Rana Priyanka S, Ignatz-Hoover James J, Guo Chunna, Mosley Amber L, Malek Ehsan, Federov Yuriy, Adams Drew J, Driscoll James J
Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio.
Division of Hematology and Oncology, Department of Medicine, Case Western Reserve University, Cleveland, Ohio.
Mol Cancer Ther. 2024 Dec 3;23(12):1743-1760. doi: 10.1158/1535-7163.MCT-23-0931.
Proteasomes generate antigenic peptides that are presented on the tumor surface to cytotoxic T-lymphocytes. Immunoproteasomes are highly specialized proteasome variants that are expressed at higher levels in antigen-presenting cells and contain replacements of the three constitutive proteasome catalytic subunits to generate peptides with a hydrophobic C-terminus that fit within the groove of MHC class I (MHC-I) molecules. A hallmark of cancer is the ability to evade immunosurveillance by disrupting the antigen presentation machinery and downregulating MHC-I antigen presentation. High-throughput screening was performed to identify compound A, a novel molecule that selectively increased immunoproteasome activity and expanded the number and diversity of MHC-I-bound peptides presented on multiple myeloma cells. Compound A increased the presentation of individual MHC-I-bound peptides by >100-fold and unmasked tumor-specific neoantigens on myeloma cells. Global proteomic integral stability assays determined that compound A binds to the proteasome structural subunit PSMA1 and promotes association of the proteasome activator PA28α/β (PSME1/PSME2) with immunoproteasomes. CRISPR/Cas9 silencing of PSMA1, PSME1, or PSME2 as well as treatment with immunoproteasome-specific suicide inhibitors abolished the effects of compound A on antigen presentation. Treatment of multiple myeloma cell lines and patient bone marrow-derived CD138+ cells with compound A increased the anti-myeloma activity of allogenic and autologous T cells. Compound A was well-tolerated in vivo and co-treatment with allogeneic T cells reduced the growth of myeloma xenotransplants in NOD/SCID gamma mice. Taken together, our results demonstrate the paradigm shifting impact of immunoproteasome activators to diversify the antigenic landscape, expand the immunopeptidome, potentiate T-cell-directed therapy, and reveal actionable neoantigens for personalized T-cell immunotherapy.
蛋白酶体产生抗原肽，这些抗原肽呈递在肿瘤表面，供细胞毒性T淋巴细胞识别。免疫蛋白酶体是高度特化的蛋白酶体变体，在抗原呈递细胞中高水平表达，并且包含三个组成型蛋白酶体催化亚基的替换，以产生具有适合于MHC I类（MHC-I）分子凹槽的疏水C末端的肽。癌症的一个标志是能够通过破坏抗原呈递机制和下调MHC-I抗原呈递来逃避免疫监视。进行了高通量筛选以鉴定化合物A，这是一种新型分子，可选择性增加免疫蛋白酶体活性，并扩大多发性骨髓瘤细胞上呈递的MHC-I结合肽的数量和多样性。化合物A使单个MHC-I结合肽的呈递增加了100倍以上，并揭示了骨髓瘤细胞上的肿瘤特异性新抗原。整体蛋白质组学完整性测定表明，化合物A与蛋白酶体结构亚基PSMA1结合，并促进蛋白酶体激活剂PA28α/β（PSME1/PSME2）与免疫蛋白酶体的结合。PSMA1、PSME1或PSME2的CRISPR/Cas9沉默以及用免疫蛋白酶体特异性自杀抑制剂处理消除了化合物A对抗原呈递的影响。用化合物A处理多发性骨髓瘤细胞系和患者骨髓来源的CD138+细胞可增加同种异体和自体T细胞的抗骨髓瘤活性。化合物A在体内耐受性良好，与同种异体T细胞联合治疗可减少NOD/SCIDγ小鼠中骨髓瘤异种移植物的生长。综上所述，我们的结果证明了免疫蛋白酶体激活剂在改变抗原格局、扩大免疫肽组、增强T细胞导向治疗以及揭示个性化T细胞免疫治疗的可操作新抗原方面的范式转变影响。
