（，）DNA甲基化与透明细胞肾细胞癌中肿瘤细胞和免疫细胞的LAG3表达、免疫细胞浸润及总生存期相关。

(, ) DNA methylation correlates with LAG3 expression by tumor and immune cells, immune cell infiltration, and overall survival in clear cell renal cell carcinoma.

作者信息

Klümper Niklas, Ralser Damian J, Bawden Emma Grace, Landsberg Jenny, Zarbl Romina, Kristiansen Glen, Toma Marieta, Ritter Manuel, Hölzel Michael, Ellinger Jörg, Dietrich Dimo

机构信息

Department of Urology, University Hospital Bonn, Bonn, Germany.

Center for Integrated Oncology Aachen/Bonn/Cologne/Dusseldorf, University Hospital Bonn, Bonn, Germany.

出版信息

J Immunother Cancer. 2020 Mar;8(1). doi: 10.1136/jitc-2020-000552.

BACKGROUND

Lymphocyte activating 3 (LAG3, LAG-3, CD223) is a promising target for immune checkpoint inhibition in clear cell renal cell carcinoma (KIRC). The aim of this study was to investigate the epigenetic regulation of in KIRC by methylation.

METHODS

We correlated quantitative methylation levels with transcriptional activity, immune cell infiltration, and overall survival in a cohort of n=533 patients with KIRC and n=160 normal adjacent tissue (NAT) samples obtained from The Cancer Genome Atlas (TCGA). Furthermore, we analyzed methylation in peripheral blood mononuclear cells (PBMCs) and KIRC cell lines. We validated correlations between LAG3 expression, immune cell infiltrates, survival, and methylation in an independent KIRC cohort (University Hospital Bonn (UHB) cohort, n=118) by means of immunohistochemistry and quantitative methylation-specific PCR.

RESULTS

We found differential methylation profiles among PBMCs, NAT, KIRC cell lines, and KIRC tumor tissue. Methylation strongly correlated with LAG3 mRNA expression in KIRCs (TCGA cohort) and KIRC cell lines. In the UHB cohort, methylation correlated with LAG3-positive immune cells and tumor-intrinsic LAG3 protein expression. Furthermore, methylation strongly correlated with signatures of distinct immune cell infiltrates, an interferon-y signature (TCGA cohort), and immunohistochemically quantified CD45, CD8, and CD4 immune cell infiltrates (UHB cohort). LAG3 mRNA expression (TCGA cohort), methylation (both cohorts), and tumor cell-intrinsic protein expression (UHB cohort) was significantly associated with overall survival.

CONCLUSION

Our data suggest an epigenetic regulation of LAG3 expression in tumor and immune cells via DNA methylation. LAG3 expression and methylation is associated with a subset of KIRCs showing a distinct clinical course and immunogenicity. Our study provides rationale for further testing DNA methylation as a predictive biomarker for response to LAG3 immune checkpoint inhibitors.

背景

淋巴细胞激活3（LAG3、LAG - 3、CD223）是透明细胞肾细胞癌（KIRC）免疫检查点抑制的一个有前景的靶点。本研究的目的是通过甲基化研究KIRC中LAG3的表观遗传调控。

方法

我们将n = 533例KIRC患者和n = 160例从癌症基因组图谱（TCGA）获得的癌旁正常组织（NAT）样本队列中的LAG3定量甲基化水平与转录活性、免疫细胞浸润和总生存期进行关联分析。此外，我们分析了外周血单个核细胞（PBMC）和KIRC细胞系中的LAG3甲基化情况。我们通过免疫组织化学和定量甲基化特异性PCR在一个独立的KIRC队列（波恩大学医院（UHB）队列，n = 118）中验证了LAG3表达、免疫细胞浸润、生存期和甲基化之间的相关性。

结果

我们发现PBMC、NAT、KIRC细胞系和KIRC肿瘤组织之间存在差异甲基化谱。甲基化与KIRC（TCGA队列）和KIRC细胞系中的LAG3 mRNA表达密切相关。在UHB队列中，甲基化与LAG3阳性免疫细胞和肿瘤内源性LAG3蛋白表达相关。此外，LAG3甲基化与不同免疫细胞浸润特征、干扰素 - γ特征（TCGA队列）以及免疫组织化学定量的CD45、CD8和CD4免疫细胞浸润（UHB队列）密切相关。LAG3 mRNA表达（TCGA队列）、甲基化（两个队列）和肿瘤细胞内源性蛋白表达（UHB队列）与总生存期显著相关。