Porcheron Chloé, Le Devehat Mailys, Roubtsova Anna, Bayat Hadi, Evagelidis Alexandra, Jafarzadeh Leila, Sachan Vatsal, Labrecque Nathalie, Fonta Holder Alexie, Susan-Resiga Delia, Essalmani Rachid, Boudreau Gabrielle, Prat Annik, Cusseddu Rebecca, Côté Jean-François, Khatib Abdel-Majid, Delisle Jean-Sébastien, Seidah Nabil G
Laboratory of Biochemical Neuroendocrinology, Clinical Research Institute of Montreal Biochemical Neuroendocrinology Research Unit, Montreal, Quebec, Canada.
Inserm, UMR1312, BRIC, Bordeaux Institute of Oncology, University of Bordeaux, Bordeaux, France.
J Immunother Cancer. 2025 Jun 15;13(6):e011364. doi: 10.1136/jitc-2024-011364.
Immunotherapy approaches based on T cells provided breakthroughs in cancer treatment but could cause many immune-related adverse events, and their efficacy is limited for many cancers with an acquired dysfunction/exhaustion of T cells. The present study presents a novel role in immunity for proprotein convertase subtilisin-kexin 7 (PCSK7), the seventh proprotein convertase of the 9-membered secretory proprotein convertase subtilisin-kexin (PCSK)-family.
We analyzed cell surface levels of various immune checkpoint proteins in human and mouse cell models in the presence or absence of PCSK7 expression. Injection of mouse colon carcinoma MC38 cells in the spleen of mice lacking either , or both (double knockout) allowed the analysis of the extent of hepatic tumor metastasis. We also estimated the cell surface expression of checkpoint proteins in CD4 and CD8 T cells from healthy human subjects in which expression was silenced by CRISPR Cas9 gRNA knockdown.
Bioinformatic and cellular studies showed enrichment of PCSK7 mRNA levels in CD8 T cells, which correlates with those of immune checkpoint proteins (ICPs; eg, , , and ) responsible for T-cell dysfunction. Indeed, cells lacking PCSK7 and CD8 T cells derived from mice exhibited ≥40% lower cell-surface levels of ICPs. Similarly, CRISPR-Cas9 editing of (i) in primary human T cells resulted in lower expression of ICPs and a reduced proportion of cells expressing multiple ICPs, without altering the expression of activation markers. Moreover, proprotein convertase subtilisin-kexin 9 (PCSK9), the ninth PCSK family member, enhances the degradation of the low-density lipoprotein-receptor and major histocompatibility complex-I proteins. Indeed, mice were previously reported to exhibit reduced liver tumor metastasis. In the present studies, we report synergistic and complementary functions of PCSK7 and PCSK9, as the loss of each one of the convertases reduced by twofold the number of liver metastases, but the strongest reduction (>90%) was observed in double KO ( , ) mice. In mouse tumors the antitumorigenic activity of CD8 T cells was enhanced and the levels of ICPs were reduced.
Cumulatively, our data provide a i strategy to reduce the levels of cell-surface ICPs, thereby rationalizing the use of i in T-cell immunotherapies alone or in combination with a PCSK9 inhibitor/silencer.
基于T细胞的免疫疗法在癌症治疗方面取得了突破，但可能会引发许多免疫相关的不良事件，并且对于许多T细胞获得性功能障碍/耗竭的癌症，其疗效有限。本研究揭示了前蛋白转化酶枯草杆菌蛋白酶/kexin 7（PCSK7）在免疫中的新作用，它是九元分泌性前蛋白转化酶枯草杆菌蛋白酶/kexin（PCSK）家族的第七个前蛋白转化酶。
我们在有或无PCSK7表达的情况下，分析了人和小鼠细胞模型中各种免疫检查点蛋白的细胞表面水平。向缺乏PCSK7、PCSK9或两者（双敲除）的小鼠脾脏注射小鼠结肠癌MC38细胞，以分析肝肿瘤转移的程度。我们还估计了健康人类受试者CD4和CD8 T细胞中检查点蛋白的细胞表面表达，其中PCSK7表达通过CRISPR Cas9 gRNA敲低而沉默。
生物信息学和细胞研究表明，CD8 T细胞中PCSK7 mRNA水平富集，这与负责T细胞功能障碍的免疫检查点蛋白（ICPs；如PD-1、CTLA-4、TIM-3和LAG-3）的水平相关。实际上，缺乏PCSK7的细胞和源自PCSK7 - / - 小鼠的CD8 T细胞显示ICPs的细胞表面水平降低≥40%。同样，在原代人T细胞中对PCSK7进行CRISPR-Cas9编辑导致ICPs表达降低，且表达多种ICPs的细胞比例降低，而不改变激活标志物的表达。此外，PCSK家族的第九个成员前蛋白转化酶枯草杆菌蛋白酶/kexin 9（PCSK9）可增强低密度脂蛋白受体和主要组织相容性复合体-I蛋白的降解。实际上，之前报道PCSK9 - / - 小鼠肝肿瘤转移减少。在本研究中，我们报告了PCSK7和PCSK9的协同和互补功能，因为每种转化酶的缺失使肝转移数量减少了两倍，但在双敲除（PCSK7 - / - ，PCSK9 - / - ）小鼠中观察到最强的减少（>90%）。在PCSK7 - / - 小鼠肿瘤中，CD8 T细胞的抗肿瘤活性增强，ICPs水平降低。
总体而言，我们的数据提供了一种降低细胞表面ICPs水平的策略，从而使单独使用PCSK7或与PCSK9抑制剂/沉默剂联合用于T细胞免疫疗法具有合理性。
