增強多型性神經膠質母細胞瘤放射治療抗性的潛在分子

Potential Molecules Enhance Malignancy of Radioresistance Glioblastoma Multiforme

林讓均(Jang-Chun Lin)

指導教授 ： 蔡若婷

共同指導教授 ： 劉偉修(Wei-Hsiu Liu)

臺北醫學大學/醫學院/臨床醫學研究所/博士(2020年)

摘要

動機：多型性神經膠質母細胞瘤(GBM)是成人最常見的原發性惡性腦瘤，臨床主要治療為手術切除合併術後同步放射治療與化學治療，然惡性腦瘤5年存活率僅小於10%，究其根本導致腦瘤病人死亡之重大原因，在於神經膠質母細胞瘤產生具放射治療抗性的癌幹細胞及放射治療後增加神經膠質母細胞侵襲能力，進而導致無法手術完全切除、神經膠質母細胞浸潤在正常腦組織中，並從放射線傷害中逃脫。
目的：本研究預計建立具放射治療抗性合併高細胞侵襲能力之神經膠質母細胞株，用於尋找增強多型性神經膠質母細胞瘤放射治療抗性的潛在分子。
研究方法：從神經膠質母細胞株中，藉由反覆交替放射線照射及細胞移動實驗(Transwell migration assay) 分離純化，建立具有高放射線抗性及高侵襲能力之癌細胞株，透過DNA晶片（DNA microarray）尋找同時與高侵襲特性、癌幹細胞及放射線抗性相關的潛在分子，進一步從過度活化或拉低潛在因子在多型性腦神經膠質瘤的表現量，觀察調節放射線抗性的可能分子機轉，利用潛在因子不同表現量的細胞株交集篩選出與癌幹細胞及細胞侵襲能力相關，並影響神經膠質母細胞癌預後潛在分子的下游分子。
研究結果：使用的腦瘤病患組織延伸出的神經膠質母細胞株(GBM-Par cell line)建立包括GBM-R1M1、GBM-R2M2、GBM-R3M3等具放射線抗性合併高細胞侵襲能力之神經膠質母細胞株。發現Musashi-1(MSI1)透過增強癌幹細胞特性及活化高細胞移動能力，產生較高的放射治療抗性。MSI1可以促進GBM的惡性腫瘤生成；高MSI1表現量的GBM患者與較低的生存率有關。此外，發現透過MSI1調控Intercellular adhesion molecule-1 (ICAM1)的 mRNA，對應不同程度ICAM1表現量的腦癌細胞株包括U87MG及05MG，顯示MSI1藉由ICAM1影響神經膠質母細胞放射線抗性機轉，增強細胞侵犯能力及腫瘤幹細胞特性例如: self-renewal, tumor-initiating ability, Sox2等。
結論：抑制MSI1表現後的神經膠質母細胞瘤，會降低腫瘤的侵襲能力並抑制癌幹細胞的特性，促進放射治療敏感度。我們的結果也顯示MSI1可藉由ICAM1訊息傳遞路徑，增強腫瘤細胞移動能力，MSI1/ICAM1亦可作為未來進一步的臨床運用。

關鍵字

多型性神經膠質母細胞癌 ； 放射線抗性 ； MSI1 ； 癌幹細胞 ； ICAM1

並列摘要

Background: Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor in adults. The standard therapy of GBM is complete surgical resection followed by concurrent chemoradiotherapy (CCRT). However, even after standard treatment, 5-year overall survival is less than 10%. The major reasons of the therapeutic failure are the existing cancer-stem like cells (CSCs) property and the highly invasive ability of the cancer cells, which might cause an intrinsic radioresistance and inability of complete surgical removal by operation, infiltrated around the normal brain and escaped from the damage of irradiation.
Aims: First, this study is to establish a highly invasive and radioresistant GBM cell line. By using these cell lines, numerous molecules (or cancer genomes) associated with radioresistance are screened and investigated.
Methods: Alterative irradiation and Transwell migration assay were performed to establish radioresistant GBM cell lines with highly invasive abilities. By employing DNA microarray, tumor genomes related to a highly invasive ability and radioresistance were identified. Furthermore, through the knockdown or overexpression of the demonstrated genes could clarify the molecular mechanism of the radioresistance and find out the downstream pathway of the genome.
Results: By using the patient-derived GBM cells to establish primary cell line (GBM-Par cell line) and highly invasive and radioresistant cell lines including GBM-R1M1、GBM-R2M2、GBM-R3M3, Musashi-1 (MSI1) was found to be associated with a highly radioresistant ability by enhancing the characteristics of CSCs and activating high cell migration ability. MSI1 can promote the tumorigenesis of GBM; GBM patients with high MSI1 expression are associated with lower survival rates. In addition, MSI1-mediated mRNA interaction promotes the translation of Intercellular adhesion molecule-1 (ICAM1). Through the different levels of ICAM-1 expression in GBM cell lines including U87MG and 05MG, MSI- modulated ICAM-1 was associated with the radioresistance, enhanced cell motility, and CSCs characteristics such as an increased expression of self-renewal transcription factor of Sox2.
Conclusions: In GBM cell lines, MSI1 inhibition might radiosensitize tumors and convert CRT-related CSC-positive selection, and reduce tumor invasion. In addition, our study revealed that MSI1/ICAM1 plays an important role in inducing radioresistance, triggering cell invasion, and rendering tumor recurrence. Thus, MSI1/ICAM-1 could be a potential therapeutic target for GBM treatment and needed further investigation.

並列關鍵字

Glioblastoma Multiforme ； Radioresistance ； MSI1 ； Cancer stem cells ； ICAM1

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