Department of General Surgery, Chiba University, Graduate School of Medicine, 1-8-1, Inohana, Chuo-ku, Chiba City, Chiba, 260-8677, Japan.
J Exp Clin Cancer Res. 2021 Jun 24;40(1):212. doi: 10.1186/s13046-021-02019-0.
Recent studies indicate that complement plays pivotal roles in promoting or suppressing cancer progression. We have previously identified C4b-binding protein α-chain (C4BPA) as a serum biomarker for the early detection of pancreatic ductal adenocarcinoma (PDAC). However, its mechanism of action remains unclear. Here, we elucidated the functional roles of C4BPA in PDAC cells and the tumor microenvironment.
We assessed stromal C4BPA, the C4BPA binding partner CD40, and the number of CD8 tumor-infiltrating lymphocytes in resected human PDAC tissues via immunohistochemical staining. The biological functions of C4BPA were investigated in peripheral blood mononuclear cells (PBMCs) and human PDAC cell lines. Mouse C4BPA (mC4BPA) peptide, which is composed of 30 amino acids from the C-terminus and binds to CD40, was designed for further in vitro and in vivo experiments. In a preclinical experiment, we assessed the efficacy of gemcitabine plus nab-paclitaxel (GnP), dual immune checkpoint blockades (ICBs), and mC4BPA peptide in a mouse orthotopic transplantation model.
Immunohistochemical analysis revealed that high stromal C4BPA and CD40 was associated with favorable PDAC prognosis (P=0.0005). Stromal C4BPA strongly correlated with the number of CD8 tumor-infiltrating lymphocytes (P=0.001). In in vitro experiments, flow cytometry revealed that recombinant human C4BPA (rhC4BPA) stimulation increased CD4 and CD8 T cell numbers in PBMCs. rhC4BPA also promoted the proliferation of CD40-expressing PDAC cells. By contrast, combined treatment with gemcitabine and rhC4BPA increased PDAC cell apoptosis rate. mC4BPA peptide increased the number of murine T lymphocytes in vitro and the number of CD8 tumor-infiltrating lymphocytes surrounding PDAC tumors in vivo. In a preclinical study, GnP/ICBs/mC4BPA peptide treatment, but not GnP treatment, led to the accumulation of a greater number of CD8 T cells in the periphery of PDAC tumors and to greater tumor regression than did control treatment.
These findings demonstrate that the combination of GnP therapy with C4BPA inhibits PDAC progression by promoting antitumor T cell accumulation in the tumor microenvironment.
最近的研究表明，补体在促进或抑制癌症进展方面起着关键作用。我们之前已经确定 C4b 结合蛋白 α 链（C4BPA）作为胰腺导管腺癌（PDAC）早期检测的血清生物标志物。然而，其作用机制尚不清楚。在这里，我们阐明了 C4BPA 在 PDAC 细胞和肿瘤微环境中的功能作用。
我们通过免疫组织化学染色评估了切除的人 PDAC 组织中的基质 C4BPA、C4BPA 结合伴侣 CD40 和浸润肿瘤的 CD8 淋巴细胞数量。我们在外周血单核细胞（PBMC）和人 PDAC 细胞系中研究了 C4BPA 的生物学功能。设计了由 C 端 30 个氨基酸组成的小鼠 C4BPA（mC4BPA）肽，该肽与 CD40 结合，用于进一步的体外和体内实验。在临床前实验中，我们评估了吉西他滨加 nab-紫杉醇（GnP）、双重免疫检查点阻断（ICBs）和 mC4BPA 肽在小鼠原位移植模型中的疗效。
免疫组织化学分析表明，高基质 C4BPA 和 CD40 与 PDAC 的良好预后相关（P=0.0005）。基质 C4BPA 与浸润肿瘤的 CD8 淋巴细胞数量强烈相关（P=0.001）。在体外实验中，流式细胞术显示重组人 C4BPA（rhC4BPA）刺激可增加 PBMC 中的 CD4 和 CD8 T 细胞数量。rhC4BPA 还促进了表达 CD40 的 PDAC 细胞的增殖。相比之下，吉西他滨和 rhC4BPA 的联合治疗增加了 PDAC 细胞的凋亡率。mC4BPA 肽在体外增加了小鼠 T 淋巴细胞的数量，并在体内增加了 PDAC 肿瘤周围浸润的 CD8 肿瘤浸润淋巴细胞的数量。在临床前研究中，GnP/ICBs/mC4BPA 肽治疗，而不是 GnP 治疗，导致 PDAC 肿瘤周围更多的 CD8 T 细胞积聚，并导致更大的肿瘤消退，而不是对照治疗。
这些发现表明，GnP 治疗与 C4BPA 的联合通过促进肿瘤微环境中抗肿瘤 T 细胞的积累来抑制 PDAC 的进展。
