Gamma-tocopherol inhibits lung and prostate cancer growth in vitro

A study published on December 13 2004 in the in the online early edition of the Proceedings of the National Academy of Sciences ( http://www.pnas.org/ ) found that gamma-tocopherol, a form of vitamin E whose health benefits have been gaining attention, could slow the growth of prostate or lung cancer cells while leaving healthy cells unharmed.

Researchers at Purdue University led by Qing Jiang, who is an assistant professor of foods and nutrition in the College of Consumer and Family Sciences, tested gamma-tocopherol's effect in androgen-sensitive and androgen-resistant prostate cancer, lung cancer and normal prostate cell cultures. Earlier research conducted by Jiang and colleagues found that gamma-tocopherol inhibited inflammation, which has been implicated in the development of cancer.

They found that gamma-tocopherol inhibited the proliferation of both prostate cancer cell lines and lung cancer cells while not affecting the normal prostate cells. It was discovered that gamma-tocopherol interrupts the synthesis of sphingolipids, which are a component of the cell membrane, and that it did so only in cancerous cells.

Dr Jiang announced, “This is the first time gamma-tocopherol has been shown to induce death in lab-grown human cancer cells while leaving healthy cells alone. This could be wonderful news for cancer patients if the effect can be reproduced in animal models. But because most nutritional supplements contain only alpha-tocopherol, a different form of vitamin E that alone does not have these anticancer properties, it may be better to supplement the diet with mixed forms of vitamin E. The study shows that the anticancer effect is enhanced when mixed forms are used."

“We hope that future research not only will clarify whether gamma-tocopherol could have applications in human cancer treatment, but also will show how we might supplement the body with the vitamin to prevent cancer from developing in the first place,” Dr Jiang added.

The report was coauthored by Jeffrey Wong, Henrik Fryst, Julie D Saba and Bruce N. Ames.

This study reflects a similar study by M oyad, M. A., Brumfield, S. K., and Pienta, K. J. Vitamin E, alpha- and gamma-tocopherol, and prostate cancer. Semin. Urol. Oncol., 17: 85-90, 1999.

Abstract: Vitamin E is one of the most researched compounds in medicine. Vitamin E is actually a general name for potentially eight different compounds, so supplements can contain several forms and vitamin E in the diet also differs from the form found over the counter. There has been a strong interest in this supplement in the prostate cancer arena primarily because of a Finnish study that demonstrated a lower morbidity and mortality from this disease in men taking 50 mg of synthetic (alpha-tocopherol) vitamin E daily. In addition, observations from laboratory and clinical studies dealing with heart disease have found that gamma-tocopherol may also play a significant role in prevention; therefore, we decided to test the ability of this compound (versus synthetic vitamin E) to control the growth of a human prostate cancer cell line. Gamma-tocopherol was found to be superior to alpha-tocopherol in terms of cell inhibition in vitro. Both forms of vitamin E (and others) should be thoroughly evaluated in the future to provide the most effective chemoprevention information to the patient.