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標題: | 以引致細胞凋亡機制治療惡性腫瘤之研究 Development Of Apoptosis Induction-Based Therapeutic Approach To Treat Malignant Tumors |
作者: | Jih-Jong Lee 李繼忠 |
指導教授: | 林中天(Chung-Tien Lin) |
共同指導教授: | 蕭宏昇(Michael Hsiao) |
關鍵字: | 細胞凋零,基因治療,惡性腫瘤, Apoptosis,gene therapy,malignant tumor, |
出版年 : | 2011 |
學位: | 博士 |
摘要: | 摘要
細胞凋亡是近來受到腫瘤醫師及腫瘤生物學家青睞的重要機制,正常組織及腫瘤組織間的複雜差異,是主要決定腫瘤細胞死亡及病人存活的關鍵,我們連續的檢驗在三種不同情況下促成腫瘤細胞凋亡的機轉以期能夠延長病人的存活時間並保留生活品質。 首先是以雞貧血病毒中之VP3基因,藉由病毒或轉殖載體之攜帶而能成功地在犬隻乳腺腫瘤細胞上表現細胞凋亡之早期變化。並且在犬乳腺腫瘤細胞之細胞凋亡是以caspase-9之路徑進行。 其次,針對Caspase及其上游調控因子在以毒魚藤所引發之細胞毒性中所代表之角色加以探討。毒魚藤能夠顯著的抑制口腔腫瘤細胞之增殖然而對於正常口腔黏膜細胞則不見此特性。流式細胞儀檢驗下經毒魚藤處理之細胞核酸分析多數呈現于G2/M休止。西方墨點法分析後則顯現為Caspase八及九之路徑則與前項研究有所不同。P53蛋白質與下游之細胞凋零分子Bax則在毒魚藤處理後表現增加。此研究證明Caspase及其上游調控因子都與毒與籐細胞毒性有顯著之相關。 第三則檢驗在人類口腔腫瘤細胞以PEI媒介之PUMA基因轉植治療之功效。PUMA是屬於p53過度表現或其它刺激因子調控之細胞凋零現象之調控因子。PUMA對多數細胞凋零刺激訊號都是細胞死亡之調控因子,顯示PUMA屬於腫瘤抑制因子。外源性之PUMA表現於細胞中可造成cytochrome c釋放、Caspase三及九之活化、PARP之裂解之細胞凋零現象。以外源性之PEI/PUMA基因轉殖於異種移植腫瘤活體模式之基因治療可以達到約百分之六十之腫瘤消退率。更進一步,我們利用PEI媒介之PUMA基因治療能夠延長異種移植口腔腫瘤動物之存活期。結論:以PEI媒介之PUMA基因治療可以為各種腫瘤基因治療之有效模式。 Abstract Apoptosis has always been an attractive mechanism that fascinates oncologists and cancer biologists in hoping to utilize it in cancer therapy. The different mechanisms involving the life and death for normal and cancer cells are intricate yet can directly impact on cancer therapy efficacy and patient survival. In this dissertation, we have consecutively exam three scenarios that ultimately cause cancer cell death and prolong patient survival. First, by using expression vectors or lentiviral vectors encoding VP3 gene from Taiwan chicken anemia virus we successfully delivered and induced canine mammary gland cells undergo pro-apoptotic changes. The change in canine mammary tumor cells was associated with caspase-9¬– but not caspase-8– mediated apoptotic pathways. Second, we examined whether caspases and their upstream regulators are involved in rotenone-induced cytotoxicity. Rotenone significantly inhibited the proliferation of oral cancer cell lines in a dose-dependent manner compared to normal oral mucosal fibroblasts. Flow cytometric analysis of DNA content showed that rotenone treatment induced apoptosis following G2/M arrest. Western blotting showed activation of both the caspase-8 and caspase-9 pathways, which differed from previous studies conducted in other cell types. Furthermore, p53 protein and its downstream pro-apoptotic target, Bax, were induced in cells after treatment with rotenone. We have demonstrated significant involvement of caspases and their upstream regulators in rotenone-induced cytotoxicity. Third, we examined the efficacy of targeted PUMA gene therapy in human oral cancer (SAS) cells using polyethylenimine (PEI)-mediated transfection for gene delivery. PUMA is a p53 up-regulated modulator of apoptosis that is induced by p53 tumor suppressor and other apoptotic stimuli. It was found to be a principal mediator of cell death in response to diverse apoptotic signals, implicating PUMA as a likely tumor suppressor. Exogenous expression of PUMA in SAS cells resulted in apoptosis with cytochrome c release, activation of caspase-3 and -9, and cleavage of PARP. Gene delivery of PEI/PUMA in SAS xenografts induced apoptosis and resulted in significant reductions (~60%) of tumor growth in vivo. Furthermore, we have shown that PEI-mediated PUMA gene therapy prolonged survival of animals with orthotopic SAS oral cancers. Conclusions. Taken together, these results indicated that PUMA gene therapy via PEI delivery could be a promising method for the treatment of oral squamous cell carcinoma. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/25963 |
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