探討miR-155如何調控FOXO3a 的表現促使非小細胞肺癌中對艾瑞莎產生抗藥性

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Title:	探討miR-155如何調控FOXO3a 的表現促使非小細胞肺癌中對艾瑞莎產生抗藥性 MiR-155-Mediated Downregulation of FOXO3a involved in the Gefitinib-Resistance of Non-Small Cell Lung Cancer
Authors:	王筱晴;Wang, Hsaio-Ching
Contributors:	癌症生物學研究所碩士班
Keywords:	艾瑞莎;肺癌;抗藥性;Gefitinib;Lung Cancer;FOXO3a;miR-155
Date:	2012-07-30
Issue Date:	2012-08-31 16:34:33 (UTC+8)
Publisher:	中國醫藥大學
Abstract:	肺癌是全世界最常見的惡性腫瘤之一，並且位居癌症死亡原因之首。Gefitinib (Iressa, 艾瑞莎) 為表皮生長因子受體之酪氨酸激酶的抑制劑，在臨床上已有效使用在非小細胞肺癌患者的治療，然而於使用一段時間後會因產生抗藥性而失效，所以探討造成艾瑞莎產生抗藥性的分子機制是極為重要與迫切的。在本實驗中，我們發現在gefitinib-resistance的肺癌細胞株(PC9/GR)中FOXO3a的表現量低於gefitinib-sensitive的肺癌細胞株(PC9/WT)。因此我們在PC9/WT細胞中降低原本表現較高的FOXO3a，發現細胞因此對艾瑞莎產生抗藥性；相反的我們在PC9/GR表現FOXO3a，造成細胞對艾瑞莎具有敏感效果。在過去的研究指出，microRNA在許多癌症的發展當中扮演相當重要的角色，其中包含對藥物的抗藥性。故我們進一步探討microRNA是否會調控FOXO3a並導致艾瑞莎產生抗藥性。利用電腦網站之資料庫，預測出會標靶至FOXO3a的microRNA。接著我們利用即時定量聚合酶連鎖反應分析上述預測出的microRNA在PC9/WT與PC9/GR中的表現，並發現在PC9/GR中miR-155的表現高於PC9/WT。此外，我們在PC9/WT表現miR-155後，發現FOXO3a表現量下降並且增加細胞對艾瑞莎產生的抗藥性。總括而言，我們的研究指出miR-155與FOXO3a之間的相關性並證明miR-155和FOXO3a在對艾瑞莎產生抗藥的肺癌中可視為潛在的標靶治療方法。 Lung cancer is one of the most common malignancies worldwide. Epidermal growth factor receptor (EGFR) regulates many biological functions including proliferation, angiogenesis, anti-apoptosis and metastasis. A specific EGFR tyrosine kinase inhibitor, gefitinib (Iressa, ZD1839), has been developed to exhibit clinical efficacy in lung cancer patients. However, acquisition of resistance to gefitinib is also observed after treatment. It is critical and timely to understand the molecular mechanisms involved in gefitinib resistance. In this study, we found the expression level of FOXO3a was lower in gefitinib resistant PC9 (PC9/GR) cells than wild type PC9 (PC9/WT) cells. Kockdowned of FOXO3a in PC9/WT cells enhanced resistance of gefitinib ; consistantly, overexpression of FOXO3a make PC9/GR cells re-sensitize to gefitinib. MicroRNAs play critical role in multiple steps of cancer progression, including drug resistance. To define whether microRNAs involved in FOXO3a-mediated gefitinib-resistance, we predicted microRNAs which may target to FOXO3a by several softwares, such as miRWalk, DIANAmT , miRanda, miRDB and TargetScan. We further analyzed the expression of these candidate microRNAs in PC9/WT and PC9/GR cells by quantitative RT-PCR. We found that miR-155 was highly expressed in PC9/GR cells than in PC9/WT cells. Overexpression of miR-155 in PC9/WT cells downregulated FOXO3a and subsequently enhanced the resistance of gefitinib. Together, our study reveals a molecular link between miR-155 and FOXO3a and provides evidence that miR-155 and FOXO3a are potential therapeutic targets in gefitinib-resistant lung cancer.
Appears in Collections:	[Graduate Institute of Cancer Biology] Theses & dissertations

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