[Effect of macrophage migration inhibitory factor (MIF) on expression of MMP-2,MMP-9,and IL-8 in nasopharyngeal carcinoma cell strains]

Abstract

Background & objective: Although nasopharyngeal carcinoma (NPC) shows highly invasive and metastatic features than other head and neck carcinomas, the major relevant mechanism is still unknown. This study was designed to investigate whether the macrophage migration inhibitory factor (MIF) can affect the expression of matrix metalloproteinase 2, 9 (MMP-2, MMP-9) and interleukin 8 (IL-8) in nasopharyngeal carcinoma (NPC) cell strains.

Methods: Two nasopharyngeal carcinoma cell strains, CNE-1 and CNE-2 were adopted in this study. The variations of expression percentages of MMP-2 or MMP-9-positive cells detected by flow cytometry in NPC cell strains with or without MIF activation were compared. Western blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) were applied to evaluate the protein and mRNA expression level of MMP-2 and MMP-9 in cell strains treated with and without MIF, respectively. The concentration of IL-8 in the supernatant of the cells with different treatments was tested using enzyme-linked immunosorbent assay (ELISA).

Results: (1)After treatment with MIF for 24 h, the percentage of MMP-9-positive cells was 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). However, the percentages of MMP-2-positive cells did not significantly change between these two cell strains with or without MIF treatment (P >0.05). (2) The relative intensity of MMP-9 protein expression was also enhanced in both cell strains (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) and there was no significant difference in MMP-2 expression intensity either in CNE-1 or CNE-2. (3)The IL-8 concentration in CNE-2 supernatant was 1201.8+/-593.3 pg/ml after treatment with MIF for 24 h, remarkably higher than that without treatment (32.7+/-20.1 pg/ml, P=0.026). However, there was no detectable difference of IL-8 concentration found in CNE-1 (P=0.581). (4)The expression level of MMP-9 mRNA, but not of MMP-2 mRNA was significantly increased both in CNE-1 and CNE-2 after treatment with MIF. In addition, the IL-8 mRNA level was only enhanced in CNE-2 but not in CNE-1.

Conclusion: MIF cytokine might play an important role in neoplastic cell invasion and metastasis by up-regulating the expression of MMP-9 and IL-8 in NPC cells through the pathway of activation of their gene transcription.