Inhibitory Effect Of Egcg On Human Osteosarcoma Cancer And Underlying Mechanism

Objective: To investigate the inhibitory effect of EGCG on human osteoscarcoma cells,and to probe the possible molecule mechanism.Methods: Human OS(143B?MG63?SaOS2)cells were treated with0~50?mol/L EGCG,the proliferation,apoptosis and migration of 143 B cells were measured by MTT,colony-forming,hoechst staining,flow cytometry,wound-healing and Transwell migration assay,respectively.The expression levels of proliferation?apoptosis and migration related proteins were detected by Western Blotting.The luciferase reporter assay was used to detect the activation of wnt/?-catenin signaling pathway.Western Blotting was carried out to detect the protein expression level of ?-catenin and its downstream molecule C-myc,CyclinD1 and MMP-7.Construct a nude mouse model of osteosarcoma and take intragastric administration.Observe the effect of EGCG on osteosarcoma.Immunohistochemically detect the expression of ?-catenin and PCNA in the tumor,and HE staining of lung tissue and bone tissue to observe the invasion of osteosarcoma.Results:When treated with EGCG,143 B cells showed significantlydecreased proliferation and migration,and highly induced apoptosis at the later stage(P < 0.05).Moreover,EGCG enhanced expression of proliferation and apoptosis-associated genes(PCNA,Caspase-3,Cleaved-caspase-3,and Cleaved-PARP).Migration-associated proteins,MMP-9,and Vimentin were less accumulated upon EGCG treatment.However,another migration protein,E-cadherin,was down-regulated.EGCG also down-regulated Wnt/?-catenin signaling associated proteins including ?-catenin,C-myc,CyclinD1,MMP-7,while the expression level of GSK-3? remained stable.Additionally,EGCG dramatically inhibited the Wnt/?-catenin signaling pathway as indicated by attenuation of luciferase activities(P<0.05).The results of animal experiments showed significant decreases in growth rate and volume of the tumor with increasing gavage concentration(P < 0.05).Immunohistochemistry analysis revealed less expression of ?-catenin and PCNA in the experimental group in contrast to control group.HE staining showed that the tumor lung metastasis and bone tissue invasion in the control group were more obvious than in the experimental group.Furthermore,the lung metastasis and bone tissue invasion were significantly inhibited in the experimental group with increasing drug dose.Conclusion: EGCG repressed proliferation and migration,promoted apoptosis,and suppressed Wnt/?-catenin signaling pathway in human OS cells.Our results suggested that inhibition of Wnt/?-catenin signaling byEGCG might be involved in its antitumor effect.