CYP24 inhibition preserves 1α,25-dihydroxyvitamin D3 anti-proliferative signaling in lung cancer cells

► The vitamin D3 catabolizing enzyme, CYP24, is aberrantly expressed in lung cancer. ► The effect of CYP24 inhibitor CTA091 on vitamin D3 (1,25D3) activity was examined. ► CTA091 significantly increased effects of 1,25D3 on endogenous gene expression. ► Expression profiling revealed cell cycle as a 1,25D3 target in lung cancer cells. ► Inhibitory effects of 1,25D3 on cell cycle and cell growth were reinforced by CTA091.