The role of vitamine D₃ in the proliferation of a human colon cancer cell line in vitro

LoVo, a cultured colon cancer cell line, is shown to posses a receptor for 1,25-dihydroxy vitamin D₃ (1α,25(OH)₂D₃) with a low capacity (28 fmol/mg protein) and high affinity (Kd: 1.9 x 10(-21O)M). When these cells were grown in monolayer culture in a chemically defined serum-free medium, a significant inhibition of proliferation was seen in the presence of 10 nM to 1μM of 1α,25(OH)₂D₃ (p<0.005). Furthermore, 1α,25(OH)₂D₃ delayed early attachment of cells. After 8 days of treatment, aggregated cuboidal cells showed a marked change to an apparently spindle like morphology. The 1α,25(OH)₂D₃ growth-inhibitory effect was modulated by verapamil (1 μM), a calcium channel blocker, hydrocortisone (1 μM) and moxestrol (1 mM), an estrogen analogue, and 2% charcoal-treated fetal bovine serum. This study represents the first demonstration of 1α,25(OH)₂D₃ modulation of growth of human colon cells.