RESUMO
Hepatocellular carcinoma (HCC), a primary type of liver cancer, is one of the leading causes of cancer related deaths worldwide. HCC patients have poor prognosis due to intrahepatic and extrahepatic metastasis. Hepatitis B virus (HBV) infection is one of the major causes of various liver diseases including HCC. Among HBV gene products, HBV X protein (HBx) plays an important role in the development and metastasis of HCC. However, the mechanism of HCC metastasis induced by HBx has not been elucidated yet. In this study, for the first time, we report that HBx interacts with the suppressor of cytokine signaling 1 (SOCS1) which negatively controls NF-κB by degrading p65, a subunit of NF-κB. NF-κB activates the transcription of factors associated with epithelial-mesenchymal transition (EMT), a crucial cellular process associated with invasiveness and migration of cancer cells. Here, we report that HBx physically binds to SOCS1, subsequently prevents the ubiquitination of p65, activates the transcription of EMT transcription factors and enhance cell migration and invasiveness, suggesting a new mechanism of HBV-associated HCC metastasis. [BMB Reports 2022; 55(5): 220-225].
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Transição Epitelial-Mesenquimal/genética , Regulação Neoplásica da Expressão Gênica , Vírus da Hepatite B/genética , Vírus da Hepatite B/metabolismo , Humanos , Neoplasias Hepáticas/metabolismo , NF-kappa B/metabolismo , Proteína 1 Supressora da Sinalização de Citocina/genética , Proteína 1 Supressora da Sinalização de Citocina/metabolismo , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Transativadores , Proteínas Virais Reguladoras e AcessóriasRESUMO
Hepatitis B virus (HBV) infection is a major cause of hepatocellular carcinoma (HCC), which is a highly aggressive cancer. HBV X protein (HBx), one of four HBV gene products, plays pivotal roles in the development and metastasis of HCC. It has been reported that HBx induces liver cancer cell migration and reorganizes actin cytoskeleton, however the molecular basis for actin cytoskeleton reorganization remains obscure. In this study, we for the first time report that HBx promotes actin polymerization and liver cancer cell migration by regulating calcium modulated protein, calmodulin (CaM). HBx physically interacts with CaM to control the level of phosphorylated cofilin, an actin depolymerizing factor. Mechanistically, HBx interacts with CaM, liberates Hsp90 from its inhibitory partner CaM, and increases the activity of Hsp90, thus activating LIMK1/cofilin pathway. Interestingly, the interaction between HBx and CaM is calcium-dependent and requires the CaM binding motif on HBx. These results indicate that HBx modulates CaM which plays a regulatory role in Hsp90/LIMK1/cofilin pathway of actin reorganization, suggesting a new mechanism of HBV-induced HCC metastasis specifically derived by HBx. [BMB Reports 2021; 54(12): 614-619].
Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Actinas/metabolismo , Calmodulina/metabolismo , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Humanos , Quinases Lim/metabolismo , Neoplasias Hepáticas/metabolismo , Polimerização , Transativadores , Proteínas Virais Reguladoras e Acessórias/metabolismoRESUMO
Nuclear factor kappaB (NF-kappaB) is associated with the transcriptional activation of genes encoding chemokines, adhesion molecules, cytokines, and anti-apoptotic proteins, which are key components in immune responses and viral infection. Many viruses modulate NF-kappaB through numerous viral gene products to allow productive infections and immune escape. Here we report that herpes simplex virus-1 infected cell protein 27 (HSV-1 ICP27), an immediate early protein of HSV-1, represses NF-kappaB activity through binding to inhibitor of kappaB (IkappaBalpha), blocking phosphorylation and ubiquitination of IkappaBalpha, and stabilizing IkappaBalpha. These data may explain how NF-kappaB activity is regulated by ICP27 to escape immune responses during the very early period of HSV-1 infection.
Assuntos
Proteínas I-kappa B/metabolismo , Proteínas Imediatamente Precoces/metabolismo , NF-kappa B/antagonistas & inibidores , Animais , Linhagem Celular , Chlorocebus aethiops , Inibidor de NF-kappaB alfa , NF-kappa B/metabolismo , Fosforilação , Ubiquitinação , Células VeroRESUMO
ETHNOPHARMACOLOGICAL RELEVANCE: A medicinal herb Tribulus terrestris Linn has been used to treat various diseases including hepatocellular carcinoma. The aim of the present study was to investigate the anticancer activity of Tribulus terrestris Linn (TT) in liver cancer cells. MATERIALS AND METHODS: The antitumor activity of aqueous TT extract was analyzed by testing the cytotoxicity and the effect on clonogenecity in HepG2 cells. Apoptosis and cell cycle arrest induced by TT were dissected by flow cytometry and its inhibitory effect on NF-κB activity was determined by analyzing the expression levels of NF-κB/IκB subunit proteins. The suppression of NF-κB-regulated gene expression by TT was assessed by RT-PCR. RESULTS: TT extract repressed clonogenecity and proliferation, induced apoptosis, and enhanced accumulation in the G0/G1 phase of liver cancer cells. It also turned out that TT extract inhibited NF-κB-dependent reporter gene expression and NF-κB subunit p50 expression, while it enhanced the cellular level of IκBα by inhibiting the phosphorylation and degradation of IκBα. In addition, IKK activity was inhibited in a dose-dependent manner. Furthermore, TT extract suppressed the transcription of genes associated with cell cycle regulation, anti-apoptosis, and invasion. CONCLUSION: These data showed that TT extract blocks proliferation and induces apoptosis in human liver cancer cells through the inhibition of NF-κB signaling. Aqueous TT extract can be used as an anticancer drug for hepatocellular carcinoma patients.