Journal
BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS
Volume 1819, Issue 1, Pages 38-56Publisher
ELSEVIER
DOI: 10.1016/j.bbagrm.2011.09.001
Keywords
TSPO; Breast cancer; Metastasis; Sp1; Sp3; Epigenetics
Categories
Funding
- National Institutes of Health [R01 ES07747]
- Susan G. Komen Breast Cancer Foundation
- Canada Research Chair in Biochemical Pharmacology
- Le Fonds de la recherche en sante du Quebec
Ask authors/readers for more resources
The translocator protein (18 kDa; TSPO) is a mitochondrial drug- and cholesterol-binding protein that has been implicated in several processes, including steroidogenesis, cell proliferation, and apoptosis. Expression of the human TSPO gene is elevated in several cancers. To understand the molecular mechanisms that regulate TSPO expression in human breast cancer cells, the TSPO promoter was identified, cloned, and functionally characterized in poor-in-TSPO hormone-dependent, non-aggressive MCF-7 cells and rich-in-TSPO hormone-independent, aggressive, and metastatic MDA-MB-231 breast cancer cells. RNA ligase-mediated 5'-rapid amplification of cDNA ends analysis indicated transcription initiated at multiple sites downstream of a GC-rich promoter that lacks functional TATA and CCAAT boxes. Deletion analysis indicated that the region from -121 to +66, which contains five putative regulatory sites known as GC boxes, was sufficient to induce reporter activity up to 24-fold in MCF-7 and nearly 120-fold in MDA-MB-231 cells. Electrophoretic mobility shift and chromatin immunoprecipitation assays indicated that Sp1, Sp3 and Sp4 bind to these GC boxes in vitro and to the endogenous TSPO promoter. Silencing of Sp1, Sp3 and Sp4 gene expression reduced TSPO levels. In addition. TSPO expression was epigenetically regulated at one or more of the identified GC boxes. Disruption of the sequence downstream of the main start site of TSPO differentially regulated TSPO promoter activity in MCF-7 and MDA-MB-231 cells, indicating that essential elements contribute to its differential expression in these cells. Taken together, these experiments constitute the first in-depth functional analysis of the human TSPO gene promoter and its transcriptional regulation. (C) 2011 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available