GLI2 knockdown using an antisense oligonucleotide induces apoptosis and chemosensitizes cells to paclitaxel in androgen-independent prostate cancer.
OBJECTIVE
GLI transcription factors mediate hedgehog signaling and have been implicated in several human malignancies, including prostate cancer. The objectives of this study were to characterize GLI2 expression levels in human prostate cancer cell lines and tissues to test the effect of antisense oligonucleotide (ASO) targeting GLI2 on androgen-independent (AI) prostate cancer cell lines.


METHODS
A tissue microarray was used to characterize differences in GLI2 expression in benign prostate hyperplasia, prostate cancer treated by neoadjuvant hormonal therapy and AI prostate cancer. The effects of GLI2 ASO on PC-3 cell growth and paclitaxel chemosensitivity were assessed in vitro and in vivo. Oligonucleotide spotted microarray analysis was used to determine alteration in GLI2 coregulated genes after ASO treatment.


RESULTS
The expression of GLI2 was significantly higher in prostate cancer than in benign prostate hyperplasia, decreased after androgen ablation in a time-dependent fashion, but became highly expressed again in AI prostate cancer. GLI2 ASO treatment of PC-3 cells reduced GLI2 mRNA and protein levels in a dose-dependent manner. GLI2 knockdown increased PC-3 cell apoptotic rates and significantly decreased cell growth and modulated levels of apoptosis-related genes, such as Bcl2, Bcl-xL, and clusterin. GLI2 knockdown also changed levels of several cell cycle regulators, such as cyclin D1, p27, and PKC-eta. Systematic administration of GLI2 ASO in athymic mice significantly delayed PC-3 tumor progression and enhanced paclitaxel chemosensitivity.


CONCLUSIONS
These findings suggest that increased levels of GLI2 correlates with AI progression and that GLI2 may be a therapeutic target in castrate-resistant prostate cancer.
Narita
Shintaro
S
The Prostate Center, Vancouver General Hospital, British Columbia, Canada.
So
Alan
A
Ettinger
Susan
S
Hayashi
Norihiro
N
Muramaki
Mototsugu
M
Fazli
Ladan
L
Kim
Youngsoo
Y
Gleave
Martin E
ME
D000728:Androgens / Q000494:pharmacology; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use; D017209:Apoptosis; D001483:Base Sequence; D045744:Cell Line, Tumor; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009376:Neoplasms, Hormone-Dependent / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D017239:Paclitaxel / Q000627:therapeutic use*; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis; D000075746:Zinc Finger Protein Gli2
D000728:Androgens; D000972:Antineoplastic Agents, Phytogenic; C082593:GLI2 protein, human; D051741:Kruppel-Like Transcription Factors; C434488:MRL1 protein, S cerevisiae; D008565:Membrane Proteins; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense; D029701:Saccharomyces cerevisiae Proteins; D000075746:Zinc Finger Protein Gli2; D017239:Paclitaxel