Effect of metformin on cell proliferation, apoptosis, migration and invasion in A172 glioma cells and its mechanisms

Abstract

The purpose of the present study was to determine the effects of metformin on the inhibition of proliferation, apoptosis, invasion and migration of A172 human glioma cells in vitro and determine the underlying mechanism. The effects of metformin at different concentrations (0, 0.1, 1 and 10 mmol/l) on the inhibition of A172 cell proliferation were detected using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell apoptosis was detected by flow cytometry. Caspase-3 activity was analyzed by spectrophotometry. The invasion and migration of cells were detected by Transwell assays. The levels of Bcl-2-associated X protein (Bax), B-cell lymphoma 2 (Bcl-2), AMP-activated protein kinase (AMPK), phosphorylated-(p)AMPK and mechanistic target of rapamycin (mTOR) protein expression were detected by western blot analysis, and changes in the malondialdehyde (MDA) content and activity of superoxide dismutase (SOD) were determined. Compared with the control group, metformin significantly increased the inhibition of proliferation and apoptosis, and significantly reduced the invasion and migration of A172 cells in dose- and time-dependent manners (P<0.05). In addition, compared with the control group, metformin significantly enhanced the activity of caspase-3, increased the expression of AMPK/pAMPK/Bax proteins and reduced the expression of mTOR/Bcl-2 proteins (P<0.05). Metformin increased the MDA content and reduced the activity of SOD in a dose-dependent manner (P<0.05). Metformin may inhibit glioma cell proliferation, migration and invasion, and promote its apoptosis; the effects may be associated with the AMPK/mTOR signaling pathway and oxidative stress.

Metformin as Potential Therapy for High-Grade Glioma

“…Research conducted by Xiong et al, focused on observing the effect of metformin on AMPK activity in gliomas. They have shown that metformin causes an increase in AMPK expression and a decrease in mTOR protein expression, thereby inhibiting proliferation and increasing tumor cell apoptosis [85]. This seems to confirm the role of AMPK/mTOR signaling pathway in the mechanism of the action of metformin, indicating its potential use in anti-cancer therapy.…”

“…A recent work presented by Xiong et al, has confirmed that metformin can also have an effect on this mechanism. In their work, the authors proved that it could affect the increase in caspase 3 activity in human GBM cells [85]. This suggests the possibility of using the mechanism of metformin-induced apoptosis in cancer therapy.…”

“…The research of Xiong et al, has shown that metformin can reduce SOD activity content in GBM cells, resulting in an increase in their exposure to free radicals and their damage. They also noted a decrease in malondialdehyde (MDA) levels, which is a good indicator of oxidative stress in the cell [85].…”

“…To this day, the complete mechanism of action of metformin on cancer cells has not been known. As mentioned earlier, it causes the inhibition of tumor cell proliferation and a decrease in the rate of cancer development, but the exact path leading to this effect is still a mystery [85]. One of the reasons for this is the multidirectional signaling pathways stimulated by the presence of drug particles.…”

“…Tirapeli et al, showed high Bcl-2 activity in glioma cells contributing to the increase of their survival [133]. Sesen et al, also noted that metformin affects the transformation leading to cell death by lowering Bcl-2 levels and increasing Bax expression [85]. This drug can also interact with other factors (P70S6 kinase, plastid ribosomal protein S6 (S6RP)) involved in the regulation of cell proliferation and death [53,134].…”