MUC16（CA125）是在卵巢癌筛查中常用的肿瘤标志物，据报道它通过作用于天然杀伤细胞（NK细胞）、B细胞和单核细胞表面的唾液酸结合免疫球蛋白样凝集素-9（Siglec-9）来抑制免疫。然而，MUC16在肿瘤微环境中对中性粒细胞的作用仍需进一步探索。本研究基于临床样本构建了外周血细胞比例和计数、血清炎症相关因子以及血清MUC16（CA125）水平之间的关联。从TCGA获得了卵巢癌组织的RNA-seq数据，随后进行了TIMER免疫细胞浸润和相关性分析。构建了卵巢癌类器官样体刺激中性粒细胞，并通过qPCR和流式细胞术对其进行了免疫表型鉴定。通过RNA测序和体外NK细胞毒杀实验验证了MUC16对中性粒细胞的作用。结果显示，血清MUC16水平与外周血中性粒细胞的比例和计数、中性粒细胞/淋巴细胞比值（NLR）、以及炎症因子IL-6、IL-8、IL-10和IL-2R呈正相关。在卵巢癌中，Siglec-9是MUC16的受体，在中性粒细胞上表达，并与中性粒细胞浸润呈正相关。在卵巢癌类器官样体和MUC16的刺激下，CD11b+、CD66b+和ICAM-1+中性粒细胞的比例显著增加，而CXCR4+中性粒细胞的比例略有下降，同时 beginalign 炎性因子MMP9、IL-8、OSM、IL-1β、TNF-α、CXCL3和ROS的表达也增加。RNA测序分析发现，MUC16刺激后中性粒细胞的炎症反应、TNFA信号通路和IL6相关信号通路上调，并 beginalign 出尔反尔 beginalign 高表达免疫抑制相关因子HHLA2、IL-6、TNFRSF9、ADORA2A、CD274（PD-L1）和IDO1。体外实验显示，MUC16刺激后中性粒细胞上清液处理后，NK细胞细胞毒作用减弱。MUC16通过Siglec-9作用于中性粒细胞，在卵巢癌中导致炎性和免疫抑制表型。© 2023. BioMed Central Ltd., part of Springer Nature.

MUC16 (CA125) is a commonly used tumor marker for ovarian cancer screening and reported to be an immunosuppressive factor by acting on the sialic acid-binding immunoglobulin-like lectin-9 (Siglec-9) on the surface of natural killer cells (NK cells), B cells, and monocytes. However, the role of MUC16 on neutrophils in the tumor microenvironment remains to be further explored.The correlation between the proportion and count of peripheral blood cells, serum inflammatory-related factors and serum MUC16 (CA125) level in patients was constructed based on clinical samples. RNAseq data was obtained from TCGA and sequencing of ovarian cancer tissues, followed by TIMER immune cell infiltration and correlation analysis. Ovarian cancer organoid was constructed to stimulate neutrophils with immunophenotype identification by qPCR and flow cytometry. MUC16 protein stimulation to neutrophils validated the role of MUC16 under the analysis of RNA sequencing and inhibition of NK cytotoxicity in vitro.The serum MUC16 level was positively correlated with the proportion and count of peripheral blood neutrophils, neutrophil-to-lymphocyte ratio (NLR) and inflammatory factors IL-6, IL-8, IL-10 and IL-2R. Siglec-9, the receptor of MUC16, was expressed on neutrophils and was positively correlated to neutrophil infiltration in ovarian cancer. After the stimulation of ovarian cancer organoids and MUC16 respectively, the proportions of CD11b+, CD66b+, and ICAM-1+ neutrophils were significantly increased, while the proportion of CXCR4+ neutrophils was slightly decreased, with increasing of of inflammatory factors MMP9, IL-8, OSM, IL-1β, TNF-α, CXCL3, and ROS. RNA-sequencing analysis revealed that inflammatory response, TNFA signaling pathway, and IL6-related pathway were upregulated in MUC16-stimulated neutrophils, accompanied by high expression of immunosuppression-related factors HHLA2, IL-6, TNFRSF9, ADORA2A, CD274 (PD-L1), and IDO1. NK cytotoxicity was decreased when treated by supernanant of MUC16-stimulated neutrophils in vitro.MUC16 acted on neutrophils by Siglec-9 leading to an inflammatory and immunosuppressive phenotype in ovarian cancer.© 2023. BioMed Central Ltd., part of Springer Nature.