CRISPR/Cas9 screenings unearth protein arginine methyltransferase 7 as a novel driver of metastasis in prostate cancer

Abstract

Owing to the inefficacy of available treatments, the survival rate of patients with metastatic prostate cancer (mPCa) is severely decreased. Therefore, it is crucial to identify new therapeutic targets to increase the survival of mPCa patients. This study aim was to identify the most relevant regulators of mPCa onset by performing two high-throughput CRISPR/Cas9 screenings. Furthermore, some of the top hits were validated using small interfering RNA (siRNA) technology, with protein arginine methyltransferase 7 (PRMT7) being the best candidate. Its inhibition, by genetic and pharmacological approaches, or its depletion, via CRISPR, significantly reduced mPCa cell capacities in vitro. Furthermore, PRMT7 ablation reduced mPCa appearance in chicken chorioallantoic membrane and mouse xenograft assays. Molecularly, PRMT7 reprograms the expression of several adhesion molecules through methylation of several transcription factors, such as FoxK1 or NR1H2, which results in primary tumor PCa cell adhesion loss and motility gain. Moreover, PRMT7 is upregulated in advanced stages of Spanish PCa tumor samples and PRMT7 pharmacological inhibition reduces the dissemination of mPCa cells. Thus, here is shown that PRMT7 is a potential therapeutic target and biomarker of mPCa.