ABSTRACT
The vitamin D3 metabolite, 20S,23S-dihydroxyvitamin D3, was chemically synthesized for the first time and identified to be the same as the enzymatically produced metabolite. The C23 absolute configurations of both 20S,23S/R-dihydroxyvitamin D3 epimers were unambiguously assigned by NMR and Mosher ester analysis. Their kinetics of CYP27B1 metabolism were investigated during the production of their 1α-hydroxylated derivatives. Bioactivities of these products were compared in terms of vitamin D3 receptor activation, anti-inflammatory, and antiproliferative activities.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemistry , Anti-Inflammatory Agents, Non-Steroidal/pharmacology , Antineoplastic Agents/pharmacology , Cholecalciferol/metabolism , Dihydroxycholecalciferols/pharmacology , Receptors, Immunologic/antagonists & inhibitors , Anti-Inflammatory Agents, Non-Steroidal/metabolism , Antineoplastic Agents/chemistry , Antineoplastic Agents/metabolism , Cell Proliferation/drug effects , Cholecalciferol/analogs & derivatives , Cholecalciferol/chemistry , Dihydroxycholecalciferols/chemistry , Dihydroxycholecalciferols/metabolism , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Humans , Models, Molecular , Molecular Structure , Receptors, Immunologic/immunology , Stereoisomerism , Structure-Activity Relationship , Tumor Cells, CulturedABSTRACT
Vitamin D3 (D3) can be metabolized by cytochrome P450scc (CYP11A1) into 20S-hydroxyvitamin D3 (20D3) as a major metabolite. This bioactive metabolite has shown strong antiproliferative, antifibrotic, pro-differentiation and anti-inflammatory effects while being non-toxic (non-calcemic) at high concentrations. Since D3 analogs with two symmetric side chains (Gemini analogs) result in potent activation of the vitamin D receptor (VDR), we hypothesized that the chain length and composition of these types of analogs also containing a 20-hydroxyl group would affect their biological activities. In this study, we designed and synthesized a series of Gemini 20D3 analogs. Biological tests showed that some of these analogs are partial VDR activators and can significantly stimulate the expression of mRNA for VDR and VDR-regulated genes including CYP24A1 and transient receptor potential cation channel V6 (TRPV6). These analogs inhibited the proliferation of melanoma cells with potency comparable to that of 1α,25-dihydroxyvitamin D3. Moreover, these analogs reduced the level of interferon γ and up-regulated the expression of leukocyte associated immunoglobulin-like receptor 1 in splenocytes, indicating that they have potent anti-inflammatory activities. There are no clear correlations between the Gemini chain length and their VDR activation or biological activities, consistent with the high flexibility of the ligand-binding pocket of the VDR.
