Combination of Silibinin and Curcumin Reduced Leptin Receptor Expression in MCF-7 Human Breast Cancer Cell Line

BACKGROUND: Leptin and leptin receptor (Ob-R) are associated with worse prognosis, distant metastasis, and poor survival of breast cancer. We investigated the cytotoxic effect of silibinin and curcumin, individually and combined, on Ob-R expression in MCF-7 cells. METHODS: This study was performed from October 2017 to April 2018 at the Department of Clinical Biochemistry, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. The cytotoxic effect of silibinin and curcumin, individually and combined, and their corresponding half-maximal inhibitory concentration (IC(50)) values were determined using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. The cells were treated with different concentrations of silibinin (50-400 μM), curcumin (10-35 μM), and their combinations for 24 and 48 hours. The expression of Ob-R was measured using the Western blot analysis by treating the cells with different concentrations of curcumin (10-25 μM), silibinin (50-250 μM), and their respective combinations. The difference in mean cell viability between the groups was calculated using one-way ANOVA followed by Tukey’s post hoc test. RESULTS: Silibinin and curcumin exerted time- and dose-dependent cytotoxic effect on MCF-7 cells. After treatment with silibinin, the IC(50) values were about 250 and 50 μM at 24 and 48 hours, respectively. In terms of treatment with curcumin, the IC(50) values were about 25 and 15 μM at 24 and 48 hours, respectively. Following treatment with silibinin, the Western blot analysis showed that Ob-R expression significantly decreased at 150 μM (P=0.031) and 200 μM (P=0.023) concentrations. Curcumin did not significantly decrease the Ob-R expression, however, the expression significantly decreased (P=0.004) when it was combined with silibinin. CONCLUSION: The combination of silibinin and curcumin significantly reduced Ob-R expression in MCF-7 cells compared with their individual effects.