Assuntos
Disgeusia , Polipose Intestinal , Humanos , Pólipos Intestinais , Diarreia/diagnóstico , Diarreia/etiologia , MucosaRESUMO
Hepatitis B virus X protein (HBx) has been termed a viral oncoprotein, and is involved in the initiation and progression of hepatocellular carcinoma (HCC). Cyclooxygenase2 (COX2) and ßcatenin have been attributed to the oncogenic activity of HBx in HBVassociated HCC. The present study aimed to determine whether there is crosstalk between COX2 and the Wnt/ßcatenin signaling pathway during HL7702HBx cell proliferation, and to investigate the associated underlying molecular mechanism. In the present study, cell proliferation assay, colony formation assay and flow cytometric analysis were used to detect the proliferative ability of cells. Reverse transcriptionquantitative polymerase chain reaction and western blotting were performed to examine the mRNA and protein expression of COX2, ßcatenin, cyclinD1 and cmyc. The results demonstrated that HL7702HBx exhibited increased cell proliferation, higher colony formation efficiency and a shortened G1 period of the cell cycle. In addition, the mRNA and protein expression levels of COX2 were increased, and this was associated with HL7702HBx cell growth. Furthermore, the expression of ßcatenin and its target genes, cyclinD1 and cmyc protooncogene protein, was upregulated by HBx via COX2. Finally, HBx promoted HL7702 cell proliferation through the Wnt/ßcatenin signaling pathway. In conclusion, the primary finding of the present study was that HBx may promote HL7702 cell proliferation via the COX2/Wnt/ßcatenin pathway. Thus, it may be helpful to further investigate the molecular mechanism of HBVassociated hepatocellular carcinoma.
Assuntos
Ciclo-Oxigenase 2/metabolismo , Transativadores/metabolismo , Via de Sinalização Wnt , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Ligação Proteica , Proteínas Virais Reguladoras e AcessóriasRESUMO
Hepatocellular Carcinoma (HCC) is the fifth most prevalent cancer worldwide. Specially, Hepatitis B viurs X protein (HBx) is a leading factor in the progression of Hepatitis B viurs-related HCC. Nutrient-deprived tumor microenvironment also contributes to tumor development. However, the role of HBx in nutrient-deprived HCC has received little investigation. Here, we show that HBx elevates PINK1-Parkin mediating mitophagy in starvation. HBx not only increases the PINK1/Parkin gene expression but also accelerates Parkin recruitment to partial mitochondria. Further analysis indicates that, HBx either promotes mitochondrial unfolded protein response, with remarkable mitochondrial LONP1 increases, or reduces LONP1 expression in cytosol inducing LONP1-Parkin pathway, both consequently enhancing mitophagy. Moreover, the enhanced mitophagy lowers mitochondrial apoptosis in starved hepatoma cells, and Bax is implied in the machinery. In addition, we define differential centrifuge, 3000â¯g or 12,000â¯g to pellet mitochondria, as an effective method to obtain distinct mitochondria. In collect, HBx regulates diverse aspects of LONP1 and Parkin, enhancing mitophagy in starvation. This study may shed new insights into the machinery development of hepatocellular carcinoma.
Assuntos
Hepatite B/virologia , Neoplasias Hepáticas/virologia , Mitocôndrias/virologia , Transativadores/metabolismo , Carcinoma Hepatocelular/metabolismo , Linhagem Celular , Humanos , Mitofagia/fisiologia , Peptídeo Hidrolases/metabolismo , Proteínas Quinases/metabolismo , Proteínas Virais Reguladoras e AcessóriasRESUMO
Chronic hepatitis B virus (HBV) infection is a leading cause of liver cirrhosis and cancer. Among the pathogenic factors of HBV, HBV X protein (HBx) is attracting increased attention. Although it is documented that HBx is a multifunctional regulator that modulates cell inflammation and apoptosis, the exact mechanism remains controversial. In the present study, we explored the effect of HBx on oxidative stress-induced apoptosis in normal liver cell line, HL-7702. Our results showed that the existence of HBx affected mitochon-drial biogenesis by modulating the opening of the mitochondrial permeability transition pore (MPTP). Notably, this phenomenon was associated with a pronounced translocation of Bax from the cytosol to the mitochon-dria during the period of exposure to oxidative stress with a release of cytochrome c and activation of cleaved caspase-3 and PARP. Moreover, MPTP blockage with cyclosporin A prevented the translocation of Bax, and inhibited oxidative stress-induced apoptotic killing in the HBx-expressing HL-7702 cells. Our findings suggest that HBx exhibits pro-apoptotic effects upon normal liver cells following exposure to oxidative stress by modulating the MPTP gateway.
