oblimersen and Disease-Models--Animal

Antisense oligonucleotides (ASO) against specific molecular targets (e.g., Bcl-2 and Raf-1) are important reagents in cancer biology and therapy. Phosphorothioate modification of the ASO backbone has resulted in an increased stability of ASO in vivo without compromising, in general, their target selectivity. Although the power of antisense technology remains unsurpassed, dose-limiting side effects of modified ASO and inadequate penetration into the tumor tissue have necessitated further improvements in ASO chemistry and delivery systems. Oligonucleotide delivery systems may increase stability of the unmodified or minimally modified ASO in plasma, enhance uptake of ASO by tumor tissue, and offer an improved therapy response. Here, we provide an overview of ASO design and in vivo delivery systems, and focus on preclinical validation of a liposomal nanoparticle containing minimally modified raf antisense oligodeoxynucleotide (LErafAON). Intact rafAON (15-mer) is present in plasma and in normal and tumor tissues of athymic mice systemically treated with LErafAON. Raf-1 expression is decreased in normal and tumor tissues of LErafAON-treated mice. Therapeutic benefit of a combination of LErafAON and radiation or an anticancer drug exceeds radiation or drug alone against human prostate, breast, and pancreatic tumors grown in athymic mice. Further improvements in ASO chemistry and nanoparticles are promising avenues in antisense therapy of cancer.

Topics: Animals; Antineoplastic Agents; Combined Modality Therapy; Disease Models, Animal; Drug Carriers; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Nude; Nanoparticles; Neoplasms; Oligodeoxyribonucleotides; Oligonucleotides, Antisense; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-raf; Thionucleotides

Topics: Animals; Antineoplastic Agents; Clinical Trials, Phase I as Topic; Disease Models, Animal; Drug Evaluation, Preclinical; Humans; Lymphoma, Follicular; Lymphoma, Non-Hodgkin; Mice; Mice, SCID; Oligonucleotides, Antisense; Proto-Oncogene Proteins c-bcl-2; Remission Induction; Thionucleotides; Treatment Outcome

Molecular mechanisms responsible for lymphoma resistance to apoptosis often involve the bcl-2 pathway. In this study, we investigated the cell signaling pathways activated in bcl-2-overexpressing human mantle cell lymphoma cell lines (JVM-2 and Z-138) that have been treated with oblimersen, a molecular gene silencing strategy that effectively suppresses bcl-2 in vitro and in vivo. Z-138 cells expressed higher levels of bcl-2 and were more sensitive to the effects of bcl-2 silencing, mediated by oblimersen or bcl-2 small interfering RNA, in vitro. Tumors derived following injection of Z-138 cells were sensitive to oblimersen as judged by decreases in tumor growth rate and decreases in cell proliferation (as measured by Ki-67). Immunohistochemistry and Western blot analysis of oblimersen-treated Z-138 tumors revealed a dose-dependent decrease in bcl-2 levels and an associated increase in the proapoptotic proteins caspase-3 and caspase-9. Silencing bcl-2 in Z-138 xenografts revealed an associated dose-dependent suppression of bax, a decrease in nuclear factor-kappaB and phospho-nuclear factor-kappaB, and transient loss of p53 levels. Coimmunoprecipitation studies suggest that the latter observation is mediated by an association between bcl-2 and phospho-mdm2. Bcl-2 silencing also led to p27 down-regulation and coimmunoprecipitation studies point to a role for bcl-2 in regulation of p27 localization/degradation. Bcl-2 silencing was also correlated with loss of cyclin D1a protein levels but not cyclin D1b levels. Coimmunoprecipitation studies indicate that bcl-2 may mediate its effects on cyclin D1a via interaction with p38 mitogen-activated protein kinase as well as a previously unreported interaction between bcl-2 and cyclin D1a.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Blotting, Western; Cell Proliferation; Cyclin D; Cyclin-Dependent Kinase Inhibitor p27; Cyclins; Disease Models, Animal; DNA-Binding Proteins; Gene Silencing; Humans; Immunoenzyme Techniques; Immunoprecipitation; Lymphoma, Mantle-Cell; Male; Mice; Mice, Knockout; Mice, Transgenic; Neoplasm Proteins; NF-kappa B; Oligonucleotides, Antisense; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-mdm2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Thionucleotides; Tumor Suppressor Protein p53; Xenograft Model Antitumor Assays