Mechanisms Of ADAM17 During The Metastasis Of Hepatocellular Carcinoma

Hepatocellular Carcinoma(HCC)is one of the most prevalent and lethal human cancer worldwide,particularly in Southeast Asia and Africa.Hepatitis B virus(HBV)infection is considered to be the main cause of the occurrence of HCC.Hepatitis B virus X protein(HBx)is encoded by HBV and plays an important role in the occurrence,development and metastasis of HBV related liver cancer.Transforming growth factor beta(TGF-β)is a polypeptide cytokine,it is widely involved in various pathophysiological processes of organisms and plays an important role in the occurrence and development of HCC.ADAM17 is a multi-domain membrane protein that is abnormally expressed in a variety of tumor cells and is closely related to the infiltration and metastasis capacity of tumor cells.In recent years,more and more studies have found that HBx protein and TGF-β can interact with each other in many ways to promote disease progression in the process of HCC,but the specific molecular mechanism is not very clear.This article aims to explore the mechanism by which HBx activates the ADAM protein downstream of the TGF-β signaling pathway and thus affects the occurrence of HCC.We first detected the expression of HBx and ADAM17,a downstream target gene of TGF-β pathway,in clinical specimens and adjacent tissues of hepatocellular carcinoma by immunohistochemistry.It was found that both of them are highly expressed in hepatocellular carcinoma and the expression is positively correlated.Then the HBx expression plasmid was transfected into hepatoma cell lines and the expression of ADAM17 was increased with the dosage of HBx transfection,indicating that HBx may activate ADAM17 expression.On this basis,we used a dual luciferase reporter gene system to detect that HBx can significantly activate the ADAM17 promoter.The above results indicate that the overexpression of ADAM17 in hepatoma cells may be related to the expression of the HBx protein,which was encoded by HBV virus itself.In order to verify the molecular mechanism of HBx affecting the expression of ADAM17,we first used TGF-β1 and SIS-3 to treat HCC cells and Western blot to detect the expression of ADAM family proteins.We found that the expression of ADAM17 was significantly affected by the TGF-β1/Smad3 pathway.Further tests showed that HBx and TGF-β1 can co-activate TGF-β1 signaling pathway and ADAM17 expression.Protein immunoprecipita-tion assays showed that HBx binds to Smad family proteins in the TGF-β1 pathway.Next,we constructed an AP-1 silenced hepatoma cell line.It was found that inhibiting the expression of AP-1 in hepatoma cells can promote the expression of ADAM17.The reporter gene assay further revealed that HBx and TGF-β1 can reverse the AP-1’s inhibition of TGF-β signaling pathway.The results of this section indicate that the expression of ADAM17 in hepatoma cells may be activated by HBx-mediated TGF-β1 signaling pathway.Finally,we established a stable hepatoma cell line silenced by ADAM17.It was found that the expression of ADAM17 in silenced hepatoma cells can significantly inhibit the proliferation and migration of cells.In vivo PET/CT imaging and pathological staining of nude mices showed that inhibition of ADAM17 expression can significantly reduce liver cancer cell metastasis.The results show that the expression of ADAM17 is closely related to the metastasis of hepatoma cells.In summary,this study found that HBx regulated the expression of ADAM17 by activating TGF-β signaling pathway,leading to the proliferation and metastasis of hepatoma cells.Our study has explored the role of HBx in the development of hepatocellular carcinoma.Herein,we demonstrated that the possible regulatory mechanism of ADAM17 expression in hepatocellular carcinoma for the first time,which would be provide a new idea for the prevention of HCC and a new target fot the treatment of HCC-related diseases.