Cancers 2010, 2(2), 233-261; doi:10.3390/cancers2020233
Article

Identification of Insulin-Like Growth Factor-I Receptor (IGF-IR) Gene Promoter-Binding Proteins in Estrogen Receptor (ER)-Positive and ER-Depleted Breast Cancer Cells

1 Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel 2 Department of Clinical and Experimental Medicine, University Magna Graecia of Catanzaro, Catanzaro 88100, Italy
* Author to whom correspondence should be addressed.
Received: 23 February 2010; Accepted: 19 March 2010 / Published: 25 March 2010
(This article belongs to the Special Issue Breast Cancer)
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Abstract: The insulin-like growth factor I receptor (IGF-IR) has been implicated in the etiology of breast cancer. Overexpression of the IGF-IR gene is a typical feature of most primary breast cancers, whereas low IGF-IR levels are seen at advanced stages. Hence, evaluation of IGF-IR levels might be important for assessing prognosis. In the present study, we employed a proteomic approach based on DNA affinity chromatography followed either by mass spectroscopy (MS) or Western blot analysis to identify transcription factors that may associate with the IGF-IR promoter in estrogen receptor (ER)-positive and ER-depleted breast cancer cells. A biotinylated IGF-IR promoter fragment was bound to streptavidin magnetic beads and incubated with nuclear extracts of breast cancer cells. IGF-IR promoter-binding proteins were eluted with high salt and analyzed by MS and Western blots. Among the proteins that were found to bind to the IGF-IR promoter we identified zinc finger transcription factors Sp1 and KLF6, ER-, p53, c-jun, and poly (ADP-ribosylation) polymerase. Furthermore, chromatin immune-precipitation (ChIP) analysis confirmed the direct in vivo binding of some of these transcription factors to IGF-IR promoter DNA. The functional relevance of binding data was assessed by cotransfection experiments with specific expression vectors along with an IGF-IR promoter reporter. In summary, we identified nuclear proteins that are potentially responsible for the differential expression of the IGF-IR gene in ER-positive and ER-depleted breast cancer cells.
Keywords: transcription factors; estrogen receptor; insulin-like growth factor I receptor promoter; biomarkers; breast cancer

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MDPI and ACS Style

Sarfstein, R.; Belfiore, A.; Werner, H. Identification of Insulin-Like Growth Factor-I Receptor (IGF-IR) Gene Promoter-Binding Proteins in Estrogen Receptor (ER)-Positive and ER-Depleted Breast Cancer Cells. Cancers 2010, 2, 233-261.

AMA Style

Sarfstein R, Belfiore A, Werner H. Identification of Insulin-Like Growth Factor-I Receptor (IGF-IR) Gene Promoter-Binding Proteins in Estrogen Receptor (ER)-Positive and ER-Depleted Breast Cancer Cells. Cancers. 2010; 2(2):233-261.

Chicago/Turabian Style

Sarfstein, Rive; Belfiore, Antonino; Werner, Haim. 2010. "Identification of Insulin-Like Growth Factor-I Receptor (IGF-IR) Gene Promoter-Binding Proteins in Estrogen Receptor (ER)-Positive and ER-Depleted Breast Cancer Cells." Cancers 2, no. 2: 233-261.

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