RESUMO
BACKGROUND: Hedyotis diffusa (HD) Willd. and Scutellaria barbata (SB) D. Don in different ratios have been frequently used to treat various cancers in clinical Traditional Chinese Medicine prescriptions. However, the optimal ratio, active fraction, and molecular mechanisms associated with the anti-breast cancer role of this herbal couplet have not been elaborated. METHODS: To screen out the optimal ratio of this herbal couplet, we compare aqueous extracts of HD, SB, or HD plus SB in different weight ratios (HS11, HS12, HS21) for their anticancer effects on murine breast cancer 4T1 cells in vitro and in vivo. EA11, the ethyl acetate fraction from HS11 (the aqueous extract of the couplet at an equal weight ratio), is further assessed for its antiproliferative effect as well as the antitumorigenic impact with the aid of immunocompetent mice. Colony formation, flow cytometry, western blot, ELISA, and qRT-PCR are used to elucidate mechanisms underlying EA11-led effects. RESULTS: HS11 presents the most potential suppression of 4T1 cell proliferation and tumor growth among these aqueous extracts. The comparison results show that EA11 is more effective than HS11 in vitro and in vivo. EA11 inhibits colony formation and induces apoptosis in a concentration-dependent manner. EA11 reduces the protein expressions of PDE7B, PD-L1, ß-catenin, and cyclin D1 while elevating the concentration of cellular cAMP and miR-200c expression in 4T1 cells. Additionally, EA11 exerts its anticancer effect partially via the inactivation of MAPK and AKT signaling pathways. CONCLUSIONS: This study implicates that EA11 prevents breast tumor development by interfering with the miR-200c-PDE7B/PD-L1-AKT/MAPK axis. EA11 may represent a potential therapeutic candidate for breast cancer.