Effect of 1,25(OH)2D3 on the growth and apoptosis of breast cancer cell li ne MCF-7 of 1,25(OH)2D3 on the growth and apoptosis of breast cancer cell li

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 analysis was performed on cell cycles, and the percentage of apoptosis was counted. Apoptotic cells were quantified by terminal deoxynucleotidyl transferase-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(O)/G(1)increased along with increasing apoptotic peak and percentage. With microscope and electron microscope observation, characteristics of apoptosis such as typical apoptotic bodies were commonly found. TUNEL also showed that 1,25(OH)(2)D(3) 10(-8)mol/Land 10(-7)mol/L groups had significantly high apoptosis percentage 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(O)/G(1) arrest, enhance the proliferation inhibition action of adriamycin, and induce apoptosis which may result from the down-regulation of the anti-apoptotic bcl-2 protein.