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    Anti-tumor activity of an oncolytic adenoviral construct expressing a small interfering RNA transgene.

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    Dissertation (942.3Kb)
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    Date
    2006-10-01
    Author
    Samuel, Shirley Kulangara.
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    Abstract
    Cancer is a leading cause of mortality in the world today. Mutation in the K-ras oncogene is common in most human cancers. K-ras oncogene expression was specifically downregulated by 58.7% by K-ras silencing siRNA, and this was accompanied by 66% growth inhibition of NCI-H441 lung cancer cells. To improve siRNA delivery and cause its stable expression in cancer cells, we used ONYX-411, an oncolytic adenovirus as a backbone to clone the K-ras silencing siRNA. This new adenoviral construct called Internavec, significantly downregulated mutant K-ras expression by 48.9% (p<0.05, n=3) as compared with 11.9% downregulation by parental ONYX-411 in HTB-79 pancreatic cancer cells. The anti-tumor activity of Internavec was examined in various cancer cell lines with and without the relevant K-ras mutation to observe the specificity of the siRNA transgene against the glycine to valine mutation on codon 12. Internavec showed enhanced anti-tumor activity in cell lines with the relevant mutation, compared with ONYX-411. Internavec (5 @ 1x108 pfu) significantly reduced the growth of subcutaneous HTB-79 pancreatic tumor xenografts in vivo by 85.5%, including complete growth suppression in 3 of 5 mice. Parental ONYX-411 or ONYX-411-siRNAGFP was markedly less effective (47.8% and 44.1% growth reduction, p<0.05, respectively). To characterize interferon-inducing activity of Internavec, landmark gene expression of the interferon pathway (OAS1, MX1) was examined following Internavec treatment, using HEK-293 cells as positive control. HEK-293 cells displayed an upregulation of OAS1 and MX1 following Poly (I:C) treatment. However, Internavec did not upregulate these interferon-pathway genes in HEK-293 or H79 lines, suggesting a lack of interferon activation by Internavec. To delineate underlying molecular events contributing to the enhanced growth inhibition, microarray experiments were performed on cells treated with Internavec. Internavec, but not ONYX-411, downregulated the expression of multiple Ras signaling-related genes (MAP4K5, PLCε1, IKBKB, FOXO3A and RAB28). These findings indicate that the knockdown of mutant K-ras serves to enhance oncolytic virus anti-tumor activity through the perturbation of additional cellular signaling events.
    URI
    http://hdl.handle.net/2104/5117
    Department
    Biomedical Studies.
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    • Electronic Theses and Dissertations
    • Theses/Dissertations - Biomedical Studies

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    Copyright © Baylor® University All rights reserved. Legal Disclosures.
    Baylor University Waco, Texas 76798 1-800-BAYLOR-U
    Baylor University Libraries | One Bear Place #97148 | Waco, TX 76798-7148 | 254.710.2112 | Contact: libraryquestions@baylor.edu
    If you find any errors in content, please contact librarywebmaster@baylor.edu
    DSpace software copyright © 2002-2016  DuraSpace
    Contact Us | Send Feedback
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