Zinc Deficiency Linked to Prostate Cancer

CORVALLIS, Ore.—Zinc may be a beneficial weapon against prostate cancer, according to a recent study conducted by Oregon State University (J Nutr. 2008;138:667-73). Increased single-strand DNA breaks (Comet assay) were observed in normal prostate epithelial cells (PrEC) grown in zinc-deficient media compared with cells grown in zinc-adequate media for seven days. Using Affymetrix HG-U133A gene chips, differential expression of genes involved in cell cycle, apoptosis, transcription, and DNA damage response and repair were identified with low cellular zinc. Among genes involved in DNA damage response and repair, tumor protein p73, MRE11 meiotic recombination 11 homolog A, X-ray repair complementing defective repair in Chinese hamster cells 4, and breast cancer 2 early onset were down-regulated and TP53 was up-regulated. Additionally, western blotting showed increased nuclear p53 protein expression with zinc deficiency. Despite increased p53 gene and nuclear protein expression, there was no significant change in p53 binding activity. Zinc deficiency also induced an increase in binding activity of transcription factors involved in regulating cell proliferation and apoptosis.
“Increased DNA damage increases your cancer risk,” Emily Ho, associate professor, Department of Nutrition and Exercise Sciences at Oregon State University and principal investigator said. “When we took zinc out of the cells, there was twice as much DNA damage as in normal cells. It’s a double whammy because we also saw that the zinc deficiency impairs the mechanism that helps repairs that damage.”