Trichostatin A 或sirtinol抑制HT29人類結腸腺瘤細胞增生的分子機轉探討

Molecular mechanisms in trichostatin A- or sirtinol-inhibited HT29 human colon adenocarcinoma cells proliferation

楊德鑫(De-Shin Yang)

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(2010年)

https://doi.org/10.6831/TMU.2010.00049

摘要

細胞凋亡抑制蛋白 (IAP)-survivin，屬於IAP蛋白家族的一員，survivin和組織蛋白去乙醯酶 (histone deacetylases；HDACs)在人類腫瘤細胞發展和形成的過程中可見其過度表現，其中包括大腸直腸癌細胞。抑制HDACs已被證明可以誘導許多型態的轉化細胞，包括生長停滯、活化凋亡路徑、有絲分裂的細胞死亡等等。然而，在大腸直腸癌細胞中，HDAC抑制劑所誘導細胞功能喪失的機轉仍未有很明確的闡明。本論文之研究發現trichostatin A (TSA)和sirtinol這兩個不同結構和不同功能的HDAC抑制劑，可以降低大腸直腸癌細胞的存活率和阻止細胞的增生。Bax，是一個促進凋亡蛋白家族的成員之一，而p21Cip/Waf1是細胞周期的調控者，此兩個蛋白都可以受到TSA或sirtinol的刺激而增加表現。此外，TSA和sirtinol也可以抑制轉錄因子特定蛋白1 (Sp1)的轉錄活性導致調解下游survivin的表現以及抑制時間相關性IKK磷酸化的程度。值得注意的，TSA或sirtinol也可以活化p38 mitogen-activated protein kinase (p38MAPK)和AMP-activated protein kinase (AMPK)。我們也發現到利用p38MAPK和AMPK抑制劑可以抑制TSA或sirtinol所誘導細胞存活率的下降，因此可以推測p38MAPK和AMPK之間具有關聯性。另外，將帶有HDAC3和HDAC4的質體轉染大腸直腸癌細胞，也可以發現到會增加癌細胞的存活率，因此可以說明HDACs會促進癌細胞存活。由以上結果顯示，抑制HDACs可能活化p38MAPK或者是AMPK訊息傳遞的路徑是經由調控Sp1轉錄和向下調控survivin而導致HT29細胞功能喪失。

關鍵字

Trichostatin A ； sirtinol ； 大腸直腸癌細胞 ； 細胞增生

並列摘要

Survivin, an inhibitor of apoptosis family member and histone deacetylases (HDACs), are often found over-expressed in human cancers including colorectal cancer and have been implicated in the development and progression of tumorigenesis. Inhibition of HDACs was demonstrated to induce different phenotypes in various transformed cells, including growth arrest, activating apoptotic pathways, mitotic cell death and senescence. However, the mechanisms underlying HDAC inhibition-induced cell death or cell cycle arrest in HT29 human colon adenocarcinoma cells remain to be fully elucidated. We demonstrated in this study that trichostatin A (TSA) or sirtinol, two structurally and functionally different HDAC inhibitors, decreased cell viability and suppressed cell proliferation in HT29 cells. Bax, a pro-apoptotic protein, and p21Cip/Waf1, a cell-cycle regulator, both are elevated in cells exposure to TSA or sirtinol. TSA and sirtinol was shown to suppress transcription factor specific protein 1 (Sp1) activity leading to survivin down-regulation. TSA or sirtinol caused IKK dephosphorylation in a time-dependent manner. In addition, TSA or sirtinol were shown to activate p38 mitogen-activated protein kinase (p38MAPK) and AMP-activated protein kinase (AMPK). Inhibitors of p38MAPK and AMPK abrogated the TSA- or sirtinol-decreased cell viability suggesting functional crosstalk. Transfection of cells with HDAC3 or HDAC4 increased cell viability further supported the role of HDACs in promoting cell survival. These results suggest that HDAC inhibition may activate p38MAPK or AMPK signaling cascade resulting in HT29 cell dysfunction via regulated Sp1 transcription and down regulating of survivin.

並列關鍵字

Trichostatin A ； sirtinol ； HT29 ； proliferation

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