類別:

黏蛋白第二十型在胰臟癌中扮演的角色

Mon, 01 Jan 2018 00:00:00 GMT

標題: 黏蛋白第二十型在胰臟癌中扮演的角色; The role of MUC20 in pancreatic cancer 作者: Syue-Ting Chen; 陳學亭摘要: 胰臟癌在十大癌症死因中排名第四位，大部份為胰腺癌。胰腺癌通常由胞外基質及星狀細胞共同形成的緻密纖維化基質所包覆，而由此纖維化基質所營造出的低養分，低氧及酸性的微環境促進了胰腺癌細胞的惡性行為。黏液蛋白(Mucins)為高度醣化之蛋白質，在惡性腫瘤的發病機轉中扮演重要角色。據研究顯示，各型的黏蛋白在胰腺癌中陸續被發現表現量異常，然而黏蛋白第二十型(MUC20) 在胰腺癌中扮演的角色仍未知。　　本篇研究結果如下：胰腺癌組織的免疫染色結果與臨床特徵之相關性統計顯示，MUC20表現量高與低病人存活率及術後局部復發率呈正相關。血清剝奪、低氧及酸性環境皆能誘發胰腺癌細胞中MUC20的表現量。以小分子干擾核糖核酸抑制胰腺癌細胞株HPAC及HPAF-II 的MUC20表現量，則由星狀細胞所誘發的HPAC及HPAF-II爬行及侵襲能力也隨之減弱。在腹腔、皮下及胰臟注射胰腺癌細胞的動物模式中，降低胰腺癌細胞MUC20的表現量可減緩其在免疫缺陷鼠體內的生長。磷酸化-受體酪氨酸激酶陣列 (Phospho-Receptor Tyrosine Kinase Array, p-RTK array) 和西方墨點法 (Western Blot) 的分析結果顯示，將胰腺癌細胞中MUC20的表現量降低可同時降低由肝細胞生長因子（Hepatocyte Growth Factor, HGF）所誘發的肝細胞生長因子受體之磷酸化 (Phospho-Hepatocyte Growth Factor Receptor, p-MET)。由HGF所誘發的胰腺癌細胞惡性表徵，可藉由降低其細胞內MUC20的表現量而將之抑制。免疫共沉澱 (co-immunoprecipitation, co-IP) 的實驗結果顯示，MUC20和MET間有實質上的交互作用。　　總結：胰腺癌細胞中MUC20表現量降低而產生其惡性表徵減弱的現象，至少部分是由於HGF/MET訊息傳遞路徑受到抑制而導致，同時也顯現MUC20極有潛力成為治療性標靶。; Mucins are heavily glycosylated proteins that play critical roles in the pathogenesis of tumour malignancies. Pancreatic ductal adenocarcinoma (PDAC) is characterised by the aberrant expression of mucins. However, the role of mucin (MUC) 20 in PDAC remains unclear. PDAC is usually surrounded by a dense fibrotic stroma consisting of an extracellular matrix and pancreatic stellate cells (PSCs). The stroma creates a nutrient-deprived, hypoxic and acidic microenvironment and promotes the malignant behaviours of PDAC cells. In this study, immunohistochemical staining demonstrated that high MUC20 expression correlated with poor progression-free survival and high local recurrence rate of PDAC patients (n = 61). The expression of MUC20 was induced by serum deprivation, hypoxia, and acidic pH in PDAC cells. MUC20 knockdown with siRNA decreased cell viability as well as migration and invasion induced by PSCs in HPAC and HPAF-II cells. In intraperitoneal, subcutaneous, and orthotopic injection models, MUC20 knockdown decreased tumour growth in immunodeficient mice. Phospho-RTK array and western blot analysis indicated that MUC20 knockdown decreased HGF-mediated phosphorylation of MET in PDAC cells. Moreover, HGF-induced malignant phenotypes could be suppressed by MUC20 knockdown. Co-immunoprecipitation revealed the physical association of MUC20 and MET. These findings suggest that MUC20 knockdown suppresses the malignant phenotypes of PDAC cells at least partially through the inhibition of the HGF/MET pathway and that MUC20 could act as a potential therapeutic target.

