Blood pressure drugs may fight lung cancer

Drugs commonly used to control high blood pressure may also shrink lung tumors.

As prescribed, the medicines -- known as angiotensin-converting enzyme (ACE) inhibitors -- keep blood pressure in check by boosting levels of the "angiotensin (1-7)" hormone, thereby prompting dilation of blood vessel walls.

Blood pressure patients taking ACE inhibitors also have lower rates of lung cancer, noted a team from Wake Forest University School of Medicine in Winston-Salem, N.C.

Investigating further, they found that angiotensin (1-7) cuts back on levels of cycloxygenase-2 (cox-2), an enzyme that promotes cell growth and is often elevated in lung cancer patients.
In the team's latest experiment, boosting angiotensin (1-7) levels in mice shrank lung cancer tumors by 30 percent.

"We are cautiously optimistic, but you know how these things go," said study co-author Patricia E. Gallagher, a researcher at Wake Forest's hypertension and vascular research center. "So many of these drugs go to trial, and while they work great in animals, when you get to the patient population, they're just not as effective. But to this point, we can say that, in mice, we got a reduction in cox-2 and a big reduction in tumor size without any toxic side effects."
The findings are reported in the March 15 issue of Cancer Research.

According to the American Cancer Society, lung cancer remains the leading cause of cancer death among men and women, killing more Americans than colon, breast, and prostate cancer combined. Because they are typically diagnosed at a later stage of disease, 6 in 10 lung cancer patients will die within the first year following diagnosis. Five-year survival is just 14 percent, and an estimated 170,000 Americans die each year from the disease.

In their study, the Gallagher team worked with a group of two- to four-week-old mice that had received transplanted lung cancer cells derived from a 58-year-old patient. The tumors were allowed to grow for 32 days.

Rather than testing ACE inhibitors themselves, the researchers injected half the mice with the angiotensin (1-7) hormone for a 28-day treatment period. The remaining mice received saline.
The experiment stimulated blood levels of angiotensin (1-7) in the mice to concentrations equivalent to those found in humans being treated with ACE inhibitors.

Subsequent dissections revealed that cox-2 levels diminished significantly in the treated mice, while lung tumors shrank by 30 percent. In contrast, tumors in mice receiving the saline solution grew to 2.5 times their pre-treatment size.

Gallagher and her colleagues uncovered no evidence of toxic side effects among the angiotensin (1-7) mice. The rodents displayed no apparent changes in body weight, heart rate or blood pressure, the researchers said.

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