No abstract

Intravesical chemotherapy after transurethral resection has been widely used as an adjuvant therapy to prevent recurrence and progression of superficial bladder cancer. Due to the insufficiency of the current chemotherapeutics, there is an urgent need to search for more novel, effective and safe intravesical agents. Previously, we have proved the in vitro apoptotic effects of fisetin, a dietary flavonoid, on bladder carcinoma cells. In the present study, we have further explored its intravesical efficacy and investigated the underlying mechanisms of its inhibitory effect of bladder cancer through an autochthonous rat model of bladder cancer induced by intravesical N-methyl-N-nitrosourea (MNU). We found that fisetin-induced apoptosis in bladder cancer is mediated via modulation of two related pathways: up-regulation of p53 and down-regulation of NF-jB pathway activity, causing changes in the ratio of pro-and antiapoptotic proteins. Meanwhile, administration of fisetin significantly reduced the incidence of MNU-induced bladder tumours by suppressing NF-jB activation and modulating the expression of NF-jB target genes that regulate cell proliferation and cell apoptosis. Our study suggests that the activation of p53 and inhibition of the NF-jB pathway may play important roles in the fisetin-induced apoptosis in bladder cancer. Furthermore, intravesical fisetin effectively inhibited, without any toxicity, the carcinogenesis of bladder cancer in MNU-initiated rats. These findings identify the in vivo chemopreventive efficacy of fisetin and suggest that fisetin could be used as a novel, effective and safe intravesical agent for bladder cancer.

Melatonin helps to maintain circadian rhythm, exerts anticancer activity, and plays key roles in regulation of glucose homeostasis and energy metabolism. Glycosylation, a form of metabolic flux from glucose or other monosaccharides, is a common post‐translational modification. Dysregulated glycosylation, particularly O‐GlcNAcylation, is often a biomarker of cancer cells. In this study, elevated O‐GlcNAc level in bladder cancer was inhibited by melatonin treatment. Melatonin treatment inhibited proliferation and migration and enhanced apoptosis of bladder cancer cells. Proteomic analysis revealed reduction in cyclin‐dependent‐like kinase 5 (CDK5) expression by melatonin. O‐GlcNAc modification determined the conformation of critical T‐loop domain on CDK5 and further influenced the CDK5 stability. The mechanism whereby melatonin suppressed O‐GlcNAc level was based on decreased glucose uptake and metabolic flux from glucose to UDP‐GlcNAc, and consequent reduction in CDK5 expression. Melatonin treatment, inhibition of O‐GlcNAcylation by OSMI‐1, or mutation of key O‐GlcNAc site strongly suppressed in vivo tumor growth. Our findings indicate that melatonin reduces proliferation and promotes apoptosis of bladder cancer cells by suppressing O‐GlcNAcylation of CDK5.

Background Abnormal glycosylation in a variety of cancer types is involved in tumor progression and chemoresistance. Glycosyltransferase C1GALT1, the key enzyme in conversion of Tn antigen to T antigen, is involved in both physiological and pathological conditions. However, the mechanisms of C1GALT1 in enhancing oncogenic phenotypes and its regulatory effects via non-coding RNA are unclear. Methods Abnormal expression of C1GALT1 and its products T antigen in human bladder cancer (BLCA) were evaluated with BLCA tissue, plasma samples and cell lines. Effects of C1GALT1 on migratory ability and proliferation were assessed in YTS-1 cells by transwell, CCK8 and colony formation assay in vitro and by mouse subcutaneous xenograft and trans-splenic metastasis models in vivo. Dysregulated circular RNAs (circRNAs) and microRNAs (miRNAs) were profiled in 3 pairs of bladder cancer tissues by RNA-seq. Effects of miR-1-3p and cHP1BP3 (circRNA derived from HP1BP3) on modulating C1GALT1 expression were investigated by target prediction program, correlation analysis and luciferase reporter assay. Functional roles of miR-1-3p and cHP1BP3 on migratory ability and proliferation in BLCA were also investigated by in vitro and in vivo experiments. Additionally, glycoproteomic analysis was employed to identify the target glycoproteins of C1GALT1. Results In this study, we demonstrated upregulation of C1GALT1 and its product T antigen in BLCA. C1GALT1 silencing suppressed migratory ability and proliferation of BLCA YTS-1 cells in vitro and in vivo. Subsets of circRNAs and miRNAs were dysregulated in BLCA tissues. miR-1-3p, which is reduced in BLCA tissues, inhibited transcription of C1GALT1 by binding directly to its 3′-untranslated region (3′-UTR). miR-1-3p overexpression resulted in decreased migratory ability and proliferation of YTS-1 cells. cHP1BP3 was upregulated in BLCA tissues, and served as an miR-1-3p “sponge”. cHP1BP3 was shown to modulate migratory ability, proliferation, and colony formation of YTS-1 cells, and displayed tumor-suppressing activity in BLCA. Target glycoproteins of C1GALT1, including integrins and MUC16, were identified. Conclusions This study reveals the pro-metastatic and proliferative function of upregulated glycosyltransferase C1GLAT1, and provides preliminary data on mechanisms underlying dysregulation of C1GALT1 via miR-1-3p / cHP1BP3 axis in BLCA.

No abstract