title: Steroid receptor coactivator-3 and activator protein-1 coordinately regulate the transcription of components of the insulin-like growth factor/AKT signaling pathway.
abstract: Steroid receptor coactivator (SRC)-3, also called amplified in breast cancer 1, is a member of the p160 nuclear receptor coactivator family involved in transcriptional regulation of target genes. SRC-3 is frequently amplified and/or overexpressed in hormone-sensitive and hormone-insensitive tumors. We reported previously that SRC-3 stimulated prostate cell growth in a hormone-independent manner through activation of AKT signaling pathway. However, the underlying mechanism remains undefined. Here, we exploited the mifepristone-induced SRC-3 LNCaP prostate cancer cell line generated in our laboratory to identify SRC-3-regulated genes by oligonucleotide microarray analysis. We found that SRC-3 up-regulates the expression of multiple genes in the insulin-like growth factor (IGF)/AKT signaling pathway that are involved in cell proliferation and survival. In contrast, knockdown of SRC-3 in PC3 (androgen receptor negative) prostate cancer cells and MCF-7 breast cancer cells reduces their expression. Similarly, in prostate glands of SRC-3 null mice, expressions of these components in the IGF/AKT signal pathway are also reduced. Chromatin immunoprecipitation assay revealed that SRC-3 was directly recruited to the promoters of these genes, indicating that they are direct targets of SRC-3. Interestingly, we showed that recruitment of SRC-3 to two target promoters, IRS-2 and IGF-I, requires transcription factor activator protein-1 (AP-1). Taken together, our results clearly show that SRC-3 and AP-1 can coordinately regulate the transcription of multiple components in the IGF/AKT pathway to ensure ligand-independent cell proliferation and survival of cancer cells.
authors.affiliation: Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Yan
authors.forename: Cheng-Tai
authors.initials: CT
authors.lastname: Yu
authors.forename: Mustafa
authors.initials: M
authors.lastname: Ozen
authors.forename: Michael
authors.initials: M
authors.lastname: Ittmann
authors.forename: Sophia Y
authors.initials: SY
authors.lastname: Tsai
authors.forename: Ming-Jer
authors.initials: MJ
authors.lastname: Tsai
mesh_terms: D000818:Animals; D051548:Histone Acetyltransferases / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D006801:Humans; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D056921:Nuclear Receptor Coactivator 3; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000096:biosynthesis / Q000235:genetics*; D015398:Signal Transduction; D013002:Somatomedins / Q000096:biosynthesis / Q000235:genetics*; D015534:Trans-Activators / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics*; D018808:Transcription Factor AP-1 / Q000096:biosynthesis / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection; D015854:Up-Regulation
chemical_list: C526297:IRS2 protein, human; D055504:Insulin Receptor Substrate Proteins; D047908:Intracellular Signaling Peptides and Proteins; C526298:Irs2 protein, mouse; D010750:Phosphoproteins; D013002:Somatomedins; D015534:Trans-Activators; D018808:Transcription Factor AP-1; D051548:Histone Acetyltransferases; C538866:NCOA3 protein, human; C538867:Ncoa3 protein, mouse; D056921:Nuclear Receptor Coactivator 3; D051057:Proto-Oncogene Proteins c-akt