Diabetes drug metformin exhibits potential against tobacco-induced lung tumors

Metformin, a drug commonly used to treat type 2 diabetes, shows potential in the prevention of tobacco-induced lung tumors, according to early research conducted at the National Cancer Institute (NCI).

Results of this study will be published in the September issue of Cancer Prevention Research, a journal of the American Association for Cancer Research. Scott Lippman, M.D., editor-in-chief of Cancer Prevention Research, and professor and chair in the department of thoracic head and neck medical oncology at the University of Texas M. D. Anderson Cancer Center, will host a teleconference on the findings.

The teleconference will take place on Wednesday, Sept. 1, 2010, at 10:30 a.m. ET.

Reporters can participate in the teleconference by using the following information:

U.S./Canada: (866) 471-9895
International: (706) 679-5207
Access Code: 92390362

Metformin significantly decreased lung tumor burden in mice exposed to a nicotine-derived nitrosamine called NNK, which is the most prevalent carcinogen in tobacco. Metformin has been previously shown to activate an enzyme called AMP-activated protein kinase that is known to inhibit mTOR, a protein that regulates cell growth and survival in tobacco carcinogen-induced lung tumors.

Researchers, led by Philip Dennis, M.D., Ph.D., a senior investigator at the NCI, treated the mice with metformin either orally or by injection. Those treated orally had between 40 and 50 percent fewer tumors, while those mice treated with injection had 72 percent fewer tumors.

Based on these findings, clinical trials of metformin are being considered to determine if this compound could be used as an effective chemoprevention agent for smokers at high risk of developing lung cancer.

"Although smoking cessation is the most important step for current smokers, over half of lung cancer cases are diagnosed in former smokers, raising the importance of identifying those at highest risk and identifying effective preventive treatments," said Dennis.

In addition to Lippman and Dennis, the following panelists will participate in the teleconference:

Michael Pollak, M.D., professor in the department of medicine and oncology at McGill University and author of a mini-review on metformin published in Cancer Prevention Research:

"This important laboratory study, together with prior laboratory and epidemiology research, suggests that metformin may be useful in cancer prevention and treatment. There is new information available about the mechanisms by which this drug, which is based on compounds present in lilac, may be useful for cancer control."

Jeffrey A. Engelman, M.D., Ph.D., director of the centers for thoracic cancers at Massachusetts General Hospital and co-author of an accompanying editorial published in Cancer Prevention Research:

"Previous epidemiology studies have shown that diabetics taking metformin have a lower risk of developing cancer. In this study, researchers carefully controlled for glucose levels, which suggests that the effect may be seen beyond the diabetic population."

Lewis Cantley, Ph.D., director of the cancer center at Beth Israel Deaconess Medical Center and co-author of an accompanying editorial also published in Cancer Prevention Research:

"Targeted therapies have impacted the course of cancer treatments, but they have yet to be widely utilized as agents for chemoprevention. As we work to better understand the mechanisms of action, therapies like metformin hold promise for delaying or preventing cancer progression and having a substantial, beneficial impact on cancer mortality."

SOURCE American Association for Cancer Research