Mechanisms triggered by calcitriol and menadione on breast cancer cells.

GUIZZARDI S; BOHL L; PICOTTO G; TOLOSA DE TALAMONI N; RODRIGUEZ V

Mar del Plata

Congreso; Reunión conjunta de SAIC, SAI y SAFE; 2016

Calcitriol regulates proliferation, differentiation,angiogenesis and cell death of breast cancer cells.  Since calcitriol produces hypercalcemiceffects in vivo as a side effect, ourworking hypothesis was that the combination of calcitriol with menadione (MEN),a glutathione (GSH) depleting drug, would enhance 1,25     (OH)2D3 (D) antiproliferative effects without undesirableside elevations of serum calcium. The aim of the present study was toinvestigate about the mechanisms involved in the antiproliferative action ofthe combined treatment. MCF-7 cells were treated with 100 nM D, 10 µM MEN, bothdrugs or vehicle (ethanol) for 96 hours. Intracellular calcium concentrationand mitochondrial membrane potential were evaluated by flow cytometry.Superoxide anion and nitric oxide (NO) levels were measured byspectrophotometry. The expression of TRPV6 and PMCA1b mRNA levelswere determined by quantitative real-time PCR and acidic vesicular organelles(AVOs) formation, by fluorescence microscopy. Statistical analyses were performedby ANOVA / Bonferroni. Both D and the combined treatment increased NOproduction. Superoxide anion levels, mitochondrial membrane permeability,intracellular calcium concentration and TRPV6 and PMCA1b mRNA levelswere enhanced only by the combined treatment, as compared to controls. Theincrement of AVOs formation suggests activation of a cell death process. Inconclusion, MEN increases the effect of calcitriol on MCF-7 cells throughoxidative and nitrosative stress, alteration in intracellular Ca2+concentrationand changes of the expression of molecules closely related to calciumregulation, thus inducing cell death pathways.