Investigation Of Signal Transducer And Activator Of Transcription 3 Signaling In The Anti-Hepatocellular Carcinoma Effects Of Rheum Palmatum

Background:Hepatocellular carcinoma(HCC)is among the most frequently occurring malignancies in China.Although advances in early diagnostic and surgical treatment techniques have improved the morbidity and mortality rate,the long-term outcome of HCC patients has not changed because of tumor relapse and metastasis.Most patients are found to be advanced and lack surgical treatment.Sorafenib,the first and only molecular-targeted drug for advanced HCC,exhibits disadvantages such as high-cost,toxicity,and poor response rate.HCC has become a major problem in China’s health.Actively exploring effective drugs for treating liver cancer has important clinical significance.STAT3 is a family of signal transduction and transcriptional activators(signal transduction and transcriptional activators,STATs)that are widely expressed in different cell types and tissues of the body.STAT3 acts as a cytoplasmic transcription factor that mediates various growth factors and the signal transduction of cytokines to the nucleus,involved in the regulation of various physiological functions such as cell growth,differentiation,and apoptosis.STAT3 activation was detected in various tumor tissues including HCC.Constitutively active STAT3 promotes tumor growth and development by regulating target proteins involved proliferative,anti-apoptotic,metastatic and angiogenic.Chinese medicine in the treating of HCC has a unique advantage RP extract has pharmacological effects such as cathartic,hemostasis,anti-inflammatory,anticancer,hepatoprotective,and antioxidation,and has been prevalently used to treat liver diseases in traditional Chinese medicine.This study explores the anti-hepatocarcinoma effect of rhubarb and its regulation of STAT3 signaling pathway through animal and cell experiments,and clarifies the intrinsic mechanism of traditional Chinese medicine against HCC,and provides new ideas for the prevention and treatment of liver cancer by traditional Chinese medicine.Method:In the animal experiments,we used a subcutaneous HCC xenograft model in nude mice to observe the anti-hepatocarcinoma effect in RP extracts,and analyzed the role of STAT3 signaling pathway in anti-hepatocarcinoma in RP by immunohistochemistry.In the cell experiments,we used MTS,Hochest33342/PI double staining,wound healing and transwell invasion assay to observe the proliferation,apoptosis,migration and invasion of RP extract on SMMC-7721 and HepG2 cells.And angiogenesis of human umbilical vein endothelial cells(HUVECs)were analyzed using tube formation assays.We used western blot to detect the expression of STAT3 signaling pathway and its downstream target protein.We used a specific JAK2/STAT3-inhibitor to examine whether the inhibitory action of RP extract on HCC is due to suppression of STAT3 signaling.Result:Animal experiments show that RP can significantly slow the growth of subcutaneous HCC xenografts in nude mice.Immunohistochemistry showed that RP can inhibit the expression and phosphorylation of STAT3 in liver cancer tissues in vivo.The results indicated that RP extract significantly reduced the viability and induced apoptosis of SMMC-7721 and HepG2 cells,and decreased the migration and invasion ability of the two HCC cells,and decreased the ability of endothelial cells to form.RP extract inhibited the phosphorylation of STAT3 and its upstream JAK2 and Src,and down-regulated the STAT3 target proteins Cyclin D1,CDK4,c-Myc(proliferation),Bcl-xL,Mcl-1,Bcl-2,Survivin(antiapoptosis),MMP-2,MMP-9(invasion)and VEGF-C(angiogenesis)expression.The effect of RP extract on anti-hepatocarcinoma was not significantly different from STATS inhibitor.Co-culture with inhibitor did not promote the anti-hepatocarcinoma effect of RP,Neither cell experiments nor animal experiments showed that RP was impaired in function of normal liver and kidney tissues.Conclusion:This study confirmed that RP inhibits the growth of HCC in vivo,and inhibits the proliferation and promotes apoptosis of HCC cells,inhibits migration and invasion of HCC cells.Combined with in vivo and in vitro experiments,we conclude that the anti-HCC effects of RP are regulated by the inhibition of the STAT3 signaling.