A novel antisense oligonucleotide inhibiting several antiapoptotic Bcl-2 family members induces apoptosis and enhances chemosensitivity in androgen-independent human prostate cancer PC3 cells

• Published in: Molecular cancer therapeutics 2005-11, Vol.4 (11), p.1689-1698
• Main Authors: Yamanaka, Kazuki, Rocchi, Palma, Miyake, Hideaki, Fazli, Ladan, Vessella, Bob, Zangemeister-Wittke, Uwe, Gleave, Martin E
• Format: Article
• Language: English
• Subjects: Androgens - metabolism; Antineoplastic Agents - pharmacology; antisense oligodeoxynucleotide; Apoptosis; Bcl-2; bcl-2 Homologous Antagonist-Killer Protein - metabolism; bcl-2-Associated X Protein - metabolism; bcl-Associated Death Protein - metabolism; bcl-X Protein - metabolism; Bcl-xL; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Down-Regulation; Gene Expression Regulation, Neoplastic; Humans; Inhibitor of Apoptosis Proteins - metabolism; Inhibitory Concentration 50; Male; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Metastasis; Neoplasm Proteins - metabolism; Oligonucleotide Array Sequence Analysis; Oligonucleotides - chemistry; Oligonucleotides, Antisense - chemistry; Oligonucleotides, Antisense - pharmacology; Paclitaxel - chemistry; Paclitaxel - pharmacology; Prostate - metabolism; prostate cancer; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Proto-Oncogene Proteins c-bcl-2 - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism
• ISSN: 1535-7163; 1538-8514
• DOI: 10.1158/1535-7163.MCT-05-0064

Bcl-2 and Bcl-xL are associated with treatment resistance and progression in many cancers, including prostate cancer. The objective of this study was to determine whether a novel bispecific antisense oligonucleotide targeting both Bcl-2 and Bcl-xL induces apoptosis and enhances chemosensitivity in androgen-independent PC3 prostate cancer cells. An antisense oligonucleotide with complete sequence identity to Bcl-2 and three-base mismatches to Bcl-xL selected from five antisense oligonucleotides targeting various regions with high homology between Bcl-2 and Bcl-xL was found to be the most potent inhibitor of both Bcl-2 and Bcl-xL expression in PC3 cells. This selected Bcl-2/Bcl-xL bispecific antisense oligonucleotide reduced mRNA and protein levels in a dose-dependent manner, reducing Bcl-2 and Bcl-xL protein levels to 12% and 19%, respectively. Interestingly, Mcl-1 was down-regulated as well, although levels of Bax, Bad, or Bak were not altered after treatment with this bispecific antisense oligonucleotide. Indirect down-regulation of inhibitor of apoptosis (IAP) family, including XIAP, cIAP-1 and cIAP-2, via second mitochondria-derived activator of caspases was also observed after bispecific antisense oligonucleotide treatment. Executioner caspase-3, caspase-6, and caspase-7 were shown to be involved in apoptosis induced by bispecific antisense oligonucleotide. This Bcl-2/Bcl-xL bispecific antisense oligonucleotide also enhanced paclitaxel chemosensitivity in PC3 cells, reducing the IC 50 of paclitaxel by >90%. These findings illustrate that combined suppression of antiapoptotic Bcl-2 family members using this antisense oligonucleotide could be an attractive strategy for inhibiting cancer progression through alteration of the apoptotic rheostat in androgen-independent prostate cancer.