Buthionine-S,R-sulfoximine potentiates growth inhibition induced by 1,25(OH)2D3 on breast cancer cells with different phenotypes

BOHL L; LIAUDAT A; PICOTTO G; MARCHIONATTI A; RODRÍGUEZ V; NARVAEZ C; WELSH J; TOLOSA DE TALAMONI N

Congreso; XXIX Reunión Anual de la Asociación Argentina de Osteología y Metabolismo Mineral; 2012

Buthionine-S,R-sulfoximine potentiates growth inhibition induced by 1,25(OH)2D3 on breast cancer cells with different phenotypes Bohl L1, Liaudat A1, Marchionatti A1, Picotto G1, Rodríguez V1, Narvaez C2, Welsh J2, Tolosa de Talamoni N1 1Lab Cañas, Cát de Bioq y Biol Mol, FCM, UNC 2University at Albany, USA 1,25(OH)2D3 induces antiproliferative effects on breast cancer tumors with undesired hypercalcemia. Combination of calcitriol with glutathione-depleting drugs, such as buthionine-S,R-sulfoximine (BSO), may enhance the steroid effects and overcome hypercalcemia. Previously we demonstrated that BSO enhanced the steroid antiproliferative action on MCF-7 breast cancer cells inducing ROS production and arresting cells in G1 phase (Bohl. et al., Cancer Inv., in press, 2012). Our aim was to deepen in the molecular mechanisms involved and to extend our study to other breast cancer cell lines. MCF-7, MCF-7DR (resistant to calcitriol) and HMLER (triple negative) cells were treated with 100 nM calcitriol, 20 µM BSO or both for 4 days. Cell growth was evaluated by crystal violet staining; superoxide dismutase (SOD) activity by spectophotometry; caspase activation by fluorescence microscopy; Bcl2 gene expression by RT-qPCR. Results were analyzed using ANOVA and Bonferroni test. BSO, 1,25(OH)2D3 and their combination inhibited cell viability in MCF-7 and HMLER cell lines being the later more sensitive to BSO. Calcitriol and/or BSO have minimal effects on MCF-7DR cells. SOD activity was induced with calcitriol and was higher with the co-treatment. The combined treatment induced caspase activation and reduced the antiapoptotic Bcl2 gene relative expression. Altogether, the potentiation of 1,25(OH)2D3 inhibitory effect on MCF-7 cell growth by the combined treatment is provoked by an alteration in the redox status and induction of apoptosis. The combination may be useful to reduce hypercalcemia and to be applied on calcitriol-resistant cells or triple negative mammary tumors.