黏蛋白型O-聚醣在肝癌中的表現情形

Tue, 01 Jan 2013 00:00:00 GMT

標題: 黏蛋白型O-聚醣在肝癌中的表現情形; Expression of mucin-type O-glycans in hepatocellular carcinoma 作者: Wei-Jen Wang; 王韋人摘要: 異常的醣化作用是癌細胞常見的一種特徵。腫瘤相關醣抗原─Tn、sialyl-Tn、T和sialyl-T抗原，是由於不正常的黏蛋白型O-聚醣醣化作用所導致。這些腫瘤相關黏蛋白型O-聚醣的表現通常與許多癌症的惡性程度以及預後有直接的相關性。曾有研究指出在肝癌中有腫瘤相關黏蛋白型O-聚醣的表現；然而，這些醣抗原與肝癌的臨床病理特性以及預後之間的關聯性仍不明確。在本篇研究中，我們利用免疫組織化學染色法檢視Tn、sialyl-Tn、T和sialyl-T抗原的在肝癌組織中的表現情形。結果顯示，有76% (69/91)、 58% (29/50)、 26% (13/50)和26% (13/50)的肝癌組織分別表現Tn、sialyl-Tn、T和sialyl-T抗原。其中，Tn抗原的表現和肝癌的腫瘤的大小和侵犯程度(T stage, p < 0.005)、組織分化程度(histological grade, p = 0.001)、有無血管侵襲(vascular invasion, p = 0.001)以及是否復發(recurrence, p < 0.05)都有統計上的正相關。有較高Tn抗原表現的病人，其五年存活率也較差(p < 0.05)。此外，我們也檢視了負責合成黏蛋白型O-聚醣的酵素的mRNA的表現量，包含有GALNTs、ST6GALNACs、ST3GALs、C1GALT1、COSMC、GCNTs、B3GNT3和B3GNT6等幾個酵素家族。結果顯示，GALNT10、ST6GALNAC2和C1GALT1的mRNA表現量在肝癌中有顯著的上升；相反的，GALNT2、ST3GAL1和B3GNT6的mRNA表現量在肝癌中有顯著的下降。此結果顯示，在肝癌病人中不正常的醣化基因的表現，可能是導致異常黏蛋白型O-聚醣表現的原因之一。總結來說，本研究發現在肝癌病人中有不正常Tn、sialyl-Tn、T和sialyl-T抗原；而其中Tn抗原的表現量與肝癌的惡性程度以及預後有顯著的相關。根據這些結果我們推測，異常黏液型O-聚醣的表現以及與其合成相關的醣類基因，在肝癌的發展中可能扮演著重要的角色。; Altered glycosylation is a common feature of cancer cells. Expressions of Tn, sialyl-Tn, T, and sialyl-T antigens are caused by aberrant mucin-type O-glycosylation. These antigens are tumor-associated carbohydrate antigens, and their expressions are often associated with malignant properties and clinical outcome of many cancers. Although the expressions of these antigens in hepatocellular carcinoma (HCC) have been reported, the correlation between their expressions and clinicapathological features and prognosis is still unclear. In this study, immunohistochemistry showed that the prevalence of Tn, sialyl-Tn, T, and sialyl-T antigens in human HCC tissues was 76% (69/91), 58% (29/50), 26% (13/50), and 26% (13/50), respectively. The expression level of Tn antigens was positively associated with advanced T stage (p < 0.005) and higher histological grade (p = 0.001), as well as increased vascular invasion (p = 0.001) and recurrence (p < 0.05) of HCC. In addition, high expression of Tn antigens significantly correlated with poor 5-year survival of HCC patients (p < 0.05). Furthermore, we analyzed the mRNA expression of glycogenes for O-glycan synthesis, including GALNTs, ST6GALNACs, ST3GALs, C1GALT1, COSMC, GCNTs, B3GNT3, and B3GNT6, in human HCC tissues by real-time RT-PCR. Among them, the mRNA levels of GALNT10, ST6GALNAC2, and C1GALT1 were significantly up-regulated, while GALNT2, ST3GAL1, and B3GNT6 were significantly down-regulated in HCC tissues compared with those in the non-tumor part. These results suggest that the expression of aberrant O-glycans in HCC may be resulted from the dysregulation of these glycogenes. In conclusion, our findings suggest that Tn, sialyl-Tn, T, and sialyl-T antigens are expressed in HCC, and the expression of Tn antigens is associated with poor prognosis of HCC patients. These results imply that mucin-type O-glycans and O-glycogenes may play roles in modulating tumor progression of HCC.

