Nicotine directly speeds the growth of lung cancer, University of South Florida researchers report.
Tobacco smoke contains agents that cause cancer. But nicotine itself isn't one of them. Instead, nicotine promotes the growth of existing cancer cells.
Exactly how nicotine does this is now becoming clear: It plugs directly into lung cells, where it jump-starts the cells' growth machinery. If those cells are cancerous, nicotine makes them grow wildly.
"These events can be expected to contribute to the growth and progression of tumors exposed to nicotine through tobacco smoke or cigarette substitutes," suggest Piyali Dasgupta, Ph.D., and colleagues at H. Lee Moffitt Cancer Center, USF, Tampa, Fla.
Dasgupta and colleagues found that nicotine plugs into receptors called nicotinic acetylcholine receptors or nAChRs. These receptors are found throughout the body.
The finding may help explain why chemotherapy for breast cancer is less effective in smokers and why cigarette smoke helps many different kinds of cancer grow.
The study appears in the August issue of the Journal of Clinical Investigation.
SOURCES: Dasgupta, P. Journal of Clinical Investigation, August 2006; advance online publication July 20, 2006.
By Daniel J. DeNoon
Reviewed by Louise Chang, M.D.
© 2006, WebMD Inc. All rights reserved