Tuesday, April 20, 2010 (Last Updated: 04/21/2010)
TUESDAY, April 20 (HealthDay News) -- Metformin, a standard type 2 diabetes treatment, may help prevent lung cancer in smokers by inhibiting tumor growth, according to an animal study presented at the annual meeting of the American Association for Cancer Research, held from April 17 to 21 in Washington, D.C.
Regan M. Memmott, of the National Cancer Institute in Bethesda, Md., and colleagues exposed mice to nicotine-derived nitrosamine (NNK), a tobacco carcinogen and promoter of lung tumorigenesis, and then treated them with metformin for 13 weeks to evaluate tumor burden. The researchers also studied the effects of metformin on a series of biomarkers for lung tumorigenesis.
The researchers found that metformin decreased tumor burden in the mice by 40 to 50 percent, and was well tolerated. In addition, they demonstrated that metformin inhibited mammalian target of rapamycin, which promotes lung tumor growth by decreasing levels of circulating insulin and insulin-like growth factor-1. This effect was greater when metformin was administered daily by injection, which reduced tumor burden by 72 percent.
"These studies show that metformin inhibits NNK-induced lung tumorigenesis, and support clinical testing of metformin as a chemopreventive agent," the authors write.
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