Effects of 1alpha, 25-dihydroxyvitamin D3 on programmed cell death of Ishikawa endometrial cancer cells through ezrin phosphorylation.

This study investigated the effects of 1α, 25-dihydroxyvitamin D3-induced cell death and its underlying molecular mechanisms in Ishikawa endometrial carcinoma cells. The effects of 1α, 25-dihydroxyvitamin D3 on Ishikawa cells were examined by 3-[4,5-dimethylthiazol-2-yl]-2.5-diphenyl-tetrazolium bromide, thiazolyl blue (MTT) assay. 1α, 25-dihydroxyvitamin D3 was shown to induce programmed cell death in Ishikawa endometrial carcinoma cells by activation of caspase-3 and caspase-9, along with elevation of Bcl-2 and Bcl-xL. Cell viability was reduced by 1α, 25-dihydroxyvitamin D3 in a concentration-dependent manner up to 2.5 μM. In addition, ezrin phosphorylation increased with the 1α, 25-dihydroxyvitamin D3 concentration (0-0.5 μM). The protein level of caspase-9 was increased by 1α, 25-dihydroxyvitamin D3 up to 0.5 μM. This is the first report regarding the efficacy and molecular mechanisms underlying the effects of 1α, 25-dihydroxyvitamin D3 in endometrial cancer cells. Our findings indicate that 1α, 25-dihydroxyvitamin D3 induces endometrial cancer cell death in a concentration-dependent manner. Impact statement Up to date, there is no report about the efficacy and molecular underlying mechanisms on the effect of vitamin D3 in endometrial cancer cells. Our findings indicate that 1α, 25-dihydroxyvitamin D3. which is an active metabolite of vitamin D3, induces Ishikawa endometrial cancer cell death in a concentration-dependent manner by activation of caspase-3 and -9, along with elevation of Bcl-2 and Bcl-xL. In addition, the same concentration of 1α, 25-dihydroxyvitamin D3 that provoked apoptotic signals caused phosphorylation of ezrin at threonine 567 in a VDR-dependent manner. This study suggests that 1α, 25-dihydroxyvitamin D3 within the optimal range (0.5 uM) would induce apoptosis through Fas-ezrin-caspase-3, -8, -9 signalling axis which may be a critical cell death regulator in Ishikawa endometrial cancer cell. Further study will be more interesting to address molecular connections or prove this critical optimal concentration range of vitamin D.