DL-BUTHIONINE-S,R-SULFOXIMINE ENHANCES ANTI-TUMORAL EFFECTS OF CALCITRIOL ON NEOPLASIC INTESTINAL CELLS

LIAUDAT AC, BOHL LP, TOLOSA DE TALAMONI NG, PICOTTO G

Buenos Aires

Congreso; Reunion Anual de la Asociacion Argentina de Osteologia y Metabolismo Mineral; 2013

AAOMM

Colon cancer is one of the most important causes of death in entire world. Prognosis and incidence of colorectal cancer are closely connected to 25(OH)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 (D), BSO, both or vehicle (ethanol) 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. Mitochondrial membrane potential (mΔΨ) and cell cycle were measured by flow cytometry. Nuclear morphology was evaluated by DAPI staining and DNA fragmentation by TUNEL assay. Results were statistically analysed by one way ANOVA and Bonferroni as a post-hoc test. BSO and D inhibited Caco-2 growth and this effect was time and dose-dependent. Total GSH levels decreased at 6 and 48 h either with BSO or BSO+D and CAT activity was modified only at 96 h with combined treatment. BSO plus D produced cell cycle arrest in S/G2 phase at 48 h and reduced mitosis cell division at 96 h. BSO and BSO+D augmented DNA fragmentation. D and BSO+D modified mΔΨ and increased FAL activity at 96h. In conclusion, BSO increases the antiproliferative effect of D on Caco-2 cells via oxidative stress induction, cell cycle arrest and DNA fragmentation. FAL activity increment suggests cell differentiation induction.