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March 17, 2007

Blood Pressure Drug Shows Potential In Lung Cancer Treatment

Topics: Medicine
Angiotensin-converting enzyme (ACE) inhibitors keep blood pressure in check by increasing the levels of the "angiotensin (1-7)" hormone [ANG-(1-7)], prompting dilation of blood vessel walls, which in turn acts to cut decrease levels of cycloxygenase-2 (cox-2), an enzyme that promotes cell growth and that has been found to be elevated in lung cancer patients.
Researcers at Wake Forest University School of Medicine report that a hormone that is important in the control of blood pressure also shrinks lung cancer tumors in mice, suggesting a new way to prevent or treat the deadly cancer in humans:
Reporting in the journal Cancer Research, the scientists said that in mice treated with the hormone, angiotensin-(1-7), tumor volume decreased by 30 percent. In mice that did not receive the treatment, the tumor size more than doubled.

... Patricia E. Gallagher, Ph.D., and E. Ann Tallant, Ph.D., senior researchers on the project, had previously reported a similar effect in lung cancer cells studied in the laboratory.

... "The current study is the first demonstration of the effect in animals," said Tallant. "Taken together, the two studies suggest a novel treatment for lung cancer, a disease that kills an estimated 170,000 Americans each year."

... Wake Forest's Comprehensive Cancer Center will begin studies of the hormone in cancer patients.

... The idea to evaluate the effects of angiotensin-(1-7) on lung cancer came from studies observing that rates of lung cancer were lower in people whose high blood pressure was treated with angiotensin-converting enzyme (ACE) inhibitors. These drugs, which include Capoten® and Lotensin®, increase levels of angiotensin-(1-7) in the bloodstream.

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Back in May 2006 we noted how those who take ACE inhibitors to lower their blood pressure also significantly decreased their risk of developing esophageal, pancreatic and colon cancer, so it now appears that lung cancer may be added to the list. We wrote at the time that researchers believe the potential benefit of ACE Inhibitors against cancer may be due to the suppression of tumor angiogenesis by blocking a growth protein and potent angiogenic factor called VEGF (Vascular Endothelial Growth Factor), which is believed to play a significant role in the growth and reproduction of tumors. Drawing from this previous work and looking at the results of more current studies, it appears that ACE inhibitors (which include such blood pressure medications as Lisinopril®, Capoten®, and Lotensin®) increase levels of the "angiotensin (1-7) which blocks VEGF, thereby decreasing up-regulation of cyclooxygenase-2 (COX2) expression.

Related:
Mechanisms of angiotensin-(1-7)-induced inhibition of angiogenesis

The Angiotensin-I-converting Enzyme Inhibitor Perindopril Suppresses Tumor Growth and Angiogenesis: Possible Role of the Vascular Endothelial Growth Factor (VEGF)

National Cancer Institute: Understanding Cancer Series: Angiogenesis

Cancer spreads by metastasis, the ability of cancer cells to penetrate into lymphatic and blood vessels, circulate through the bloodstream, and then invade and grow in normal tissues elsewhere.

In large measure, it is this ability to spread to other tissues and organs that makes cancer a potentially life-threatening disease, so there is great interest in understanding what makes metastasis possible for a cancerous tumor.


Posted by Richard at March 17, 2007 1:12 PM



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