Zinc is an essential and the second most abundant trace element in humans. It is critical for the growth, development and differentiation of cells, as well as for RNA transcription, DNA synthesis, cell division and cell activation. Zinc deficiency affects mainly functions of the immune system, but other consequences include inferior sperm activity, skin lesions, growth retardation, impaired wound healing, anemia and gastrointestinal disorders. Zinc supplementation protects against the hepatotoxic effects of alcohol, enhances the transport of water and electrolytes across the intestinal mucosa and improves immune and anti-inflammatory responses. Zinc is also known as an essential mineral for normal mobilization of vitamin A from the liver to the plasma. Besides, it increases the promoter response to 1,25-dihydroxyvitamin D in osteoblasts. On the other hand, excessive amounts of free zinc in tissues are toxic and accelerated zinc accumulation of zinc is a potent killer of neurons and glial cells. Over 300 signaling molecules and transcription factors contain zinc as a cofactor. Free zinc in immune and tumor cells is regulated by 14 distinct zinc importers (ZIP) and transporters. An elevated amount of zinc transporters LIV-1, a subfamily of ZIP zinc transporters, appears in estrogen receptor–positive breast cancer and has been used as a reliable breast cancer marker. However, the fact that malignant cells are unable to accumulate zinc is an important factor in the development and progression of malignancy of prostate cancer.

19.2.2014