Increased cell migration of nasopharyngeal carcinoma cell lines in vitro by macrophage migration inhibitory factor
LI Zhi(Email:email@example.com), LIN Su-xia, LIANG Ying-jie.Department of Pathology, Sun Yat-sen Medical College, Sun Yat-sen University,Guangzhou 510089,China
ObjectiveTo study whether macrophage migration inhibitory factor (MIF) can increase the ability of invasion of nasopharyngeal carcinoma cell lines in vitro, and to investigate the mechanism of invasion and metastasis of tumor cells during the early stage of nasopharyngeal carcinoma (NPC). Methods The invasion and migration of NPC cell lines, CNE-1 and CNE-2, were evaluated by micron-migration assay in a chamber with 8-μm porosity polycarbonate filter membra ne. Flow cytometry and western blotting were adopted respectively to evaluate the protein expression level of matrix metalloproteinase 2 and 9 (MMP2, MMP9) in MIF treated or non-treated tumor cell lines. The concentrations of interleukin 8(IL-8) secreted into the culture supernatant by the cells were measured by using Enzyme-linked immunoabsorbent assay (ELISA). Results(1) After treatment with MIF for 24 hours, the number of cells passing through the 8-μm filter membrane were increased in CNE-1 (113.7±20.9) and CNE-2 (311.3±48.9), as compared with tha t of non-MIF treated NPC cells. A significant statistic difference (P=0.005, P=0 .001) was obtained in both CNE-1 and CNE-2 cells. (2) After treatment with MIF, the number of MMP9-positive cells increased in both CNE-1 (from 28.5%±2.45% to 82.4%±3.49%,P=0.001)and CNE-2 (from 32.8%±3.48% to 86.1%±1.62%,P=0.002) cell lines. In addition, an enhanced MMP9 protein expression up to 3-fold was observed in both cell lines. However, the expression level of MMP2 did not changed significantly between treated and non-treated cell lines (P0.05). (3) The concentration of IL-8 in the culture supernatant of CNE-2 was 1201.8±593.3 pg/ml after treatment with MIF for 24 h, remarkably higher than that without MIF treatment (32.7±20.1 pg/ml, P=0.026). A similar change was not detected in CNE-1 (P=0.581) cells. Conclusions(1) MIF can increase cell migration of CNE-1 and CNE-2 NPC cell lines in vitro. (2) A higher expression level of MMP9 and an up-regulated IL-8 by MIF may play a very important role in the progress of NPC, such as invasion and metastasis.