Elevated levels of MMP12 sourced from macrophages are associated with poor prognosis in urothelial bladder cancer

BackgroundUrothelial bladder cancer is most frequently diagnosed at the non-muscle-invasive stage (NMIBC). However, recurrences and interventions for intermediate and high-risk NMIBC patients impact the quality of life. Biomarkers for patient stratification could help to avoid unnecessary interventions whilst indicating aggressive measures when required.MethodsIn this study, immuno-oncology focused, multiplexed proximity extension assays were utilised to analyse plasma (n = 90) and urine (n = 40) samples from 90 newly-diagnosed and treatment-naive bladder cancer patients. Public single-cell RNA-sequencing and microarray data from patient tumour tissues and murine OH-BBN-induced urothelial carcinomas were also explored to further corroborate the proteomic findings.ResultsPlasma from muscle-invasive, urothelial bladder cancer patients displayed higher levels of MMP7 (p = 0.028) and CCL23 (p = 0.03) compared to NMIBC patients, whereas urine displayed higher levels of CD27 (p = 0.044) and CD40 (p = 0.04) in the NMIBC group by two-sided Wilcoxon rank-sum tests. Random forest survival and multivariable regression analyses identified increased MMP12 plasma levels as an independent marker (p < 0.001) associated with shorter overall survival (HR = 1.8, p < 0.001, 95% CI:1.3-2.5); this finding was validated in an independent patient OLINK cohort, but could not be established using a transcriptomic microarray dataset. Single-cell transcriptomics analyses indicated tumour-infiltrating macrophages as a putative source of MMP12.ConclusionsThe measurable levels of tumour-localised, immune-cell-derived MMP12 in blood suggest MMP12 as an important biomarker that could complement histopathology-based risk stratification.As MMP12 stems from infiltrating immune cells rather than the tumor cells themselves, analyses performed on tissue biopsy material risk a biased selection of biomarkers produced by the tumour, while ignoring the surrounding microenvironment.

Automated summary

In this study, plasma and urine samples from bladder cancer patients were analyzed to identify potential biomarkers. It was found that MMP7 and CCL23 levels were higher in plasma, while CD27 and CD40 levels were higher in urine. Increased levels of MMP12 in plasma were associated with shorter overall survival. Tumor-infiltrating macrophages were identified as a possible source of MMP12.