Progression of carcinoma cells is associated with alterations in chromatin structure and factor binding at the E-cadherin promoter in vivo.
E-cadherin has been identified as a tumor (invasion) suppressor gene, which is mutated in 50% of diffuse-type human gastric carcinomas. In other carcinomas, the expression of E-cadherin is down-regulated in the poorly differentiated cells such as from breast, bladder, lung and colon. We have here examined the in vivo properties of the genomic E-cadherin promoter in well and poorly differentiated carcinoma cell lines in order to gain insights into the mechanisms of E-cadherin down-regulation in tumors. In vivo footprinting analysis revealed that positive regulatory elements of the E-cadherin promoter (a GC-rich region, the CCAAT-box and a palindromic element) are specifically bound by transcription factors in E-cadherin-expressing but not in non-expressing cells. The tested cell systems include more than a dozen carcinomas cell lines as well as mammary epithelial cells where E-cadherin expression can be switched off by activation of a Fos-estrogen receptor fusion protein and rhabdomyosarcoma cells where E-cadherin expression was induced by transfection with E1A. Mapping of DNase I hypersensitive sites showed that the chromatin structure in the promoter region is loosened in expressing but condensed in non-expressing cells. Furthermore, the endogenous E-cadherin promoter is specifically methylated at CpG sites in the undifferentiated cells. We also show that the in vivo properties of the promoter in E-caherin-negative carcinoma cells are similar as in mesenchymal cells, i.e. fibroblasts or sarcoma cells. These data suggest that silencing of the E-cadherin promoter during epithelialmesenchymal transition and tumor progression is due to a loss of factor binding in vivo and to chromatin rearrangement in the regulatory region.
Hennig
G
G
Max-Delbrück-Centrum für Molekulare Medizin, Berlin, Germany.
Behrens
J
J
Truss
M
M
Frisch
S
S
Reichmann
E
E
Birchmeier
W
W
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015820:Cadherins / Q000235:genetics*; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology*; D002843:Chromatin / Q000648:ultrastructure*; D004268:DNA-Binding Proteins / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D005796:Genes; D066298:In Vitro Techniques; D008745:Methylation; D051379:Mice; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D014407:Tumor Cells, Cultured
D015820:Cadherins; D002843:Chromatin; D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D003850:Deoxyribonuclease I