title: Novel pre-mRNA splicing of intronically integrated HBV generates oncogenic chimera in hepatocellular carcinoma.
abstract: Hepatitis B virus (HBV) integration is common in HBV-associated hepatocellular carcinoma (HCC) and may play an important pathogenic role through the production of chimeric HBV-human transcripts. We aimed to screen the transcriptome for HBV integrations in HCCs.
  
  
  
  Transcriptome sequencing was performed on paired HBV-associated HCCs and corresponding non-tumorous liver tissues to identify viral-human chimeric sites. Validation was further performed in an expanded cohort of human HCCs.
  
  
  
  Here we report the discovery of a novel pre-mRNA splicing mechanism in generating HBV-human chimeric protein. This mechanism was exemplified by the formation of a recurrent HBV-cyclin A2 (CCNA2) chimeric transcript (A2S), as detected in 12.5% (6 of 48) of HCC patients, but in none of the 22 non-HCC HBV-associated cirrhotic liver samples examined. Upon the integration of HBV into the intron of the CCNA2 gene, the mammalian splicing machinery utilized the foreign splice sites at 282nt. and 458nt. of the HBV genome to generate a pseudo-exon, forming an in-frame chimeric fusion with CCNA2. The A2S chimeric protein gained a non-degradable property and promoted cell cycle progression, demonstrating its potential oncogenic functions.
  
  
  
  A pre-mRNA splicing mechanism is involved in the formation of HBV-human chimeric proteins. This represents a novel and possibly common mechanism underlying the formation of HBV-human chimeric transcripts from intronically integrated HBV genome with functional impact.
  
  
  
  HBV is involved in the mammalian pre-mRNA splicing machinery in the generation of potential tumorigenic HBV-human chimeras. This study also provided insight on the impact of intronic HBV integration with the gain of splice sites in the development of HBV-associated HCC.
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Pathology, The University of Hong Kong, Hong Kong.
authors: Yung-Tuen
authors: YT
authors: Chiu
authors: Department of Psychiatry, The University of Hong Kong, Hong Kong.
authors: John K L
authors: JK
authors: Wong
authors: Department of Psychiatry, The University of Hong Kong, Hong Kong.
authors: Shing-Wan
authors: SW
authors: Choi
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Pathology, The University of Hong Kong, Hong Kong.
authors: Karen M F
authors: KM
authors: Sze
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Pathology, The University of Hong Kong, Hong Kong.
authors: Daniel W H
authors: DW
authors: Ho
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Pathology, The University of Hong Kong, Hong Kong.
authors: Lo-Kong
authors: LK
authors: Chan
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Pathology, The University of Hong Kong, Hong Kong.
authors: Joyce M F
authors: JM
authors: Lee
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Surgery, The University of Hong Kong, Hong Kong.
authors: Kwan
authors: K
authors: Man
authors: Department of Psychiatry, The University of Hong Kong, Hong Kong.
authors: Stacey
authors: S
authors: Cherny
authors: Department of Pediatrics and Adolescent Medicine, The University of Hong Kong, Hong Kong.
authors: Wan-Ling
authors: WL
authors: Yang
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Pathology, The University of Hong Kong, Hong Kong. Electronic address: jackwong@pathology.hku.hk.
authors: Chun-Ming
authors: CM
authors: Wong
authors: Department of Psychiatry, The University of Hong Kong, Hong Kong. Electronic address: pcsham@hku.hk.
authors: Pak-Chung
authors: PC
authors: Sham
authors: State Key Laboratory for Liver Research, The University of Hong Kong, Hong Kong; Department of Pathology, The University of Hong Kong, Hong Kong. Electronic address: iolng@hku.hk.
authors: Irene O L
authors: IO
authors: Ng
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000821:virology; D056751:Cyclin A2 / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics; D007438:Introns; D008113:Liver Neoplasms / Q000235:genetics / Q000821:virology; D015514:Oncogene Proteins, Fusion / Q000096:biosynthesis; D012322:RNA Precursors / Q000235:genetics; D012326:RNA Splicing; D059467:Transcriptome; D016662:Virus Integration
chemical_list: C503721:CCNA2 protein, human; D056751:Cyclin A2; D015514:Oncogene Proteins, Fusion; D012322:RNA Precursors
keywords: Cyclin A2; HBV integration; Hepatocellular carcinoma; Splicing