黏液蛋白醣化酶 N-acetylegalactosaminyltransferase 1 (GALNT1) 在肝細胞癌扮演之角色

Thu, 01 Jan 2015 00:00:00 GMT

標題: 黏液蛋白醣化酶 N-acetylegalactosaminyltransferase 1 (GALNT1) 在肝細胞癌扮演之角色; The role of N-acetylegalactosaminyltransferease 1 (GALNT1) in hepatocellular carcinoma 作者: Miao-Juei Huang; 黃妙瑞摘要: 肝細胞癌在全球癌症死亡率排名第三位。由於肝細胞癌的惡性行為之特性，在臨床診斷及治療上仍然是一大問題。黏液型醣化修飾作用為蛋白質最常見的轉譯後修飾作用。從過去研究指出，不正常的醣化修飾會參與在癌症發展過程中。GALNT1為黏液型醣化作用步驟中的第一步酵素。但是目前對於GALNT1在肝細胞癌所扮演的角色卻仍然非常不清楚。本研究發現GALNT1在肝細胞癌有高度表現，並且高度表現GALNT1的病人其存活率相較低表現之病人差。從細胞實驗我們發現高表現GALNT1的肝癌細胞可以促進肝癌細胞的惡性行為，例如：細胞遷移和侵襲 ; 反之，降低GALNT1表現則會抑制肝細胞惡性行為。此外，抑制GALNT1表現肝癌細胞會抑制EGF所誘發的細胞遷移和侵襲之惡性行為。並且抑制GALNT1表現可以影響EGFR上的醣化修飾，進而抑制EGFR的磷酸化，進而促進EGFR的降解作用。本研究顯示GALNT1在肝細胞癌中表現量增加，透過抑制GALNT1的表現可以抑制由EGFR所誘發肝癌細胞的惡性行為。未來在肝細胞癌治療研究中，GALNT1是一個具有潛力的方向。; Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related mortality worldwide. Management of HCC imposes great challenge due to its malignant characteristics and limited therapeutic drug efficacy. O-glycosylation is a common protein modification, however, aberrant O-glycosylation is associated with many cancer malignancies. GALNT1 is a GalNAc-transferase pivotal in the initiation of protein O-glycosylation, yet, the functional roles of GALNT1 in cancer, particularly HCC, are unknown. In this study we found that GALNT1 is frequently up-regulated in HCC; and higher GALNT1 expression is associated with poorer patient survival. Indeed, overexpression of GALNT1 shows enhanced but knockdown suppressed HCC cell migration and invasion. Further investigation found that knockdown of GALNT1 significantly suppressed EGF-induced HCC cell migration and invasion. Mechanistic investigation shows that knockdown of GALNT1 decreased EGF-triggered EGFR activation and enhanced EGFR degradation by altered O-glycans on EGFR. This study demonstrates that GALNT1 is often overexpressed in HCC and inhibiting GALNT1 expression is sufficient to suppress malignant behaviors of HCC cells by decreasing EGFR signaling suggesting that GALNT1 may be a potential target of therapeutic drug development in the management of HCC.

