膠質瘤是原發性腦腫瘤中最常見的亞型，是人類腫瘤中侵襲性強、強浸潤能力、神經破壞性強的腫瘤。膠質瘤細胞來源被認為是神經幹細胞 (NSCs) 和寡突膠細胞前體細胞 (OPCs)，因為腫瘤細胞也表達NSCs和OPCs的細胞標記。白細胞介素-33 (IL-33) 作為一種組織損傷後的警示蛋白質，它可以在細胞核中偵測到，並在N-端含有染色質結合基因序列和和核定位序列。IL-33可被蛋白酶 (如caspase-3) 切割，其作為一種典型的細胞因子，可以釋放到細胞外。成熟的IL-33或與染色質相關的IL-33已證明可與受體ST-2結合並在細胞中誘導細胞內信號通路。我們之前已經討論過高度表現之IL-33因子參與膠質瘤細胞的致瘤性，並通過IL-33/ST-2路徑，探討其抗腫瘤作用。在研究過程中，發現IL-33在膠質瘤細胞核中表達豐富，但核中IL-33對於膠質瘤細胞中功能仍不清楚。在本次研究中，我們利用大鼠C6膠質瘤細胞株，讓其過度表達IL-33。在IL-33過度表達的C6細胞 (C6-IL33oe) 中大量表現TGFβ，於C6-IL33oe之癌細胞與小膠質細胞共培養中誘導小膠質細胞增殖大量在IL-33 表達量增加的同時BRCA1/BRCA2-Containing Subunit 3 (Brcc3)表現量降低，我們用免疫沈澱證明IL-33結合於組蛋白H2A上，經由cacpase-3活化劑 (PAC-1) 處理後減少纖維上IL-33的表現。另外，我們觀察到DNA修復相關基因Rad51、BRCA1在C6-IL33oe細胞中上調。進一步處理，烷基化劑替莫唑胺 (TMZ) 藥物後，可增加對照組C6模擬細胞和C6-IL33oe細胞中DNA修復指標γH2A的水平。然而，通過細胞活力測定和群落形成分析，C6-IL33oe細胞對於TMZ藥物的損傷是具有抗性的。當C6-IL33oe細胞被藥物順鉑處理後，也觀察到類似的結果。這些發現與C6-IL33oe基因敲除後人腦膠質瘤細胞DNA修復基因表達下降的結果相互呼應，說明核內IL-33可能在DNA修復中起重要作用，從而降低膠質瘤對於藥物的敏感性。我們還發現在繼代代數增加IL33oe細胞增生速度加快細胞核產生形變IL-33基因表現量降低，Brcc3補償性增加使得癌細胞對癌症化療藥物產生更強的抗性。
關鍵字: 膠質母細胞瘤、介白素33、γH2AX、DNA 修復

SUMMARY
Glioma, the most common subtype of primary brain tumors, is aggressive, highly invasive, and neurologically destructive tumors among human cancers. Glioma cells are believed to be derived from neural stem cells (NSCs) and oligodendrocyte precursor cells (OPCs) since the tumor cells also express the common cell markers of NSCs and OPCs. Recently studies have mentioned that intereukin-33 (IL-33) an alarmin present in the cell nuclei, play an important role in cancer cells by regulating and promoting a inflammatory microenvironment. We have previously addressed that IL-33 involved in glioma cell tumorigenicity possibly through IL-33/ST-2 axis. Interestingly, we also found that IL-33 expression was enriched in the glioma cell nuclei; however, the function of nuclear IL-33 in glioma cells remains largely unknown, and we also clarified that IL-33 plays a function role in the nuclear of glioma cells. And then, we used that doing Immunofluorescence and co-Inmmunoprecipitationg proved the nuclear of IL-33 combine with histone H2A. Here, we conducted the forced overexpression of IL-33 in a rat C6 glioma cell line. Here we showed that microglia in activated with IL-33 overexpressed C6 cells (C6-IL33oe). IL-33 associated with DNA fibers in the IL-33 overexpressed C6 cells (C6-IL33oe) was reduced by exposure to the cacpase-3 activator (PAC-1). Moreover, we observed that DNA repair-associated gene Rad51 was upregulated in C6-IL33oe cells. Further pharmaceutic experiments revealed that exposure to the alkylating agent temozolomide (TMZ) both increased the level of a DNA repair indicator γH2AX and IL-33 protein level in the control C6 MOCK cells and C6-IL33oe cells. However, through the cell viability assay and colony formation analysis, C6-IL33oe cells were resistant to TMZ insult. Similar results were observed when C6-IL33oe cells were treated with another DNA damaging agent Cisplatin. These findings in conjunction with the results showing the downregulation of DNA repair gene in human glioma cells with IL-33 gene knockdown demonstrate that nuclear IL-33 might play a significant role in DNA repair to desensitize the response of glioma cells to anti-tumor agents.
Key Words: Glioblastomas, IL-33, γH2AX, DNA repair

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