Activating transcription factor-1-mediated hepatocyte growth factor-induced down-regulation of thrombospondin-1 expression leads to thyroid cancer cell invasion.
Hepatocyte growth factor (HGF) plays a major role in the pathogenesis of a variety of human epithelial tumors including papillary carcinoma of the thyroid. Previous reports demonstrated that HGF, acting through the Met receptor, repressed thrombospondin-1 (TSP-1) expression. To study the mechanisms by which HGF down-regulated TSP-1 expression, we transiently transfected a panel of deleted human TSP-1 promoter reporter plasmids into papillary thyroid carcinoma cells. We identified a region between -1210 and -1123 bp relative to the transcription start site that is responsive to HGF treatment and harbors a cAMP-responsive element (CRE) at position -1199 (TGACGTCC). Overexpression of various members of the CRE-binding protein family identified activating transcription factor-1 (ATF-1) as the transcription factor responsible for HGF-induced repression of TSP-1 promoter activity. This inhibition was associated with a concomitant increase in the abundance of nuclear ATF-1 protein. Gel shift and antibody supershift studies indicated that ATF-1 was involved in DNA binding to the TSP-1-CRE site. Finally, we utilized small hairpin RNA to target ATF-1 and showed that these small interfering RNA constructs significantly inhibited ATF-1 expression at both the RNA and the protein level. ATF-1 knockdown prevented HGF-induced down-regulation of TSP-1 promoter activity and protein expression and also reduced HGF-dependent tumor cell invasion. Taken together, our results indicate that HGF-induced down-regulation of TSP-1 expression is mediated by the interaction of ATF-1 with the CRE binding site in the TSP-1 promoter and that this transcription factor plays a crucial role for tumor invasiveness in papillary carcinoma of the thyroid triggered by HGF.
Ghoneim
Christelle
C
Unité Matrice Extracellulaire et Régulations Cellulaires, Laboratory of Biochemistry, Université de Reims Champagne Ardenne (URCA), CNRS, 51687 Reims, France.
Soula-Rothhut
Mahdhia
M
Blanchevoye
Charlotte
C
Martiny
Laurent
L
Antonicelli
Frank
F
Rothhut
Bernard
B
D051697:Activating Transcription Factor 1; D002291:Carcinoma, Papillary / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D017228:Hepatocyte Growth Factor / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D000071701:Regulatory Factor X Transcription Factors; D020218:Response Elements; D019700:Thrombospondin 1 / Q000096:biosynthesis* / Q000235:genetics; D013964:Thyroid Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors
C531110:ATF1 protein, human; D051697:Activating Transcription Factor 1; D004268:DNA-Binding Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000071701:Regulatory Factor X Transcription Factors; D019700:Thrombospondin 1; D014157:Transcription Factors; D017228:Hepatocyte Growth Factor