title: Acquisition of chemoresistant phenotype by overexpression of the antiapoptotic gene testosterone-repressed prostate message-2 in prostate cancer xenograft models.
abstract: Testosterone-repressed prostate message-2 (TRPM-2) expression is highly up-regulated in normal and malignant prostate cells after androgen withdrawal. Although recent studies have suggested a protective role of TRPM-2 expression against apoptosis in several experimental models, the functional role of TRPM-2 in chemotherapy-induced apoptosis remains undefined. Here, we demonstrated that overexpression of TRPM-2 in human androgen-dependent LNCaP prostate cancer cells by stable transfection rendered them highly resistant to paclitaxel treatment than control LNCaP cells, with a 20-fold higher IC50 through the inhibition of apoptotic cell death. In mice bearing TRPM-2-overexpressing LNCaP tumors, tumor volume and serum prostate-specific antigen increased two to three times faster after castration and paclitaxel treatment compared with mice bearing control tumors. We then tested the efficacy of combined treatment with antisense TRPM-2 oligodeoxynucleotide (ODN) and paclitaxel in the mouse androgen-dependent Shionogi tumor model. Antisense TRPM-2 ODN treatment significantly enhanced paclitaxel chemosensitivity of Shionogi tumor cells in a dose-dependent manner, reducing the IC50 by 75%. Combined treatment of Shionogi cells with 500 nM antisense TRPM-2 ODN and 10 nM paclitaxel-induced apoptosis, either agent alone did not. Adjuvant administration of antisense TRPM-2 ODN and polymeric micellar paclitaxel after castration resulted in reduced TRPM-2 levels in vivo and a significant delay of emergence of androgen-independent recurrent Shionogi tumors compared with administration of either agent alone. Furthermore, combined treatment of mice bearing androgen-independent recurrent Shionogi tumors with antisense TRPM-2 ODN and micellar paclitaxel inhibited tumor growth compared with treatment with either agent alone. Collectively, these findings demonstrate that TRPM-2 overexpression helps confer a chemoresistant phenotype through inhibition of apoptosis, and that antisense TRPM-2 ODN may be useful in enhancing the effects of cytotoxic chemotherapy in hormone-refractory prostate cancer.
authors.affiliation: The Prostate Centre, Vancouver General Hospital, British Columbia, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Miyake
authors.forename: C
authors.initials: C
authors.lastname: Nelson
authors.forename: P S
authors.initials: PS
authors.lastname: Rennie
authors.forename: M E
authors.initials: ME
authors.lastname: Gleave
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D051152:Clusterin; D053938:DNA Fragmentation; D018450:Disease Progression; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D018832:Molecular Chaperones; D009368:Neoplasm Transplantation; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D017239:Paclitaxel / Q000494:pharmacology; D010641:Phenotype; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000235:genetics*; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D000972:Antineoplastic Agents, Phytogenic; C495242:CLU protein, human; C495243:Clu protein, mouse; D051152:Clusterin; D006023:Glycoproteins; D018832:Molecular Chaperones; D016376:Oligonucleotides, Antisense; D017430:Prostate-Specific Antigen; D017239:Paclitaxel