論文名稱:

口腔鱗狀上皮癌細胞經檳榔子萃取物處理後NF-κB 活化與氧化壓力之關係

 

The Relationships between Nuclear Factor-kappaB Activation and Reactive Oxygen Species Formation in Areca Nut Extract-treated Oral Epithelial Cancer Cells

研究生:

陳俊憲  Chun-Hsien 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:

張國威  Kuo-Wei Chang

        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:

39217008

          學年度:

93

          語文別:

中文

          出版年:

94

關鍵字:

檳榔子萃取物  Areca Nut Extract (ANE)

 

氧化物  Reactive Oxygen Species (ROS)

 

  Nuclear Factor-kappaB (NF-κB)

全文說明:

(本論文 20080802 對校內公開)

 

電子全文

        論文頁數:

82

摘要:

在台灣,約有250萬國人有嚼食檳榔之習慣。嚼食檳榔和口腔白斑症、口腔黏膜下纖維化和口腔癌,有強烈的因果關係。Nuclear factor-kappaB (NF-κB)為一種轉錄因子,亦為細胞壓力反應之訊息系統。在某些癌症中發現NF-κB呈現活化的狀態; 活化態的NF-κB提供腫瘤生成有利條件。活性氧化物(reactive oxygen species, ROS)為具有高度氧化力的分子。ROS之生成可由細胞內或細胞外物質所誘發。當細胞內的ROS過量時會攻擊DNA、蛋白質和細胞膜脂質而造成無法修復的傷害,此與癌症、老化及疾病生成極有關。

 

先前本實驗室發現:以檳榔子萃取物(areca nut extract, ANE)處理OECM-1OC3細胞株,其NF-κB的活性有明顯的增加。此外,研究也發現ANE可使細胞內ROS增多;但NF-κBROS之關聯性並不清楚。本計畫欲探討:口腔表皮細胞中,ANENF-κBROS之關聯性。結果發現:SAS細胞株經ANE處理後,其NF-κB的活性有的增加現象;伴隨有活化態NF-κB蛋白之調高而細胞質之IκBα蛋白之降低;IκBαmRNA表現量增加,此可能為一種回饋反應。經ANE處理之SAS細胞株,其ROS有呈時間依附性之增加,但調控ROS之關鍵酵素(Cu/ZnSODcatalase)表現並無明顯變化。SAS細胞株以N-acetyl cysteine (NAC)可以有效抑制ANE誘發的ROS。當SAS細胞株預先處理NAC,再處理ANE後,其NF-κB的活性和IκBαmRNA表現量無法被NAC抑制。用pCMV-IκBα質體DNA轉染SAS細胞株後,其IκBα蛋白質大量增加且有效抑制NF-κB的活化;以此方式抑制NF-κB的活化路徑後,ANE所誘發的ROS並無明顯增加。因此初步推論為:在SAS細胞株中,ANE誘發產生的ROS不調控NF-κB的活化過程;然而,由ANE活化的NF-κB可能調控ROS的產生。

 

There are around 2.5 million areca chewers in Taiwan. Areca chewing is tightly associated with the high incidence of oral leukoplakia, oral submucosa fibrosis and oral cancer in our country. NF-κB is a transcription factor. It is also a central dogma of signals responses to stresses. In several cancers, persistent activation of NF-κB was found. Activated NF-κB seems to be advantageous for neoplastic growth. Reactive oxygene species (ROS) are highly oxidative molecules. Endogenous and exogenous elements can elicit the ROS formation in cells. Accumulation of ROS causes the breakage of DNA, protein and membranous lipids resulting in irreversible cellular damages. These damages are associated with carcinogenesis, senescence and disease genesis.

 

In our laboratory, we have found that treatment of oral cancer cells with areca nut extract (ANE) induced the activation of NF-κB. Besides, experiments also showed that ANE can induce ROS in various types of cells. However, the consequential relationship between NF-κB activation and ROS formation are not clear. The aim of the present study was to clarify the inter-relationship among ANE, NF-κB and ROS in oral epithelial cells. We found that the treatment of SAS oral cancer cells with ANE activated NF-κB. Increase of activated (nuclear) NF-κB was accompanied by the down-regulation of cytosolic IκBα. There was also increase in IκBα mRNA expression, which was considered to be a refractory response. In SAS cells, increase of ROS in a time-dependent manner was found following ANE treatment. However, the level of Cu/ZnSOD and catalase, key ROS regulators, was not affected. N-acetyl cysteine (NAC) can inhibit the ROS induced by ANE. Pretreatment with NAC can not abrogate the NF-κB activation and the increase in IκBα mRNA expression as induced by ANE in SAS cells. Transient transfection of SAS cells with IκBα overexpression plasmid abrogated cytosolic IκBα down-regulation and NF-κB activation induced by ANE. In addition, the ANE-induced ROS was diminished. The findings implicate preliminarily that ROS induced by ANE is not involved in the activation of NF-κB, while it is likely that the activation of NF-κB induced by ANE is responsible for ROS formation in SAS cells.