Characterization and therapeutic targeting of the miR-21/PPP2R2A/ERK molecular circuit in bladder cancer

MicroRNAs play an important role in the pathogenesis of different types of cancer including bladder cancer. MiR-21 has been identified to have an oncogenic function, while its inhibition suppresses tumor growth. Here, we followed an integrated bioinformatics and molecular analyses to identify the molecular mediators of miR-21 oncogenic function in bladder cancer and evaluate the therapeutic potential of a chemically-modified miR-21 inhibitor in bladder xenografts. MiR-21 expression was found to up-regulated in human bladder cancers relative to normal tissues and miR-21 inhibition suppressed bladder cancer cell properties, including growth, invasiveness and anchorage-independence. Intravenous administration of an antisense oligonucleotide against miR-21 harboring locked-nucleic-acid (LNA-miR-21) modifications blocked bladder tumor growth in vivo. Transcriptomic analysis of 28 bladder cancer cell lines revealed a gene signature that negatively correlated with miR-21 expression levels. Bioinformatics and 3’UTR luciferase assay analyses revealed a direct interaction between miR-21 the 3’UTR of PPP2R2A gene. Inhibition of PPP2R2A expression induced bladder cancer growth, suggesting its tumor suppressor function. Gene profiling followed by IPA network analysis revealed that PPP2R2A regulates the ERK1/2 molecular network. Taken together, PPP2R2A is the functional mediator of miR-21 oncogenic activity on bladder cancer and LNA-miR-21 could have a therapeutic potential in bladder cancer patients. The significantly different expressed genes are obtained by ANOVA using miR-21 levels as catagories in 28 Bladder Cancer cell lines based on the gene experssion microarray experiment. PPP2R2A was found in the significantly different expressed genes in ANOVA analysis, having negative correlation with miR-21 expression levels. This data provided the supportive evidence to be associated with the paper and suggests PPP2R2A function in tumor suppressor.