Scientists have made a new discovery, which may become a new weapon in fight against breast cancer. Scientists at Wake Forest University Baptist Medical Center have shown that a peptide found in blood and tissue inhibits the growth of human breast tumors in mice. The finding has been recently published in the journal Cancer Research.They demonstrated that the peptide angiotensin-(1-7) attacked breast cancer in two ways: by inhibiting the growth of the breast cancer cells themselves and by inhibiting the growth of cancer-associated fibroblasts (CAFs), cells found in the tumor microenvironment-the tissue surrounding the tumor. In this study, mice were injected with human breast cancer cells to form the two most common types of breast tumors – estrogen-receptor and HER2 sensitive. Once the tumors grew, the mice were injected with either angiotensin-(1-7) or saline for 18 days. In the mice treated with angiotensin-(1-7), there was a 40 percent reduction in tumor size as compared to the saline-injected mice. Breast tumor fibrosis also was reduced by 64 to 75 percent in the mice treated with the peptide as compared to the saline-injected mice.