論文名稱:

薑黃素於口腔癌細胞株對類胰島素生長因子結合蛋白第五型轉錄的調控方式

 

The Regulation of Curcumin on Insulin-like Growth Factor Binding Protein-5 Transcription in oral cancer cells

研究生:

林依瑩  I-Ying Lin

 

(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:

39317006

          學年度:

94

          語文別:

中文

          出版年:

95

關鍵字:

薑黃素  curcumin

 

類胰島素生長因子結合蛋白第五型  insulin-like growth factor binding protein-5

 

口腔癌  oral cancer

全文說明:

(本論文 20080719 對校內公開)

 

電子全文

        論文頁數:

59

摘要:

類胰島素生長因子結合蛋白(Insulin-Like Growth Factor Binding Proteins, IGFBPs)可與類胰島素生長因子(Insulin-Like Growth Factor, IGF)結合,扮演IGF攜帶者的角色,並調控IGF生理上的可利用性,調控細胞代謝、生長、分化,與存活。IGFBPs尚有IGF-independent activity,目前詳細的途徑仍未明確,已知與細胞生長、分化,凋亡有關。而實驗室先前研究發現多數口腔鱗狀上皮細胞癌細胞株,皆無法偵測到IGFBP-5mRNA和蛋白質表現;以及在口腔癌組織中,發現IGFBP-5蛋白質表現有調降的情形,顯示IGFBP-5可能與口腔癌形成過程有關。研究並發現將正常人類口腔角質細胞與口腔癌細胞株以薑黃素(curcumin) 處理,可誘導IGFBP-5啟動子活性增加,而導致IGFBP-5 mRNA、蛋白質表現量上升。進一步研究薑黃素如何調控IGFBP-5啟動子,經由啟動子刪除分析,找到薑黃素調控IGFBP-5啟動子活性的關鍵區域,為基因序列轉錄起始點算起-84+23的位置,且以資料庫分析,預測此區段上有糖皮質激素接受器(glucocorticoid receptor, GR)、細胞核κ因子(nuclear factor-kappaB, NF-κB)、活化蛋白第二型αactivator protein-2α, AP-2α)、CCAAT加強子結合蛋白αCCAAT/enhancer binding protein α, C/EBPα)等轉錄因子結合位置。透過啟動子點突變實驗已確定NF-κB結合位置非影響IGFBP-5啟動子活性的調控因子,GR扮演抑制IGFBP-5啟動子活性的角色。本研究進一步發現AP-2αC/EBPα之結合位置存在可影響薑黃素調控IGFBP-5啟動子的活性。而且薑黃素可降低AP-2αmRNA表現,但不影響AP-2αDNA結合能力。薑黃素調高C/EBPαmRNA與細胞核內蛋白質表現,及C/EBPαDNA結合能力,故C/EBPα結合區域之活化扮演重要角色。

 

Insulin-like growth factor binding proteins (IGFBPs) can bind to insulin-like growth factor, (IGF) for regulating the bio-availability of IGF. Moreover, IGFBPs also exhibit IGF-independent activity, which together with IGF-dependent activity, affect the cell growth, differentiation and apoptosis . IGFBP-5 was found to be down-regulated in oral squamous cell carcinoma (OSCC) cell lines and tissues, indicating an association between IGFBP-5 function and oral tumorigenesis. Previous investigations indicated that curcumin can activate the promoter activity of IGFBP-5, resulting in the up-regulation of IGFBP-5 mRNA and protein expression. From truncation analysis, a promoter region from -84 nt to +23 nt relative to transcription start site was mapped to be critical for IGFBP-5 regulation. This region was predicted to have glucocorticoid receptor (GR), nuclear factor-kappaB (NF-κB), activator protein-2α (AP-2α) and CCAAT/enhancer binding protein α (C/EBPα) binding sites. Site-directed mutagenesis analysis has excluded the involvement of NF-κB in regulating IGFBP-5 promoter activity. GR was found to be a repressor for IGFBP-5 activation. This study further stratified that AP-2α and C/EBPα binding sites could be essential for the curcumin-mediated IGFBP-5 up-regulation. Down-regulation in AP-2α mRNA expression was noted, but the activition of AP-2α binding activity was not detected. Up-regulation of C/EBPα mRNA expression, nuclear C/EBPα protein expression and C/EBPα binding activity was noted following curcumin treatment, indicated the role of C/EBPα activation for IGFBP-5 up-regulation.