Scutellaria barbata D.Don Inhibits Colorectal Cancer Growth via Suppression of Wnt/β-Catenin Signaling Pathway

Objective： To investigate the effect of the ethanol extract of Scutellaria barbata D. Don（EESB） on colorectal cancer（CRC） growth and Wnt/β-catenin signaling pathway in vivo and in vitro. Methods： In vivoexperiment, CRC xenograft mouse model was constructed with injection of HT-29 cells. Following xenograft implantation, twenty mice were randomly divided into EESB-treated group（n=10） and control group（n=10） by a random number table, and were given with intra-gastric administration of 2 g/kg EESB or saline, 5 days a week for 16 days, respectively. At the end of experiment, tumors were removed and weighed by electronic scales. The proliferation biomarker Ki-67 of tumor was evaluated by immunohistochemistry（IHC） assay. In vitro study, HT-29 cells were treated with 0, 0.5, 1.5, 2.5 mg/m L EESB for 24 h. At the end of the treatment, the viability and survival of HT-29 cells were determined by methylthiazolyldiphenyl-tetrazolium bromide（MTT） assay and colony formation assay, respectively. The m RNA expression of c-Myc, Survivin and adenomatous polyposis coli（APC） was examined by reverse transcription-polymerase chain reaction（RT-PCR） both in tumor tissues of CRC xenograft mice and HT-29 cells. Protein expression of c-Myc, Survivin, APC, and β-catenin as well as β-catenin phosphorylation level were evaluated by IHC assay or Western blotting. Results： EESB significantly reduced tumor weight in CRC xenografts mice, compared with the control group（P〈0.05）. IHC assay showed that EESB significantly inhibited protein expression of Ki-67 in tumor tissues（P〈0.05）. MTT assay showed that EESB significantly reduced HT-29 cell viability in a dose-dependent manner（P〈0.05）. Colony formation assay showed that EESB dose-dependently decreased the survival of HT-29 cells（P〈0.05）. In addition, RT-PCR assay showed that EESB decreased the m RNA expression of c-Myc and Survivin and increased APC expression, both in tumor tissues of CRC xenograft mice and HT-29 cells（P〈0.05）. IHC assay or Western blotting showed that EESB decreased protein expression of β-catenin, c-Myc and Survivin, as well as increased APC expression and β-catenin phosphorylation in tumor tissues or HT-29 cells（P〈0.05）. Conclusions： EESB significantly reduced tumor growth in CRC xenografts mice, and inhibited the viability and survival of HT-29 cells. EESB could suppress the activation of the Wnt/β-catenin pathway, which might be one of the mechanisms whereby Scutellaria barbata D. Don exerts its anticancer activity.