Lee Swanson Research Update

Vitamin E, Selenium May Alter Genes In Prostate Cancer

March 2009

Selenium and vitamin E may offer protection against prostate cancer by changing the expression (the conversion of a gene's information) of certain genes in prostates linked to tumors, says a new study from Texas.

Writing in the Journal of the National Cancer Institute, scientists from the University of Texas MD Anderson Cancer Center in Houston report that exposure of biopsy samples from people with cancer to vitamin E, selenium or both, expressed different genes, with the combined exposure producing results similar to that observed in people with no prostate cancer.

"To the best of our knowledge, this study was the first detailed systematic pathological interrogation to be completed in preoperative patients with favorable risk prostate cancer," wrote lead author Dimitra Tsavachidou.

A number of studies, most notably the Nutritional Prevention of Cancer study and the Alpha-tocopherol, Beta-carotene Cancer Prevention Study, have reported that the nutrients, alone or in combination, may reduce the risk of prostate cancer.

Tsavachidou and her co-workers took prostate biopsy samples from surgically removed prostate after pre-operative treatment with vitamin supplements in order to investigate if there are any effects on gene expression.

The researchers report that the expression of certain genes did differ between tumor samples from patients who had taken vitamin E (400 IU), selenium (200 mcg), both supplements, or placebo.

The study, which involved 39 patients and lasted for between three and six weeks, found that gene expression patterns differed between the groups. Indeed, the expression of several pathways associated with cancer was altered in the supplement groups compared with the placebo group.

Notably, the researchers reported a change in the expression of the TP53 gene, which codes for p53, an important protein involved in the functioning of a normal cell cycle and acting as a tumor suppressor.

"These p53 findings are also consistent with those in proteomic studies of patients' serum in which combined selenium and vitamin E induced protein expression patterns that were indicative of being free of prostate cancer," wrote Tsavachidou and her co-workers.

In an insightful accompanying editorial in the JNCI, Eric Klein, MD, from Glickman Urological and Kidney Institute in Ohio, said the new study is "…noteworthy for demonstrating that even short-term exposure (i.e., 3-6 weeks) to these agents can affect expression of a majority of the genes interrogated and, in the robust demonstration of the utility of the preprostatectomy model, for deriving information on modulation of biomarkers."

"Certainly, the findings lend credence to the previous evidence that selenium and vitamin E might be active as cancer preventatives," added Dr. Klein

Journal of the National Cancer Institute Published online ahead of print.

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