CXC趋化因子配体8促进结直肠癌微环境中M2型巨噬细胞趋化及浸润

CXC趋化因子配体8(CXC chemokine ligand 8,CXCL8)在结直肠癌等多种肿瘤中高表达,并促进肿瘤恶性进展。研究发现,结直肠癌微环境中有大量M2型巨噬细胞浸润,但CXCL8是否影响M2型巨噬细胞的浸润及其潜在机制尚未可知。本文旨在探讨CXCL8对结直肠癌中M2型巨噬细胞浸润及趋化作用的影响。本研究首先分析了TCGA数据库结直肠癌样本中CXCL8表达水平及免疫细胞浸润情况,并在临床组织中进行验证。随后Western 印迹及qRT-PCR检测5种结直肠癌细胞株CXCL8的表达情况。佛波酯(PMA)及IL-4诱导THP-1至M2型巨噬细胞后,与HCT116、SW480细胞及过表达CXCL8的HCT116(CXCL8/HCT116)、SW480(CXCL8/SW480)共培养,检测M2型巨噬细胞趋化情况。白细胞介素1β(IL-1β)处理HCT116、SW480细胞,检测CXCL8表达情况,与M2型巨噬细胞共培养,分析趋化结果。结果显示,患者癌组织CXCL8表达高于癌旁组织,CXCL8高表达癌组织中存在更多M2型巨噬细胞浸润;IL-1β作用于HCT116或SW480后,CXCL8的mRNA及蛋白质表达水平升高(P<0.05)。Transwell实验证实,CXCL8趋化M2型巨噬细胞(P<0.05)。综上所述,结直肠癌细胞中CXCL8可由IL-1β诱导产生,CXCL8表达增加能够促进M2型巨噬细胞的趋化,结直肠癌微环境中M2型巨噬细胞大量浸润可能与CXCL8表达升高有关。

CXCL8 Promotes M2 Macrophage Chemotaxis and Infiltration in Colorectal Cancer Microenvironment

CXC chemokine ligand 8 (CXCL8) is highly expressed in many human tumors including colorectal cancer, and it can promote the malignant progression of tumors. It was reported that M2 macrophages were abundant in colorectal cancer microenvironment, but whether CXCL8 affects the infiltration of M2 macrophages and its potential mechanism are not yet clear. The study aimed to investigate the effect of CXCL8 on M2 macrophage infiltration and chemotaxis in the colorectal cancer. Firstly, we analyzed the CXCL8 expression and immune cell infiltration in human colorectal cancer tissues from TCGA RNA-seq data. The expression of CXCL8 was verified by immunohistochemistry in tissues obtained from Shanxi Provincial Cancer Hospital. Then, Western blot and qRT-PCR were employed to detect CXCL8 expression in five colorectal cancer cell lines. THP-1 cells were allowed to differentiate into M2 macrophages via the phorbol myristate acetate (PMA) and IL-4 treatment, followed by detection of the chemotaxis of M2 macrophages towards HCT116,SW480 and CXCL8-HCT116,CXCL8-SW480 cell lines. HCT116 and SW480 cells were treated with interleukin 1β (IL-1β) to detect the expression of CXCL8, and co-cultured with M2 macrophages to analyze the chemotactic activity. The results revealed that the expression of CXCL8 was increased in pairs of CRC tissues versus normal adjacent tissues, and there were more M2 macrophage infiltration in cancer tissues with high expression of CXCL8. The mRNA and protein expression of CXCL8 in HCT116 and SW480 were increased after the IL-1β treatment (P<0.05). We confirmed that CXCL8 is a chemotactic factor for M2 macrophages by transwell assays (P<0.05). In conclusion, CXCL8 in colorectal cancer cells can be induced by IL-1β in colorectal cancer cells and the upregulation of CXCL8 can promote the chemotaxis of M2 macrophages. The massive infiltration of M2 macrophages in colorectal cancer microenvironment may be related with the increased expression of CXCL8.