ANTI-TUMOR EFFECTS OF CALCITRIOL AND DL-BUTHIONINE ON NEOPLASIC INTESTINAL

A C. LIAUDAT; BOHL L; TOLOSA DE TALAMONI NG; PICOTTO G

Jornada; XII Jornadas de Investigación Científica Fac. de Medicina UNC; 2011

ANTI-TUMOR EFFECTS OF CALCITRIOL AND DL-BUTHIONINE-S,R-SULFOXIMINE ON NEOPLASIC INTESTINAL CELLSLiaudat AC, Bohl LP, Tolosa de Talamoni NG, Picotto GLaboratorio Dr. F. Cañas, Facultad de Ciencias Médicas, Universidad Nacional de Córdoba.Colon cancer prognosis and incidence are connected to vitamin D3 serum levels. Besides, oxidant drugs like D,L-buthionine-S,R-sulfoximine (BSO) increase tumour cell sensibility, specially in resistant cancers. The aim of this study was to evaluate the mechanisms involved in the effects of calcitriol and BSO on colon cancer cell growth. Caco-2 human colon cancer cells were treated with calcitriol (1-200 nM), BSO (2-500 µM), both or vehicle at different times. Cell proliferation was evaluated by crystal violet staining. Catalase (CAT), superoxide dismutase (SOD), alkaline phosphatase (FAL) activities and glutathione levels (GSH) were analysed by spectrophotometry. Apoptosis was evaluated by Anexin V and PI staining, as well as DNA ladder formation and caspase-3 activity assay. Mitochondrial membrane potential and cell cycle were measured by flow cytometry. Results were statistically analysed by one way ANOVA and Bonferroni as a test post-hoc. Calcitriol and BSO inhibited Caco-2 growth and this effect was time and dose-dependent. Total GSH levels decreased at 6 and 48 hs either with BSO or the combined treatment. At 96 hs, CAT activity as well as mitochondrial membrane potential were modified only with the combined treatment while SOD activity was not changed by any treatment. Calcitriol and calcitriol plus BSO increased FAL activity but cell cycle was not affected. Additionally, the determination of apoptotic cell death by these techniques was negative. In conclusion, BSO increases the antiproliferative effect of calcitriol on Caco-2 cells through oxidative stress induction, which can be only partially compensated by the antioxidant system. Apoptotic cell death seems not to be involved. FAL activity increment suggests cell differentiation induction.