title: Regulation of the colonic vitamin D system for prevention of tumor progression: an update.
abstract: A compromised vitamin D status and nutritional calcium deficit are linked with sporadic colorectal cancer incidence. 25(OH)D(3) serum concentration is a major determinant of 1,25-dihydroxyvitamin D3 (1,25[OH](2)D(3)) synthesis in colonic mucosa, which expresses the vitamin D receptor and both the synthesizing (CYP27B1) and catabolic (CYP24A1) hydroxylases. Receptor-bound, 1,25(OH)(2)D(3) regulates proliferation, differentiation and apoptosis in an autocrine/paracrine manner. During early malignancy 1,25(OH)(2)D(3) synthesis is often enhanced to counteract hyperproliferation. In many advanced tumors, vitamin D catabolism surpasses synthesis. In vivo, expression and activity of CYP27B1 and vitamin D receptor are stimulated by (phyto)estrogens. Conversely, low nutritional calcium and folate enhance vitamin D catabolism. These insights could explain the lower colorectal cancer incidence in females, the chemopreventive potency of vitamin D and calcium against colorectal cancer, and the benefit of nutritional folate as a methyl donor for epigenetic regulation of the vitamin D system.
authors.affiliation: Department of Pathophysiology, Medical University of Vienna, Waehringerguertel 18-20, A-1090 Vienna, Austria. heide.cross@meduniwien.ac.at
authors.forename: Heide S
authors.initials: HS
authors.lastname: Cross
authors.forename: Enikoe
authors.initials: E
authors.lastname: Kallay
mesh_terms: D002471:Cell Transformation, Neoplastic / Q000378:metabolism; D003106:Colon / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D012727:Sex Characteristics; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D014807:Vitamin D