Regulation of human osteocalcin promoter in hormone-independent human prostate cancer cells.
Osteocalcin (OC) is a small (6 kDa) polypeptide whose expression was thought to be limited to mature osteoblasts. The discovery of OC expression in prostate cancer specimens led us to study the regulation of OC gene in androgen-independent metastatic human prostate PC3 cells. An 800-bp human OC (hOC) promoter-luciferase construct exhibited strong basal and vitamin D-induced activity in OC-positive human prostate and osteosarcoma cell lines. Through deletion analysis of the hOC promoter, the functional hierarchy of the cis-acting elements, OSE1, OSE2, and AP-1/VDRE, was established in PC3 cells (OSE1 > AP-1/VDRE > OSE2). By juxtaposing dimers of these 3 cis-elements, we produced a minimal hOC promoter capable of displaying high tissue specific activity in prostate cancer cells. Our study demonstrated three groups of transcription factors, Runx2, JunD/Fra-2, and Sp1, responsible for the high hOC promoter activity in PC3 cells by binding to the OSE2, AP-1/VDRE, and OSE1 elements, respectively. Among the three groups of transcription factors, the expression levels of Runx2 and Fra-2 are higher in the OC-positive PC3 cells and osteoblasts, compared with the OC-negative LNCaP cells. Interestingly, unlike the mouse OC promoter, the OSE1 site in hOC promoter is regulated by members of Sp1 family instead of the osteoblast-specific factor Osf1. The molecular basis for androgen-independent prostate cancer cells behaving like mature osteoblasts may be explained by the interplay and coordination of these transcription factors under the tight regulation of autocrine and paracrine mediators.
Yeung
Fan
F
Department of Urology, University of Virginia, Charlottesville, Virginia 22908, USA.
Law
Wai K
WK
Yeh
Ching-Hua
CH
Westendorf
Jennifer J
JJ
Zhang
Ye
Y
Wang
Ruoxiang
R
Kao
Chinghai
C
Chung
Leland W K
LW
D001483:Base Sequence; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002762:Cholecalciferol / Q000494:pharmacology; D050659:Core Binding Factor Alpha 1 Subunit; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D017353:Gene Deletion; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D015675:Osteocalcin / Q000235:genetics*; D012516:Osteosarcoma / Q000378:metabolism / Q000473:pathology; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000378:metabolism* / Q000473:pathology*; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D016329:Sp1 Transcription Factor / Q000096:biosynthesis; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D050659:Core Binding Factor Alpha 1 Subunit; D009363:Neoplasm Proteins; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D015675:Osteocalcin; D002762:Cholecalciferol; D008156:Luciferases