In vivo and in vitro expression of octamer binding proteins in human melanoma metastases, brain tissue, and fibroblasts.
The pattern of octamer sequence-specific DNA binding proteins expressed in human melanoma was examined in nuclear extracts of seven surgically-isolated tumors, short-term cultures of these tumors, and 25 human melanoma cell lines to determine the in vivo and in vitro distribution of the melanocytic-associated Oct-M1 and Oct-M2 octamer binding activities. In the biopsy tissue and cultured melanoma cells of a metastasis from the cerebellum, two other binding activities (N-Oct-2 and N-Oct-6) in addition to the Oct-M1, Oct-M2 and the generally expressed Oct-1 protein were detected; this profile was consistent with that seen in normal human and mouse brain tissue. Melanoma tissue removed from lymph nodes and cell lines established from them also showed Oct-1, Oct-M1, Oct-M2, and N-Oct-2. N-Oct-2 was distinguished from the comigrating Oct-2A activity by failure to react with Oct-2A-specific antibody. All but one of the 25 melanoma cell lines exhibited Oct-1, Oct-M1, and Oct-M2 and/or N-Oct-2 activity, whereas cultured normal melanocytes expressed only Oct-1 and Oct-M1. In contrast to murine fibroblasts, which express only Oct-1, human fibroblast strains also expressed Oct-2A binding activity, which was confirmed by reactivity with Oct-2A antibody and the presence of Oct-2A mRNA and indicated that Oct-2A has a more general role than that of a lymphoid-specific transcription factor. Overall, the results indicate that expression of neural-specific Oct factors in human melanoma is (1) aberrant compared with normal melanocytes, (2) can be modulated by the surrounding tissue in a brain metastasis, and (3) may be part of the altered program of differentiation accompanying transformation.
Thomson
J A
JA
Queensland Cancer Fund Research Unit, Queensland Institute of Medical Research, Herston, Australia.
Parsons
P G
PG
Sturm
R A
RA
D000818:Animals; D001483:Base Sequence; D001923:Brain Chemistry; D004268:DNA-Binding Proteins / Q000032:analysis*; D005347:Fibroblasts / Q000737:chemistry*; D006801:Humans; D008545:Melanoma / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D050813:Octamer Transcription Factor-2; D014157:Transcription Factors / Q000032:analysis; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D050813:Octamer Transcription Factor-2; C058435:POU2F2 protein, human; C489206:Pou2f2 protein, mouse; D014157:Transcription Factors