Upregulation of the truncated basic hair keratin 1(hHb1-DeltaN) in carcinoma cells by Epstein-Barr virus (EBV).
To investigate the role of Epstein-Barr virus (EBV) in epithelial tumors, we compared the expression pattern of cellular genes in the EBV-infected gastric carcinoma cell line, NU-GC-3, and its uninfected control. Subtractive suppression hybridization (SSH) was combined with high-density DNA array screening to identify differentially expressed genes. We have discovered that EBV infection upregulated a truncated variant of human basic hair keratin 1 (hHb1-DeltaN), a gene that had previously been identified in metastatic breast carcinoma. We verified the differential expression of hHb1-DeltaN in 3 independent EBV-positive and -negative NU-GC-3 clones by Northern blotting. We further verified the EBV-dependent upregulation of hHb1-DeltaN in 3 other carcinoma cell lines (AGS, TWO3 and DLD1) by RT-PCR. Inhibition of CpG methylation by 5-Aza-CdR induced hHb1-DeltaN mRNA expression in the EBV-negative clones but did not alter the expression in the EBV-positive clones. The expression of hHb1-DeltaN protein was detectable by immunofluorescence and Western blotting in EBV-positive but not in EBV-negative NU-GC-3 clones after proteasome inhibitor (MG132) treatment. hHb1-DeltaN protein formed fibrous structures in the cytoplasm and accumulated in distinct nuclear bodies in the euchromatic areas of the cell nucleus. We suggest that the unstable hHb1-DeltaN protein may inhibit some of the functions of the keratin cytoskeleton and/or interfere with transcription regulation. It also may establish a link between EBV and the low differentiated or anaplastic status of the carcinomas that carry the virus.
Nishikawa
Jun
J
Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, Sweden.
Kiss
Csaba
C
Imai
Shousuke
S
Takada
Kenzo
K
Okita
Kiwamu
K
Klein
George
G
Szekely
Laszlo
L
D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D018899:CpG Islands; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D004854:Herpesvirus 4, Human / Q000502:physiology*; D006801:Humans; D007633:Keratins / Q000235:genetics / Q000378:metabolism*; D007976:Leupeptins / Q000494:pharmacology; D020411:Oligonucleotide Array Sequence Analysis; D014176:Protein Biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000821:virology; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D015853:Cysteine Proteinase Inhibitors; D004791:Enzyme Inhibitors; D007976:Leupeptins; D007633:Keratins; D000077209:Decitabine; D015254:DNA Modification Methylases; D001374:Azacitidine; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde