July 31, 2006

Nicotine fuels growth of established tumors

NEW YORK (Reuters Health) - Scientists from the University
of South Florida in Tampa say they have a new understanding of
the mechanisms underlying nicotine's ability to trigger tumor

Their studies, reported online in the Journal of Clinical
Investigation, suggest that nicotine functions like a growth
factor, by binding to nicotine receptors on bronchial cells as
well as on lung cancer cells.

"While there is no evidence that nicotine contributes to
the induction of tumors, it has been demonstrated that nicotine
promotes the growth of solid tumors in vivo, suggesting that
nicotine might be contributing to the progression of tumors
already initiated," note Dr. Piyali Dasgupta and colleagues.
But until now it has been unclear which molecules mediate these

Dasgupta's team showed that stimulation of lung cancer
cells, as well as bronchial cells, with doses of nicotine leads
to robust cell proliferation that is dependent on nicotine

Nicotine's effects -- triggering a cascade of molecular
activity in the cells and leading to tumor growth -- are
"analogous to those of growth factors," the researchers report.

Dasgupta's group concludes that "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."

On the other hand, the findings "may open new avenues for
targeting cancer therapy," since some of the interactions
triggered by nicotine could be interrupted in the researchers'

SOURCE: Journal of Clinical Investigation, July 20, 2006.