MONDAY, April 30, 2007 (HealthDay News) -- Italian researchers are shedding light on how leptin, a hormone found in fat cells, may play a major role in the development and progression of breast cancer.
The research, presented April 29 at the Experimental Biology meeting in Washington, D.C., identifies a new mechanism for the link between obesity and breast cancer and suggests new targets for drugs to interfere with that mechanism, said researcher Dr. Sebastiano Ando.
He noted that obesity increases the risk of breast cancer in postmenopausal women, shortens the time between cancer recurrence, and lowers overall survival rates. In a previous study, Ando's team found that leptin increases the amount of estradiol (a type of estrogen) in breast tissue.
This new study found that combined exposure to leptin and estradiol increased the size of breast cancer tumors in both mice and in tissue cultures. This growth in tumor size was accompanied by an increase in E-cadherin, an intracellular adhesion molecule generally regarded as a tumor suppressor.
But the researchers said their findings suggest that E-cadherin may act as a tumor enhancer when it's exposed to leptin and estradiol. In that case, E-cadherin's ability to help cells gather together enhances the transformation of normal cells to cancerous cells, thus stimulating tumor growth.
Ando and his colleagues found that this increased cell growth was halted when they used an E-cadherin antibody or a calcium-chelating agent to block E-cadherin function in the presence of estradiol.
The U.S. National Cancer Institute has more about breast cancer.