Some scientists see the findings as suggesting possible routes for new research on anti-cancer drugs. But the lead author of the study is skeptical. "I don't know what the potential is," said Dr. Chang Yan Chen, of the department of radiation oncology at Beth Israel Deaconess Medical Center and Harvard Medical School, in Boston.
Dr. Julian Kim, a breast cancer surgeon and chief of oncologic surgery at University Hospitals Case Medical Center in Cleveland, Ohio, said, "This adds to the whole body of literature on how things that we ingest could potentially be harmful in terms of causing breast cancer or making existing breast cancer worse."
Much of the past research on nicotine has been on the human nervous system, but recent studies have demonstrated that the chemical can also trigger signaling systems in non-neuronal cells, including cancer cells. "It has been known that there are 10 to 12 nicotine receptors that express on the surface of various cells," said Chen. "We do not know why nicotine receptors express in all the cell surfaces from various tissue origins, but we do know that nicotine - can promote certain intracellular signaling in lung cancer."
In their recent study, Chen and his team found that certain epithelium-like cells of the breast produce different forms of a special nicotine receptor known as nAChR. When nicotine is attracted to these receptors and binds there, they begin "telling" the cells to grow in the out-of-control fashion that defines cancer.
And, once the cells are cancerous, the receptors tell them to migrate to distant parts of the body through the bloodstream, a process known as metastasis. Yet nicotine didn't seem to be able to accomplish this on its own. Nonetheless, the study couldn't identify which other factors might be assisting nicotine in the cancer scenario. This portion of the study was done in the test tube, but Chen reproduced the findings in mice.