- 學位論文
探討YY1與GRP78於檳榔子萃取物誘發口腔癌細胞株上皮-間質細胞轉化現象之角色
Studies on the roles of YY1 and GRP78 in areca nut-induced epithelial-mesenchymal transition in oral cancer cell lines
摘要
口腔鱗狀細胞癌在台灣為高死亡率的腫瘤之一，而引發口腔癌發生的危險因子包含吸菸、酗酒與嚼食檳榔。實驗室先前利用蛋白質體學的方法，分析OC2與OCSL兩株惡性度不同的口腔鱗狀細胞癌細胞株，並鑑定出一些與內質網壓力(ER stress)相關的蛋白質，其中之一為葡萄糖調節蛋白78(Glucose-regulated protein 78, GRP78)，發現GRP78在低度惡性細胞OC2之mRNA與蛋白質表現量皆高於高度惡性細胞OCSL。以檳榔子萃取液(Areca Nut Extract, ANE)處理OC2後，發現隨著ANE濃度提高，GRP78的表現量會顯著地降低。而減少的機制可能與組蛋白修飾有關，而不是經由DNA甲基化。YY1轉錄因子為GRP78啟動子上之轉錄因子，隨著ANE濃度的提高YY1 mRNA與蛋白質表現量也跟著降低。以ANE處理口腔鱗狀癌細胞OC2會發生上皮細胞-間質轉化(Epithelial-mesenchymal transitions, EMT)，降低E-cadherin和提高vimentin的表現。OC2細胞中抑制YY1的表現會減少E-cadherin的表現，而大量表現GRP78則使E-cadherin增加。相反地，YY1大量表現在OCSL細胞可以增加GRP78的量，從細胞群落生成試驗也發現可減少群落的生成。綜合這些結果，我們推測ANE影響EMT的機制或許與YY1/GRP78訊息傳遞路徑相關，而此路徑或許就是ANE造成口腔癌細胞癌化的原因之一。
並列摘要
Oral squamous cell carcinoma (OSCC) is an aggressive tumor with high mortality and often occurs in betel quid chewers in Taiwan. Previously, we demonstrated that some ER stress-related proteins were differentially expressed in two OSCC cell lines (OC2 and OCSL). One of these proteins, 78-kDa glucose-regulated protein (GRP78) was found to be up-regulated in low grade OC2 cell line, but down-regulated in high grade OCSL cell line. In this study, we identified the YY1/GRP78/EMT signaling pathway in oral cancer cell lines after areca nut extracts (ANE) treatment. Expressions of YY1 or GRP78 decreased gradually in a dosage-dependent manner after ANE treatment in OC2. And this down-regulation of GRP78 expression might be correlated with the histone modification, but not with DNA methylation. In addition, we also observed the correlation between epithelial mesenchymal transition (EMT) biomarkers, such as vimentin and E-cadherin, and YY1/GRP78 after ANE treatment in OC2. Knockdown of YY1 down-regulated E-cadherin expression, and overexpression of GRP78 up-regulated E-cadherin expression in OC2, respectively. On the other hand, overexpression of YY1 in OCSL increased the level of GRP78 and decreased the formation of cell colonies. Taken together, these data suggested that ANE affected YY1/GRP78/EMT pathway, which might be one way to cause the carcinogeneisis in oral cancer cells.