KDM4B在结直肠癌中调控抗肿瘤免疫的机制研究OA

Objective·To investigate the role and molecular mechanism of lysine demethylase 4B(KDM4B)in anti-tumor immunity of colorectal cancer(CRC).Methods·KDM4B expression levels in tumor and para-tumor tissues from a CRC tissue microarray were assessed by immunohistochemistry(IHC)staining.Transcriptomic sequencing datasets from the Gene Expression Omnibus(GEO)database were utilized to analyze the correlations of KDM4B mRNA expression with patient prognosis and intratumoral CD8⁺ T cell infiltration in CRC.Gene Set Enrichment Analysis(GSEA)was conducted on CRC samples with high and low KDM4B expression to identify KDM4B-related biological processes.KDM4B-related biological processes were examined in CRC cells subjected to KDM4B knockdown or B3 treatment using quantitative real-time PCR(qPCR),immunofluorescence(IF)staining,and Western blotting.Mouse subcutaneous tumor models were employed to evaluate the impact of Kdm4b knockdown or B3 treatment on CT26 tumor growth,as well as intratumoral CD8⁺ T cell infiltration and cytotoxicity in vivo.Additionally,the anti-tumor efficacy of B3 treatment,anti-programmed cell death protein-1(PD-1)antibody therapy,and their combination(B3+anti-PD-1)was compared in CT26 subcutaneous tumor models.Results·IHC staining results revealed that KDM4B expression was significantly higher in CRC tissues than in para-tumor tissues(P<0.001).Analysis of transcriptomic datasets from the GEO database showed that CRC patients in the KDM4B-low expression group exhibited longer overall survival and increased intratumoral CD8⁺ T cell infiltration(both P<0.05).GSEA results indicated that low KDM4B expression was significantly correlated with type Ⅰinterferon response and Th1-type cytotoxic response.qPCR,IF staining,and Western blotting results showed that KDM4B knockdown or B3 treatment promoted DNA double-strand breaks,activated the cyclic GMP-AMP synthase-stimulator of interferon genes(cGAS-STING)signaling pathway,and increased the expression of type Ⅰ interferons and Th1-type chemokines in CRC cells(all P<0.05).In vivo experiments demonstrated that Kdm4b knockdown or B3 treatment suppressed CT26 tumor growth,and enhanced intratumoral CD8⁺ T cells infiltration and granzyme B expression(all P<0.05).Moreover,compared with B3 or anti-PD-1 antibody monotherapy,the combination of B3 and anti-PD-1 antibody exhibited stronger anti-tumor effects against mouse CT26 subcutaneous tumors(all P<0.05).Conclusion·KDM4B knockdown or B3 treatment enhances the expression of type Ⅰinterferons and Th1-type chemokines in CRC cells,promotes CD8⁺ T cell-mediated anti-tumor immunity in vivo,and sensitizes CRC to anti-PD-1 antibody therapy.