A chemical screen identifies PRMT5 as a therapeutic vulnerability for paclitaxel-resistant triple-negative breast cancer

Highlights•Paclitaxel-resistant triple-negative breast cancer is vulnerable to PRMTs inhibition•Inhibiting type I PRMTs and PRMT5 synergizes to suppress paclitaxel-resistant TNBC growth•Targeting PRMTs induces intron retention in AURKB, leading to mitotic catastropheSummaryPaclitaxel-resistant triple negative breast cancer (TNBC) remains one of the most challenging breast cancers to treat. Here, using an epigenetic chemical probe screen, we uncover an acquired vulnerability of paclitaxel-resistant TNBC cells to protein arginine methyltransferases (PRMTs) inhibition. Analysis of cell lines and in-house clinical samples demonstrates that resistant cells evade paclitaxel killing through stabilizing mitotic chromatin assembly. Genetic or pharmacologic inhibition of PRMT5 alters RNA splicing, particularly intron retention of aurora kinases B (AURKB), leading to a decrease in protein expression, and finally results in selective mitosis catastrophe in paclitaxel-resistant cells. In addition, type I PRMT inhibition synergies with PRMT5 inhibition in suppressing tumor growth of drug-resistant cells through augmenting perturbation of AURKB-mediated mitotic signaling pathway. These findings are fully recapitulated in a patient-derived xenograft (PDX) model generated from a paclitaxel-resistant TNBC patient, providing the rationale for targeting PRMTs in paclitaxel-resistant TNBC.Graphical abstract