Background and Objective: Epigenetic alterations are common events in clear cell renal cell carcinoma (ccRCC), and protein arginine methyltransferase 1 (PRMT1) is an important epigenetic regulator in cancers. However, its role in ccRCC remains unclear. Methods: We investigated PRMT1 expression level and its correlations to clinicopathological factors and prognosis in ccRCC patients based on ccRCC tissue microarrays (TMAs). Genetic knockdown and pharmacological inhibition using a novel PRMT1 inhibitor DCPT1061 were performed to investigate the functional role of PRMT1 in ccRCC proliferation. Besides, we confirmed the antitumor effect of PRMT1 inhibitor DCPT1061 in ccRCC cell-derived tumor xenograft (CDX) models as well as patient-derived tumor xenograft (PDX) models. Results: We found PRMT1 expression was remarkably upregulated in tumor tissues and associated with poor pathologic characters and outcomes of ccRCC patients. Furthermore, genetic knockdown and pharmacological inhibition of PRMT1 by a novel potent inhibitor DCPT1061 dramatically induced G1 cell cycle arrest and suppressed ccRCC cell growth. Mechanistically, RNA sequencing and further validation identified Lipocalin2 (LCN2), a secreted glycoprotein implicated in tumorigenesis, as a crucial regulator of ccRCC growth and functional downstream effector of PRMT1. Epigenetic silencing of LCN2 autocrine secretion by PRMT1 deficiency decreased downstream p-AKT, leading to reduced p-RB and cell growth arrest through the neutrophil gelatinase associated lipocalin receptor (NGALR). Moreover, PRMT1 inhibition by DCPT1061 not only inhibited tumor growth but also sensitized ccRCC to sunitinib treatment in vivo by attenuating sunitinib-induced upregulation of LCN2-AKT-RB signaling. Conclusion: Taken together, our study revealed a PRMT1-dependent epigenetic mechanism in the control of ccRCC tumor growth and drug resistance, indicating PRMT1 may serve as a promising target for therapeutic intervention in ccRCC patients.
Keywords: clear cell renal cell carcinoma; lipocalin2 (LCN2); protein arginine methyltransferase 1; sunitinib; therapeutic.
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