MZF1 possesses a repressively regulatory function in ERCC1 expression.
ERCC1 is a critical gene within the nucleotide excision repair pathway. Overexpression of ERCC1 through promoter-mediating transcriptional regulation is associated with repair of cisplatin-induced DNA damage and clinical resistance to platinum-chemotherapy. Several transcriptional repressors and activators within the 5'-flanking region of the ERCC1 gene may be involved in the up-regulation of this gene. Minimal sequence within the promoter region required for ERCC1 transcription was analyzed by CAT assay and demonstrated that the region of -220 to -110 is essential to constitutive expression of ERCC1 gene in ovarian cancer cell line A2780/CP70. A more forward upstream region seems to be responsible for cisplatin-induced expression. Study of the functional cis-element in this region by electrophoretic mobility shift assay indicates that a MZF1-like site as well as an AP1-like site responded in a time-dependent manner to cisplatin stimulation with altered binding activities. EMSA with MZF1 ZN1-4 consensus oligonucleotides suggests that the MZF1 N-terminal domain of zinc finger cluster may bind to the MZF1-like site of the ERCC1 promoter region. MZF1 mRNA in A2780/CP70 cells decreased upon cisplatin exposure as analyzed by quantitative PCR, suggesting that MZF1 may mediate cisplatin-invoked gene expression in these cells. Overexpression of MZF1 repressed the ERCC1 promoter activity as determined in co-transfection assay, suggesting that MZF1 might be a repressor of ERCC1 transcription upon cisplatin exposure. In summary, our studies revealed a core promoter region and adjacent drug-responsible region within the ERCC1 promoter. The drug-responsible region contains cis-elements of activator, AP1 and repressor, MZF1. In response to cisplatin treatment, decreased MZF1 and increased AP1 binding activities appear to be the leading mechanism of up-regulation of ERCC1 expression. Our findings imply potential therapeutic strategies to antagonize drug resistant mechanisms in treatment of human ovarian cancer.
Yan
Qing-Wu
QW
Department of Biochemistry and Molecular Pharmacology, and Mary Babb Randolph Cancer Center, Robert C. Byrd Health Sciences Center, West Virginia University, 1610-C Health Sciences South, Morgantown, WV 26506-9300, USA.
Reed
Eddie
E
Zhong
Xiao-Song
XS
Thornton
Keith
K
Guo
Yi
Y
Yu
Jing Jie
JJ
D000230:Adenocarcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D000970:Antineoplastic Agents / Q000494:pharmacology; D001483:Base Sequence; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology / Q000627:therapeutic use; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004720:Endonucleases / Q000235:genetics* / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D008969:Molecular Sequence Data; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000032:analysis; D012334:RNA, Neoplasm / Q000032:analysis; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation; D016335:Zinc Fingers
D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; C085969:MZF1 protein, human; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D018808:Transcription Factor AP-1; D014157:Transcription Factors; C071447:ERCC1 protein, human; D004720:Endonucleases; D002945:Cisplatin