Peroxidasin is associated with a mesenchymal-like transcriptional phenotype and promotes invasion in metastatic melanoma

Cutaneous melanoma is a highly invasive, heterogeneous and treatment resistant cancer. Its ability to dynamically shift between transcriptional states or phenotypes results in an adaptive cell plasticity that may drive cancer cell invasion or the development of therapy resistance. The expression of peroxidasin (PXDN), an extracellular matrix peroxidase, has been proposed to be associated with the invasive metastatic melanoma phenotype. We have confirmed this association by analysing the transcriptomes of 44 metastatic melanoma cell lines characterised by either high or low PXDN expression. This analysis highlighted a strong association between high PXDN expression and the undifferentiated invasive melanoma phenotype. To assess the functional role of PXDN in melanoma invasion, we performed a knockout of PXDN in a highly invasive cell line. PXDN knockout decreased the invasive potential by ∼50% and decreased the expression of epithelial-mesenchymal transition and invasive marker genes as determined by RNAseq and substantiated by proteomic analysis. Bioinformatics analysis of differentially expressed genes following PXDN knockout highlighted decreases in genes linked to extracellular matrix formation, organisation and degradation as well as signalling pathways like the WNT pathway. This study provides compelling evidence that PXDN plays a functional role in melanoma invasion by promoting an invasive, mesenchymal-like transcriptional phenotype.