NF-IL6, a member of the C/EBP family of transcription factors, binds and trans-activates the human MDR1 gene promoter.
Revealing the regulatory mechanisms involved in P-glycoprotein expression is important to our understanding of multidrug resistance (MDR) in tumor cells. The MDR1 gene encoding P-glycoprotein contained a promoter sequence (-157 to -125) that was found to be homologous with other mdr gene promoters and that specifically interacted with a nuclear protein. The nuclear protein was identified, using a HeLa lambda gt11 cDNA expression library, to be the transcriptional regulator nuclear factor for interleukin-6 (NF-IL6), a member of the C/EBP family of transcription factors that bound an NF-IL-6-like consensus element 5'-TTTCGCAGT-3'. Furthermore, a glutathione S-transferase fusion protein (10.1-glutathione S-transferase) containing the partial NF-IL6 cDNA was also found to specifically interact with the MDR1 promoter sequence. Co-transfection of an NF-IL6 expression vector with a chloramphenicol acetyltransferase reporter gene driven by 1018 base pairs of MDR1 5'-flanking sequences demonstrated that NF-IL6 trans-activated the MDR1 promoter. This trans-activation was significantly reduced when the NF-IL6 element in the reporter gene construct was deleted or mutated. Identification of NF-IL6 as an important transcriptional regulator and the implications of its potential role in MDR1 gene induction in response to a variety of stimuli are discussed.
Combates
N J
NJ
Oncology Research Group, Sandoz Research Institute, Sandoz Pharmaceutical Corporation, East Hanover, New Jersey 07936.
Rzepka
R W
RW
Chen
Y N
YN
Cohen
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D
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D017124:Conserved Sequence; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D022762:CCAAT-Enhancer-Binding Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D015850:Interleukin-6; D009687:Nuclear Proteins; D014157:Transcription Factors