During human melanoma progression AP-1 binding pairs are altered with loss of c-Jun in vitro.
We demonstrated previously that c-Jun, JunB and c-Fos RNA were dysregulated in metastatic melanoma cells compared with normal human melanocytes. The purpose of this study was to evaluate the distribution in composition of AP-1 dimers in human melanoma pathogenesis. We investigated AP-1 dimer pairing in radial growth phase-like (RGP) (w3211) and vertical growth phase-like (VGP) (w1205) human melanoma cells and metastatic cell lines (cloned from patients, c83-2c, c81-46A, A375, respectively) compared with melanocytes using electrophoretic mobility shift assay (EMSA), Western blot and transfection analyses. There are progressive variations in AP-1 composition in different melanoma cell lines compared with normal melanocytes, in which c-Jun, JunD and FosB were involved in AP-1 complexes. In w3211, c-Jun, JunD and Fra-1 were involved in AP-1 binding, while in w1205, overall AP-1 binding activity was decreased significantly and supershift binding was detected only with JunD antibodies. In metastatic c81-46A and A375 cells, only JunD was involved in AP-1 binding activity, but in a third (c83-2c) c-Jun, JunD and Fra-1 were present. Western blot evaluation detected c-Jun in melanocytes and w3211, but this component was decreased significantly or was not detectable in w1205, c81-46A and A375 cells. In contrast, JunD protein was elevated in c81-46A and c83-2c cells compared with melanocytes and RGP and VGP cell lines. Normal melanocytes and c83-2c cells (which have c-Jun involved in AP-1 binding), transfected with c-Jun antisense and treated with cisplatin, showed higher viability compared with untransfected cells, while in c81-46A cells (in which only JunD is detectable) no change in cell viability was observed following treatment with cisplatin and c-jun antisense transfection. A dominant-negative c-Jun mutant (TAM67) significantly increased the soft agar colony formation of w3211 and c83-2c cells. These results suggest that components of AP-1, especially c-Jun, may offer a new target for the prevention or treatment of human melanoma progression.
Yang
Sun
S
Department of Medicine, Chao Family Comprehensive Cancer Center, University of California, Irvine, Orange, CA 92868, USA.
McNulty
Susan
S
Meyskens
Frank L
FL
D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D006801:Humans; D008544:Melanocytes / Q000166:cytology / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D020320:Oligoribonucleotides, Antisense; D011401:Promoter Regions, Genetic / Q000502:physiology*; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000187:drug effects / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology
D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D020320:Oligoribonucleotides, Antisense; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D014157:Transcription Factors