Androgen up-regulates vascular endothelial growth factor expression in prostate cancer cells via an Sp1 binding site.
BACKGROUND
Vascular Endothelial Growth Factor (VEGF) is regulated by a number of different factors, but the mechanism(s) behind androgen-mediated regulation of VEGF in prostate cancer are poorly understood.


RESULTS
Three novel androgen receptor (AR) binding sites were discovered in the VEGF promoter and in vivo binding of AR to these sites was demonstrated by chromatin immunoprecipitation. Mutation of these sites attenuated activation of the VEGF promoter by the androgen analog, R1881 in prostate cancer cells. The transcription factors AR and Sp1 were shown to form a nuclear complex and both bound the VEGF core promoter in chromatin of hormone treated CWR22Rv1 prostate cancer cells. The importance of the Sp1 binding site in hormone mediated activation of VEGF expression was demonstrated by site directed mutagenesis. Mutation of a critical Sp1 binding site (Sp1.4) in the VEGF core promoter region prevented activation by androgen. Similarly, suppression of Sp1 binding by Mithramycin A treatment significantly reduced VEGF expression.


CONCLUSIONS
Our mechanistic study of androgen mediated induction of VEGF expression in prostate cancer cells revealed for the first time that this induction is mediated through the core promoter region and is dependent upon a critical Sp1 binding site. The importance of Sp1 binding suggests that therapy targeting the AR-Sp1 complex may dampen VEGF induced angiogenesis and, thereby, block prostate cancer progression, helping to maintain the indolent form of prostate cancer.
School of Biomedical Sciences, Kent State University, Kent, OH, USA.
Kurtis
K
Eisermann
Carly J
CJ
Broderick
Anton
A
Bazarov
Mustafa M
MM
Moazam
Gail C
GC
Fraizer
D059002:Androgen Receptor Antagonists / Q000494:pharmacology; D000813:Anilides / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D002843:Chromatin / Q000378:metabolism; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D015741:Metribolone / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms; D011485:Protein Binding; D011944:Receptors, Androgen / Q000378:metabolism; D020218:Response Elements; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D045165:Testosterone Congeners / Q000494:pharmacology / Q000502:physiology*; D014105:Tosyl Compounds / Q000494:pharmacology; D015533:Transcriptional Activation; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics* / Q000378:metabolism
D059002:Androgen Receptor Antagonists; D000813:Anilides; D002843:Chromatin; D009570:Nitriles; D011944:Receptors, Androgen; D016329:Sp1 Transcription Factor; D045165:Testosterone Congeners; D014105:Tosyl Compounds; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D015741:Metribolone; C053541:bicalutamide