Nicotine May Promote Growth of Established Tumors
Physiological concentration of nicotine acts like growth factor on cultured lung and tumor cells
THURSDAY, July 20 (HealthDay News) -- While nicotine is not carcinogenic, it may promote the growth of already formed non-small cell lung cancers, according to a report in the August issue of the Journal of Clinical Investigation published online July 20 in advance of print publication.
Srikumar Chellappan, Ph.D., of the H. Lee Moffitt Cancer Center and Research Institute at the University of South Florida in Tampa, and colleagues used cultured non-small cell lung cancer (NSCLC) cells and primary, normal human epithelial and endotheial lung samples to monitor the action of physiological concentrations of nicotine.
Nicotine treatment of quiescent lung cancer cells caused a robust proliferative response (80 to 90 percent of cells in S-phase) within 18 hours and was due to activation of the alpha 7-nicotinic acetylcholine receptor (nAChR). Nicotine's action on NSCLC cells was reminiscent of growth factor stimulation, triggering activation of the mitogenic factors Raf-1 and Src and release of the Rb-dependent cell cycle regulatory pathway.
"While tobacco carcinogens can initiate and promote tumorigenesis, the results of the present study raise the possibility that exposure to nicotine, by either cigarette substitutes or nicotine supplements, might confer a proliferative advantage to tumors already initiated," the authors write. "Elucidation of the signaling events mediated by nAChRs present on non-neuronal cells may open new avenues for targeting cancer therapy."