Abstract
BackgroundThis study aimed to explore hyper-O-linked N-acetylglucosaminylation (O-GlcNAcylation) with an elevation of the expression of O-linked-β-N-acetylglucosamine transferase (OGT) in human bladder cancer.MethodsImmunohistochemical staining for OGT and O-GlcNAcylation was performed in 20 paired human bladder cancer and adjacent normal tissues, as well as in human bladder cancer tissue microarrays (N = 169). The expression level of OGT and O-GlcNAcylation in cell lines were detected using the Western blot analysis. The effects of O-GlcNAcylation on the cell proliferation of bladder cancer were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and clone formation assays. Cell apoptosis and cell cycle analysis were detected using flow cytometry. The autophagy of bladder cancer cells was investigated using the Western blot analysis, and GFP–LC3 plasmid was used to detect the autophagic flux. MTT assay was performed to detect the sensitivity of bladder cancer cells to cisplatin after OGT knockdown.ResultsThe expression of OGT and the O-GlcNAcylation were upregulated in bladder cancer tissues and cell lines. O-GlcNAcylation and OGT were observed in nucleus and cytoplasm and found to be higher in muscle-invasive bladder cancer (MIBC) than in non-muscle-invasive bladder cancer (NMIBC). Reducing hyper-O-GlcNAcylation by OGT knockdown inhibited the proliferation of bladder cancer cells in vitro and xenograft tumor growth in vivo, triggered apoptosis, as well as led to cell cycle arrest. It also increased autophagy in bladder cancer cells. This study demonstrated increased autophagy pro-survival, but not pro-death. Reducing hyper-O-GlcNAcylation by OGT knockdown facilitated the chemosensitivity of bladder cancer cells to cis-platinum.ConclusionsThe data indicated that hyper-O-GlcNAcylation enhanced oncogenic phenotypes and was involved in DNA damage response in bladder cancer.
Highlights
This study aimed to explore hyper-O-linked N-acetylglucosaminylation (O-GlcNAcylation) with an elevation of the expression of O-linked-β-N-acetylglucosamine transferase (OGT) in human bladder cancer
O-GlcNAcylation and the expression of OGT were upregulated in bladder cancer cell lines and tissue specimens Previous studies revealed that O-GlcNAcylation was upregulated in various cancers [30,31,32,33,34,35]
O-GlcNAc modification levels were examined in human bladder cancer cell lines compared with human bladder epithelial permanent cell line
Summary
This study aimed to explore hyper-O-linked N-acetylglucosaminylation (O-GlcNAcylation) with an elevation of the expression of O-linked-β-N-acetylglucosamine transferase (OGT) in human bladder cancer. Wang et al BMC Cancer (2018) 18:1141 glucose status of cells [8]. About 2–3% of glucose entering the cell passes through the hexosamine biosynthetic pathway (HBP), which regulates the O-GlcNAcylation of intracellular proteins [9]. O-GlcNAcylation has been reported to modulate cell functions, and multiple proteins have been demonstrated with O-GlcNAc modification over these years [11]. Rozanski et al reported mRNA expression of OGT in the urine of 51.7% patients with bladder cancer, but not in the urine of healthy individuals [16]. No further studies about OGT and O-GlcNAcylation in bladder cancer have been reported to date
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