Role of the human Y box-binding protein YB-1 in cellular sensitivity to the DNA-damaging agents cisplatin, mitomycin C, and ultraviolet light.
The Y box-binding protein (YB-1) binds to DNA sequences, present in the control regions of many genes, that contain an inverted CCAAT box. The binding activity of a nuclear factor, designated MDR-NF1, to an inverted CCAAT box in the promoter of the multidrug resistance 1 (MDR1) gene has previously been shown to be increased in nuclear extracts of cells exposed to UV radiation or various anticancer agents. The MDR-NF1 cDNA has now been cloned by screening a human colon library with an active fragment of the MDR1 promoter. The amino acid sequence encoded by the cloned cDNA was identical to that of YB-1. Northern blot analysis revealed that YB-1 mRNA was present in all human tissues examined. Rabbit antibodies were generated against synthetic peptides corresponding to YB-1, and indirect immunofluorescence microscopy with these antibodies showed that the concentration of YB-1 in all cisplatin-resistant cell lines examined was higher than that in the respective drug-sensitive parental cells. Transfection of human epidermoid cancer KB cells with a YB-1 antisense construct established two cell lines with reduced concentrations of YB-1. These transfectants showed increased sensitivity to cisplatin, mitomycin C, and UV radiation but not to vincristine, doxorubicin, camptothecin, or etoposide. Thus, YB-1 may protect cells from the cytotoxic effects of agents that induce cross-linking of DNA, suggesting a novel function of this ancestor DNA-binding protein.
Ohga
T
T
Department of Biochemistry, Kyushu University School of Medicine, Fukuoka, Japan.
Koike
K
K
Ono
M
M
Makino
Y
Y
Itagaki
Y
Y
Tanimoto
M
M
Kuwano
M
M
Kohno
K
K
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D000970:Antineoplastic Agents / Q000633:toxicity*; D022762:CCAAT-Enhancer-Binding Proteins; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002945:Cisplatin / Q000633:toxicity*; D003110:Colonic Neoplasms; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000502:physiology*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D007624:KB Cells; D008297:Male; D016685:Mitomycin / Q000633:toxicity*; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis; D014157:Transcription Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays; D051840:Y-Box-Binding Protein 1
D000906:Antibodies; D000970:Antineoplastic Agents; D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; D016685:Mitomycin; D002945:Cisplatin