Effects of FPR2 gene silencing on the proliferation, migration and invasion of human glioma U87 cells

Abstract

Objective: To investigate the effects of formyl peptide receptor 2 (FPR2) silencing on the proliferation, migration and invasion of human glioma U87 cells and its possible mechanisms. Methods: The expression of FPR2 was detected in normal glial cells, glioma cells, normal brain tissues and glioma tissues using Western blot and immunohistochemistry staining. A synthesized siRNA duplex was employed to inhibit FPR2 in human glioma cells (U87). The knockdown efficiency was evaluated by real-time reverse transcription-polymerase chain reaction (RT-qPCR) and Western blot. MTT, transwell assays and flow cytometry analyses were used to determine the cell proliferation, migration, invasion and apoptotic rates of U87 cells, respectively. Mice xenograft experiments were used to observe the effect of FPR2 silencing on the tumorigenesis of U87 cells in vito. Western blot and enzyme-linked immunosorbent assays were performed to detect the expression and release of cell cycle and migration-related proteins. Results: The expression of FPR2 was significantly higher in glioma cell lines and glioma tissues than that in normal glial cells and brain tissues. Compared with blank control and negative control, FPR2 mRNA and protein levels in siRNA group were significantly downregulated. The cell proliferation inhibitory rates in FPR2 siRNA group were (23.1±5.1)%, (39.6±5.6)% and (44.4±6.7)% at 24 h, 48 h and 72 h, respectively, which were significantly increased than those in negative control group [(3.2±0.6)%, (5.7±0.8)% and (7.9±0.9)%, respectively; P<0.05]. The apoptosis rate in FPR2 siRNA group was (17.4±2.1)%, which was significantly elevated than that in the negative control group with (5.4±0.5)% and blank control group with (3.8±0.3)% (all P<0.05). In addition, the numbers of migrated cells were 108.7±9.5 in FPR2 siRNA group, which was significantly lower than that in blank control group 312.9±17.5 and negative control group (304.4±15.7, all P<0.05). Likewise, the numbers of invaded cells were 19.3±3.2 in FPR2 siRNA group, which was significantly lower than that in blank control group 106.9±8.5 and negative control group (102.4±7.4, all P<0.05). Moreover, the growth of FPR2 siRNA transfected U87 cells in vivo was remarkably decreased comparing with the negative group (P<0.05). Furthermore, the expression of cyclin D1 and VEGF in FPR2 silencing U87 cells was suppressed mainly through β-catenin signaling pathway. Conclusions: FPR2 silencing by siRNA can inhibit the growth, migration and invasion ability, but promote the apoptosis of U87 cells. The possible mechanisms might be associated with the inhibitory expression of cyclin D1 and VEGF.