Curcumin inhibits adverse psychological stress-induced proliferation and invasion of glioma cells via down-regulating the ERK/MAPK pathway.

Curcumin is a natural polyphenol extracted from the rhizome of Curcuma that has an important antitumour effect, but its effect on adverse psychological stress-induced tumour proliferation and invasion has not been reported to date. Here, we found that curcumin not only inhibited the growth of xenografts in chronically stressed nude mice, but also decreased the expression of matrix metalloproteinase (MMP)-2/9 and CD147 in tumour tissues. Exogenous norepinephrine (NE) was used to stimulate glioma cells to simulate the stress environment in vitro, and it was found that curcumin inhibited the NE-induced proliferation and invasion of glioma cells in a dose-dependent manner. Further research found that the effects of NE on glioma cells could lead to the activation of the mitogen-activated protein kinase (MAPK) signalling pathway through β-adrenergic receptor, while curcumin suppressed the level of extracellular signal-regulated kinase (ERK)1/2 phosphorylation. In addition, blocking ERK1/2 expression with U0126 resulted in the down-regulated expression of CD147, which further led to the decreased expression of MMP-2 and MMP-9. Curcumin could also inhibit the expression of cyclin D1/CDK4/6 and anti-apoptotic protein Bcl-2/Bcl-XL induced by NE, and induced cell cycle changes and increased apoptosis. Therefore, curcumin may be a potential candidate drug for preventing and treating the progression of glioma induced by adverse psychological stress.