UHRF1 Promotes Bladder Cancer Progression By Regulating MALAT1/MEG3/RGS2

Objective: We first identified the target genes and long coding RNA(lncRNA)regulated by epigenetic factor UHRF1.We investigated whether UHRF1/target gene/lncRNA regulates bladder cancer cell proliferation and migration and revealed the molecular mechanism of bladder cancer cell biological behavior regulated by UHRF1/target gene/lncRNA.We also explore the underlying mechanism of the UHRF1/target gene/lncRNA in the regulation of cancer biology.Methods: We constructed the overexpression vector or interference vector of UHRF1 to overexpress or inhibit UHRF1 expression in bladder cancer cells.Using qPCR chip we identified target genes and lncRNA regulated by UHRF1.The expression of UHRF1/target gene /lncRNA was inhibited in bladder cancer cells using RNAi,and then cell proliferation,cell invasion and cell cycle were assayed.In vivo,the regulation of UHRF1/target gene/lncRNA in tumor growth and metastasis in mice was detected by mouse tumor cells.Results: The expression level of UHRF1 is increased in bladder cancer cell lines and in most bladder cancer tissues compared with normal controls.UHRF1 overexpression increases bladder cancer cell proliferation,whereas inhibition of UHRF1 suppresses cell proliferation.MEG3 levels were significantly reduced in bladder cancer tissues compared with normal controls,and autophagy activity was increased in bladder cancer tissues.We demonstrated that MEG3 markedly suppressed autophagy activation,whereas MEG3 knockdown activated autophagy in human bladder cancer cell lines.More important,autophagy inhibition abrogated MEG3 knockdown-induced cell proliferation.MALAT-1 levels were upregulated in bladder cancer tissues compared with adjacent normal tissues.SiRNA-mediated MALAT-1 silencing impaired in vitro bladder cancer cell migration.Downregulation of MALAT-1 resulted in a decreased of the epithelial-mesenchymal transition(EMT)-associated ZEB1,ZEB2 and Slug levels,and an increase of E-cadherin levels.We further demonstrated that MALAT-1 promoted EMT by activating Wnt signaling in vitro.UHRF1 inhibits RGS2 expression by increasing the methylation of CpG nucleotides of RGS2 promoter.The high expression of UHRF1 is correlated with aberrant TGS2 promoter methylation in bladder tumors,which results in the loss of TGS2 expression confirmed by demethylation analysis in cell lines.Functionally,re-expression of RGS2 partly abrogates UHRF1-induced bladder cell proliferation.Conclusion: These data suggest that UHRF1 is an important mediator of bladder cancer progression.UHRF1 inhibits the expression of MEG3,destroys the inhibition of MEG3 on autophagy activity,thereby regulates the cell cycle,proliferation and migration of cells to promote.UHRF1 also upregulates the expression of MALAT1,and results in the activation of Wnt/ beta-catenin signaling pathway and induces EMT of bladder cancer cell.Upregulation of UHRF1 in bladder cancer also reduces the expression level of RGS2 by hypermethylation of RGS2 promoter.UHRF1 suppresses the expression of RGS2,so as to relieve the inhibition of cell proliferation and promotes carcinogenesis.In this study,we confirmed that the up-regulation of UHRF1 promotes the proliferation and migration of bladder cancer,and our results provides a new way for early diagnosis and clinical treatment of bladder cancer.