Mitogen-activated protein kinase pathway is involved in androgen-independent PSA gene expression in LNCaP cells.
BACKGROUND
Prostate specific antigen (PSA) is regulated by growth factors and hormones through functional androgen responsive elements in the promoter region of the PSA gene. However, the molecular basis for androgen independent PSA elevation in hormone refractory prostate cancer is unknown. The purpose of this study was to investigate the role of MAP kinase activation in androgen independent regulation of PSA expression.


METHODS
LNCaP cells transfected with MEK1 expression vector with or without the MAP kinase inhibitor U0126 under low androgen conditions were analyzed by luciferase assay and electrophoretic mobility shift assay (EMSA).


RESULTS
Transfection experiments of the proximal PSA promoter linked to Luc-reporter identified one region designated as "B" motif centered at -60 bp to be essential for basal activation. Co-transfection with the MEK1 activated vector enhanced PSA expression, while mutation of the "B" motif totally abrogated this induction. EMSA showed a specific DNA-protein complex, but Sp1 family members and AR do not interact with the "B" region by supershift analysis.


CONCLUSIONS
Our data suggest that enhanced androgen-independent PSA gene expression in MAP kinase-induced LNCaP cells is mediated, at least in part, by the "B" motif of the PSA promoter.
Franco
Omar E
OE
Department of Urology, Mie University School of Medicine, Tsu, Mie, Japan.
Onishi
Takehisa
T
Yamakawa
Kensuke
K
Arima
Kiminobu
K
Yanagawa
Makoto
M
Sugimura
Yoshiki
Y
Kawamura
Juichi
J
D000728:Androgens / Q000494:pharmacology; D001681:Biological Assay; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008156:Luciferases / Q000032:analysis; D048369:MAP Kinase Kinase 1; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics* / Q000494:pharmacology*; D010957:Plasmids; D017430:Prostate-Specific Antigen / Q000096:biosynthesis* / Q000235:genetics*; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000494:pharmacology*; D014162:Transfection; D014407:Tumor Cells, Cultured
D000728:Androgens; D017931:DNA Primers; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases; D017430:Prostate-Specific Antigen