Assuntos
Apoptose , Hepatócitos/fisiologia , Proteínas de Transporte da Membrana Mitocondrial/fisiologia , Estresse Oxidativo/fisiologia , Transativadores/fisiologia , Apoptose/genética , Linhagem Celular , Hepatócitos/metabolismo , Humanos , Peróxido de Hidrogênio/farmacologia , Fígado/citologia , Fígado/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Estresse Oxidativo/genética , Transporte Proteico/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Transativadores/genética , Proteínas Virais Reguladoras e Acessórias , Proteína X Associada a bcl-2/metabolismoRESUMO
Hepatocellular carcinoma (HCC) is one of the most common malignant diseases, and HBx leads to the development of HBV-associated HCC. Mitochondria are key organelles that regulate apoptosis, cellular energetics and signal transduction pathways, and are the source of HBx-induced reactive oxygen species (ROS). Recent findings have shown that HBx interacts with the inner mitochondrial membrane protein, COXIII, via the yeast two-hybrid system, mating experiment and coimmunoprecipitation. The aim of the present study was to examine the co-localizaiton of HBx and COXIII in HL-7702 cells and to investigate ensuing alterations of mitochondrial function. An HL-7702 cell line stably expressing the HBx gene by lentivirus vectors was constructed. Confocal microscopy was utilized to assess the interaction between HBx protein and COXIII. Expression of COXIII, activities of cytochrome c oxidase (COX) and the mitochondrial membrane potential, which were functionally relevant to the HBx protein-COXIII interaction, were investigated in cell cultures. Moreover, the intracellular ROS levels were detected by flow cytometry. The results demonstrated that HBx co-localized with the inner mitochondrial protein, COXIII, in HL-7702 cells, causing the upregulation of COXIII protein expression as well as COX activity. However, HBx did not alter the mitochondrial membrane potential and mitochondria exhibited only slight swelling in HL-7702-HBx cells. Moreover, HBx elevated the generation of mitochondrial ROS in HL-7702-HBx cells. The main finding of the present study was that the co-localization of HBx and COXIII leads to upregulation of the mitochondrial function and ROS generation, which are associated with the oncogenesis of HBV-associated HCC.
Assuntos
DNA Mitocondrial/metabolismo , Mitocôndrias/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transativadores/metabolismo , Regulação para Cima/genética , Apoptose/genética , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/virologia , Linhagem Celular , DNA Mitocondrial/genética , Células HEK293 , Vírus da Hepatite B/metabolismo , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/virologia , Potencial da Membrana Mitocondrial/genética , Mitocôndrias/genética , Transdução de Sinais/genética , Ativação Transcricional/genética , Proteínas Virais Reguladoras e AcessóriasRESUMO
HBx is a multifunctional regulator that interacts with host factors to contribute to the development of hepatocellular carcinoma. In this study, to explore the co-localization of HBx and COXIII in HepG2 cells and to investigate the molecular mechanism of HBx in HepG2 cell growth promotion, we first constructed a HepG2 cell line stably expressing the HBx gene in vitro by lentivirus vectors. In addition, we found that HBx co-localized with the inner mitochondrial protein, COXIII, in HepG2 cells by confocal laser scanning microscopy. It led to changes of mitochondrial biogenesis and morphology, including upregulation of COXIII protein expression, increased cytochrome c oxidase activity and higher mitochondrial membrane potential. The upregulation of COX-2 caused by HBx through generation of mitochondrial reactive oxygen species promoted cell growth. Thus, we conclude that co-localization of HBx and COXIII leads to upregulation of COX-2 that promotes HepG2 cell growth. Such a mechanism provides deeper insights into the molecular mechanism of HBV-associated hepatocellular carcinoma.