Wang Xin, Yang Xiaodong, Tsai Ying, Yang Li, Chuang Kuang-Hsiang, Keng Peter C, Lee Soo Ok, Chen Yuhchyau
Department of Radiation Oncology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642.
Radiat Res. 2017 Jan;187(1):50-59. doi: 10.1667/RR14503.1. Epub 2017 Jan 5.
Radiotherapy is effective in reducing primary tumors, however, it may enhance macrophage infiltration to tumor sites, accelerating tumor progression in several ways. We investigated whether radiation can increase macrophage infiltration into non-small cell lung carcinoma (NSCLC) cells. Analysis of in vitro macrophage (differentiated THP-1 cells) migration to either nonirradiated or irradiated tumor cells showed increased migration to the irradiated tumor cells. Because the IL-6 levels in A549 and H157 cells were significantly increased after irradiation, we then investigated whether this increased IL-6 level contributes to radiation-induced macrophage migration. Radiation-induced macrophage infiltration was reduced when IL-6 was knocked down in tumor cells, indicating a positive IL-6 role in this process. To validate this in vitro result, an orthotopic mouse model was developed using a luciferase-tagged H157siIL-6/scramble control (sc) cell set. After tumors developed, the lungs were irradiated, and infiltration of endogenous macrophages and tail-vein injected fluorescent macrophages to tumor sites was investigated. In both groups, increased macrophage infiltration was observed in H157sc cell-derived xenografts compared to H157siIL-6 cell-derived xenografts, confirming the positive IL-6 role in the radiation-induced macrophage infiltration process. In mechanistic dissection studies, radiation-induced up-regulation of CCL2 and CCL5 by IL-6 was detected, and blocking the action of CCL2/CCL5 molecules significantly reduced the number of migrated macrophages to tumor cells after irradiation. These results demonstrate that targeting the IL-6 signaling or CCL2/CCL5 molecules in combination with conventional radiotherapy potentially blocks undesired radiation-induced macrophage infiltration.
放射疗法在缩小原发性肿瘤方面是有效的，然而，它可能会增强巨噬细胞向肿瘤部位的浸润，通过多种方式加速肿瘤进展。我们研究了辐射是否会增加巨噬细胞向非小细胞肺癌（NSCLC）细胞的浸润。对体外巨噬细胞（分化的THP-1细胞）向未照射或照射过的肿瘤细胞的迁移分析表明，向照射过的肿瘤细胞的迁移增加。由于照射后A549和H157细胞中的IL-6水平显著升高，我们随后研究了这种升高的IL-6水平是否有助于辐射诱导的巨噬细胞迁移。当肿瘤细胞中的IL-6被敲低时，辐射诱导的巨噬细胞浸润减少，表明IL-6在这一过程中起积极作用。为了验证这一体外结果，使用荧光素酶标记的H157siIL-6/对照（sc）细胞系建立了原位小鼠模型。肿瘤形成后，对肺部进行照射，并研究内源性巨噬细胞和尾静脉注射的荧光巨噬细胞向肿瘤部位的浸润情况。在两组中，与H157siIL-6细胞衍生的异种移植相比，在H157sc细胞衍生的异种移植中观察到巨噬细胞浸润增加，证实了IL-6在辐射诱导的巨噬细胞浸润过程中的积极作用。在机制剖析研究中，检测到IL-6对CCL2和CCL5的辐射诱导上调，并且阻断CCL2/CCL5分子的作用显著减少了照射后迁移到肿瘤细胞的巨噬细胞数量。这些结果表明，在传统放疗的基础上靶向IL-6信号通路或CCL2/CCL5分子可能会阻止不期望的辐射诱导的巨噬细胞浸润。
