二甲双胍（metformin）最初提取自法国紫丁香，是应用最为广泛的治疗糖尿病药物。最近几年来，流行病学家开始注意到每天服用二甲双胍的糖尿病患者癌症发生率及与癌症相关的死亡率均降低。

    在本周举行的2012年美国癌症研究协会（AACR）年会上，来自几个研究小组的资料表明， 二甲双胍对几种类型的均有抑制作用。 二甲双胍有望用于对其敏感的癌症预防与治疗。

A diabetes drug that treats cancer

In the mid-2000s, epidemiologists began noticing that diabetics taking daily doses of metformin—the most widely prescribed medication for hyperglycemia and type 2 diabetes—showed decreased cancer incidence and cancer-related mortality. Originally isolated from the French lilac (Galega officinalis), metformin lowers circulating insulin through the indirect activation of AMP-activated protein kinase (AMPK)—a regulator of cellular metabolism.

At the 2012 American Association for Cancer Research (AACR) annual meeting, held in Chicago this week, several research groups presented data supporting an inhibitory role for metformin in several types of cancers. The new studies suggest metformin could be adopted for both the prevention and treatment of metformin-sensitive cancers.

In a phase II clinical trial involving 22 men with prostate cancer, for example, thrice-daily doses of 500 mg of metformin, given from the day of diagnosis until the routine prostatectomy nearly 6 weeks later, markedly reduced the size of the tumors in some of the men.

“Although these are preliminary results, metformin appeared to reduce the growth rate of prostate cancer in a proportion of men,” Anthony Joshua, an oncologist at Princess Margaret Hospital in Toronto who presented the results at the meeting on Saturday, March 31, said in a press release.

Similarly, treatment with metformin improved the survival rate of patients with both pancreatic cancer and diabetes by nearly two-fold, according to a retrospective study carried out by University of Texas researchers.

Administration of metformin to mice with premalignant oral lesions also slowed the progression of the lesions into cancers by 70 to 90 percent, a team led by National Institutes of Health (NIH) researcher J. Silvio Gutkind reported. Specifically, the team found that metformin prevented the development of the lesions into head and neck cancers by inhibiting mTORC1—a protein complex known to respond a wide array of cellular signals including growth factors, nutrients, DNA damage, and energy levels.

And in a study published yesterday (April 3) in Cancer Prevention Research, an AACR journal, researchers led by molecular biologist Geoffrey Girnun of the University of Maryland School of Medicine reported that metformin slowed tumor growth in mice with chemically induced liver cancer. They found that metformin decreased the expression of enzymes involved in lipid synthesis in the liver, an important process for tumor growth.

http://the-scientist.com/2012/04/04/news-from-cancer-meeting/