Department of Medical Oncology and Cancer Center, Shiga University of Medical Science, Otsu, Shiga, Japan.
Center for Advanced Medicine Against Cancer, Shiga University of Medical Science, Otsu, Shiga, Japan.
Sci Rep. 2023 Mar 29;13(1):5087. doi: 10.1038/s41598-023-32177-4.
Epidermal growth factor receptor (EGFR)-mutated (mt) lung adenocarcinoma (LA) is refractory to immune checkpoint inhibitors (ICIs). However, the mechanisms have not been fully elucidated. CD8 T cell infiltration was significantly lower in EGFR-mt than in EGFR-wild-type LA, which was associated with suppression of chemokine expression. Since this T cell-deserted tumor microenvironment may lead to the refractoriness of ICIs against EGFR-mt LA, we investigated the mechanism by focusing on the regulation of chemokine expression. The expression of C-X-C motif ligand (CXCL) 9, 10 and 11, which constitute a gene cluster on chromosome 4, was suppressed under EGFR signaling. The assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) revealed open chromatin peaks near this gene cluster following EGFR-tyrosine kinase inhibitor (TKI) treatment. The histone deacetylase (HDAC) inhibitor recovered the expression of CXCL9, 10 and 11 in EGFR-mt LA. Nuclear HDAC activity, as well as histone H3 deacetylation, were dependent on oncogenic EGFR signaling. Furthermore, the Cleavage Under Targets and Tagmentation (CUT & Tag) assay revealed a histone H3K27 acetylation peak at 15 kb upstream of CXCL11 after treatment with EGFR-TKI, which corresponded to one of the open chromatin peaks detected by ATAC-seq. The data suggest that EGFR-HDAC axis mediates silencing of the chemokine gene cluster through chromatin conformational change, which might be relevant to the ICI resistance by creating T cell-deserted tumor microenvironment. Targeting this axis may develop a new therapeutic strategy to overcome the ICI resistance of EGFR-mt LA.
表皮生长因子受体（EGFR）突变（mt）肺腺癌（LA）对免疫检查点抑制剂（ICI）有抗性。然而，其机制尚未完全阐明。与 EGFR 野生型 LA 相比，EGFR-mt 的 CD8 T 细胞浸润明显较低，这与趋化因子表达的抑制有关。由于这种 T 细胞匮乏的肿瘤微环境可能导致针对 EGFR-mt LA 的 ICI 产生抗性，我们通过关注趋化因子表达的调节来研究其机制。构成 4 号染色体上基因簇的 C-X-C 基序配体（CXCL）9、10 和 11 的表达在 EGFR 信号下受到抑制。高吞吐量测序的转座酶可及染色质分析（ATAC-seq）检测到 EGFR 酪氨酸激酶抑制剂（TKI）治疗后该基因簇附近的开放染色质峰。组蛋白去乙酰化酶（HDAC）抑制剂恢复了 EGFR-mt LA 中 CXCL9、10 和 11 的表达。核 HDAC 活性以及组蛋白 H3 去乙酰化依赖于致癌性 EGFR 信号。此外，靶向下切割和标签（CUT & Tag）分析显示，EGFR-TKI 治疗后 CXCL11 的上游 15kb 处存在一个组蛋白 H3K27 乙酰化峰，与 ATAC-seq 检测到的一个开放染色质峰相对应。数据表明，EGFR-HDAC 轴通过染色质构象变化介导趋化因子基因簇的沉默，这可能通过创建 T 细胞匮乏的肿瘤微环境与 ICI 抗性有关。靶向该轴可能为克服 EGFR-mt LA 的 ICI 抗性开发新的治疗策略。
