Vitamin E refers to a group of eight fat-soluble compounds that include both tocopherols and tocotrienols. Of the many different forms of vitamin E, γ-tocopherol is the most common in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine and dressings. Researchers have identified an elusive anti-cancer property of vitamin E that has long been presumed to exist, but difficult to find. Many animal studies have suggested that vitamin E could prevent cancer, but human clinical trials following up on those findings have not shown the same benefits.
Vitamin E refers to a group of eight fat-soluble compounds that include both tocopherols and tocotrienols. Of the many different forms of vitamin E, γ-tocopherol is the most common in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine and dressings. Researchers have identified an elusive anti-cancer property of vitamin E that has long been presumed to exist, but difficult to find. Many animal studies have suggested that vitamin E could prevent cancer, but human clinical trials following up on those findings have not shown the same benefits.
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As of 2009, human trials and surveys that have investigated potential association of vitamin E intake with incidence of cancer remain generally inconclusive. Antioxidants such as vitamin E help protect against the damaging effects of free radicals, which may contribute to the development of chronic diseases such as cancer.
Some evidence associates higher intake of vitamin E with a decreased incidence of prostate cancer and breast cancer. Some studies correlate additional cofactors, such as specific vitamin E isomers, e.g. gamma-tocopherol, and other nutrients, e.g. selenium, with dramatic risk reductions in prostate cancer.
In this new work, researchers showed in prostate cancer cells that one form of vitamin E inhibits the activation of an enzyme that is essential for cancer cell survival. The loss of the enzyme, called Akt, led to tumor cell death. The vitamin had no negative effect on normal cells.
"This is the first demonstration of a unique mechanism of how vitamin E can have some benefit in terms of cancer prevention and treatment," said lead author Ching-Shih Chen, professor of medicinal chemistry and pharmacognosy at The Ohio State University and an investigator in Ohio State’s Comprehensive Cancer Center.
"Our goal is to develop a safe pill at the right dose that people could take every day for cancer prevention. It takes time to optimize the formulation and the dose," he said.
Chen has filed an invention disclosure with the university, and Ohio State has filed a patent application for the agent.
Vitamin E occurs in numerous forms based on their chemical structure, and the most commonly known form belongs to a variety called tocopherols. In this study, researchers showed that, of the tocopherols tested, the gamma form of tocopherol was the most potent anti-cancer form of the vitamin.
The scientists manipulated the structure of that vitamin E molecule and found that the effectiveness of this new agent they created was 20-fold higher than the vitamin itself in cells. In experiments in mice, this agent reduced the size of prostate cancer tumors.
These findings suggest that an agent based on the chemical structure of one form of vitamin E could help prevent and treat numerous types of cancer – particularly those associated with a mutation in the PTEN gene, a fairly common cancer-related genetic defect that keeps Akt active.
The researchers began the work with both alpha and gamma forms of the vitamin E molecule. Both inhibited the enzyme called Akt in very targeted ways, but the gamma structure emerged as the more powerful form of the vitamin.
In effect, the vitamin halted Akt activation by attracting Akt and another protein, called PHLPP1, to the same region of a cell where the vitamin was absorbed: the fat-rich cell membrane. PHLPP1, a tumor suppressor, then launched a chemical reaction that inactivated Akt, rendering it unable to keep cancer cells alive.
"This is a new finding. We have been taking vitamin E for years but nobody really knew about this particular anti-cancer mechanism," Chen said.
When mice with tumors created by these two prostate cancer cell lines were injected with the agent, the treatment suppressed tumor growth when compared to a placebo, which had no effect on tumor size. Chemical analysis of the treated tumors showed that the Akt enzyme signal was suppressed, confirming the effects were the same in animals as they had been in cell cultures.
For further information see Cancer and Vitamin E.
Pure E image via Wikipedia.
