2015-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/646875摘要：大腸直腸癌近年於世界和臺灣的十大癌症死因皆排名前三位，且超過三分之一病患乃 因遠端器官轉移導致死亡。而抑癌基因所在之染色體發生刪除是大腸直腸癌常見的基因變 異，我們先前的研究利用失異合性(Loss of Heterozygosity, LOH)分析，建構大腸直腸癌之第 四號染色體的高解析度刪除圖譜，定位出一個位於4q28的刪除區域，其中僅有一個已知功 能的基因Protocadherin 10 (PCDH10)，進一步於171例大腸直腸癌之LOH分析證實PCDH10 發生基因刪除與大腸直腸癌遠端器官轉移和病患較差的存活率有顯著相關，因此我們假設 PCDH10為大腸直腸癌相關的抑癌基因。接續我們檢測大腸直腸癌細胞株和病患腫瘤組織 PCDHM的基因表現，於12株大腸直腸癌細胞株皆無法測得PCDHM mRNA表現，而定量分 析53對臨床腫瘤與其正常粘膜組織，41例(77.4%)腫瘤之PCDHM基因表現量明顯低於其鄰 近正常粘膜組織，支持PCDHM為大腸直腸癌相關的抑癌基因。為了證實PCDH10的抑癌功 能，我們於大腸直腸癌細胞HCT116篩選穩定表現PCDH10之細胞株，並進行細胞體外和小 鼠體内之抑癌功能鑑定，當HCT116細胞重新表現PCDH10可以抑制癌細胞增生、胞落形成、 移行和侵犯能力。此外，利用皮下和脾臟注射之小鼠模式，發現表現PCDH10可以抑制 HCT116細胞於小鼠體内的腫瘤生長和肝臟轉移能力，同時，於脾臟注射之肝臟轉移模式， 注射表現PCDH10之癌細胞的小鼠其存活率較佳。然而，目前PCDH10之抑癌機轉仍是未知， 我們初步研究發現:PCDH10可減緩細胞經血清飢餓培養後細胞週期進行並增加細胞凋亡， 進而抑制癌細胞增生能力。此外，PCDH10可以抑制經TNFa誘導之大腸直腸癌細胞的上皮 間質轉化(Epithelial-to-Mesenchymal Transition)作用，而降低其轉移能力。藉由以上的研究 進展，此三年研究計晝，我們將探討PCDHM基因抑制腫瘤生成和肝臟轉移的分子機轉。 本計晝研究目標如下：1. 探討PCDH10調控細胞週期的訊息傳遞路徑2. 探討PCDH10調控細胞凋亡的訊息傳遞路徑3. 探討PCDH10調控腫瘤轉移的訊息傳遞路徑4. 探討PCDH10調控癌幹細胞特性的訊息傳遞路徑5. 利用大腸直腸癌腫瘤檢體驗證PCDH10之抑癌功能的分子機轉6.鑑定PCDH10相互作用之蛋白7. 建立PCDH10之抑癌功能的分子機轉模型<br> Abstract: Colorectal cancer (CRC) is one of the leading types of cancer death worldwide, and over one third of these patients will die of their disease mainly due to distant metastasis. Genomic deletion that occurs at tumor suppressor loci is a common genetic aberration in CRC. In our recently published study, we identified that Protocadherin 10 (PCDH10), a novel tumor suppressor gene in human cancers, is located in a common deleted region at chromosome 4q28 in CRC. The allelic loss of PCDH10 was determined in 171 pairs of primary tumors and corresponding normal mucosae by loss of heterozygosity study. The genetic aberration was significantly associated with tumor progression and distant metastasis, as well as was an independent predictor of poor survival for patients with CRC. Expression of PCDH10 gene was silenced or markedly down-regulated in all of 12 CRC cell lines tested and 41 (77.4%) of 53 colorectal carcinomas compared with their matched normal mucosae. Ectopic expression of PCDH10 suppressed cancer cell proliferation, anchorage-independent growth, migration, and invasion in vitro. Subcutaneous injection of PCDH10-expressing CRC cells in SCID mice revealed the reduction of tumor growth compared with that observed in mock-inoculated mice. Furthermore, via intrasplenic implantation, the re-expression of PCDH10 in silenced cells restrained liver metastasis and improved survival in SCID mice. However, the mechanisms by which PCDH10 exerts its tumor suppressor functions still remain largely unknown. In our preliminary study, PCDH10 might reduce cell proliferation through retardation of cell cycle progression and enhancement of apoptosis after serum starvation. In addition, PCDH10 could attenuate TNFa-induced epithelial-to-mesenchymal transition in CRC cell line HCT116. With these progresses, in the three-year project, we pursue to explore the molecular mechanisms underlying PCDH10-mediated suppression of tumorigenesis and metastasis. Seven specific aims are proposed as follows:Aim 1: To investigate the cell cycle-related signaling pathways modulated by PCDH10 Aim 2: To investigate the apoptosis-related signaling pathways modulated by PCDH10 Aim 3: To investigate the metastasis-related signaling pathways modulated by PCDH10 Aim 4: To investigate the stemness-related signaling pathways modulated by PCDH10 Aim 5: To validate molecular mechanisms underlying PCDH10-mediated tumor suppression in primary CRC tissues Aim 6: To identify the interaction partners of PCDH10Aim 7: To establish a hypothetical model of PCDH10-mediated tumor suppression大腸直腸癌抑癌基因PCDH10基因分子機轉Colorectal cancerTumor suppressor genePCDH10Molecular mechanism