Silencing β-linked N-acetylglucosamine transferase induces apoptosis in human gastric cancer cells through PUMA and caspase-3 pathways

Abstract

Abstract. β-linked N-acetylglucosamine (GlcNAc) is a monosaccharide that is catalyzed by O-GlcNAcylation transferase (OGT) to bind serine or threonine hydroxyl moieties of numerous nuclear and cytoplasmic proteins. Recent studies have shown that O-GlcNAcylation is elevated in various cancer types, which is associated with oncogenesis and tumor progression. However, whether OGT is expressed and/or plays a role in gastric cancer is unknown. In the present study, we used qPCR to determine that OGT mRNA levels are significantly elevated in gastric cancer tissues compared with that in corresponding adjacent tissues. In addition, in vivo silencing of OGT in nude mice suppressed tumor proliferation and decreased tumor burden. Furthermore, in vitro OGT knockdown induced more cell apoptosis through increasing PUMA and caspase-3 expression. We used a glycan-binding protein gene microarray to identify potential downstream target genes of OGT, and found that apoptosis-related genes such as galectin and HBEGF were decreased after OGT suppression, suggesting that OGT silencing induces apoptosis in gastric cancer tissues. We concluded that OGT plays a key role in gastric cancer proliferation and survival, and could be a potential target for therapy. Since OGT and O-GlcNAcylation plays an important role in normal biological process, aberrant regulation contributes to the development of wide range of diseases, including cancer. OGT and O-GlcNAcylation is elevated in breast cancer cell lines and tissues, particularly in metastatic lymph nodes. Also it has been demonstrated that O-GlcNAcylation could promote breast cancer tumorigenesis and metastasis (4,5). In colon and lung cancer, O-GlcNAcylation and OGT are also upregulated, compared with that in the corresponding adjacent tissues. Additionally, it demonstrated that O-GlcNAcylation enhanced cell growth and invasion, and may play important roles in lung and colon cancer formation and progression (6). In laryngeal cancer, OGT and O-GlcNAcase (OGA) mRNA level was related to larger tumor size, nodal metastases, higher grader and tumor size, their protein level showed a trend of more advanced tumors to be more frequently OGT and OGA positive, suggesting that O-GlcNAcylation may have an effect on tumor aggressiveness (7).Gastric cancer is the fourth most common cancer worldwide and the second most frequent cause of cancer-related death (8,9), with ~27% 5-year survival rate (10). Although elevated OGT levels were reported in various epithelial cancers, it remains unclear whether OGT is upregulated and how OGT exerts its function in gastric cancer. In the present study, we show that OGT mRNA levels are upregulated in human gastric cancer compared with that in adjacent tissues. Additionally, OGT function is analyzed. Silencing OGT inhibits BCG-823

miR-483 is down-regulated in gastric cancer and suppresses cell proliferation, invasion and protein O-GlcNAcylation by targeting OGT

“…Moreover, we found that miR-483 can suppress total protein O-GlcNAcylation in gastric cancer cells through directly targeting OGT. Our data are consistent with previous studies which showed that down-regulation of OGT inhibited cell growth and invasion of gastric cancer cells in vitro [32,33]. Our results reveal that miR-483 is critical in controlling the protein O-GlcNAcylation levels and regulating the proliferation and invasion potential of gastric cancer cells.…”

Drug resistance related to aberrant glycosylation in colorectal cancer

“…Several studies have correlated expression of OGT and chemotherapy sensitivity. OGT silencing increases the sensitivity to 5-FU of BCG-823 gastric cancer cell line by enhancing expression of p53 upregulated modulator of apoptosis (PUMA) and caspase-3 pro-apoptotic proteins [ 159 ]. In this sense, Pepe et al showed in HepG2 hepatoblastoma cells that OGT stabilizes the transcriptional complex β-catenin/upstream stimulatory factor 1 (USF1) at the promoter of miR-483-3p, a microRNA responsible for transcription downregulation of PUMA [ 160 ].…”

GNB2L1 and its O-GlcNAcylation regulates metastasis via modulating epithelial-mesenchymal transition in the chemoresistance of gastric cancer

“…Our data also revealed that not only GNB2L1, but its O-GlcNAcylation as well, was important for EMT in chemoresistance. It is well-known that O-GlcNAcylation and its transferase OGT was elevated in gastric cancer and involved in the survival of gastric cancer cells [ 26 ]. And a growing amount of studies supported the critical roles of O-GlcNAcylation in gastric cancer metastasis [ 27 , 28 ].…”