論文名稱:

B[a]P及檳榔萃取物對人類口腔角質細胞內IGFBP-5基因表現之調控

 

The Regulation of IGFBP-5 Expression by B[a]P and Areca Nut Extract in Human Oral Keratinocytes

研究生:

陳漪曼  Yi-Man Chen

 

(以作者名查詢陽明大學館藏系統)

 

(以作者名查詢全國圖書書目資訊網)

指導教授:

林姝君  Shu-Chun Lin

        學位類別:

碩士

        學校名稱:

國立陽明大學

系所名稱:

口腔生物研究所

            學號:

880H07

          學年度:

89

          語文別:

中文

          出版年:

90

關鍵字:

類胰島素生長因子結合蛋白第五型  IGFBP-5

 

檳榔萃取物  ANE

 

菸草內之致癌物  B[a]P

 

人類口腔角質細胞  HOK

全文說明:

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摘要:

中文摘要 近幾年來,惡性腫瘤成為台灣地區十大死因之首,而且致死百分比逐年增加,而口腔癌在十大癌症死亡率排名第七位。口腔癌為包括唇、口、舌底、頰等區域之癌症,90%的口腔惡性腫瘤是鱗狀細胞癌,且為男性癌症死亡率之第五位。造成口腔鱗狀細胞癌之生成因素包括抽煙、嚼食檳榔及飲酒等。由我們實驗室之前的研究得知在口腔鱗狀細胞癌組織中,IGFBP-5的表現量明顯低於正常組織,甚至測不到;且當誘發正常口腔角質細胞(NHOK)及口腔鱗狀上皮癌細胞株(SCC25)走向分化的過程中也發現到,IGFBP-5蛋白質有增加的情形。因此本研究欲延續上述所觀察到的現象,進一步探討導致口腔癌的危險因子,如菸草中的致癌成分B(a)P或老檳榔萃取物對於正常口腔角質細胞中IGFBP-5基因之調控如何。本研究發現,B(a)P及老檳榔萃取物對於正常口腔角質細胞中IGFBP-5基因之表現均有抑制之效果,且此抑制效果不但發生於基因轉錄階段,甚至還持續到轉譯階段;類似的結果也在SCC25細胞中觀察到。上述的情形同時伴隨著involucrin表現減少的情形,這樣的結果似乎代表了抽煙或是嚼食檳榔具有抑制口腔角質細胞IGFBP-5基因之表現及分化之能力。將IGFBP-5表現質體送入原本不表現此基因的OECM1細胞中時,雖然測得RNA、蛋白質表現。經由流式細胞儀觀察發現,含有IGFBP-5表現質體的細胞之細胞週期間並未有顯著的差異。此外,由於有文獻探討綠茶中之萃取物(EGCG)具有促進NHOK細胞中Involucrin基因表現之能力,進而促使NHOK細胞分化,因此我們欲觀察在此過程中IGFBP-5是否也受到調控。結果發現,IGFBP-5蛋白質表現量隨著EGCG濃度上升而提高。綜觀上述的結果,NHOK細胞中IGFBP-5基因之表現同時會受到煙草或檳榔中致癌物以及綠茶成分完全相反之調控,同時還觀察到involucrin蛋白質之變化,或許暗示著:藉由調控NHOK細胞中IGFBP-5基因之表現可能在口腔鱗狀細胞癌之癌化機轉中扮演關鍵的角色。

   
 

Abstract For recent years, malignant tumors had become the chief cause of human death in Taiwan, and the percentage of mortality increases year by year. Oral cancer is the fifth most common malignancy of the male population in Taiwan, and 90 % of that are oral squamous cell carcinomas(OSCCs). Most of the OSCCs are associated with smokingbetel quid chewing or drinkng alcohol. Tumor formation is related to several factors , and carcinogenesis is a multi-stage process which is due to accumulation of gene alternations or changes of gene expression difined by molecular biology. Previous findings from our laboratory had shown that IGFBP-5 protein was primarily expressed on spinous and granular stratums which are differentiating normal human oral epithelium tissues. Down-regulation or loss of expression of IGFBP-5 protein was observed by immunohistochemistry in OSCCs compared with matched normal tissues. Moreover, there is up-regulation of  IGFBP-5 protein during the differentiation process of normal human oral keratinocytes (NHOKs) and SCC25. To continue the previous work from our laboratory, the purpose of this study is to investigate IGFBP-5 gene expression by B(a)P and ripen areca nut extract (rANE) in NHOKs . The results in this study suggest that B(a)P and rANE exhibited inhibition effects on IGFBP-5 gene expression both on transcription and translation levels in NHOKs. Similar results also exhibited on SCC25 which is a oral squamous cell carcinoma cell line. Those findings suggest that IGFBP-5 may play a critical role during the carcinogenesis of NHOKs. Further , we transfect-ed a IGFBP-5 over-expression plasmid to OECM1 to examine if IGFBP-5 has anti-cancer cell proliferation activity. There’s no striking influences on cell cycle of clones among control and IGFBP-5 over-expression OECM1 examing by flow cytometry. Besides , there’s evidence indicated that EGCG , a pers-pective chmopreventive constituent of green tea, regulates keratinocyte differentiation indicated by up-regulation of involucrin expression. Therefore, we have studied the effects of EGCG on IGFBP-5 protein in keratinocytes. The results showed a concentration-dependent up-regulation on IGFBP-5 gene expression by EGCG . The opposite effect of EGCG to B(a)P and rANE on IGFBP-5 correlates the hypothesis that EGCG may serve as a chemopreventive reagent for OSCCs. In conclusion , the regulation of IGFBP-5 gene expression in NHOK may provide a new perspective on mechanism of carcinogenesis of OSCCs.