Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA.
Oncogene. 2014 Dec 4;33(49):5649-54. doi: 10.1038/onc.2013.532. Epub 2013 Dec 23.
Macrophage polarization contributes to distinct human pathologies. In tumors, a polarized M2 phenotype called tumor-associated macrophages (TAMs) are associated with promotion of invasion and angiogenesis. In cancer cells, vacuolar ATPase (V-ATPase), a multi-subunit enzyme, is expressed on the plasma/vesicular membranes and critically influences the metastatic behavior. In addition, the soluble, cleaved N-terminal domain of a2 isoform of V-ATPase (a2NTD) is associated with in vitro induction of pro-tumorigenic properties in monocytes. This activity of a2 isoform of V-ATPase (a2V) caused us to investigate its role in cancer progression through the evaluation of the immunomodulatory properties of a2NTD. Here, we present direct evidence that surface expression of V-ATPase is associated with macrophage polarization in tumor tissue. Macrophages from BALB/c mice (peritoneal/bone marrow derived) were stimulated with recombinant a2NTD in both ex vivo and in vivo systems and evaluated for TAM characteristics. a2V was highly expressed in tumor tissues (breast and skin) as well as on the surface of tumor cell lines. The a2NTD-stimulated macrophages (a2MΦ) acquired TAM phenotype, which was characterized by elevated expression of mannose receptor-1, Arginase-1, interleukin-10 and transforming growth factor-β. a2MΦ also exhibited increased production of other tumorigenic factors including matrix metalloproteinase-9 and vascular endothelial growth factor. Further, a2MΦ were cocultured with mouse B-16F0 melanoma cells for their functional characterization. The coculture of these a2MΦ subsequently increased the invasion and angiogenesis of less invasive B-16F0 cells. When cocultured with naive T cells, a2MΦ significantly inhibited T-cell activation. The present data establish the role of V-ATPase in modulating a macrophage phenotype towards TAMs through the action of a2NTD, suggesting it to be a potential therapeutic target in cancer.
巨噬细胞极化导致了不同的人类病理。在肿瘤中，一种极化的 M2 表型称为肿瘤相关巨噬细胞（TAMs），与促进侵袭和血管生成有关。在癌细胞中，液泡型 ATP 酶（V-ATPase）是一种多亚基酶，表达在质膜/小泡膜上，并对转移行为有重要影响。此外，V-ATPase a2 同工型的可溶性、裂解的 N 端结构域（a2NTD）与单核细胞体外诱导促肿瘤特性有关。V-ATPase a2 同工型（a2V）的这种活性促使我们通过评估 a2NTD 的免疫调节特性来研究其在癌症进展中的作用。在这里，我们提供了直接证据，证明 V-ATPase 的表面表达与肿瘤组织中的巨噬细胞极化有关。用重组 a2NTD 在体外和体内系统刺激 BALB/c 小鼠（腹腔/骨髓来源）的巨噬细胞，并评估其 TAM 特征。a2V 在肿瘤组织（乳腺和皮肤）以及肿瘤细胞系的表面高度表达。a2NTD 刺激的巨噬细胞（a2MΦ）获得了 TAM 表型，其特征是甘露糖受体-1、精氨酸酶-1、白细胞介素-10 和转化生长因子-β的表达水平升高。a2MΦ 还表现出其他肿瘤发生因子如基质金属蛋白酶-9 和血管内皮生长因子的产生增加。此外，a2MΦ 与小鼠 B-16F0 黑色素瘤细胞共培养以进行功能表征。这些 a2MΦ 的共培养随后增加了侵袭性较低的 B-16F0 细胞的侵袭和血管生成。当与幼稚 T 细胞共培养时，a2MΦ 显著抑制 T 细胞活化。这些数据确立了 V-ATPase 通过 a2NTD 调节巨噬细胞表型向 TAMs 的作用，表明它可能成为癌症的潜在治疗靶点。
