Li Zhi, Ren Yi, Wu Qi-chang, Lin Su-xia, Liang Ying-jie, Liang Hui-zhen
Department of Pathology, Sun Yat-sen Medical College, Sun Yat-sen University, Guangzhou 510089, China.
Chin Med J (Engl). 2004 Jan;117(1):107-14.
Nasopharyngeal carcinoma (NPC) shows highly invasive and metastatic features. This study aims to investigate macrophage migration inhibitory factor (MIF)-induced invasion of NPC cells in vitro and the effects on matrix metalloproteinases (MMPs) and interleukin-8 (IL-8), and to study the mechanism of tumor cell invasion and metastasis in the early stage of NPC.
Two nasopharyngeal carcinoma cell lines, CNE-1 and CNE-2, were adopted in this study. The NPC cell invasion and migration were evaluated by microinvasion assay. The variation of expression percentages of MMP2- or MMP9-positive cells was detected by flow cytometry in two cell lines with or without MIF treatment. Western blotting and RT-PCR were used to assay the protein and mRNA expressions of MMP2 and MMP9. The IL-8 concentration secreted by NPC cells was compared with the cells with different treatments using ELISA.
After treating with MIF for 48 hours, the cell numbers of CNE-1 and CNE-2 which went through the 8-microm filter membrane were increased. Compared with non-MIF treated NPC cells, significant difference could be found both in CNE-1 (P = 0.005) and CNE-2 cells (P = 0.001). The percentages of MMP9-positive cells were significantly increased in both CNE-1 [from (28.5 +/- 2.5)% to (82.4 +/- 3.5)%, P = 0.001] and CNE-2 [from (32.8 +/- 3.5)% to (86.1 +/- 1.6)%, P = 0.002]. The relative intensity of MMP9 protein expression was also enhanced in both cell lines (CNE-1: from 83.1 +/- 6.0 to 242.9 +/- 22.9, P = 0.002; CNE-2: from 84.4 +/- 4.3 to 278.9 +/- 29.7, P = 0.003). Correspondingly, the increased MMP9 mRNA expression level was significantly detectable in both cell lines. The concentration of IL-8 in the supernatant of CNE-2 was higher [(1201.8 +/- 593.3) pg/ml] after treatment. It was also remarkably higher than that in the supernatant of CNE-2 without treatment (P = 0.026). However, there was no significant difference in the concentration variation of IL-8 in CNE-1 (P = 0.581), while the IL-8 mRNA level was only enhanced in CNE-2.
MIF can induce potent invasion of NPC cell lines in vitro, and the infiltrating lymphocytes in NPC might be responsible for the invasion and metastasis of tumor cells. MIF cytokine which is secreted by these infiltrating lymphocytes might contribute to the invasion as well as metastasis of NPC in the early stages by induction of MMP9 and IL-8 in an indirect pathway.
鼻咽癌（NPC）具有高度侵袭和转移特征。本研究旨在探讨巨噬细胞移动抑制因子（MIF）诱导的鼻咽癌细胞体外侵袭以及对基质金属蛋白酶（MMPs）和白细胞介素-8（IL-8）的影响，并研究鼻咽癌早期肿瘤细胞侵袭和转移的机制。
本研究采用两种鼻咽癌细胞系，CNE-1和CNE-2。通过微侵袭试验评估鼻咽癌细胞的侵袭和迁移能力。采用流式细胞术检测MIF处理组和未处理组两种细胞系中MMP2或MMP9阳性细胞表达百分比的变化。运用蛋白质印迹法和逆转录-聚合酶链反应（RT-PCR）检测MMP2和MMP9的蛋白质及mRNA表达。采用酶联免疫吸附测定（ELISA）比较不同处理的鼻咽癌细胞分泌的IL-8浓度。
用MIF处理48小时后，穿过8微米滤膜的CNE-1和CNE-2细胞数量增加。与未用MIF处理的鼻咽癌细胞相比，CNE-1细胞（P = 0.005）和CNE-2细胞（P = 0.001）均有显著差异。CNE-1细胞中MMP9阳性细胞百分比显著增加[从（28.5±2.5）%增至（82.4±3.5）%，P = 0.001]，CNE-2细胞中也显著增加[从（32.8±3.5）%增至（86.1±1.6）%，P = 0.002]。两种细胞系中MMP9蛋白表达的相对强度也均增强（CNE-1：从83.1±6.0增至242.9±22.9，P = 0.002；CNE-2：从84.4±4.3增至278.9±29.7，P = 0.003）。相应地，两种细胞系中MMP9 mRNA表达水平均显著升高。处理后CNE-2细胞上清液中IL-8浓度更高[（1201.8±593.3）pg/ml]，也显著高于未处理的CNE-2细胞上清液（P = 0.026）。然而，CNE-1细胞中IL-8浓度变化无显著差异（P = 0.581），而IL-8 mRNA水平仅在CNE-2细胞中升高。
MIF可在体外诱导鼻咽癌细胞系的强力侵袭，鼻咽癌中的浸润淋巴细胞可能是肿瘤细胞侵袭和转移的原因。这些浸润淋巴细胞分泌的MIF细胞因子可能通过间接途径诱导MMP9和IL-8，从而在鼻咽癌早期促进侵袭和转移。
