Kynurenine promotes the immune escape of colorectal cancer cells via NAT10-mediated ac4C acetylation of PD-L1
Zaibiao Wang, Zaibiao Wang, Manman Yin, Ruhang Zhou, Ming Li, Jie Peng, Zhengguang Wang, Zhengguang Wang
Abstract
• Kynurenine suppressed T-cell activation and promoted immune escape. • Kynurenine promoted NAT10-mediated ac 4 C mRNA modification. • NAT10 inhibition improved T-cell activation and suppressed immune escape. This study aimed to investigate the role of kynurenine in Colorectal Cancer (CRC) and the underlying mechanism. Enzyme-linked immunosorbent assay was employed to assess the kynurenine concentration. Flow cytometry was utilized to analyze the percentages of CD3+CD4+ and CD3+CD8+ T -cells. Immunofluorescence was used to measure the expression of Programmed Death-Ligand 1 (PD-L1). RNA modification levels in CRC cells were analyzed using a dot blot assay. The interaction between NAT10 and PD-L1 was assessed via RNA immunoprecipitation, dual-luciferase reporter, and immunofluorescence assays. A xenograft tumor rat model was established. Results indicated that kynurenine suppressed T-cell activation and promoted immune escape. Besides, kynurenine promoted N-Acetyltransferase 10 (NAT10)-mediated N4-acetylcytidine (ac 4 C) modification. Moreover, NAT10 inhibition improved T-cell activation and suppressed immune escape. Mechanically, NAT10 is bound with the mRNA of PD-L1. Rescue experiments showed that PD-L1 inhibitor treatment reversed the suppressed T-cell activation and the promoted immune escape induced by NAT10 overexpression. In vivo, studies indicated that NAT10 deficiency reversed the promoted tumor growth induced by kynurenine treatment. In conclusion, kynurenine promoted the immune escape of CRC cells via NAT10-mediated ac 4 C acetylation of PD-L1.