Investigation of the expression of Bin1, a putative suppressor, in human hepatoma cells.
Recent data suggest that Bin1, a novel C-MYC interacting protein, is a suppressor gene whose loss of expression is a frequent aberration associated with several malignancies. The mechanism responsible for loss of BIN1 expression is not understood. The purpose of this study is to investigate DNA profile of the BIN1 gene in human hepatoma Hep G2 cells, previously documented with lack of BIN1 expression. Chromosome and molecular analyses of Hep G2 cells were initiated to exclude the possibility of genetic alterations as a factor affecting BIN1 gene expression in these cells. We used Hep G2 cell line and its hepatitis B virus (HBV) transfected variants--Hep G2T14.1 and Hep G2215 cell lines. The cytogenetic localization of BIN1 was identified in the 2q14 region. Fluorescence in situ hybridization (FISH) with the chromosome 2 whole chromosome painting probe (WCP) demonstrated three or four intact copies of chromosome 2 in all three hepatoma cell lines studied. FISH analyses with the BIN1-specific probe of the Hep G2, Hep G2T14.1, and Hep G2215 metaphase chromosomes document no rearrangement of the BIN1 gene on any of the multiple copies of chromosome 2. FISH with the specific HBV probe did not identify the HBV integration site in Hep G2T14.1 and Hep G2215 cells within the BIN1 locus. Southern blot analyses revealed no genetic rearrangements in the BIN1 gene in any of the cell lines studied. Our RNA analyses (northern blot and RT-PCR) document lack of BIN1 message in Hep G2 cells in contrast to the presence of BIN1 in Hep G2T14.1 and Hep G2215 cells. No difference was identified in other transcripts analyzed, including c-myc. Analyses of BIN1 expression of Hep G2 cells at different passages were initiated and document low levels of BIN1 transcript in Hep G2 cells of passage < 85. Furthermore, BIN1 transcript was identified in additional seven HCC cell lines analyzed. Our data indicate that lack of Bin1 expression in HepG2 cells previously documented is a characteristic of cells of passage > 85 and is not due to genetic loss, or rearrangement within the BIN1 DNA sequence. Loss of the BIN1 transcript is not a characteristic of HCCs analyzed.
Livezey
K W
KW
MCP Hahnemann University, School of Medicine, Department of Pathology, Philadelphia, Pennsylvania, USA.
Negorev
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D
Simon
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D048868:Adaptor Proteins, Signal Transducing; D015152:Blotting, Northern; D015139:Blotting, Southern; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000821:virology; D002352:Carrier Proteins / Q000235:genetics*; D020223:Chromosome Painting; D002889:Chromosomes, Human, Pair 2; D004262:DNA Restriction Enzymes; D015870:Gene Expression; D016147:Genes, Tumor Suppressor; D006515:Hepatitis B virus / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008113:Liver Neoplasms / Q000235:genetics* / Q000821:virology; D009687:Nuclear Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins
D048868:Adaptor Proteins, Signal Transducing; C101410:BIN1 protein, human; D002352:Carrier Proteins; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; D004262:DNA Restriction Enzymes