Zinc and Cancer Prevention
Zinc (Zn) is an essential micronutrient that performs several structural, catalytic and regulatory functions that are involved in key cellular processes, such as oxidative stress response, immunological function, DNA repair, cell proliferation, apoptosis and others. Alterations in Zn homeostasis may contribute to the emergence and progression of different types of cancer. Indeed, highly incident geographical areas for esophagus, stomach and liver cancers directly overlap the ones with increased risk of Zn deficiency worldwide, suggesting an underlying role of this nutritional imbalance in carcinogenesis. Indeed, low serum, plasma and/or tissue Zn concentrations are common features of these cancer patients. As such, experimental data indicates that dietary Zn deficiency predisposes the development of preneoplastic and neoplastic esophageal, gastric and hepatic lesions in different rodent models. These studies also suggest the beneficial roles of Zn replenishment and supplementation on carcinogenesis. Regarding mammary carcinogenesis, data is sometimes inconsistent, depending on complex Zn homeostasis in premalignant/malignant breast tissue, as well as on the period of Zn exposure (early-in-life or adult phase). Therefore, this chapter glances at some of the key biological roles of this micronutrient and sheds light on how dietary zinc deficiency, replenishment and supplementation modifies carcinogenesis, focusing on the main effects and molecular mechanisms.