Blood pressure hormone may inhibit growth of lung cancer

07/30/04

WINSTON-SALEM, N.C. – A hormone that is important in the control of blood pressure may also inhibit the growth of lung cancer cells, say scientists at Wake Forest University Baptist Medical Center, writing in the new issue of the journal Carcinogenesis.

Patricia E. Gallagher, Ph.D., and E. Ann Tallant, Ph.D., said the hormone, called angiotensin-(1-7), "may represent a novel chemotherapeutic and chemopreventive treatment for lung cancer."

Their studies found that angiotensin-(1-7) significantly slows the growth of three different types of human lung cancer cells in the laboratory. "Our experiments provide the first evidence that angiotensin-(1-7) inhibits the proliferation of human lung cancer cells," they said.

They hypothesized that the hormone serves as a natural regulator of cell growth, both by reducing the rapid proliferation of cells common in cancer and by increasing cancer cell death.

Gallagher and Tallant have been working with angiotensin-(1-7) for years as members of the Hypertension and Vascular Disease Center faculty. The director of the center, Carlos M. Ferrario, M.D., discovered angiotensin-(1-7) in 1988, and found it to be a critical element of the blood pressure control system.

Angiotensin-(1-7) relaxes (dilates) the walls of the blood vessels, causing blood pressure to be lowered while its hormonal counterpart, angiotensin II, constricts blood vessels, causing blood pressure to rise. A major class of blood pressure medications, called ACE inhibitors, work by reducing angiotensin II and increasing angiotensin-(1-7).

Evidence from population studies in Scotland had suggested that people who were taking ACE inhibitors for high blood pressure had a reduced risk both of cancer occurrence and of cancer death. The effect was most pronounced in lung cancer.

"Our results suggest that the reduced cancer risk observed in patients after administration of ACE inhibitors may be due, at least in part, to the elevated levels of angiotensin-(1-7)," Tallant and Gallagher said.

The cells for their research came from lung cancers in a 60-year-old female, a 58-year-old male and a 65-year-old male. None of the other angiotensin hormones tested slowed the growth of these lung cancer cells.

Tallant and Gallagher said their studies may point the way to a more successful treatment for lung cancer, still one of the most deadly forms of cancer, with only 13 percent of patients alive after five years.

They said either the administration of angiotensin-(1-7) directly, or through compounds that elevate the angiotensin circulating through the body, such as ACE inhibitors, may both treat and prevent lung cancer, with reduced side effects.

The work was supported by the National Institutes of Health and by a pilot project grant from the Comprehensive Cancer Center of Wake Forest University.

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