A blood pressure drug that is already generically available may help block a gene in many breast cancer cases and help shrink tumours, U.S. researchers report.
The gene, called AGTR1 (angiotensin II receptor type I), affects blood pressure by causing blood vessels to narrow. But it also causes normal cells to behave like cancer cells in up to 20 per cent of breast cancers.
The blood pressure drug losartan, which targets AGTR1, appears to reverse that behaviour, a team at the University of Michigan found.
In a study published in the Proceedings of the National Academy of Sciences, researchers found that tumours in certain mice shrunk after treatment with losartan.
The research was conducted by transplanting human tumours that expressed AGTR1 into mice.
After two weeks of giving the mice losartan, the researchers found that tumours shrank by 20 per cent. After eight weeks, tumours shrank by 30 per cent, reported lead researcher Dr. Arul Chinnaiyan, a professor of Pathology at the UM Medical School.
"We suspect our analysis has uncovered a new crop of potentially important breast cancer genes," says Chinnaiyan.
"What's also exciting is this gene is blocked by a drug that's already available on the market."
Many genes affect breast cancer growth. One of them, ERBB2 - also known as HER2 -- is already known to fuel as many as 25 to 30 per cent of breast tumours. The gene mutation is targeted by the drug Herceptin, known generically as trastuzumab.
AGTR1, is a similar gene and it active in 10 to 20 per cent of the breast tumours -- none of them HER2-positive tumours.
"AGTR1 is very analogous to HER2, or ERBB2," Chinnaiyan said in a statement.
"HER2 is a bona fide treatment target for patients with that type of breast cancer. Losartan may be a viable therapy for women with AGTR1 over-expressing breast tumours.
"This study lays the groundwork for a clinical trial to test losartan to treat breast cancers positive for AGTR1."
The University of Michigan has filed a patent on AGTR1 and is currently seeking a commercial partner to help bring this technology to market.
