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Proc Natl Acad Sci U S A. 2001 Jan 30;98(3):992-9.

Defective repression of c-myc in breast cancer cells: A loss at the core of the transforming growth factor beta growth arrest program.

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  • 1Cell Biology Program, Memorial Sloan-Kettering Cancer Center and Howard Hughes Medical Institute, New York, NY 10021, USA.

Abstract

Loss of growth inhibitory responses to the cytokine transforming growth factor beta (TGF-beta) in cancer cells may result from mutational inactivation of TGF-beta receptors or their signal transducers, the Smad transcription factors. In breast cancer, however, loss of TGF-beta growth inhibition often occurs without a loss of these signaling components. A genome-wide analysis of rapid TGF-beta gene responses in MCF-10A human mammary epithelial cells and MDA-MB-231 breast cancer cells shows that c-myc repression, a response that is key to the TGF-beta program of cell cycle arrest, is selectively lost in the cancer cell line. Transformation of MCF-10A cells with c-Ha-ras and c-erbB2 oncogenes also led to a selective loss of c-myc repression and cell cycle arrest response. TGF-beta stimulation of epithelial cells rapidly induces the formation of a Smad complex that specifically recognizes a TGF-beta inhibitory element in the c-myc promoter. Formation of this complex is deficient in the oncogenically transformed breast cells. These results suggest that a Smad complex that specifically mediates c-myc repression is a target of oncogenic signals in breast cancer.

PMID:
11158583
PMCID:
PMC14697
DOI:
10.1073/pnas.98.3.992
[PubMed - indexed for MEDLINE]
Free PMC Article
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