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Updated: Jun 4, 2026

An Orthotopic Bladder Tumor Model and the Evaluation of Intravesical saRNA Treatment
Published on: July 28, 2012
RNAi-based therapeutics targeting survivin and PLK1 for treatment of bladder cancer
Shaguna Seth1, Yoshiyuki Matsui, Kathy Fosnaugh
1Discovery Research and Pharmaceutical Development, Marina Biotech Inc., Bothell, Washington 98021, USA. sseth@marinabio.com
Abstract:
Harnessing RNA interference (RNAi) to silence aberrant gene expression is an emerging approach in cancer therapy. Selective inhibition of an overexpressed gene via RNAi requires a highly efficacious, target-specific short interfering RNA (siRNA) and a safe and efficient delivery system. We have developed siRNA constructs (UsiRNA) that contain unlocked nucleobase analogs (UNA) targeting survivin and polo-like kinase-1 (PLK1) genes. UsiRNAs were encapsulated into dialkylated amino acid-based liposomes (DiLA(2)) containing a nor-arginine head group, cholesteryl hemisuccinate (CHEMS), cholesterol and 1, 2-dimyristoyl-phosphatidylethanolamine-polyethyleneglycol 2000 (DMPE-PEG2000). In an orthotopic bladder cancer mouse model, intravesical treatment with survivin or PLK1 UsiRNA in DiLA(2) liposomes at 1.0 and 0.5 mg/kg resulted in 90% and 70% inhibition of survivin or PLK1 mRNA, respectively. This correlated with a dose-dependent decrease in tumor volumes which was sustained over a 3-week period. Silencing of survivin and PLK1 mRNA was confirmed to be RNA-induced silencing complex mediated as specific cleavage products were detected in bladder tumors over the duration of the study. This report suggests that intravesical instillation of survivin or PLK1 UsiRNA can serve as a potential therapeutic modality for treatment of bladder cancer.
Insights
New unlocked nucleobase analog siRNA (UsiRNA) delivered via liposomes effectively silenced survivin and PLK1 genes in a bladder cancer model, reducing tumor volume. This RNA interference therapy shows promise for bladder cancer treatment.
Area of Science:
- * Molecular Biology
- * Cancer Therapeutics
- * Nanotechnology
Background:
- * RNA interference (RNAi) offers a novel strategy for cancer therapy by silencing aberrant gene expression.
- * Developing effective short interfering RNA (siRNA) and delivery systems is crucial for targeted gene silencing.
- * Survivin and polo-like kinase-1 (PLK1) are key genes implicated in bladder cancer progression.
Purpose of the Study:
- * To develop and evaluate novel siRNA constructs (UsiRNA) targeting survivin and PLK1 genes for bladder cancer therapy.
- * To assess the efficacy of UsiRNA encapsulated in a novel liposome delivery system (DiLA(2)) for intravesical administration.
- * To confirm the mechanism of gene silencing and its impact on tumor growth in a preclinical model.
Main Methods:
- * Design and synthesis of unlocked nucleobase analog siRNA (UsiRNA) targeting survivin and PLK1.
- * Encapsulation of UsiRNA into specifically formulated dialkylated amino acid-based liposomes (DiLA(2)).
- * Evaluation of intravesical DiLA(2)-UsiRNA treatment in an orthotopic bladder cancer mouse model, assessing mRNA inhibition, tumor volume, and mechanism of action.
Main Results:
- * Intravesical administration of UsiRNA targeting survivin or PLK1 in DiLA(2) liposomes achieved significant mRNA inhibition (90% and 70%, respectively).
- * Treatment resulted in a dose-dependent and sustained reduction in bladder tumor volumes over a 3-week period.
- * Gene silencing was confirmed to be mediated by the RNA-induced silencing complex (RISC), with detectable cleavage products in tumors.
Conclusions:
- * Survivin or PLK1 UsiRNA delivered via DiLA(2) liposomes demonstrate potent therapeutic potential for bladder cancer.
- * Intravesical instillation of these UsiRNAs represents a promising RNA interference-based treatment strategy.
- * The developed UsiRNA and DiLA(2) delivery system offer a viable approach for targeted cancer gene therapy.
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