Department of Surgery, University of Virginia Health System, Charlottesville, Virginia.
Department of Microbiology, Immunology, and Cancer Biology, University of Virginia Health System, Charlottesville, Virginia.
Clin Cancer Res. 2018 Mar 15;24(6):1415-1425. doi: 10.1158/1078-0432.CCR-17-2283. Epub 2017 Dec 29.
Patients with pancreatic ductal adenocarcinoma (PDAC) who undergo surgical resection and adjuvant chemotherapy have an expected survival of only 2 years due to disease recurrence, frequently in the liver. We investigated the role of liver macrophages in progression of PDAC micrometastases to identify adjuvant treatment strategies that could prolong survival. A murine splenic injection model of hepatic micrometastatic PDAC was used with five patient-derived PDAC tumors. The impact of liver macrophages on tumor growth was assessed by (i) depleting mouse macrophages in nude mice with liposomal clodronate injection, and (ii) injecting tumor cells into nude versus NOD--gamma mice. Immunohistochemistry and flow cytometry were used to measure CD47 ("don't eat me signal") expression on tumor cells and characterize macrophages in the tumor microenvironment. engulfment assays and mouse experiments were performed with CD47-blocking antibodies to assess macrophage engulfment of tumor cells, progression of micrometastases in the liver and mouse survival. clodronate depletion experiments and NOD--gamma mouse experiments demonstrated that liver macrophages suppress the progression of PDAC micrometastases. Five patient-derived PDAC cell lines expressed variable levels of CD47. In engulfment assays, CD47-blocking antibodies increased the efficiency of PDAC cell clearance by macrophages in a manner which correlated with CD47 receptor surface density. Treatment of mice with CD47-blocking antibodies resulted in increased time-to-progression of metastatic tumors and prolonged survival. These findings suggest that following surgical resection of PDAC, adjuvant immunotherapy with anti-CD47 antibody could lead to substantially improved outcomes for patients. .
胰腺导管腺癌 (PDAC) 患者在接受手术切除和辅助化疗后，由于疾病复发，只有 2 年的预期生存时间，且常常在肝脏。我们研究了肝巨噬细胞在 PDAC 微转移进展中的作用，以确定可以延长生存时间的辅助治疗策略。使用五个患者来源的 PDAC 肿瘤建立了肝微转移 PDAC 的鼠脾注射模型。通过（i）用脂质体氯膦酸盐注射耗尽裸鼠中的巨噬细胞，以及（ii）将肿瘤细胞注射到裸鼠与 NOD--gamma 鼠中，评估了肝巨噬细胞对肿瘤生长的影响。免疫组织化学和流式细胞术用于测量肿瘤细胞上的 CD47（“不要吃我信号”）表达，并对肿瘤微环境中的巨噬细胞进行特征描述。进行吞噬实验和小鼠实验，使用 CD47 阻断抗体评估巨噬细胞对肿瘤细胞的吞噬作用、肝微转移的进展以及小鼠的存活情况。氯膦酸盐耗竭实验和 NOD--gamma 小鼠实验表明，肝巨噬细胞抑制 PDAC 微转移的进展。五个患者来源的 PDAC 细胞系表达不同水平的 CD47。在吞噬实验中，CD47 阻断抗体以与 CD47 受体表面密度相关的方式增加了巨噬细胞清除 PDAC 细胞的效率。用 CD47 阻断抗体治疗小鼠导致转移性肿瘤进展时间延长，生存时间延长。这些发现表明，在 PDAC 手术后，用抗 CD47 抗体进行辅助免疫治疗可能会为患者带来显著改善的结果。
