firmlink between nicotine breast cancer

TAIPEI -- There is no doubt that smoking or the inhalation of second-hand cigarette smoke can cause breast cancer, Taiwan researchers said yesterday, citing their recent findings in a study on smoking and breast cancer.The study found that a receptor, known as alpha 9 (a9), on breast tissue cells is very sensitive to nicotine.With a constant nicotine stimulus, the receptor can transform a normal cell into a cancer cell, said professor Ho Yuan-soon of Taipei Medical University's School of Medical Laboratory Science and Biotechnology.

In turn, “the stimulated cell automatically produces more a9,” Ho explained. “Gradually the receptor triggers the cell's transformation and the proliferation of a tumor.”
When the stimulated cell was planted in the body of laboratory mice with immunodeficiency, cancer cells proliferated rapidly, “as if they were fueled,” the researchers said.
The research team then sought to stem the a9 activity by means of gene modification, which resulted in an obvious shrinking of the tumors, Wu said.
The study, which was done on tissue samples from 267 breast cancer patients in Taiwan, found that in the cases of the women who smoked heavily, the a9 receptor was two to three times more active than in those who did not smoke, Wu said.
The more active the a9 receptor, the more aggressive the breast cancer, Wu said.
The study proved a direct link between breast cancer and smoking, the researchers said.
It also located the biomolecule target for the future development of breast cancer cures, according to the research team.
The study will be published in the U.S. journal of the National Cancer Institute on Sept. 8.