title: Increased ATG5-ATG12 in hepatitis B virus-associated hepatocellular carcinoma and their role in apoptosis.
abstract: OBJECTIVE
  To investigate autophagy-related genes, particularly ATG12, in apoptosis and cell cycle in hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) and non-HBV-HCC cell lines.
  
  
  METHODS
  The expression of autophagy-related genes in HBV-associated hepatocellular carcinoma and non-HBV-HCC cell lines and human liver tissues was examined by quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blotting. The silencing of target genes was used to examine the function of various genes in apoptosis and cell cycle progression.
  
  
  RESULTS
  The expression of autophagy related genesATG5,ATG12,ATG9AandATG4Bexpression was analyzed in HepG2.2.15 cells and compared with HepG2 and THLE cells. We found thatATG5andATG12mRNA expression was significantly increased in HepG2.2.15 cells compared to HepG2 cells (P< 0.005). Moreover, ATG5-ATG12 protein levels were increased in tumor liver tissues compared to adjacent non-tumor tissues mainly from HCC patients with HBV infection. We also analyzed the function of ATG12 in cell apoptosis and cell cycle progression. The percentage of apoptotic cells increased by 11.4% in ATG12-silenced HepG2.2.15 cells (P< 0.005) but did not change in ATG12-silenced HepG2 cells under starvation with Earle's balanced salt solution. However, the combination blockade of Notch signaling and ATG12 decreased the apoptotic rate of HepG2.2.15 cells from 55.6% to 50.4% (P< 0.05).
  
  
  CONCLUSIONS
  ATG12 is important for HBV-associated apoptosis and a potential drug target for HBV-HCC. Combination inhibition of ATG12/Notch signaling had no additional effect on HepG2.2.15 apoptosis.
authors.affiliation: Areerat Kunanopparat, Nattiya Hirankarn, Center of Excellence in Immunology and Immune-mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Areerat
authors.initials: A
authors.lastname: Kunanopparat
authors.affiliation: Areerat Kunanopparat, Nattiya Hirankarn, Center of Excellence in Immunology and Immune-mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Ingorn
authors.initials: I
authors.lastname: Kimkong
authors.affiliation: Areerat Kunanopparat, Nattiya Hirankarn, Center of Excellence in Immunology and Immune-mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Tanapat
authors.initials: T
authors.lastname: Palaga
authors.affiliation: Areerat Kunanopparat, Nattiya Hirankarn, Center of Excellence in Immunology and Immune-mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Pisit
authors.initials: P
authors.lastname: Tangkijvanich
authors.affiliation: Areerat Kunanopparat, Nattiya Hirankarn, Center of Excellence in Immunology and Immune-mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Boonchoo
authors.initials: B
authors.lastname: Sirichindakul
authors.affiliation: Areerat Kunanopparat, Nattiya Hirankarn, Center of Excellence in Immunology and Immune-mediated Diseases, Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Nattiya
authors.initials: N
authors.lastname: Hirankarn
mesh_terms: D017209:Apoptosis; D001343:Autophagy; D000071192:Autophagy-Related Protein 12 / Q000378:metabolism*; D000071187:Autophagy-Related Protein 5 / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000150:complications* / Q000378:metabolism; D002453:Cell Cycle; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D015870:Gene Expression; D056945:Hep G2 Cells; D006509:Hepatitis B / Q000150:complications* / Q000378:metabolism; D006515:Hepatitis B virus; D006801:Humans; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms / Q000150:complications* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: C466624:ATG12 protein, human; C502778:ATG5 protein, human; D000071192:Autophagy-Related Protein 12; D000071187:Autophagy-Related Protein 5; D012333:RNA, Messenger; D051880:Receptors, Notch
keywords: ATG12; Apoptosis; Autophagy; Cell cycle; Hepatitis B virus; Hepatocellular carcinoma; Notch signaling