在 HPAC 胰臟癌細胞抑制 N-acetylgalactosaminyltransferase 1 的表現會抑制其惡性特性

Abstract

胰臟癌的死亡率在台灣十大癌症中排名第八。被診斷罹患胰臟癌的病人，其五年存活率只有5％。異常的醣化作用(glycosylation)會影響許多細胞的特性，包括:細胞的增生、侵入和轉移能力等。醣基轉移酶(glycosyltransferases)表現的改變，是癌症的特徵之一。N-acetylgalactosaminyltransferase 1 (GALNT1)會調節黏蛋白型氧型醣化作用(mucin-type O-glycosylation)，並促進膀胱和胰臟癌的惡性特性。公共資料庫中的數據顯示，在胰臟癌的組織中，GALNT1mRNA 表現量較正常的胰臟組織高。然而，GALNT1 在胰臟癌中所扮演的角色仍然不清楚。本研究中我們證實在HPAC胰臟癌細胞中，抑制GALNT1 表現，會抑制細胞之生長、移動及侵入能力。此外，抑制GALNT1 表現，並藉由10％胎牛血清(fetal bovine serum, FBS)或肝細胞生長因子(hepatocyte growth factor receptor, HGFR)誘導，會抑制肝細胞生長因子受體和ERK 的磷酸化。以上的實驗結果，證實抑制GALNT1 表現，會抑制胰臟癌細胞的惡性特性，而肝細胞生長因子受體，可能參與調節此過程。我們也構築pET-30a/GALNT1 質體(plasmid)，藉由大腸桿菌誘導產生GALNT1-His Tag 重組蛋白作為抗原，並透過皮下注射方式施打紐西蘭白兔，使其產生免疫反應。由西方墨點實驗，證實抗血清中含有對GALNT1-His Tag 重組蛋白產生特異性的抗體。未來，將會進一步純化GALNT1 多株抗體(polyclonal antibody)，期望可應用於GALNT1 的研究。

Pancreatic cancer is the eighth of the leading cause of cancer-related deaths in Taiwan.The five-year survival rate is only 5% for pancreatic cancer patients. Aberrant glycosylation can influence many cellular properties including cell proliferation,migration and invasion. Altered expression of glycosyltransferases is one of the unique characteristics of cancers. N-acetylgalactosaminyltransferase 1(GALNT1) initiates mucin-type O-glycosylation. It has been reported to promote the malignant character of bladder and liver cancer cells. Public databases showed that the expression of GALNT1 mRNA is up-regulated in pancreatic tumors compared withnormal pancreas. However, the role of GALNT1 in pancreatic cancer is still unclear. In this study, we showed that knockdown of GALNT1 inhibited cell growth, migration and invasion in HPAC pancreatic cancer cells. Furthermore, knockdown of GALNT1 inhibited phosphorylation of hepatocyte growth factor receptor (HGFR) and ERK induced by 10% fetal bovine serum (FBS) or HGF. Taken together, these findings suggest that GALNT1 knockdown inhibits the malignant character of pancreatic cancer cells, and the HGFR signaling pathway could be involved in this process. In addition, we constructed GALNT1-pET plasmid and produced GALNT1-His Tag recombinant protein by E.coli. The GALNT1-His Tag recombinant protein was used as an antigen to immunize New Zealand white rabbits. Western blot analysis validated the specificity of anti-serum against GALNT1- His Tag recombinant protein, indicating that this GALNT1 polyclonal antibody can be used for future studies on GALNT1.