Urothelial
bladder cancer (UBC) represents a public health problem because of its high incidence/relapse rates. At present, there are no suitable
biomarkers for early diagnosis or relapse/progression prognosis. To improve diagnostic accuracy and overcome the disadvantages of current diagnostic strategies, the detection of UBC
biomarkers in easily accessible biofluids, such as urine, represents a promising approach compared with painful biopsies. We investigated the levels of MMP23 genes (microarray and qPCR) and
protein (western blot and
enzyme-linked
immunosorbent assay) in a set of samples (blood, plasma and urine) from patients with UBC and controls as
biomarkers for this
cancer. MMP23B and its pseudogene MMP23A resulted downregulated in blood cells from UBC compared with controls (66 cases, 70 controls; adjusted P-value = 0.02 and 0.03, respectively). In contrast, MMP23B
protein levels in plasma (53 UBC, 49 controls) and urine (59 UBC, 57 controls) increased in cases, being statistically significant in urine. MMP23B dosage observed in urine samples was related to both
tumor risk classification and grading. As the lack of correlation between
mRNA and
protein levels could be due to a posttranscriptional regulation mediated by
microRNAs (
miRNAs), we investigated the expression of urinary
miRNAs targeting MMP23B. Five
miRNAs resulted differentially expressed between cases and controls. We reported the first evidence of MMP23B secretion in plasma and urine, suggesting a role of this poorly characterized
metalloproteinase in UBC as a potential non-invasive
biomarker for this
cancer. Further analyses are needed to elucidate the mechanism of regulation of MMP23B expression by
miRNAs.