目的：研究N6-甲基化腺嘌呤（N6-methyladenosine，m6A）甲基化转移酶KIAA1429在结直肠癌（colorectal cancer，CRC）中对程序性细胞死亡配体1（programmed deathligand-1，PD-L1）表达及CD8⁺ T细胞浸润的影响。方法：利用在线数据库分析KIAA1429在CRC中的表达对PD-L1表达、CD8⁺T细胞浸润的影响。收集2020年至2022年南京医科大学附属泰州人民医院连续收治的经病理确诊的CRC患者的癌组织样本及癌旁组织样本，采用免疫组织化学染色法检测，并比较其中KIAA1429、PD-L1水平及CD8⁺ T细胞浸润情况。在CRC细胞株中，采用定量聚合酶链反应（quantitative polymerase chain reaction，qPCR）及蛋白印迹法分别检测敲减KIAA1429基因后CRC细胞中的PD-L1 mRNA及蛋白表达水平。在CRC同源移植瘤小鼠中敲减KIAA1429基因后，每3 d记录一次肿瘤大小及小鼠体重，利用流式细胞术检测瘤组织中CD8⁺T细胞浸润水平变化。结果：生物信息分析表明，KIAA1429在CRC中高表达（P<0.05），且与不良预后相关（P=0.028），并与CD8⁺ T细胞浸润程度呈负相关（P=3.981×10^-2）。病理组织免疫组化结果显示，CRC中KIAA1429的表达水平显著高于癌旁组织（P=2.196×10^-7），且KIAA1429与PD-L1的表达水平呈正相关（P=1.017×10^-7），与CD8⁺T细胞的浸润程度呈负相关（P=0.021）。在CRC细胞中敲减KIAA1429基因，能够下调PD-L1的mRNA及蛋白表达（P<0.01）。在CRC移植瘤小鼠中敲减KIAA1429基因可以抑制肿瘤生长（P<0.01），提高CD8⁺T细胞浸润水平（P<0.05）。结论：m6A甲基化转移酶KIAA1429可能通过上调PD-L1表达和减少CD8⁺ T免疫细胞浸润，从而抑制CRC肿瘤免疫。靶向KIAA1429可能有助于改善CRC患者预后，提高CRC免疫治疗疗效。

Objective This study aims to investigate the effect of the N6-methyladenosine (m6A) methyltransferase KIAA1429 on programmed death-ligand 1 (PD-L1) expression and CD8⁺ T cell infiltration in colorectal cancer (CRC). Methods The effects of KIAA1429 expression on PD-L1 expression and CD8⁺T cell infiltration in CRC were analyzed using online databases. Tissue samples from tumor and adjacent normal regions were collected from patients with pathologically confirmed CRC treated at the Affiliated Taizhou People's Hospital of Nanjing Medical University, admitted and diagnosed between 2020 and 2022. Immunohistochemical (IHC) staining was performed to evaluate and compare the expression levels of KIAA1429 and PD-L1, as well as the degree of CD8⁺ T cell infiltration. In CRC cell lines, quantitative polymerase chain reaction (qPCR) and western blotting were used to measure PD-L1 mRNA and protein expression levels after KIAA1429 knockdown, respectively. After KIAA1429 knockdown in CRC syngeneic mouse models, tumor size and body weight were recorded every 3 days, and flow cytometry was used to assess changes in CD8⁺ T cell infiltration degree within the tumor tissue. Results Bioinformatics analysis indicated that KIAA1429 was highly expressed in CRC (P<0.05), associa-ted with poor prognosis (P=0.028), and negatively correlated with CD8⁺T cell infiltration degree (P=3.981×10^-2). IHC results demonstrated that KIAA1429 expression levels in CRC were significantly higher than in adjacent normal tissues (P=2.196×10^-7), positively correlated with PD-L1 expression levels (P=1.017×10^-7), and negatively correlated with CD8⁺T cell infiltration degree (P=0.021). KIAA1429 knockdown in CRC cells downregulated both PD-L1 mRNA and protein expression levels (P<0.01). In the CRC syngeneic mouse models, KIAA1429 knockdown inhibited tumor growth (P<0.01) and enhanced CD8⁺T cell infiltration degree (P<0.05). Conclusions The m6A methyltransferase KIAA1429 may suppress tumor immunity in CRC by upregulating PD-L1 expression and reducing CD8⁺T cell infiltration. Targeting KIAA1429 may help improve the prognosis of CRC patients and enhance the efficacy of CRC immunotherapy.