Adenovirus (Ad) has been one of the most commonly used vectors in gene therapy for many years. One of the limitations of using Ad for cancer therapy is that Ad does not spread within a tumor well. As such, fusogenic proteins have been incorporated into these vectors in an attempt to improve spread through cell-cell fusion. Fusogenic protein mediated cell fusion is also associated with syncytiosome release and cell death, which promote an immune response and suggests that fusogenic proteins may be effective as a sole therapeutic for cancer treatment. In this study, I examined whether the reptilian reovirus p14 fusion-associated small transmembrane (FAST) protein can improve Ad efficacy in cancer models in vitro and in vivo. Ad-mediated FAST protein expression induced cell-cell fusion in human embryonic kidney 293 cells and in human lung adenocarcinoma A549 cells. Infected cells had decreased membrane integrity, cellular metabolic activity and increased cleaved caspase-3 expression. In an A549 xenograft nude mouse model, AdFAST did not induce tumor cell fusion or promote mouse survival compared to control mice. In murine 4T1 mammary carcinoma cells, FAST protein expression had modest effects on cell fusion and metabolic activity in vitro. When AdFAST was administered intratumorally in a 4T1 syngeneic mouse model, there were no obvious signs of cell fusion or improved mouse survival. As FAST protein expression promotes membrane permeability, whether AdFAST could enhance the bystander effect of cancer therapies or promote uptake of anti-cancer drugs was investigated in vitro. FAST protein expression in combination with thymidine kinase/ganciclovir or etoposide administration did not have an enhanced effect. Addition of Smac-mimetic compound (SMC) was not effective in the SMC resistant A549 cell line, but the combinational therapy was able to decrease metabolic activity in SMC susceptible SNB75 cells. AdFAST and administration of the membrane impermeable chemotherapeutic drug bleomycin decreased metabolic activity and promoted cleaved caspase-3 expression in A549 cells. Overall, my results suggest that FAST protein expression could improve adenovirus efficacy and could be used with other anti-cancer treatments.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/32319 |
| Date | January 2015 |
| Creators | Wong, Carmen Man |
| Contributors | Parks, Robin |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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