人体免疫细胞是天然的癌细胞杀手，但是癌细胞通过免疫细胞程序性死亡受体PD-1及其配体PD-L1等免疫检查点，可以诱导免疫逃逸，防止自己被人体免疫细胞杀死，而免疫检查点抑制剂等免疫治疗药物可恢复人体免疫细胞抗癌能力。虽然免疫治疗对三阴性乳腺癌已经取得巨大进展，但是仍有大量患者未能对免疫治疗获益。因此，迫切需要确定诱导免疫逃逸的关键分子并且阐明其对三阴性乳腺癌的具体机制。
2025年1月9日，英国《生物医学中心》旗下《生物学标志物研究》在线发表复旦大学附属肿瘤医院隋辛怡①、曹朔文①、宋效清①、刘西禹①、陈超、王稚晴、张文娟、马林晓曦、金希、马丁、肖毅、吴松阳、徐颖、邵志敏✉️、范蕾✉️等学者的研究报告，首次阐明死亡因子样蛋白质MORF4L2可诱导三阴性乳腺癌细胞产生免疫抑制微环境和免疫治疗耐药。
该研究首先通过单个细胞测序和大量细胞测序进行生物学标志物筛选，采用免疫组织化学、多重免疫荧光和三阴性乳腺癌小鼠原位肿瘤异种移植模型确定免疫逃逸驱动关键分子，随后通过基因转录测序、体外共培养系统、流式细胞术、蛋白质印迹法、酶联免疫吸附分析和实时定量聚合酶链反应进行机制分析。
结果发现，PD-1抑制剂耐药患者与敏感患者相比，MORF4L2表达水平显著较高。MORF4L2通过诱导巨噬细胞浸润趋化并促进典型活化巨噬细胞M1极化为替代活化巨噬细胞M2，增强对PD-1抑制剂耐药能力，从而创造免疫抑制微环境。
机制分析表明，MORF4L2作为NuA4组蛋白乙酰转移酶复合物的一部分，参与组蛋白H4第12位赖氨酸残基乙酰化修饰H4K12Ac并激活巨噬细胞集落刺激因子CSF1下游转录。CSF1由肿瘤细胞分泌并与巨噬细胞表面CSF1受体CSF1R结合，将M1趋化并极化为M2。此外，该研究还发现粒状头转录因子GRHL2可以通过与MORF4L2增强子区域结合促进MORF4L2转录。值得注意的是，CSF1R抑制剂索图替尼通过阻断GRHL2 → MORF4L2 → H4K12Ac → CSF1信号传导轴可恢复PD-1抑制剂敏感性。
因此，该研究结果表明，GRHL2 → MORF4L2 → H4K12Ac → CSF1信号传导轴对三阴性乳腺癌PD-1抑制剂耐药具有重要作用，CSF1R抑制剂索图替尼可以逆转该信号传导轴所致三阴性乳腺癌免疫治疗耐药，故有必要进一步开展临床研究进行验证。
Biomark Res. 2025 Jan 9;13(1):6. IF: 9.5
MORF4L2 induces immunosuppressive microenvironment and immunotherapy resistance through GRHL2/MORF4L2/H4K12Ac/CSF1 axis in triple-negative breast cancer.
Sui XY, Cao SW, Song XQ, Liu XY, Chen C, Yan Q, Wang ZQ, Zhang WJ, Ma LX, Jin X, Ma D, Xiao Y, Wu SY, Xu Y, Shao ZM, Fan L.
Fudan University Shanghai Cancer Center, Shanghai, China; Shanghai Medical College, Fudan University, Shanghai, China; School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, China.
BACKGROUND: Although immunotherapy has achieved great progress in advanced triple-negative breast cancer (TNBC), there are still numerous patients who do not benefit from immunotherapy. Therefore, identification of the key molecule that induces immune escape and clarification of its specific mechanism in TNBC are urgently needed.
METHODS: In this research, single cell sequencing and bulk sequencing were conducted for biomarker screening. Immunohistochemistry, multiplex immunofluorescence, and orthotopic TNBC tumor model were applied in identifying the key molecule driving immune escape. At the mechanical level, RNA sequencing, in vitro co-culturing system, flow cytometry, Western blotting, ELISA, and real-time qPCR were carried out.
RESULTS: Mortality factor 4 like 2 (MORF4L2) expression is significantly up-regulated among patients who developed anti-PD1 resistance. MORF4L2 enhances anti-PD1 resistance by inducing the chemotaxis of macrophage infiltration and promoting their polarization towards the alternative activation phenotype (M2), thus creating an immunosuppressive microenvironment. Mechanistically, MORF4L2 actes as part of NuA4 histone acetyltransferase (HAT) complex, contributes to to histone 4 lysine 12 acetylation (H4K12Ac) and activates the downstream transcription of macrophage colony-stimulating factor (CSF1). CSF1 is secreted by tumor cells and binds to the macrophage-surface CSF1 receptor (CSF1R), which chemotactically converted and polarized macrophages to the M2 phenotype. Furthermore, we revealed that grainyhead like transcription factor 2 (GRHL2) could promote MORF4L2 transcription by binding to the MORF4L2 enhancer region. Notably, BLZ945, an inhibitor of CSF1R, restored the anti-PD1 sensitivity by blocking the GRHL2/MORF4L2/H4K12Ac/CSF1 axis.
CONCLUSIONS: GRHL2/MORF4L2/H4K12Ac/CSF1 axis plays an important role in anti-PD1 resistance. CSF1R inhibitors can reverse GRHL2/MORF4L2-mediated anti-PD1 resistance.
KEYWORDS: Anti-PD1; Combination therapy; Histone 4 lysine 12 acetylation; Mortality factor 4 like 2; Triple-negative breast cancer; Tumor microenvironment.
PMID: 39780291
DOI: 10.1186/s40364-024-00719-1
