N-acetylglucosaminyltransferase V （GnT-V） is an important tumorigenesis and metastasis-associated enzyme. To study its biofunction, the GnT-V stably suppressed cell line （GnT-V-AS/7721） was constructed from 7721 h...N-acetylglucosaminyltransferase V （GnT-V） is an important tumorigenesis and metastasis-associated enzyme. To study its biofunction, the GnT-V stably suppressed cell line （GnT-V-AS/7721） was constructed from 7721 hepatocarcinoma cells in previous study. In this study, cDNA array gene expression profiles were compared between GnT-V-AS/7721 and parental 7721 cells. The data indicated that GnT-V-AS/7721 showed a characteristic expression pattern consistent with the ER stress. The molecular mechanism of the ER stress was explored in GnT-V-AS/7721 by the analysis on key molecules in both two unfolded protein response （UPR） pathways. For ATF6 and Irel/XBP-1 pathway, it was evidenced by the up-regulation of BIP at mRNA and protein level, and the appearance of the spliced form ofXBP-1. As for PERK/eIF2α pathway, the activation of ER eIF2α kinase PERK was observed. To confirm the results from GriT-V-AS/7721 cells, the key molecules in the UPR were examined again in 7721 cells interfered with the GnT-V by the specific RNAi treatment. The results were similar with those from GnT-V-AS/7721, indicating that blocking of GnT-V can specifically activate ER stress in 7721 cells. Rate of 3H-Man incorporation corrected with rate of 3H-Leu incorporation in GnT-V-AS/7721 was down-regulated greatly compared with the control, which demonstrated the deficient function of the enzyme synthesizing N-glycans after GnT-V blocking. Moreover, the faster migrating form of chaperone GRP94 associated with the underglycosylation, and the extensively changed N-glycans structures of intracellular glycoproteins were also detected in GnT-V-AS/7721. These results supported the mechanism that blocking of GnT-V expression impaired functions of chaperones and N-glycan-synthesizing enzymes, which caused UPR in vivo.展开更多
BACKGROUND: The incidence of extrahepatic bile duct carcinoma (EBDC) has been increasing, especially in aged people, but the glycobiology of the tumor is not elucida- ted. In this study we investigated the expressions...BACKGROUND: The incidence of extrahepatic bile duct carcinoma (EBDC) has been increasing, especially in aged people, but the glycobiology of the tumor is not elucida- ted. In this study we investigated the expressions of three glycosyltransferases in 35 patients with EBDC and 35 pa- tients with benign biliary duct disease (BBDD) as well as their clinicopathological significance. METHOD: The patients were divided into several sub- groups by tumor differentiation, TNM stage, and invasion by the standards recommended by UICC. Tumor samples were immediately frozen in liquid nitrogen after resection, followed by mRNA determination of enzymes in the tissue using a mRNA selective reverse trancriptase-polymerase chain reaction kit. The mRNA levels of different groups were semi-quantitatively compared. RESULTS: The mRNA levels of N-acetylglucosaminyltrans- ferase V (GnT-V) and a subtype of α2,3 sialyltransferases for N-glycans, ST3Gal- were elevated 7.75 and 5.39 times in EBDC as compared with BBDD, respectively, and they were correlated to several clinicopathological factors including tumor advancement, differentiation, metastasis, and invasiveness. The mRNA expression of another sialyl- transferase, ST6Gal- , was also 0.63-fold higher in EBDC than in BBDD, but not involved in the clinicopathological characteristics. CONCLUSION: The elevated expression of these three gly- cosyltransferases can be considered as an important molecu- lar event in the occurrence and progression of EBDC.展开更多
文摘N-acetylglucosaminyltransferase V （GnT-V） is an important tumorigenesis and metastasis-associated enzyme. To study its biofunction, the GnT-V stably suppressed cell line （GnT-V-AS/7721） was constructed from 7721 hepatocarcinoma cells in previous study. In this study, cDNA array gene expression profiles were compared between GnT-V-AS/7721 and parental 7721 cells. The data indicated that GnT-V-AS/7721 showed a characteristic expression pattern consistent with the ER stress. The molecular mechanism of the ER stress was explored in GnT-V-AS/7721 by the analysis on key molecules in both two unfolded protein response （UPR） pathways. For ATF6 and Irel/XBP-1 pathway, it was evidenced by the up-regulation of BIP at mRNA and protein level, and the appearance of the spliced form ofXBP-1. As for PERK/eIF2α pathway, the activation of ER eIF2α kinase PERK was observed. To confirm the results from GriT-V-AS/7721 cells, the key molecules in the UPR were examined again in 7721 cells interfered with the GnT-V by the specific RNAi treatment. The results were similar with those from GnT-V-AS/7721, indicating that blocking of GnT-V can specifically activate ER stress in 7721 cells. Rate of 3H-Man incorporation corrected with rate of 3H-Leu incorporation in GnT-V-AS/7721 was down-regulated greatly compared with the control, which demonstrated the deficient function of the enzyme synthesizing N-glycans after GnT-V blocking. Moreover, the faster migrating form of chaperone GRP94 associated with the underglycosylation, and the extensively changed N-glycans structures of intracellular glycoproteins were also detected in GnT-V-AS/7721. These results supported the mechanism that blocking of GnT-V expression impaired functions of chaperones and N-glycan-synthesizing enzymes, which caused UPR in vivo.
文摘BACKGROUND: The incidence of extrahepatic bile duct carcinoma (EBDC) has been increasing, especially in aged people, but the glycobiology of the tumor is not elucida- ted. In this study we investigated the expressions of three glycosyltransferases in 35 patients with EBDC and 35 pa- tients with benign biliary duct disease (BBDD) as well as their clinicopathological significance. METHOD: The patients were divided into several sub- groups by tumor differentiation, TNM stage, and invasion by the standards recommended by UICC. Tumor samples were immediately frozen in liquid nitrogen after resection, followed by mRNA determination of enzymes in the tissue using a mRNA selective reverse trancriptase-polymerase chain reaction kit. The mRNA levels of different groups were semi-quantitatively compared. RESULTS: The mRNA levels of N-acetylglucosaminyltrans- ferase V (GnT-V) and a subtype of α2,3 sialyltransferases for N-glycans, ST3Gal- were elevated 7.75 and 5.39 times in EBDC as compared with BBDD, respectively, and they were correlated to several clinicopathological factors including tumor advancement, differentiation, metastasis, and invasiveness. The mRNA expression of another sialyl- transferase, ST6Gal- , was also 0.63-fold higher in EBDC than in BBDD, but not involved in the clinicopathological characteristics. CONCLUSION: The elevated expression of these three gly- cosyltransferases can be considered as an important molecu- lar event in the occurrence and progression of EBDC.
