MicroRNA Biomarkers for Patients With Muscle-Invasive Bladder Cancer Undergoing Selective Bladder-Sparing Trimodality Treatment

Purpose: Trimodality therapy with maximal transurethral resection of bladder tumor and definitive chemoradiation reserving cystectomy for salvage of local recurrence is an accepted treatment alternative to upfront cystectomy for selected patients with muscle-invasive bladder cancer. There is a need for molecular biomarkers to predict which patients will respond to bladder preservation therapy. Methods and Materials: We sought to identify biomarkers with the ability to predict response to chemoradiation and survival after selective bladder preservation therapy in a cohort of 40 patients using a microRNA profiling approach. In vitro experiments were performed using transitional cell carcinoma lines CRL1749, HTB5, and HTB4. Results: We identified a panel of microRNAs associated with overall survival in our bladder preservation cohort and in the TCGA cohort. We also identified several microRNAs, including miR-23a and miR-27a, microRNAs of the miR-23a cluster, to be suggestively associated with complete response to chemoradiation therapy. The microRNAs were significantly associated with overall survival in The Cancer Genome Atlas cohort. In vitro studies suggest that the functional roles of miR-23a and miR-27a involve targeting the SFRP1 protein, a negative regulator of the Wnt signaling pathway. The upregulation of β-catenin in the Wnt signaling pathway mediated proliferation, migration, invasion, and sensitivity to radiation and cisplatin treatment in bladder cancer cells. Conclusions: Our results indicate that miR-23a and miR-27a act as oncomirs, and once independently validated, they may help appropriately triage selected bladder cancer patients to individualize treatment.