Griseofulvin造成人類乳癌細胞(MCF-7)細胞週期停滯與凋亡之分子機制探討

Studies on the Molecular Mechanisms of Griseofulvin-induced G2/M Cell Cycle Arrest and Apoptosis in Human Breast Cancer Cells (MCF-7)

翁志銘(Chih-Ming Weng)

指導教授 ： 何元順 博士

臺北醫學大學/醫學院/醫學檢驗生物技術學研究所/碩士(2003年)

摘要

Griseofulvin (GF)目前是一種被廣泛使用的口服抗黴菌藥物，現已知道GF有抗癌的效果，其主要的作用機制是經由干擾微小管(Microtubule)的聚合(polymerization)，來達到使細胞凋亡(Apoptosis)的目的。在本研究中，發現到GF會誘發人類乳癌細胞MCF-7生長週期的停滯(G2/M arrest)及凋亡現象(Apoptosis)。而這樣的現象，會在使用了低濃度的Paclitaxel (TA)後被加強，同時GF的致效濃度也會由原本的10 ?M下降至5 ?M。而在其他不同細胞的反應上，實驗中觀察到了這樣的組合對於人類血癌細胞HL-60、大腸癌細胞HT-29這兩株p53缺陷的細胞會同時誘發細胞週期停滯和凋亡；在另一株大腸直腸癌細胞COLO-205，這株p53正常的細胞中，則觀察到了高比例的細胞凋亡，並沒有明顯的細胞週期停滯現象。另外本研究中也發現，在MCF-7細胞中，隨著GF濃度的增加，14-3-3?蛋白有被活化的現象，?這樣的現象也在使用了低濃度的TA變的更明顯；而在CDC2蛋白活性的分析上，實驗中也看到了CDC2蛋白活性被抑制，推測是因為14-3-3蛋白被活化而抑制了CDC2蛋白之活性。另外，本篇研究也觀察到在TA單獨處理細胞時，會使Akt/PKB的活性被抑制，而在將GF和TA共同處理MCF-7細胞後，Akt/PKB的活性被抑制的更明顯。因此本論文最後推測GF誘發G2/M細胞週期的停滯，與14-3-3?蛋白的活化有相當密切的關係，且低濃度的TA會經由抑制細胞內Akt/PKB活化路徑來強化GF誘發細胞凋亡的作用。

關鍵字

灰黴素 ； 紫杉醇 ； G2/M 週期停滯 ； 細胞凋亡 ； 14-3-3 sigma蛋白

並列摘要

Griseofulvin (GF) is an antifungal antibiotic produced by various species of Penicillium. It is a spindle poison which could interfere with the organization of microtubules at mitosis or other processes mediated by the microtubules networks. In this study, we found GF could induce G2/M cell cycle arrest and apoptosis in MCF-7 cells. And this effect could be enhanced by low concentration of Paclitaxel (TA). In other cells, including HL-60, HT-29, COLO 205, and A431, we also found the G2/M arrest and apoptosis in the p53-defect cells (HL-60 and HT-29 and A431); but apoptosis in the p53-wild type cells (COLO 205). When MCF-7 cells treated with GF, we found GF can induce 14-3-3? ?activation in dose-dependent manner, and this effect also enhanced by low concentration of TA. We also found when MCF-7 cells cotreated with GF and TA and the CDC2 kinase activity was inhibited, suggested that CDC2 kinase activaity was inhibited by 14-3-3?. Besides that, we found that TA can inhibit the avtivity of Akt/PKB, and when MCF-7 cells cotreated with GF and TA, we saw a dramatically inhibition of activity of Akt/PKB. Our data will support that GF induced G2/M arrest by activated 14-3-3???and low concentration of TA will inhibit the Akt/PKB pathway to enhance GF-induce apoptosis in MCF-7 cells.

並列關鍵字

Griseofulvin ； Paclitaxel ； G2/M phase arrest ； Apoptosis ； 14-3-3 sigma protein

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