Cloning of an ets-Related Transcription Factor Involved in a Novel Epigenetic Mechanism of Mammary Carcinogenesis
Abstract
Our previous studies in pubescent female rats suggested that nitrosomethylurea (NMU) mediated epigenetic effects on DNA conformation within the Ha-ras promoter contributes to mammary carcinogenesis. The DNA region affected by NMU includes a transcriptional element identical to Ha-ras response element (HRE) found in human Ha-ras promoter. To identify the trans-acting factors that bind to the HRE sequence in mammary cells, we employed sequence specific DNA affinity chromatography and amino acid sequencing by tandem mass spectroscopy. CARG box-binding factor A (CBF-A) is the major protein species in mammary cells that bind specifically to the rat and human HRE sequence with high affinities. Transient transfection assays using reporter plasmids verified that mutations within the HRE that disrupt binding of CBF-A, also reduced the activity of the rat Ha-ras promoter. We demonstrated a correlation between HRE binding activity, induction of Ha-ras mRNA expression and cell cycle progression following serum stimulation in the mammary carcinoma cell line. Our results further showed that CBF-A activity is regulated by post-translational modifications. Further results indicated increased CBF-A activity in chemically induced rodent tumors, suggesting an plays an important role in the regulation of the Ha-ras promoter during in vivo carcinogenesis.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2001
- Accession Number
- ADB267884
Entities
People
- Helmut Zarbl