黏液蛋白醣化酵素GALNT2經由降低表皮生長因子接受器的磷酸化抑制胃癌的惡性程度

Fri, 01 Jan 2016 00:00:00 GMT

標題: 黏液蛋白醣化酵素GALNT2經由降低表皮生長因子接受器的磷酸化抑制胃癌的惡性程度; Mucin glycosylating enzyme GALNT2 suppresses the malignancy of gastric adenocarcinoma by reducing EGFR phosphorylation 作者: Wan-Ting Hu; 胡椀婷摘要: 背景: 胃癌在癌症相關死亡率中高居第三位，雖然其發生率隨時間有逐漸下降的趨勢，但病人的預後仍然不佳，平均五年存活率只有29%。目前研究觀察到異常的醣化作用會影響癌細胞的惡性程度。在我們之前的研究發現乙烯半乳糖胺轉移酶2(Glycosyltransferase N-acetylgalactosaminyltransferase 2, GALNT2)在胃癌病人中表現量比正常胃腺組織少，其表現降低時會透過活化肝細胞生長因子受體(MET)而增加胃癌的惡性程度。此外，在受體酪氨酸激酶磷酸化陣列試驗(RTK array)中則觀察到降低GALNT2的表現量會增加表皮生長因子受體(Epidermal Growth Factor Receptor, EGFR)的活化，但對於GALNT2是否能透過調節EGFR的磷酸化而影響胃癌的進展依然是未知. 目的: 探討GALNT2是否能透過修飾EGFR醣基構造及調節磷酸化程度進而影響胃癌的惡性程度。材料及方法: 以細胞株實驗分析，抑制GALNT2的表現後對於AGS的細胞存活率(MTT試驗)、轉移 (transwell migration assay) 及侵襲行為(matrigel invasion assay) 的影響。利用Vicia villosa agglutinin (VVA) pull down assay觀察EGFR的醣化作用。利用臨床胃癌檢體的免疫組織化學染色分析，pEGFR和GALNT2 表現與預後的相關性。結果: 抑制GALNT2會增加EGFR和Akt磷酸化但減少EGFR的醣化作用。此外EGFR及Akt的抑制劑可以有效減少因抑制GALNT2而增加的轉移及侵襲能力，但細胞存活率在控制組及抑制GALNT2組別間不管是否有加入EGFR抑制劑都無顯著差異。臨床檢體中，44% (31/70)的病中人有表現pEGFR，且其與GALNT2表現量呈現正相關，但和其餘臨床病理特徵與預後沒有太大相關性。結論: 在研究中觀察到GALNT2可以透過修飾EGFR醣化作用及減少其磷酸化和下游訊息傳遞而抑制胃癌細胞的惡性程度。; Background: Gastric cancer is the third leading cause of cancer-related deaths worldwide. Despite a steady decline in gastric cancer incidence and mortality, the overall 5-year survival rate of patients with gastric cancer is about 29%. Aberrant glycosylation affects the tumorigenesis and progression of cancers. In our previous study, we found that down-regulation of GALNT2 enhanced malignancy of gastric cancer as a result of increasing MET phosphorylation and affected activation of epidermal growth factor receptor (EGFR). Nevertheless, it remains unknown whether GALNT2 could regulate the malignancy through modifying EGFR phosphorylation. Aims: To investigate whether GALNT2 could modify the malignant characteristics in gastric cancer by affecting EGFR phosphorylation and glycosylation. Materials and methods: Effects of GALNT2 knockdown on cell viability (MTT assay), migration (transwell migration assay) and invasion (matrigel invasion assay) of gastric cancer cell line (AGS) were analyzed. The Vicia villosa agglutinin (VVA) pull down assay was conducted to detect O-glycosylation of EGFR. Immunohistochemistry was performed to study the correlation of p-EGFR expression with GALNT2 and prognosis. Results: Knockdown of GALNT2 in AGS cells decreased the VVA binding to EGFR, but increased phosphorylation of EGFR and Akt. Furthermore, knockdown of GALNT2 enhanced the migration and invasion of AGS cells, which were reversed by treated with EGFR inhibitor (gefitinib) or Akt inhibitor (MK2206). However, there was no difference on cell viability between siC and siGALNT2-transfected groups, treated with either DMSO or gefitinib. Clinically, p-EGFR was over- expressed in 44% (31/70) of gastric cancer tissues. p-EGFR was positively correlated with GALNT2 but not associated with clinical outcomes. Conclusions: Our in vitro studies indicate that GALNT2 may suppress the malignancy of gastric cancer by modifying glycosylation of EGFR and reducing activation of EGFR-Akt pathway.