乳腺癌的免疫疗法并未取得显著成功。凝血因子FVIIa（FVIIa）-组织因子（TF）介导的蛋白酶活化受体2（PAR2）的激活显示促进转移和免疫调节细胞因子的分泌，但FVIIa在癌症免疫学中的作用仍不明确。在这里，我们旨在研究FVIIa是否可以保护乳腺癌细胞免受CD8 T细胞介导的杀伤。将外周血单个核细胞（PBMC）衍生的CD8 T细胞与经过车辆或FVIIa预处理的MDAMB468细胞共培养。通过流式细胞术和ELISA测量CD8 T细胞的增殖和活性。采用野生型或TF/PAR2缺失的4T1细胞的异种移植模型，来确定FVIIa对乳腺癌免疫逃避的影响。在这里，我们证明TF-FVIIa通过激活PAR2在乳腺癌细胞中诱导了程序性死亡配体1（PD-L1）。PAR2的激活触发大肿瘤抑制因子激酶1（LATS1）失活，导致YAP（yes-associated protein）/TAZ（transcriptional co-activator with PDZ-binding motif）的磷酸化丧失和YAP/TAZ的核内定位。YAP/TAZ的抑制减少了PD-L1的表达并增加了CD8 T细胞的活性。我们进一步证明，除了通过转录诱导PD-L1外，PAR2的激活还通过增强N-糖基转移酶STT3A和STT3B介导的糖基化来提高PD-L1的稳定性。在乳腺癌的小鼠模型中，肿瘤细胞特异性的PAR2耗尽导致PD-L1的下调，并增加了抗PD-1免疫疗法的疗效。总之，我们显示了癌细胞中FVIIa介导的信号级联作为一种肿瘤的固有机制，抑制免疫以促进癌症免疫逃避。© 2023 International Society on Thrombosis and Haemostasis。由Elsevier Inc.出版。版权所有。

Immunotherapy for breast cancer has not gained significant success. Coagulation factor FVIIa (FVIIa)-tissue factor (TF) mediated activation of protease-activated receptor 2 (PAR2) is shown to promote metastasis and secretion of the immune-modulatory cytokines but the role of FVIIa in cancer immunology is still not well understood.Here, we aim to investigate whether FVIIa protects breast cancer cells from CD8 T cell-mediated killing.Peripheral blood mononuclear cell (PBMC)-derived CD8 T cells were co-cultured with vehicle or FVIIa pre-treated MDAMB468 cells. The proliferation and activity of CD8 T cells were measured by flow cytometry and ELISA. An allograft model, using wild-type or TF/PAR2-deleted 4T1 cells, was employed to determine the effect of FVIIa on breast cancer immune evasion in vivo.Here, we demonstrate that TF-FVIIa induces programmed death-ligand 1 (PD-L1) in breast cancer cells by activating PAR2. PAR2 activation triggers large tumor suppressor kinase 1 (LATS1) inactivation leading to loss of yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) phosphorylation and subsequent nuclear localization of YAP/TAZ. YAP/TAZ inhibition reduces PD-L1 expression and increases CD8 T cell activity. We further demonstrate that, apart from transcriptional induction of PD-L1, PAR2 activation also increases PD-L1 stability by enhancing its glycosylation through N-glycosyltransferases STT3A and STT3B. In a mouse model of breast cancer, tumor cell-specific PAR2 depletion leads to PD-L1 downregulation and increases anti-PD-1 immunotherapy efficacy. In conclusion, we show that FVIIa-mediated signaling cascade in cancer cells serves as a tumor intrinsic mechanism of immunosuppression to promote cancer immune evasion.Copyright © 2023 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.