The Mechanism Study Of Pro-apoptotic Effect Of Theabrownin On Human Osteosarcoma By Activating P53 Signaling Pathway

Objective:To evaluate the anti-osteosarcoma effect of theabrowin,and clarify the mechanism.Providing the basis of preliminary studies and scientific evidence for the development of new traditional Chinese medicine for anticancer.Methods:To evaluate its anti-osteosarcoma effect,we established a xenograft model of zebrafish and employed U2OS cells for in vivo and in vitro assays.Using flow cytometry,immunofluorescence and western blot to evaluated the anti-tumor effect of theabrowin and seeking its mechanism.Results:The animal data showed that TB significantly inhibited the tumor growth with stronger effect than that of chemotherapy.The cellular data confirmed that TB triggered DNA damage and induced apoptosis of U2OS cells by regulation of Mki67,PARP,Caspase 3(Casp3),and H2AX,and western blot assay showed an activation of p53 signaling pathway with TB treatment.When P53 was knocked down by siRNA,the subsequent downstream signaling was blocked,indicating a P53-dependent mechanism of TB on U2OS cells(P53 wt).By using osteosarcoma cell lines with P53 mutation(HOS,SAOS-2,and MG63),we found that TB exerted stronger inhibitory effect on U2OS cells than that on P53-mut cell lines,but it also exerted obvious effect on SAOS-2 cells(P53 null)at high concentrations,suggesting an activation of P53-independent pathway in the P53-null cells.Interestingly,theabrownin was found to have no toxicity on normal tissue in vivo and could even increase the cell viability of P53-wt normal cells.Conclusion:Theabrownin could exert strong anti-osteosarcoma activity by triggering DNA damage on U2OS cells via p53 signaling pathway.This component may be a promising candidate for osteosarcoma therapy and further drug development.