The Altered Water System: Excess Levels of Free Radicals Contribute to Carcinogenesis by Altering Arginine Vasopressin Production and Secretion and Promoting Dysregulated Water Homeostasis in Concert with Other Factors

A large body of evidence accumulated during the last decade has revealed diverse roles of dysregulated water homeostasis in tumorigenesis. In particular, many tumors hypersecrete arginine vasopressin (AVP) causing hypoosmolar conditions associated with different cancers. Excess levels of free radicals and nonosmotic stimuli may act as signals in water homeostasis and induce the production and secretion of AVP. Hypoosmolar conditions cause alterations in the expression of many genes. Other alterations in hydration patterns may induce mutations and increase the levels of protein kinases to contribute to oncogenesis. Furthermore, AVP regulates the hypothalamic-pituitary-adrenal axis and angiogenesis, and its overproduction may contribute to tumor growth and metabolism. This review article describes a mechanism by which oxygen radical species and other free radicals act as signaling molecules that, in concert with increased AVP production and secretion, pleiotropically affect tumor growth and metabolism, resulting in dysregulated proliferation, cell cycle arrest, apoptosis, and genomic instability