Identification of microRNAome in rat bladder reveals miR-1949 as a potential inducer of bladder cancer following spinal cord injury

The costs of spinal cord injury and its complications are high in personal, social and financial terms. Complications include bladder cancer, for which the risk is 16-28 times higher than that of the general population, There is currently little consensus regarding the cause of this discrepancy. As microRNAs are stable biomarkers and potential therapeutic targets of cancer, the present study aimed to explore the underlying mechanisms of this phenomenon by examining changes in the microRNAome. Rats were used to produce models of spinal cord injury. Microarrays and bioinformatics were used to investigate the cancer-associated microRNAs that are upregulated in rat bladders following spinal cord injury. In order to validate the results, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting and immunohistochemistry were performed. The expression of miR-1949 was found to be deregulated and abundant in the rat bladder following spinal cord injury. Bioinformatics demonstrated that retinoblastoma 1, which is involved in tumorigenesis, is a target gene of miR-1949. qRT-PCR, western blotting and immunohistochemistry confirmed the results of the microarray analysis. In addition, it was shown that miR-1949 expression was not influenced by aging. Furthermore, the expression of miR-1949 was stable until the third month following spinal cord injury, after which it significantly increased. If this increase was prolonged, the expression of retinoblastoma 1 may decline to a carcinogenic level. The present study suggests a role for miR-1949 in the translational regulation of retinoblastoma 1 and in subsequent bladder tumorigenesis following spinal cord injury.