Targeting the adiponectin:leptin ratio for postmenopausal breast cancer prevention.

Obesity is a risk factor for postmenopausal breast cancer. Elevated estrogen levels are thought to be a growth factor associated with this relationship. However, there is increasing evidence that factors produced directly in adipose tissue, adipokines, specifically adiponectin and leptin, impact breast cancer development. Serum adiponectin levels are reduced in women diagnosed with breast cancer and in vitro studies using human breast cancer cell lines have shown antiproliferative action of adiponectin. In contrast, elevated serum leptin levels were associated with breast cancer in some studies. In mice which lack the leptin receptor or are leptin deficient oncogene-induced mammary tumors were not detected while leptin enhanced proliferation of breast cancer cell lines, particularly those that express estrogen receptors. Of particular interest, one recent study reported that the adiponectin:leptin ratio was reduced in women with breast cancer. Here we speculate that the ratio of these adipokines may be more important in breast cancer than their absolute concentrations. Additionally, we propose strategies to alter this ratio and thus provide protection against the development of breast cancer.