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-μm 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.

A recombinant Newcastle disease virus expressing MMP8 promotes oncolytic efficacy

Oncolytic virus is an emerging anti-cancer strategy. However, extracellular matrix(ECM), as a physical barrier, limits virus spread within the tumor. To overcome the obstacle, we constructed a recombinant Newcastle disease virus(NDV) expressing matrix metalloproteinase(MMP8)(NDV-MMP8) using with reverse genetic technology. In vitro, NDV-MMP8 was identified and verified by WB and ELISA. Cell viability was detected by CCK-8 assay. In vivo, we established two liver cancer xenograft models. NDV-MMP8 was injected into the tumor to observe the tumor volume and survival of mice. The changes in extracellular matrix were observed by Masson’s trichrome staining. Virus expression in tumor tissues was detected by immunofluorescence assay. The virus titer in tumor tissues was detected by TCID50. Histopathological changes were detected by hematoxylin and eosin(HE) and terminal deoxynucleotidyl transferase d UTP nick end labeling(TUNEL) staining. Intratumoral administration of NDV-MMP8 can effectively degrade ECM, promote the spread of the virus within the tumor, and reduce tumor growth rate. Therefore, the method of increasing intratumoral virus accumulation by degradation of the ECM to enhance the oncolytic effect has great potential for clinical application.