MECHANISMS TRIGGERED BY CALCITRIOL AND MENADIONE ON BREAST CANCER CELLS

GUIZZARDI S; PICOTTO G; RODRÍGUEZ V; BOHL LP; TOLOSA DE TALAMONI NG

Congreso; LXI REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIÓN CLÍNICA (SAIC); 2016

Calcitriol regulates proliferation, differentiation, angiogenesisand cell death of breast cancer cells. Since calcitriol produces hypercalcemiceffects in vivo as a side effect, our working hypothesiswas that the combination of calcitriol with menadione (MEN), aglutathione (GSH) depleting drug, would enhance 1,25 (OH)2D3(D) antiproliferative effects without undesirable side elevations ofserum calcium. The aim of the present study was to investigateabout the mechanisms involved in the antiproliferative action ofthe combined treatment. MCF-7 cells were treated with 100 nMD, 10 µM MEN, both drugs or vehicle (ethanol) for 96 hours.Intracellular calcium concentration and mitochondrial membranepotential were evaluated by flow cytometry. Superoxide anionand nitric oxide (NO) levels were measured by spectrophotometry.The expression of TRPV6 and PMCA1b mRNA levels weredetermined by quantitative real-time PCR and acidic vesicularorganelles (AVOs) formation, by fluorescence microscopy. Statisticalanalyses were performed by ANOVA / Bonferroni. Both Dand the combined treatment increased NO production. Superoxideanion levels, mitochondrial membrane permeability, intracellularcalcium concentration and TRPV6 and PMCA1b mRNA levelswere enhanced only by the combined treatment, as compared tocontrols. The increment of AVOs formation suggests activation ofa cell death process. In conclusion, MEN increases the effect ofcalcitriol on MCF-7 cells through oxidative and nitrosative stress,alteration in intracellular Ca2+concentration and changes of theexpression of molecules closely related to calcium regulation, thusinducing cell death pathways.