title: Oxidative DNA damage correlates with cell immortalization and mir-92 expression in hepatocellular carcinoma.
abstract: BACKGROUND
  MicroRNAs expression has been extensively studied in hepatocellular carcinoma but little is known regarding the relationship, if any, with inflammation, production of reactive oxygen species (ROS), host's repair mechanisms and cell immortalization. This study aimed at assessing the extent of oxidative DNA damage (8-hydroxydeoxyguanosine - 8-OHdG) in different phases of the carcinogenetic process, in relation to DNA repair gene polymorphism, telomeric dysfunction and to the expression of several microRNAs, non-coding genes involved in post-transcriptional regulation, cell proliferation, differentiation and death.
  
  
  METHODS
  Tissue samples obtained either at surgery, [neoplastic (HCC) and adjacent non-cancerous cirrhotic tissues (NCCT)] at percutaneous or laparoscopic biopsy (patients with HCV or HBV-related hepatitis or patients undergoing cholecystectomy) were analysed for 8-OHdG (HPLC-ED), OGG1 (a DNA repair gene) polymorphism (PCR-RFLP), telomerase activity, telomere length (T/S, by RT-PCR), Taqman microRNA assay and Bad/Bax mRNA (RT-PCR). Fifty-eight samples from 29 HCC patients (obtained in both neoplastic and peritumoral tissues), 22 from chronic hepatitis (CH) and 10 controls (cholecystectomy patients - CON) were examined.
  
  
  RESULTS
  Eight-OHdG levels were significantly higher in HCC and NCCT than in CH and CON (p=0.001). Telomerase activity was significantly higher in HCC than in the remaining subgroups (p=0.002); conversely T/S was significantly lower in HCC (p=0.05). MiR-199a-b, -195, -122, -92a and -145 were down-regulated in the majority of HCCs while miR-222 was up-regulated. A positive correlation was observed among 8-OHdG levels, disease stage, telomerase activity, OGG1 polymorphisms and ALT/GGT levels. In HCC, miR-92 expression correlated positively with telomerase activity, 8-OHdG levels and Bad/Bax mRNA.
  
  
  CONCLUSIONS
  The above findings confirm the accumulation, in the progression of chronic liver damage to HCC, of a ROS-mediated oxidative DNA damage, and suggest that this correlates with induction of telomerase activity and, as a novel finding, with over-expression of miR-92, a microRNA that plays a role in both the apoptotic process and in cellular proliferation pathways.
authors.forename: Romilda
authors.initials: R
authors.lastname: Cardin
authors.affiliation: Department of Surgery, Oncology and Gastroenterology, Section of Gastroenterology, University of Padova, Via Giustiniani 2, Padova 35128, Italy.
authors.forename: Cardin
authors.initials: C
authors.lastname: Romilda
authors.forename: Marika
authors.initials: M
authors.lastname: Piciocchi
authors.forename: Piciocchi
authors.initials: P
authors.lastname: Marika
authors.forename: Alessandro
authors.initials: A
authors.lastname: Sinigaglia
authors.forename: Sinigaglia
authors.initials: S
authors.lastname: Alessandro
authors.forename: Enrico
authors.initials: E
authors.lastname: Lavezzo
authors.forename: Lavezzo
authors.initials: L
authors.lastname: Enrico
authors.forename: Marina
authors.initials: M
authors.lastname: Bortolami
authors.forename: Bortolami
authors.initials: B
authors.lastname: Marina
authors.forename: Andromachi
authors.initials: A
authors.lastname: Kotsafti
authors.forename: Kotsafti
authors.initials: K
authors.lastname: Andromachi
authors.forename: Umberto
authors.initials: U
authors.lastname: Cillo
authors.forename: Cillo
authors.initials: C
authors.lastname: Umberto
authors.forename: Giacomo
authors.initials: G
authors.lastname: Zanus
authors.forename: Zanus
authors.initials: Z
authors.lastname: Giacomo
authors.forename: Claudia
authors.initials: C
authors.lastname: Mescoli
authors.forename: Mescoli
authors.initials: M
authors.lastname: Claudia
authors.forename: Massimo
authors.initials: M
authors.lastname: Rugge
authors.forename: Rugge
authors.initials: R
authors.lastname: Massimo
authors.forename: Fabio
authors.initials: F
authors.lastname: Farinati
authors.forename: Farinati
authors.initials: F
authors.lastname: Fabio
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000378:metabolism; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D016000:Cluster Analysis; D004249:DNA Damage; D045647:DNA Glycosylases / Q000235:genetics; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000378:metabolism; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000378:metabolism
chemical_list: C541874:MIRN92 microRNA, human; D035683:MicroRNAs; D000080242:8-Hydroxy-2'-Deoxyguanosine; D019098:Telomerase; D045647:DNA Glycosylases; C479058:oxoguanine glycosylase 1, human; D003849:Deoxyguanosine