Induction of AP-1 activity by androgen activation of the androgen receptor in LNCaP human prostate carcinoma cells.
BACKGROUND
The androgen receptor and activator protein-1 (AP-1) transcription factors affect growth regulation in normal and cancerous prostate cells. Effects of androgen-activated androgen receptor on AP-1 activity were determined in the LNCaP human prostate carcinoma cell model.


METHODS
Cells were exposed to 1 nM androgen +/- antiandrogen bicalutamide. Cellular growth and cell cycle effects were determined by DNA, viability, and bromodeoxyuridine (BrdU) fluorescence activated cell sorter (FACS) assays. AP-1 effects were determined by an AP-1-luciferase enzyme reporter vector for transcriptional activity, electrophoretic mobility shift assay (EMSA)/antibody supershift for DNA-binding, quantitative RT-PCR for mRNA, and immunoblot for protein.


RESULTS
Androgen induced G(1) growth arrest. This growth arrest was abrogated by treatment with bicalutamide, demonstrating that growth arrest by androgen was due to androgen receptor activation. Concurrently, AP-1 DNA-binding and transcriptional activity was induced over 96 hr androgen exposure, which was also inhibited by bicalutamide. Interestingly, although no change in AP-1 transcriptional activity was observed 24 hr after androgen exposure, there was an increase in Fra-2 expression and AP-1 DNA-binding. Paradoxically, while Fra-2 mRNA and protein levels continued to increase, binding of Fra-2 to the AP-1 site decreased over 96 hr, with a concomitant increase in JunD AP-1-binding and a marked increase in expression of the 35 kDa form of JunD. Enhanced expression of this short form of JunD is a novel effect of androgen exposure that occurred during the 24-96 hr time period, as growth effects emerged.


CONCLUSIONS
Activation of androgen receptor by androgen induces changes in AP-1 activity and AP-1 factor DNA-binding that may contribute significantly to androgen-induced changes in prostate cancer cell growth.
University of Wisconsin Comprehensive Cancer Center, University of Wisconsin, Madison, USA.
Dawn R
DR
Church
Elyse
E
Lee
Todd A
TA
Thompson
Hirak S
HS
Basu
Maureen O
MO
Ripple
Eric A
EA
Ariazi
George
G
Wilding
D000726:Androgen Antagonists / Q000494:pharmacology; D000728:Androgens / Q000378:metabolism*; D000813:Anilides / Q000494:pharmacology; D002453:Cell Cycle / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005434:Flow Cytometry; D051921:Fos-Related Antigen-2; D006801:Humans; D008297:Male; D009570:Nitriles; D011471:Prostatic Neoplasms / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011944:Receptors, Androgen / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology; D014105:Tosyl Compounds; D018808:Transcription Factor AP-1 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology
D000726:Androgen Antagonists; D000728:Androgens; D000813:Anilides; D004268:DNA-Binding Proteins; C497872:FOSL2 protein, human; D051921:Fos-Related Antigen-2; D009570:Nitriles; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D011944:Receptors, Androgen; D014105:Tosyl Compounds; D018808:Transcription Factor AP-1; D014157:Transcription Factors; C053541:bicalutamide