Shu Gan Jie Yu herbal combination enhances tamoxifen sensitivity in breast cancer cells via modulation of the SNCG/p-ERα,mTOR /AKT and p-ERK pathway.

OBJECTIVE: This study aims to investigate the therapeutic effects and potential mechanisms of Shu Gan Jie Yu herbal combination (Cyperus rotundus L., Citrus medica L. var. Sarcodactylis Swingle and Rosa rugosa Thunb; CCR) combined with Tamoxifen (TAM) in inhibiting estrogen receptor-positive (ER+) breast cancer. METHODS: The water extract of the CCR was tested on MCF-7, T47D cell lines, and their SNCG-overexpressing counterparts. The CCK8 assay was used to evaluate the effects of CCR, TAM alone, and their combined application. CompuSyn and SynergyFinder software were employed to assess whether the combination therapy exhibited synergistic effects. Colony formation assays and flow cytometry were conducted to examine the impact on proliferation and apoptosis of SNCG-overexpressing cells, respectively. Co-immunoprecipitation (CoIP) and dual-luciferase reporter gene assays were used to investigate the interaction between SNCG and ERα. Western blot analysis was performed to evaluate the effects of CCR and TAM, alone or in combination, on the expression of ERα, SNCG, and phosphorylated proteins in MCF-7 and T47D cells, as well as on the expression of ERα, SNCG, EGFR, AKT, mTOR, MAPK, ERK and their phosphorylated forms in SNCG-overexpressing cells. RESULTS: In our study, treatment with CCR enhanced the inhibitory effects of TAM on the breast cancer cell lines examined. CoIP and dual-luciferase reporter gene assays indicated a potential protein-protein interaction between SNCG and ERα, suggesting that SNCG overexpression enhanced ERα promoter activity. Overexpression of SNCG led to the upregulation of ERα. CCR combined with TAM markedly suppressed cell migration and colony formation, and significantly induced apoptosis. These effects were mechanistically associated with reduced protein expression levels of SNCG, p-ERα, and key molecules in the mTOR/AKT and p-ERK signaling pathways. CONCLUSION: Our results indicate that CCR exhibits potent anti-proliferative activity against ER + breast cancer. Moreover, the combination of CCR and TAM synergistically enhances the anti-proliferative activity, at least in part via modulation of the SNCG/p-ERα, inhibiting the mTOR/AKT and p-ERK signaling pathways.