Robert B. Campbell (Ph.D.)
Ralph H. Loring, Robert A. Schatz, M. V. Sitkovskiĭ, Dinah Sah
Date of Award
Doctor of Philosophy
Department or Academic Unit
Bouvé College of Health Sciences. Department of Pharmaceutical Sciences
angiogenesis, Cancer, kinesin spindle protein, siRNA, tumor vasculature
Cancer - Treatment, Liposomes, Small interfering RNA, Neovascularization
Pharmacy and Pharmaceutical Sciences
Cancer is a major health problem in the United States and many other parts of the world. However, cancer treatment is severely limited by the lack of highly effective cytotoxic agents and selective delivery. The discovery of RNA interference makes it possible to treat some conditions by silencing disorder-causing genes of targeting cells which are otherwise difficult to eradicate with more conventional therapies. However, before siRNA technology could be widely used as a therapeutic approach, strategies used for siRNA delivery should minimize uptake by phagocytes, enzymatic degradation by nucleases and should be taken up preferentially by the intended cell population. Kinesin spindle proteins (KSP) are the motor proteins which play critical roles during mitosis. KSP can be the ideal targets for anti-mitotics because they are exclusively expressed in mitotic cells. In the present study, we intend to develop, characterize and evaluate a liposome-based delivery system which can deliver KSP-siRNA selectively to the tumor vasculature (thus inhibiting angiogenesis, destroying tumor vasculature and eventually, eradicating tumor growth). We developed ten liposome preparations with different compositions of lipids. Based on the loading, targeting and silencing efficiency of siRNA formulated with different liposomes, DOPC-based cationic liposomes, over DOPE-based nanosystems, with a modest amount of polyetheleneglycol was selected to deliver KSP-siRNA to tumor-bearing mice. Efficacy studies revealed tumor suppression was observed when KSP-siRNA was delivered using Pegylated cationic liposomes, but not in mice that received naked KSP-siRNA or KSP-siRNA in commercially available transfecting agents. The results were further supported by MRI analysis. To evaluate the role that vasculature supply plays in the development of the tumor, we also performed tumor response studies using a tumor model consisting of tumor cells which are resistant to KSP-siRNA. A prolonged suppression of tumor growth was achieved only when a high dose (5mg/kg), but not a relatively low dose (2mg/kg) KSP-siRNA was administered, suggesting that a combined treatment approach containing both anti-vasculature and anti-cancer agents should be considered to achieve the best treatment outcome. Finally, it was confirmed by qRT-PCR that the tumor growth inhibition was due to the successful knock-down of KSP mRNA.
Ying, Bo, "siRNA-loaded cationic liposomes for cancer therapy: development, characterization and efficacy evaluation" (2010). Pharmaceutical Science Dissertations. Paper 9. http://hdl.handle.net/2047/d20000644
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