Alteration of gene expression in human hepatocellular carcinoma with integrated hepatitis B virus DNA.
OBJECTIVE
Integration of hepatitis B virus (HBV) DNA into the human genome is one of the most important steps in HBV-related carcinogenesis. This study attempted to find the link between HBV DNA, the adjoining cellular sequence, and altered gene expression in hepatocellular carcinoma (HCC) with integrated HBV DNA.


METHODS
We examined 15 cases of HCC infected with HBV by cassette ligation-mediated PCR. The human DNA adjacent to the integrated HBV DNA was sequenced. Protein coding sequences were searched for in the human sequence. In five cases with HBV DNA integration, from which good quality RNA was extracted, gene expression was examined by cDNA microarray analysis.


RESULTS
The human DNA sequence successive to integrated HBV DNA was determined in the 15 HCCs. Eight protein-coding regions were involved: ras-responsive element binding protein 1, calmodulin 1, mixed lineage leukemia 2 (MLL2), FLJ333655, LOC220272, LOC255345, LOC220220, and LOC168991. The MLL2 gene was expressed in three cases with HBV DNA integrated into exon 3 of MLL2 and in one case with HBV DNA integrated into intron 3 of MLL2. Gene expression analysis suggested that two HCCs with HBV integrated into MLL2 had similar patterns of gene expression compared with three HCCs with HBV integrated into other loci of human chromosomes.


CONCLUSIONS
HBV DNA was integrated at random sites of human DNA, and the MLL2 gene was one of the targets for integration. Our results suggest that HBV DNA might modulate human genes near integration sites, followed by integration site-specific expression of such genes during hepatocarcinogenesis.
Tamori
Akihiro
A
Department of Hepatology, Osaka City University Graduate School of Medicine, Osaka, Japan. atamori@med.osaka-cu.ac.jp
Yamanishi
Yoshihiro
Y
Kawashima
Shuichi
S
Kanehisa
Minoru
M
Enomoto
Masaru
M
Tanaka
Hiromu
H
Kubo
Shoji
S
Shiomi
Susumu
S
Nishiguchi
Shuhei
S
D000328:Adult; D000368:Aged; D001483:Base Sequence; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000821:virology; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006509:Hepatitis B / Q000235:genetics / Q000821:virology; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D007680:Kidney Neoplasms / Q000235:genetics* / Q000821:virology; D020930:MAP Kinase Kinase Kinases / Q000235:genetics; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D016662:Virus Integration / Q000235:genetics
D004273:DNA, Neoplasm; D004279:DNA, Viral; D012333:RNA, Messenger; D020930:MAP Kinase Kinase Kinases; C093290:MAP3K10 protein, human