microRNA-497-5p-based screening identifies a novel synthetic lethal-type interaction via PKMYT1 and WEE1 in pleural mesothelioma.

Diffuse pleural mesothelioma (DPM) is an incurable surface neoplasm governed by tumor suppressor losses with limited therapeutic options. Despite the advantages of leveraging the tumor suppressive activity of microRNA (miRNA/miR), clinical translation remains limited due to incomplete understanding of their context-specific gene targets. Here, we employed a biotinylated-miRNA pull-down approach to systematically identify direct targets of miR-497-5p, an miRNA markedly downregulated in DPM. Surprisingly, multiple identified targets were not predicted by algorithms. Using patient samples, cell lines, murine xenograft models, and our localized nanoparticle miRNA delivery platform, we validated miR-497-5p anti-tumor mechanisms, which consisted of pro-apoptotic and anti-cell-cycle effects. Of multiple additional gene associations to DPM biology, we identified a synthetic lethal-type interaction whereby miR-497-5p co-inhibits PKMYT1 and WEE1 cell-cycle kinases (G2/M regulators). They were significantly overexpressed (poorly prognostic) in DPM, suggesting an efficacious treatment regimen to be explored. We demonstrate the utility of experimentally deriving the miR-497-5p targetome, explaining its pathophysiological role in DPM and why it is a rational therapeutic for further development.