ISSN:
0730-2312
Keywords:
human c-myc
;
transcription factors
;
promoters
;
human breast cancer
;
nuclear proteins
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
The expression of the c-myc gene is essential for the proliferation of both hormone-dependent and -independent human breast cancer cells. The regulation of c-myc gene expression in MCF-7 (hormone-dependent, estrogen-receptor (ER)-positive) and MDA MB 231 (hormone-independent, ER-negative) human breast cancer cells differs, with the c-myc gene of MCF-7 but not MDA MB 231 cells being regulated at the transcriptional level by estrogen. We have shown previously that the DNAase I hypersensitive (DH) sites in the c-myc chromatin of hormone-dependent and -independent human breast cancer cells were similar, with the exception of DH site II2, DH site II2, which maps near the P0 promoter, was less sensitive in hormone-dependent than in hormone-independent cells. As DH sites generally indicate the presence of sequence-specific DNA-binding proteins, we undertook a study to identify the nuclear proteins isolated from MCF-7 and MDA MB 231 cells that bound to the P0 and P2 promoter regions of the c-myc gene in vitro. The studies presented here provide evidence that Sp1 and/or Sp1-like proteins bind to the P0 and P2 promoter regions of the c-myc gene of MCF-7 and MDA MB 231 cells. Furthermore, evidence is presented for the presence of several previously unidentified sequence-specific DNA-binding proteins binding to these promoters. The DNA-binding activities of these latter proteins differed in the nuclear extracts of the MCF-7 and MDA MB 231 human breast cancer cells. © 1996 Wiley-Liss, Inc.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
