Effect of 1,25(OH)(2)D-3 on the growth and apoptosis of breast cancer cellline MCF-7

Objective To study the effect of 1, 25-dihydroxyvitamin D-3(1,25(OH)(2)D-3) on the growth and apoptosis of breast cancer cell line MCF-7. Methods Cell number was determined using the MTT method. Flow cytometric an alysis was performed on cell cycles, and the percentage of apoptosis was co unted. Apoptotic cells were quantified by terminal deoxynucleotidyl transfe rase-mediated dUTP nick end labeling (TUNEL), and bcl-2 protein expression was estimated with Western blotting. Results After incubation with 1,25(OH)(2)D-3 10(-7)mol/L for 48 hours, MCF- 7 cells exhibited significant growth in a dose- and time-dependent manner. Flow cytometric analysis indicated that cell numbers in G(0)/G(1) increased along with increasing apoptotic peak and percentage. With microscope and e lectron microscope observation, characteristics of apoptosis such as typica l apoptotic bodies were commonly found. TUNEL also showed that 1,25(OH)(2)D -3 10(-8)mol/L and 10(-7)mol/L groups had significantly high apoptosis perc entage than control group with dose-dependence on induction apoptosis. And Western blot showed that 1,25(OH)(2)D-3 10(-8)mol/L could down-regulate bcl -2 protein and 10(-7)mol/L could almost block bcl-2 protein expression. Conclusions 1,25(OH)(2)D-3 can inhibit cell growth with G(0)/G(1) arrest, e nhance the proliferation inhibition action of adriamycin, and induce apopto sis which may result from the down-regulation of the anti-apoptotic bcl-2 p rotein.