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UBC Theses and Dissertations

Development of Coxsackievirus B3 as an oncolytic agent for lung cancer therapy Liu, Huitao


Lung cancer is the leading cause of cancer-related death for both sexes worldwide. KRAS and TP53/RB1 are the most frequently mutated genes in lung adenocarcinoma and small cell lung cancer, respectively. However, lung cancer associated with these gene mutations has a poor outcome and there is a lack of effective treatment options. Recent advances in virus-based cancer treatment, termed virotherapy, provide a promising new treatment option. Oncolytic viruses are a group of viruses that are either naturally capable of or can be genetically engineered to specifically destroy cancer cells while sparing normal cells. My laboratory previously found that coxsackievirus B3 (CVB3) has extremely potent oncolytic effects against KRAS-mutant lung adenocarcinoma. Nevertheless, the evident toxicity restricts its use for cancer therapy. In this dissertation, I aimed to engineer CVB3 to decrease its damage to normal tissues. My hypothesis was that modification of CVB3 by inserting target-sequence (TS) of tumor-suppressive and/or organ-selective miRNA will reduce its toxicity, while retaining oncolytic potency. I generated a miRNA-modified CVB3 by inserting tumor-suppressive miR-145/-143-TS into the 5’UTR of viral genome. In vitro experiments revealed that this miR-CVB3 strongly infects and lyses both KRAS- and TP53/RB1-mutant lung cancer cells, but with a markedly reduced cytotoxicity toward normal cells. In vivo study using a xenograft mouse model demonstrated that a single dose of the miR-CVB3 via systemic administration significantly suppresses tumor growth with greatly attenuated viral pathogenesis as compared to wildtype CVB3. Notably, after a prolonged treatment (>35 days), reversion mutants (loss of miRNA-TS inserts) were identified in ~40% mice, revealing the instability of miR-CVB3. To improve the stability and further reduce the toxicity, I re-engineered CVB3 by replacing the same length of viral genome at the non-coding region with TS of cardiac-selective miR-1/miR-133 and pancreas-enriched miR-216/miR-375 or inserting these miRNA-TS into the coding P1 region of viral genome. Serial passaging of these newly established CVB3s in cultured cells validated significantly improved stability compared with the initial miR-CVB3. Their safety was also verified in immunocompetent and tumor-bearing immunodeficient mice. Taken together, my research provides valid strategies to develop CVB3 as a safe oncolytic virus for lung cancer treatment.

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