Androgen receptor down-regulation in prostate cancer with phosphorodiamidate morpholino antisense oligomers.
OBJECTIVE
Androgen receptor (AR) has a pivotal role in the growth and proliferation of prostate cancer (PCa). Even in advanced stages of PCa AR continues to be expressed and appears to be functional. Since the mechanisms of AR activation in androgen independent PCa have yet to be clearly defined, the decrease in AR protein by antisense compounds is an attractive therapeutic option. In this study we evaluated a novel antisense phosphorodiamidate morpholino oligomer (PMO) targeting the translational start site of AR mRNA in vitro and in vivo in a PCa xenograft and murine prostate.


METHODS
AR antisense PMOs targeting the AR initiation AUG were tested in vitro and in LNCaP cells, and in vivo in LAPC-4 xenografts and normal mouse prostate. Effects on AR protein and PSA expression were assessed.


RESULTS
AR antisense PMOs specifically down-regulated AR protein levels in a plasmid based screening system and also decreased endogenous AR levels in androgen responsive LNCaP cells in culture compared to control nonspecific PMOs. Pretreatment and posttreatment biopsies in the LAPC-4 xenograft model demonstrated that the antisense AR PMO administered intraperitoneally specifically decreased AR protein levels and serum PSA. Analysis of tissue distribution of the AR PMO by high performance liquid chromatography based methodology showed significant PMO levels in tumor tissue and mouse prostate, and there was a dose dependent decrease in AR protein levels in murine AR antisense PMO treated mouse prostates.


CONCLUSIONS
An AR antisense PMO with unique chemical properties administered once daily can decrease AR protein levels and PSA in vivo. The reduction of AR protein with an antisense PMO may be an effective method of interfering with AR mediated growth in advanced human PCa.
Cancer Biology Program, Hematology-Oncology Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA.
Yoo-Joung
YJ
Ko
Gayathri R
GR
Devi
Carla A
CA
London
Anthony
A
Kayas
Muralimohan T
MT
Reddy
Patrick L
PL
Iversen
Glenn J
GJ
Bubley
Steven P
SP
Balk
D000818:Animals; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009025:Morpholines / Q000494:pharmacology*; D060172:Morpholinos; D009368:Neoplasm Transplantation; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D011467:Prostate / Q000378:metabolism; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects; D011944:Receptors, Androgen / Q000187:drug effects / Q000378:metabolism*; D014162:Transfection
D009025:Morpholines; D060172:Morpholinos; D016376:Oligonucleotides, Antisense; D011944:Receptors, Androgen; D008156:Luciferases; D017430:Prostate-Specific Antigen