Hepatitis B virus X protein promotes human hepatoma cell growth via upregulation of transcription factor AP2α and sphingosine kinase 1  

作　　者：Zhan-ping LU Ze-lin XIAO Zhe YANG Jiong LI Guo-xing FENG Fu-quan CHEN Ying-hui LI Jin-yan FENG Yu-en GAO Li-hong YE Xiao-dong ZHANG 

机构地区：[1]State Key Laboratory of Medicinal Chemical Biology, Department of Cancer Research, College of Life Sciences, Nankai University, Tianjin 300071, China [2]State Key Laboratory of Medicinal Chemical Biology, Department of Biochemistry, College of Life Sciences, Nankai University, Tianjin 300071, China

出　　处：《Acta Pharmacologica Sinica》2015年第10期1228-1236,共9页中国药理学报（英文版）

基　　金：Acknowledgements This work was supported by grants from the National Basic Research Program of China （973 Program, No 2015CB553703, 2015CB553905）, the National Natural Science Foundation of China （No 81272218, 81372186） and the Project of Prevention and Treatment of Key Infectious Diseases （No 2014ZX0002002005）.

摘　　要：Aim： Sphingosine kinase 1 （SPHK1） is involved in various cellular functions, including cell growth, migration, apoptosis, cytoskeleton architecture and calcium homoeostasis, etc. As an oncogenic kinase, SPHK1 is associated with the development and progression of cancers. The aim of this study was to investigate whether SPHK1 was involved in hepatocarcinogenesis induced by the hepatitis B virus X protein （HBx）. Methods： The expression of SPHK1 in hepatocellular carcinoma （HCC） tissue and hepatoma cells were measured using qRT-PCR and Western blot analysis. HBx expression levels in hepatoma cells were modulated by transiently transfected with HBx or psi-HBx plasmids. The SPHK1 promoter activity was measured using luciferase reporter gene assay, and the interaction of the transcription factor AP2α with the SPHK1 promoter was studied with chromatin immunoprecipitation assay. The growth of hepatoma cells was evaluated in vitro using MTT and colony formation assays, and in a tumor xenograft model.Results： A positive correlation was found between the mRNA levels of SPHK1 and HBx in 38 clinical HCC samples （r=＋0.727, P〈0.01）. Moreover, the expression of SPHK1 was markedly increased in the liver cancer tissue of HBx-transgenic mice. Overexpressing HBx in normal liver cells LO2 and hepatoma cells HepG2 dose-dependently increased the expression of SPHK1, whereas silencing HBx in HBx-expressing hepatoma cells HepG2-X and HepG2.2.15 suppressed SPHK1 expression. Furthermore, overexpressing HBx in HepG2 cells dose-dependently increased the SPHK1 promoter activity, whereas silencing HBx in HepG2-X cells suppressed this activity. In HepG2-X cells, AP2α was found to directly interact with the SPHK1 promoter, and silencing AP2α suppressed the SPHK1 promoter activity and SPHK1 expression. Silencing HBx in HepG2-X cells abolished the HBx-enhanced proliferation and colony formation in vitro, and tumor growth in vivo.Conclusion： HBx upregulates SPHK1 through the transcription factor AP2α, which promotes Aim： Sphingosine kinase 1 （SPHK1） is involved in various cellular functions, including cell growth, migration, apoptosis, cytoskeleton architecture and calcium homoeostasis, etc. As an oncogenic kinase, SPHK1 is associated with the development and progression of cancers. The aim of this study was to investigate whether SPHK1 was involved in hepatocarcinogenesis induced by the hepatitis B virus X protein （HBx）. Methods： The expression of SPHK1 in hepatocellular carcinoma （HCC） tissue and hepatoma cells were measured using qRT-PCR and Western blot analysis. HBx expression levels in hepatoma cells were modulated by transiently transfected with HBx or psi-HBx plasmids. The SPHK1 promoter activity was measured using luciferase reporter gene assay, and the interaction of the transcription factor AP2α with the SPHK1 promoter was studied with chromatin immunoprecipitation assay. The growth of hepatoma cells was evaluated in vitro using MTT and colony formation assays, and in a tumor xenograft model.Results： A positive correlation was found between the mRNA levels of SPHK1 and HBx in 38 clinical HCC samples （r=＋0.727, P〈0.01）. Moreover, the expression of SPHK1 was markedly increased in the liver cancer tissue of HBx-transgenic mice. Overexpressing HBx in normal liver cells LO2 and hepatoma cells HepG2 dose-dependently increased the expression of SPHK1, whereas silencing HBx in HBx-expressing hepatoma cells HepG2-X and HepG2.2.15 suppressed SPHK1 expression. Furthermore, overexpressing HBx in HepG2 cells dose-dependently increased the SPHK1 promoter activity, whereas silencing HBx in HepG2-X cells suppressed this activity. In HepG2-X cells, AP2α was found to directly interact with the SPHK1 promoter, and silencing AP2α suppressed the SPHK1 promoter activity and SPHK1 expression. Silencing HBx in HepG2-X cells abolished the HBx-enhanced proliferation and colony formation in vitro, and tumor growth in vivo.Conclusion： HBx upregulates SPHK1 through the transcription factor AP2α, which promotes

关 键 词：hepatitis B virus X protein hepatocellular carcinoma HepG2 ceils tumor xenograft model sphingosine kinase 1 transcription factor AP2α ceil proliferation 

分 类 号：Q691.5[生物学—生物物理学] Q556.9