三阴性乳腺癌中Med19通过调控CXCL11表达抑制CD8+ T细胞免疫浸润机制研究

Immunotherapy has become a promising new treatment for triple-negative breast cancer (TNBC). Intratumor CD8+ T cell infiltration is essential for TNBC immunotherapy. We found that Med19 was an oncogene in breast cancer and negatively correlated with CD8A expression. After knockdown Med19 expression in TNBC cells, the microarray results showed that chemokine CXCL11 expression was increased, which has been reported to play an anti-tumor role in promoting the infiltration of CD8+ T cells. Furthermore, inhibition of Med19 expression increased the sensitivity of TNBC cells to CD8+ T cells killing effect. We speculated that Med19 may affect CD8+ T cells immune infiltration in TNBC through regulating the expression of CXCL11. To explore the potential mechanism of Med19 in regulating CXCL11, we performed Co-IP and mass spectrometry to identify the molecules interacting with Med19. In this project, we will further clarify the mechanism of Med19 in cells, animal model and TNBC patient tissues. This study is expected to illustrate the mechanism of Med19 in regulating CXCL11 to affect CD8+ T cells immune infiltration in TNBC and provide a potential target for TNBC immunotherapy.

免疫治疗成为三阴性乳腺癌（triple-negative breast cancer，TNBC）新的具有前景的治疗手段。肿瘤局部CD8+T细胞浸润对TNBC免疫治疗发挥疗效至关重要。我们研究发现，Med19是乳腺癌中癌基因，且与肿瘤中CD8A负相关。抑制Med19表达，芯片结果显示趋化因子CXCL11表达升高，CXCL11被报道通过促进CD8+T细胞浸润发挥抗肿瘤作用。抑制Med19表达，TNBC细胞对CD8+T细胞杀伤作用敏感性增强，我们推测Med19可能通过调控CXCL11表达影响TNBC中CD8+T细胞免疫浸润。通过Co-IP和质谱分析鉴定Med19相互作用分子，进一步探究Med19调控CXCL11的机制。本项目拟从细胞、动物以及临床样本水平进一步阐明Med19作用机制，有望揭示Med19调控CXCL11影响TNBC中CD8+T免疫浸润机制，为TNBC免疫治疗提供新的分子靶点。

乳腺癌是一种严重威胁女性健康且异质性很高的疾病。肿瘤局部CD8+T细胞浸润增多有利于免疫治疗发挥疗效。本课题组前期研究发现，中介体复合物亚基19（MED19）在乳腺癌中作为一个癌基因发挥促肿瘤作用。本研究中，抑制MED19的表达，可以明显抑制乳腺癌细胞的增殖、周期进展以及增强细胞对化疗药物的敏感性。上调表达则呈现相反的趋势。通过芯片测序结果发现，抑制MED19的表达后，引起趋化因子CXCL11的表达上调，GO通路分析显示，细胞对外界刺激反应的通路和正向调节细胞因子相关的通路显著被富集。生物信息学分析发现，Kaplan-Meier生存曲线分析显示MED19高表达预测较差的临床预后，而相反，CXCL11高表达的患者呈现出较好的临床预后。TCGA乳腺癌数据集生物信息学分析结果显示，CXCL11高表达与免疫反应激活、增加抗肿瘤免疫细胞浸润、免疫检查点分子表达以及增强对免疫治疗和化疗的敏感性相关。验证实验结果表明，MED19与CXCL11呈负调控关系。共培养实验结果显示，抑制MED19可增强CD8+ T细胞对肿瘤细胞的杀伤作用。上调MED19的表达则呈相反趋势，而同时上调CXCL11的表达可逆转MED19过表达引起的对CD8+ T细胞的杀伤抵抗作用。体内实验结果也显示抑制MED19表达后，可增强瘤体内CD8+ T细胞的浸润。乳腺癌临床样本检测结果也显示，MED19在肿瘤中呈现高表达，而CXCL11和CD8A呈现低表达，且CXCL11和CD8A的表达与MED19的表达均呈负相关趋势，而CXCL11和CD8A的表达呈正相关趋势。机制研究表明，MED19可能通过与NF-κB2相互作用调控CXCL11的表达，进而影响肿瘤微环境中CD8+ T细胞免疫浸润。上述结果提示，MED19在乳腺癌中作为一个癌基因，不仅影响肿瘤细胞本身的恶性表型，还可能通过调控趋化因子，影响肿瘤微环境中免疫细胞的浸润。