Triciferol functions as a multiple ligand with combined VDR agonist and HDAC antagonist activities. Triciferol binds directly to the VDR (IC50=87 nM), and functions as an agonist with 1,25D-like potency on several 1,25D target genes. Triciferol induces marked tubulin hyperacetylation, and augments histone acetylation. Antiproliferative and cytotoxic activities.In Vitro: Triciferol (0-10000 nM; 0-72 hours) is significantly more efficacious in suppressing the proliferation of estrogen receptor-negative human MDA-MB231 breast cancer cells.
Treatment of MCF-7 cells with Triciferol (100-1000 nM) induces ≈2.5-fold higher rates of cell death than equimolar amounts of 1,25D.