All-trans retinoic acid inhibits migration, invasion and proliferation, and promotes apoptosis in glioma cells in vitro

All-trans retinoic acid (ATRA) is a derivative of vitamin A that can induce differentiation and apoptosis, as well as inhibit proliferation, in glioma cells. However, the effect of ATRA on the migration and invasiveness of glioma remains poorly understood. In addition, although it is universally accepted that ATRA can induce apoptosis and inhibit proliferation in glioma cells, the association between the concentration and effects of ATRA remain unclear. Therefore, the present study investigated the effects of ATRA treatment on the migration, invasion, apoptosis and proliferation of glioma cells. The U87 and SHG44 glioma cell lines were treated with various concentrations of ATRA, consisting of 0, 5, 10, 20 and 40 mu mol/l. A scratch wound healing assay and a Matrigel invasion assay were used to investigate cell migration and invasion, respectively. Flow cytometry was performed to investigate apoptosis and cell cycle distribution. Reverse transcription-quantitative polymerase chain reaction and western blotting were used to investigate the expression of matrix metalloproteinase (MMP)-2 and -9 in each cell treatment group. Following treatment with ATRA, the migration, invasion and proliferation of the glioma cells were significantly inhibited, and the apoptosis rate was significantly increased compared with that of the blank control group. Furthermore, a dose-effect association was identified between each effects and ATRA treatment. The mRNA and protein expression of MMP-2 in U87 glioma cells was not significantly affected following treatment with low concentrations of ATRA, consisting of 5 and 10 mu mol/l ATRA, compared with the expression in the control group (P>0.05). However, treatment with high concentrations of ATRA, consisting of 20 and 40 mu mol/l ATRA, significantly downregulated the expression levels of MMP-2 in U87 cells. In contrast to U87 cells, the administration of ATRA treatment to SHG44 glioma cells resulted in a significant and dose-dependent downregulation in MMP-2 mRNA and protein expression (P<0.01). In addition, significant downregulation of MMP-9 expression was identified in the two glioma cell lines (P<0.01). The results of the present study indicate that treatment with ATRA may inhibit migration, invasion and proliferation, and promote apoptosis in glioma cells. Furthermore, the current study indicates that the inhibition of glioma cell invasion by ATRA may be partially associated with its effect ability to downregulate MMP expression.