has been linked to cholesterol before. A 2006 study reported that people who took statins, another cholesterol-lowering drug, were less likely to have advanced prostate cancer that spread to other organs, says epidemiologist Elizabeth Platz of Johns Hopkins Bloomberg School of Public Health in Baltimore, a coauthor of the statin study. But the new work is the first study that “tries to determine the mechanism” of the link between cholesterol and prostate cancer, Platz says.

Slowing the growth of prostate tumors would improve quality of life for men with prostate cancer, Solomon says. Many prostate cancers are relatively slow-growing anyway, but limiting tumor growth even more with a low-cholesterol diet and Zetia could lower the risk of impotence and incontinence, which often come with prostate surgery. But first work is needed to determine that Zetia has the same effect on prostate tumors in people as it did in the mice in the study, the researchers say.

Lowering cholesterol could impact blood vessel development in other types of tumors in a similar way, the researchers speculate. But the prostate produces more cholesterol than most other organs — and seems to accumulate it too. “It could be that prostate tumors have a different interaction with cholesterol than other types of tumors,” Platz notes. “The prostate seems to be particularly susceptible to cholesterol.”

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