Macrophage migration inhibitory factor enhances neoplastic cell invasion by inducing the expression of matrix metalloproteinase 9 and interleukin-8 in nasopharyngeal carcinoma cell lines.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Li
Zhi
Z
Department of Pathology, Sun Yat-sen Medical College, Sun Yat-sen University, Guangzhou 510089, China. pathol@gzsums.edu.cn
Ren
Yi
Y
Wu
Qi-chang
QC
Lin
Su-xia
SX
Liang
Ying-jie
YJ
Liang
Hui-zhen
HZ
D015153:Blotting, Western; D045744:Cell Line, Tumor; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D016209:Interleukin-8 / Q000032:analysis*; D008263:Macrophage Migration-Inhibitory Factors / Q000494:pharmacology*; D020778:Matrix Metalloproteinase 2 / Q000032:analysis; D020780:Matrix Metalloproteinase 9 / Q000032:analysis*; D009303:Nasopharyngeal Neoplasms / Q000473:pathology*; D009361:Neoplasm Invasiveness / Q000503:physiopathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D016209:Interleukin-8; D008263:Macrophage Migration-Inhibitory Factors; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9