Abstract
BackgroundReplication-competent adenoviruses (Ad) produced cytotoxic effects on infected tumors and have been examined for the clinical applicability. A biomarkers to predict the cytotoxicity is valuable in a clinical setting.MethodsWe constructed type 5 Ad (Ad5) of which the expression of E1A gene was activated by a 5′ regulatory sequences of survivin, midkine or cyclooxygenase-2, which were highly expressed in human tumors. We also produced the same replication-competent Ad of which the fiber-knob region was replaced by that of Ad35 (AdF35). The cytotoxicity was examined by a colorimetric assay with human tumor cell lines, 4 kinds of pancreatic, 9 esophageal carcinoma and 5 mesothelioma. Ad infectivity and Ad-mediated gene expression were examined with replication-incompetent Ad5 and AdF35 which expressed the green fluorescence protein gene. Expression of cellular receptors for Ad5 and AdF35 was also examined with flow cytometry. A transcriptional activity of the regulatory sequences was investigated with a luciferase assay in the tumor cells. We then investigated a possible correlation between Ad-mediated cytotoxicity and the infectivity/gene expression, the transcriptional activity or the p53 genotype.ResultsWe found that the cytotoxicity was greater with AdF35 than with Ad5 vectors, but was not correlated with the Ad infectivity/gene expression irrespective of the fiber-knob region or the E1A-activating transcriptional activity. In contrast, replication-competent Ad produced greater cytotoxicity in p53 mutated than in wild-type esophageal carcinoma cells, suggesting a possible association between the cytotoxicity and the p53 genotype.ConclusionsSensitivity to Ad-mediated cytotoxic activity was linked with the p53 genotype but was not lineally correlated with the infectivity/gene expression or the E1A expression.
Highlights
Replication-competent adenoviruses (Ad) produced cytotoxic effects on infected tumors and have been examined for the clinical applicability
Cytotoxicity of replication-competent Ad vector belongs to type 5 (Ad5) and Adenovirus vector bearing the type-35-derived fiberknob structure (AdF35) We examined cytotoxic activity of the replicationcompetent Ad5 and AdF35 on human pancreatic and esophageal carcinoma, and mesothelioma with the WST assay
We compared relative cytotoxicity between Ad5 and AdF35 which were activated by the same transcriptional regulatory region and showed the cytotoxicity with Half maximal inhibitory concentration (IC50) values which were expressed as vp per cell. (Table 1, Additional file 1: Figure S1)
Summary
Replication-competent adenoviruses (Ad) produced cytotoxic effects on infected tumors and have been examined for the clinical applicability. Adenoviruses (Ad) are one of the agents extensively investigated and are easy to be genetically manipulated to produce replication-restricted types for human tumors. Further understanding of Ad biology enabled us to produce modified Ad of which the infectivity was changed by replacing the fiber-knob region since the region mediated Ad binding to the cellular receptors [4]. Ad5 bearing the Ad35-derived fiber-knob structure (AdF35) infected CD46-positive cells irrespective of CAR expression [6, 7]. The expression levels of CAR molecules in human tumors were variable and often down-regulated, rendering replication-competent Ad5 less cytotoxic to human tumors [8]. AdF35 can infect human tumors better than Ad5 [10] and produced greater cytotoxicity [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
