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postgraduate thesis: Epstein-barr virus (EBV) infection and STAT3 activation in nasopharyngeal epithelial cells

TitleEpstein-barr virus (EBV) infection and STAT3 activation in nasopharyngeal epithelial cells
Authors
Issue Date2012
PublisherThe University of Hong Kong (Pokfulam, Hong Kong)
Citation
Zhang, G. [张贵焘]. (2012). Epstein-barr virus (EBV) infection and STAT3 activation in nasopharyngeal epithelial cells. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4786966
AbstractThe etiology of nasopharyngeal carcinoma (NPC) is based on intricate interactions among environmental factors, genetic susceptibility and Epstein-Barr virus (EBV) infection. Information concerning the role of EBV infection, particularly during the early stage of NPC development is poorly understood. Our laboratory has shown that stable infection of EBV could be achieved in immortalized epithelial cell lines which harbor genetic alterations and altered cell signaling pathway. In this study, these cell models were used to elucidate early events involved in EBV infection in premalignant nasopharyngeal epithelial cell models and their implications on development and progression of nasopharyngeal carcinoma. The response of EBV-infected cells to a stromal inflammatory cytokine, interleukin-6 (IL-6), was examined. EBV infection and long-term propagation of EBV-infected nasopharyngeal epithelial cells confer enhanced sensitivity to STAT3 activation induced by IL-6. IL-6-induced STAT3 activation reinforced their malignant properties in nasopharyngeal epithelial cells and may play a role in the development of nasopharyngeal carcinoma. Furthermore, constitutive STAT3 activation was demonstrated to facilitate malignant transformation of EBV-infected premalignant nasopharyngeal epithelial cells to cancer cells, suggesting that EBV infection and STAT3 activation might synergistically promote the development of NPC. This study also provides support for the existence of a positive feedback loop of IL-6/STAT3/LMP in NP460hTert-EBV cells, which enhanced STAT3 activation in EBV-infected cells. Elevated levels of IL-6Rα expression were observed in EBV-infected NP460hTert cells compared with uninfected cells and were largely responsible for the enhanced sensitivity of IL-6-induced STAT3 activation in these cells. High expression level of IL-6Rα could amplify IL-6 signaling in nasopharyngeal epithelial cells to promote growth proliferation in NP460hTert cells and increase the growth rate of xenografted NPC cells in immune-suppressed animals, suggesting that IL-6Rα overexpression may play a role of contributing to the development of nasopharyngeal carcinoma. The serum concentrations of both IL-6 and sIL-6R were also higher in NPC patients than healthy individuals and may have prognostic values to predict clinical outcome and disease progression in NPC patients. In conclusion, these data support the hypothesis that EBV infection under inflammatory environment may activate aberrant gene expressions and cell signaling to facilitate malignant transformation. The inflammatory cytokine, IL-6, may mediate the role of EBV infection in the development of NPC.
DegreeDoctor of Philosophy
SubjectNasopharynx - Cancer
Epithelial cells
Epstein-Barr virus
Interleukin-6
Epstein-Barr virus diseases
Dept/ProgramAnatomy
Persistent Identifierhttp://hdl.handle.net/10722/209213

 

DC FieldValueLanguage
dc.contributor.authorZhang, Guitao-
dc.contributor.author张贵焘-
dc.date.accessioned2015-04-11T23:10:03Z-
dc.date.available2015-04-11T23:10:03Z-
dc.date.issued2012-
dc.identifier.citationZhang, G. [张贵焘]. (2012). Epstein-barr virus (EBV) infection and STAT3 activation in nasopharyngeal epithelial cells. (Thesis). University of Hong Kong, Pokfulam, Hong Kong SAR. Retrieved from http://dx.doi.org/10.5353/th_b4786966-
dc.identifier.urihttp://hdl.handle.net/10722/209213-
dc.description.abstractThe etiology of nasopharyngeal carcinoma (NPC) is based on intricate interactions among environmental factors, genetic susceptibility and Epstein-Barr virus (EBV) infection. Information concerning the role of EBV infection, particularly during the early stage of NPC development is poorly understood. Our laboratory has shown that stable infection of EBV could be achieved in immortalized epithelial cell lines which harbor genetic alterations and altered cell signaling pathway. In this study, these cell models were used to elucidate early events involved in EBV infection in premalignant nasopharyngeal epithelial cell models and their implications on development and progression of nasopharyngeal carcinoma. The response of EBV-infected cells to a stromal inflammatory cytokine, interleukin-6 (IL-6), was examined. EBV infection and long-term propagation of EBV-infected nasopharyngeal epithelial cells confer enhanced sensitivity to STAT3 activation induced by IL-6. IL-6-induced STAT3 activation reinforced their malignant properties in nasopharyngeal epithelial cells and may play a role in the development of nasopharyngeal carcinoma. Furthermore, constitutive STAT3 activation was demonstrated to facilitate malignant transformation of EBV-infected premalignant nasopharyngeal epithelial cells to cancer cells, suggesting that EBV infection and STAT3 activation might synergistically promote the development of NPC. This study also provides support for the existence of a positive feedback loop of IL-6/STAT3/LMP in NP460hTert-EBV cells, which enhanced STAT3 activation in EBV-infected cells. Elevated levels of IL-6Rα expression were observed in EBV-infected NP460hTert cells compared with uninfected cells and were largely responsible for the enhanced sensitivity of IL-6-induced STAT3 activation in these cells. High expression level of IL-6Rα could amplify IL-6 signaling in nasopharyngeal epithelial cells to promote growth proliferation in NP460hTert cells and increase the growth rate of xenografted NPC cells in immune-suppressed animals, suggesting that IL-6Rα overexpression may play a role of contributing to the development of nasopharyngeal carcinoma. The serum concentrations of both IL-6 and sIL-6R were also higher in NPC patients than healthy individuals and may have prognostic values to predict clinical outcome and disease progression in NPC patients. In conclusion, these data support the hypothesis that EBV infection under inflammatory environment may activate aberrant gene expressions and cell signaling to facilitate malignant transformation. The inflammatory cytokine, IL-6, may mediate the role of EBV infection in the development of NPC.-
dc.languageeng-
dc.publisherThe University of Hong Kong (Pokfulam, Hong Kong)-
dc.relation.ispartofHKU Theses Online (HKUTO)-
dc.rightsThe author retains all proprietary rights, (such as patent rights) and the right to use in future works.-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subject.lcshNasopharynx - Cancer-
dc.subject.lcshEpithelial cells-
dc.subject.lcshEpstein-Barr virus-
dc.subject.lcshInterleukin-6-
dc.subject.lcshEpstein-Barr virus diseases-
dc.titleEpstein-barr virus (EBV) infection and STAT3 activation in nasopharyngeal epithelial cells-
dc.typePG_Thesis-
dc.identifier.hkulb4786966-
dc.description.thesisnameDoctor of Philosophy-
dc.description.thesislevelDoctoral-
dc.description.thesisdisciplineAnatomy-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.5353/th_b4786966-
dc.date.hkucongregation2012-

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