Transcriptome analysis of PRMT5 inhibition in STSs. A, Volcano plot showing differential gene expression after RNA-seq with the IB111 cell line that was untreated or treated with GSK595 for 10 days at the IC50 in biological triplicates. A total of 556 genes (green dots) and 486 genes (red dots) were significantly downregulated or upregulated after treatment. B, Pathway analysis of RNA-seq shown in A. MSigDB and FGSEA were used to identify hallmark pathways or Gene Ontology (GO) biological process terms in which the genes of an identified set were enriched. C and D, Four sarcoma cell lines (the IB111, IB114, IB115, and IB128 cells lines) were untreated or treated with GSK595 for 10 days at IC80 in triplicate, and their transcriptomes were analyzed using an nCounter Metabolic Pathways Panel from NanoString. C, Volcano plot showing differentially expressed genes in the panel. Blue dots and red dots represent significantly downregulated and upregulated genes after treatment, respectively. Gray dots represent nonsignificantly regulated genes. D, The three pathways showing the highest gene enrichment as determine with NanoString gene signatures following the single-sample GSEA method.
ARTICLE ABSTRACT
Patients with advanced soft-tissue sarcomas (STS) have few therapeutic options. Protein arginine methyltransferase 5 (PRMT5), an anticancer target, has been extensively investigated in recent years in epithelial tumors. To date, no data related to the biological role of PRMT5 inhibition and its potential effect as a treatment in STS have been reported.To investigate the therapeutic potential of PRMT5 targeting in STS, we first evaluated the prognostic value of PRMT5 expression in two different cohorts of patients with STS. We then used the potent and selective GSK3326595 (GSK595) compound to investigate the antitumor effect of the pharmacologic inhibition of PRMT5 in vitro via MTT, apoptosis, cell cycle, clonogenicity, and proliferation assays. In vivo studies were performed with two animal models to evaluate the effects of GSK595 on tumor growth. The mechanisms of action were investigated by RNA sequencing, metabolic pathway analysis, Western blotting, and glucose uptake/lactate production assays.High PRMT5 gene expression levels were significantly associated with worsened metastasis-free survival of patients with STS. GSK595 decreased the global symmetric dimethylarginine level, the proliferation rate and clonogenicity of STS cell lines in vitro and tumor growth in vivo. Moreover, PRMT5 inhibition regulated aerobic glycolysis through downregulation of key enzymes of glycolysis as well as glucose uptake and lactate production.The current study demonstrated that PRMT5 regulates STS cell metabolism and thus represents a potential therapeutic target for STS. Additional studies in diverse sarcoma subtypes will be essential to confirm and expand upon these findings.
STSs have limited therapeutic options. We show here the poor prognostic value of high PRMT5 expression in STS. Moreover, we demonstrate that the pharmacologic inhibition of PRMT5 has significant antitumor activity through the downregulation of glycolysis. Our findings support the clinical investigation of PRMT5 inhibition in STSs.
