Abstract：
OBJECTIVE: Immunotherapy using PD-L1 blockade is effective in only a small group of cancer patients, and resistance is common. This emphasizes the importance of understanding the mechanisms of cancer immune evasion and resistance.
METHODS: A genome-scale CRISPR-Cas9 screen identified Bap1 as a regulator of PD-L1 expression. To measure tumor size and survival, tumor cells were subcutaneously injected into both syngeneic WT mice and immunocompromised mice. The phenotypic and transcriptional characteristics of Bap1-deleted tumors were examined using flow cytometry, RNA-seq, and CUT&Tag-seq analysis.
RESULTS: We found that loss of histone deubiquitinase Bap1 in cancer cells activates a cDC1-CD8+ T cell-dependent anti-tumor immunity. The absence of Bap1 leads to an increase in genes associated with anti-tumor immune response and a decrease in genes related to immune evasion. As a result, the tumor microenvironment becomes inflamed, with more cDC1 cells and effector CD8+ T cells, but fewer neutrophils and regulatory T cells. We also found that the elimination of Bap1-deleted tumors depends on the tumor MHCI molecule and Fas-mediated CD8+ T cell cytotoxicity. Our analysis of TCGA data further supports these findings, showing a reverse correlation between BAP1 expression and mRNA signatures of activated DCs and T-cell cytotoxicity in various human cancers.
CONCLUSIONS: The histone deubiquitinase Bap1 could be used as a biomarker for tumor stratification and as a potential therapeutic target for cancer immunotherapies.
METHODS: A genome-scale CRISPR-Cas9 screen identified Bap1 as a regulator of PD-L1 expression. To measure tumor size and survival, tumor cells were subcutaneously injected into both syngeneic WT mice and immunocompromised mice. The phenotypic and transcriptional characteristics of Bap1-deleted tumors were examined using flow cytometry, RNA-seq, and CUT&Tag-seq analysis.
RESULTS: We found that loss of histone deubiquitinase Bap1 in cancer cells activates a cDC1-CD8+ T cell-dependent anti-tumor immunity. The absence of Bap1 leads to an increase in genes associated with anti-tumor immune response and a decrease in genes related to immune evasion. As a result, the tumor microenvironment becomes inflamed, with more cDC1 cells and effector CD8+ T cells, but fewer neutrophils and regulatory T cells. We also found that the elimination of Bap1-deleted tumors depends on the tumor MHCI molecule and Fas-mediated CD8+ T cell cytotoxicity. Our analysis of TCGA data further supports these findings, showing a reverse correlation between BAP1 expression and mRNA signatures of activated DCs and T-cell cytotoxicity in various human cancers.
CONCLUSIONS: The histone deubiquitinase Bap1 could be used as a biomarker for tumor stratification and as a potential therapeutic target for cancer immunotherapies.
摘要：
目的：使用PD-L1阻断的免疫治疗仅对一小部分癌症患者有效，抵抗是常见的。这强调了了解癌症免疫逃避和抵抗机制的重要性。
方法：基因组规模的CRISPR-Cas9筛选将Bap1鉴定为PD-L1表达的调节因子。为了测量肿瘤大小和存活率，将肿瘤细胞皮下注射到同基因WT小鼠和免疫受损小鼠中。使用流式细胞术检查Bap1缺失肿瘤的表型和转录特征，RNA-seq,以及CUT和Tag-seq分析。
结果：我们发现癌细胞中组蛋白去泛素酶Bap1的丢失激活了cDC1-CD8+T细胞依赖性抗肿瘤免疫。Bap1的缺失导致与抗肿瘤免疫应答相关的基因增加和与免疫逃避相关的基因减少。因此,肿瘤微环境发炎，更多的cDC1细胞和效应CD8+T细胞，但中性粒细胞和调节性T细胞较少。我们还发现，Bap1缺失肿瘤的消除取决于肿瘤MHCI分子和Fas介导的CD8T细胞毒性。我们对TCGA数据的分析进一步支持了这些发现，显示在各种人类癌症中BAP1表达和活化DC的mRNA签名与T细胞的细胞毒性之间的反向相关性。
结论：组蛋白去泛素酶Bap1可用作肿瘤分层的生物标志物，并作为癌症免疫治疗的潜在治疗靶点。
方法：基因组规模的CRISPR-Cas9筛选将Bap1鉴定为PD-L1表达的调节因子。为了测量肿瘤大小和存活率，将肿瘤细胞皮下注射到同基因WT小鼠和免疫受损小鼠中。使用流式细胞术检查Bap1缺失肿瘤的表型和转录特征，RNA-seq,以及CUT和Tag-seq分析。
结果：我们发现癌细胞中组蛋白去泛素酶Bap1的丢失激活了cDC1-CD8+T细胞依赖性抗肿瘤免疫。Bap1的缺失导致与抗肿瘤免疫应答相关的基因增加和与免疫逃避相关的基因减少。因此,肿瘤微环境发炎，更多的cDC1细胞和效应CD8+T细胞，但中性粒细胞和调节性T细胞较少。我们还发现，Bap1缺失肿瘤的消除取决于肿瘤MHCI分子和Fas介导的CD8T细胞毒性。我们对TCGA数据的分析进一步支持了这些发现，显示在各种人类癌症中BAP1表达和活化DC的mRNA签名与T细胞的细胞毒性之间的反向相关性。
结论：组蛋白去泛素酶Bap1可用作肿瘤分层的生物标志物，并作为癌症免疫治疗的潜在治疗靶点。
