Trichostatin A 誘導神經膠瘤細胞死亡的分子機轉探討

Molecular mechanism in Trichostatin A- induced C6 cell death

張財興(Tsai-Hsing Chang)

指導教授 ： 許銘仁

共同指導教授 ： 許準榕

臺北醫學大學/醫學院/醫學科學研究所/碩士(2009年)

https://doi.org/10.6831/TMU.2009.00001

摘要

組織蛋白 (Histone) 的乙醯化修飾作用被認為會促進基因之轉錄作用。組織蛋白的乙醯化會受到兩種相互拮抗之酵素所調控，分別為組織蛋白乙醯轉移酶 (histone acetyltransferases；HATs)，可促進組織蛋白乙醯化；另一則為可移除乙醯基之組織蛋白去乙醯酶 (histone deacetylases；HDACs)。HDAC 因可調控基因表現，而被認為會參與多種生理反應調控，如細胞週期與細胞分化等。近來更有研究發現 HDAC 在大部分癌細胞中會大量表現。Trichostatin A (TSA) 是一種天然的 HDAC 抑制劑，已有研究指出 TSA 會促進癌細胞週期滯留、細胞分化、細胞凋亡以及抑制癌細胞的轉移。然而 TSA 誘導細胞死亡的分子作用機轉仍不清楚。在本論文，我們研究發現 TSA 會降低 C6 神經膠瘤細胞的細胞存活率，利用流式細胞儀和 DNA 斷片分析更進一步證實 TSA 可誘導 C6 細胞凋亡。報告基因實驗發現 TSA 可增加轉錄因子 p53 的轉錄活性與細胞凋亡蛋白 Bax 的表現。此外 TSA 也可有意義地降低 ” 細胞凋亡抑制蛋白家族” (Inhibitor of apoptosis) 成員 survivin 的表現量。除了影響細胞凋亡蛋白，TSA 也會降低 IKK 蛋白激酶磷酸化與抑制 NF-?羠 之活化。和先前報導相似，TSA 同時也會誘導細胞週期蛋白 p21Cip1/Waf1 的表現與抑制 cyclin D1。總而言之，我們的研究發現 TSA 可能透過增加 p53 轉錄活性而進一步誘導增加 Bax 的表現和抑制 survivin 的表現，同時藉由抑制 IKK-NF-?羠 訊息路徑而使得 C6 細胞凋亡。除了誘導細胞凋亡，TSA 也可能透過影響細胞週期蛋白 p21Cip1/Waf1 和 cyclin D1 而使得細胞週期滯留。

關鍵字

神經膠瘤細胞

並列摘要

Histone acetylation is typically associated with increased transcription and is regulated by two opposing classes of enzymes: histone acetyltransferases (HATs), which add acetyl group to histone, and histone deacetylases (HDACs), which catalyze their removal. HDACs have been shown to participate in various physiological responses including cell-cycle progression and differentiation. Many studies demonstrated that several types of cancer cell are characterized by the elevation of HDAC expression. Trichostatin A (TSA), a HDAC inhibitor, was demonstrated to induce cell cycle arrest, promote cell differentiation or apoptosis, and inhibit metastasis in cancer cells. However, the precise mechanism involved in TSA-induced cell death remains unclear. In the present study, TSA was demonstrated to decrease cell viability in C6 glioma cells. TSA also induced cell apoptosis as determined by flowcytometry and DNA laddering. TSA increased p53 reporter activity as determined by reporter assay. Apoptotic protein such as Bax was elevated in C6 cells exposure to TSA. Survivin, a member of inhibitor of apoptosis (IAP) protein, was significantly decreased in TSA-treated C6 cells. In addition to apoptotic proteins, TSA was also shown to decrease IKK phosphorylation and to inhibit NF-?羠 reporter activity. Similar to previous studies, TSA induced p21Cip1/Waf1 expression and decreased cyclin D1 expression. Taken together, TSA may cause cell apoptosis through increasing p53 activity resulting in Bax expression and survivin supression. IKK-NF-?羠 cascade inhibition may also contributed to TSA apoptotic effect. Furthermore, TSA may also affect cell cycle progression through regulating p21Cip1/Waf1 and cyclin D1 expression.

並列關鍵字

Trichostatin A, glimo cell

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