Macrophage migration inhibitory factor regulatesproliferation of gastric cancer cellsvia the PI3K/Akt pathway

Abstract

To investigate the effects of macrophage migration inhibitory factor (MIF) on proliferation of human gastric cancer MGC-803 cells and expression of cyclin D1 and p27(Kip1) in them, and further determine whether the effects are related to the PI3K/Akt signal transduction pathway. Gastric cancer MGC-803 cells were cultured and then treated with 50 microg/L recombinant human MIF (rhMIF) with and without a PI3K inhibitor, LY294002 (25 micromol/L). MTT assay was used to detect the proliferation of MGC-803 cells. Cell cycle was detected by flow cytometry. Expression of cyclin D1 and p27(Kip1) mRNA was by reverse transcription-polymerase chain reaction. Protein expression of phosphorylated Akt (p-Akt), Akt, cyclin D1 and p27(Kip1) was examined by immunocytochemistry and Western blotting. rhMIF significantly stimulated the proliferation of MGC-803 cells and cell cycle progression from G1 phase to S phase in a concentration- and time-dependent manner. After the MGC-803 cells were treated with rhMIF for 24 h, the expression of cyclin D1 was significantly up-regulated compared with the cells not treated with rhMIF at both mRNA and protein levels (0.97 +/- 0.02 vs 0.74 +/- 0.01, P = 0.002; 0.98 +/- 0.05 vs 0.69 +/- 0.04, P = 0.003). The p27(Kip1) was down-regulated but only statistically significant at the protein level. rhMIF significantly increased the expression of p-Akt, which reached the peak at 30 min, but did not affect the expression of Akt. However, LY294002 inhibited all the effects of rhMIF. Macrophage MIF increases the proliferation of gastric cancer cells, induces the expression of cyclin D1 at the transcriptional level and inhibits the expression of p27(Kip1) at the post-transcriptional level via the PI3K/Akt pathway.