Identification of the elements regulating the expression of the cell adhesion molecule MCAM/MUC18. Loss of AP-2 is not required for MCAM expression in melanoma cell lines.
The cell adhesion molecule melonoma cell adhesion molecule (MCAM)/MUC18/CD146 is specifically up-regulated on tumors of neuroectodermal origin and in animal models confers metastatic capacity to human melanoma cells. To identify critical regions regulating MCAM expression in melanomas, 1 kilobase of the MCAM 5' region was analyzed for promoter activity and transcription factor binding in 1 glioma, 1 carcinoma, and 4 melanoma cell lines. The minimal MCAM promoter (-106/+22 base pair (bp)) consists of 4 Sp-1 sites, two AP-2 elements, one cAMP responsive element, and the initiator surrounding the transcriptional start site. Analysis of mutated constructs indicated that the cAMP-responsive element is a major transcriptional activator in the majority of cell lines. Site-directed mutagenesis revealed that, in AP-2 expressing cells, the AP-2 site within the core promoter (-23 bp) has an inhibitory influence on MCAM expression while the AP-2 sites at -131 and -302 bp are activating. Functional AP-2 was observed in both MCAM positive and MCAM negative melanoma cell lines indicating that expression of MCAM does not require loss of this transcription factor. Furthermore, all MCAM constructs were strongly expressed in MCAM negative as well as MCAM positive cells, indicating that the expression of this gene is not controlled solely by the presence of transactivating factors binding to the investigated region.
Mintz-Weber
C S
CS
Institute for Immunology, University of Munich, Munich 80336, Germany.
Johnson
J P
JP
D015703:Antigens, CD; D000954:Antigens, Surface / Q000235:genetics*; D001483:Base Sequence; D051929:CD146 Antigen; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D008545:Melanoma / Q000235:genetics*; D008562:Membrane Glycoproteins; D016297:Mutagenesis, Site-Directed; D019006:Neural Cell Adhesion Molecules; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D017384:Sequence Deletion; D050656:Transcription Factor AP-2; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics*; D014407:Tumor Cells, Cultured
D015703:Antigens, CD; D000954:Antigens, Surface; D051929:CD146 Antigen; D017931:DNA Primers; D004268:DNA-Binding Proteins; C497902:MCAM protein, human; D008562:Membrane Glycoproteins; D019006:Neural Cell Adhesion Molecules; D012333:RNA, Messenger; D050656:Transcription Factor AP-2; D014157:Transcription Factors