出版年:

2001

研究生:

沈卉菁

研究生(英文姓名):

Hui-Ching Shen

論文名稱:

c-met 基因參與膀胱致癌過程的分子機轉

英文論文名稱:

The molecular mechanism of c-met involved in bladder carcinogensis

指導教授:

劉校生 ; 周楠華

指導教授(英文姓名):

Hsiao-Sheng Liu ; Nan-Haw Chow

學位類別:

碩士

校院名稱:

國立成功大學　

系所名稱:

微生物暨免疫學研究所

學號:

S46884024

學年度:

89

語文別:

中文

論文頁數:

94

關鍵詞:

c-met 基因 ; 膀胱癌 ; 酪胺酸蛋白質

英文關鍵詞:

c-met ; bladder carcinogensis ; tyrosine kinase protein

被引用次數:

0

[ 摘要 ]

中文摘要
蛋白質酪胺酸活化酵素是人體內主要的致癌基因。在許多的細胞控制機轉，比如細胞生長、移動、黏著以及惡性轉化上，都扮演重要的角色。表皮生長因子受體和 ErbB2 (c-erbB2, HER2/neu)是其中最好的例子。c-met之產物為酪胺酸活化酵素之一員，有一個橫貫細胞膜的區域。它的配合基是肝細胞生長因子 (hepatocyte growth factor/scatter
factor, HGF/SF)。HGF/SF-Met相關的訊息傳導在細胞生長、移動、上皮生成和胚胎形成扮演重要的角色。此外，HGF/SF-Met相關的訊息傳導在致癌過程中也扮演重要的角色。已知過量c-met基因表現與腫瘤的轉移密切相關， 在部份癌症病患也會有較差的存活機會。比如乳癌、膽道癌症、胃癌、子宮內膜癌、肝癌、大腸癌和腎臟細胞癌等。膀胱癌中Met之表現是被高量活化的一種。因此我們挑選了c-met基因，做為深入研究其在膀胱癌中之生物效應和細胞內訊息傳遞之途徑，做為將來的研究基礎。
我們利用五株不同癌化等級的膀胱癌細胞株 RT4，
TSGH8301，TCCSUP，J82，T24 和一株正常膀胱上皮細胞 E6探討c-met表現量與癌化程度之關係。結果發現c-met在腫瘤細胞株上的表現強度，在許多第二級第三級之腫瘤細胞中出現。而且在臨床上也發現，c-met的表現與病患的預後和癌化進程相符合。為了瞭解 c-met 在膀胱的致癌過程中所扮演的角色，進一步以利用c-met 表現量最低的 T24細胞株建立了三個可誘導c-met
表現之永久細胞株(MetT1-T3)。分析 c-met 相關之訊息傳導路徑及其生物特性，結果顯示，即使在沒有HGF的刺激下，MetT1-T3
細胞株在c-met 過量表現時會自我磷酸化並活化起來。在此情況下細胞之不著地生長的能力增強，且細胞之移動能力有增強的趨勢，但細胞的生長並無顯著差異。c-met 過量表現也能不同程度地活化下列訊息傳導路徑: Ras，JNK，P38，PI(3)K，ElK，c-jun，
c-CHOP 及 Stat3。除此之外，c-met 過量表現也能增強膀胱癌
細胞對抗癌藥物 Doxorubicin 和 Methotrexate 之抗性。此外
c-met 之過量表現可抑制Methotrexate 對膀胱癌細胞造成之細
胞凋亡。進一步分析得知，Ras路徑，AKT的活化及 Bcl-2 過量
表現均扮演重要的角色。總言之在膀胱癌中正常c-met 之過量
表現即可造成細胞不著地生長，移動變快及抗細胞凋亡之生物特性。其主要路徑則為Ras-MAPK及PI(3)K。這些知識為建立膀胱癌基因標的治療模式提供寶貴之線索。

[ 英文摘要 ]

Protein tyrosine kinases (PTKs) are a major class of proto-oncogenes and play a crucial role in many cell regulatory processes, such as proliferation, migration, adhesion, and, potentially cellular transformation. Epidermal growth factor receptor and ErbB2 (c-erbB-2, HER-2/neu) are well known examples. The c-met proto-oncogene encodes a trans-membrane tyrosine kinase receptor (MET) for the hepatocyte growth factor/scatter factor (HGF/SF). HGF/SF-MET signaling clearly plays a role in a variety of normal cellular processes, such as cell motility, proliferation, epithelial morphogenesis, and normal embryogenesis. In addition, there is a substantial body of experimental evidence supporting the oncogenic role of the HGF/SF-MET signaling pathway. High levels of MET expression have been correlated with the metastatic spread of tumors and poor survival in patients with breast carcinoma, extrahepatic biliary tract cancer, gastric cancer, endometrial carcinoma, hepatocellular carcinoma, colorectal cancer, and renal cell carcinoma. In our molecular profiling of PTKs in bladder cancer, c-met was among the most frequently detected receptor-typed PTKs. The purpose of this study was to examine the molecular mechanisms of c-met expression in carcinoma cells, and the clinical relevance of MET over-expression in the progression of human bladder cancer.
We demonstrated that expression of c-met gene positively correlates with the histological grading of bladder cancer cell lines (RT4, TSGH8301, TCCSUP, J82, and T24), and that c-met overexpression correlates with patient survival and disease progression. Thus, the biological responses and associated signal pathways related to c-met overexpression were examined. T24 cells expressing very low level of
c-met were used to establishe stable cell lines expressing inducible c-met (MetT1-T3). Overexpression and auto-posphorylation of c-met transgene were observed in MetT1-T3 cells without stimulation of hepatocyte growth factor (HGF). Overexpression of c-met increased the anchorage-independent growth of the transfectants; however, the growth rate was unaffected. c-met overexpression was found to activate the following signal pathways, such as Ras, JNK, p38, PI3K, Elk, c-jun, c-CHOP, and Stat3 at various degrees. In addition c-met overexpression protects cancer cells from apoptosis induced by Doxorubicin and Methotrexate. Both Akt activation and Bcl-2 overexpression may play a role in the anti-apoptotic effect of c-met on human bladder cancer cells. In summary, the results of this study support that the c-met proto-oncogene plays an important role in the process of bladder carcinogenesis, and is a useful prognostic indicator for a more aggressive clinical course. MET and downstream signaling molecules may serve as important biological targets for bladder cancer therapy.