Linarin suppresses glioma through inhibition of NF-κB/p65 and up-regulating p53 expression in vitro and in vivo.

Glioma is the most common form of malignant brain cancer with high mortality rate in human. Therefore, finding effective therapeutic strategy and revealing the underlying molecular mechanism is necessary. Plant-extracted flavonoid glycosides have been suggested to be bioactive compounds with pleiotropic functions, such as anti-cancer, anti-inflammatory, antioxidant and effects. Our study was attempted to explore the anti-cancer role of linarin (acacetin-7-O-ß-d-rutinoside) in glioma in vitro and in vivo. Nuclear factor kappa-B (NF-κB) activity is a common phenomenon in various cancers, resulting in abnormal cell proliferation, malignant transformation, or resistance to cell death. P53, an essential tumor suppressor, plays an important role in preventing tumor progression. Our data indicated that linarin suppressed glioma cell proliferation and migration by inducing apoptosis, which was through reducing cell cycle-related signals, including Survivin, p-Rb, and Cyclin D1, while promoting p21, Bax, Caspase-3 and poly (ADP-ribose) polymerase (PARP) activation. Also, we found that linarin-reduced cellular proliferation of glioma was dependent on p53 up-regulation and Nuclear factor kappa-B (NF-κB)/p65-down-regulation, thereby inhibiting glioma cell growth. We further conformed the inhibitory effect of linarin in vivo using xenograft tumor model. Linarin significantly triggered apoptosis as well as the tumor growth in animals, accompanied with p53 increase and p65 decrease. Our data illustrated that linarin could be used as a promising candidate against glioma progression.

Quercetin nanoparticles induced autophagy and apoptosis through AKT/ERK/Caspase-3 signaling pathway in human neuroglioma cells: In vitro and in vivo.

Neuroglioma is a complex neuroglial tumor involving dysregulation of many biological pathways at multiple levels. Quercetin is a potent cancer therapeutic agent presented in fruit and vegetables, preventing tumor proliferation, and is a well known cancer therapeutic agent and autophagy mediator. Recent studies showed that drug delivery by nanoparticles have enhanced efficacy with reduced side effects. In this regard, gold-quercetin into poly (dl-lactide-co-glycolide) nanoparticles was examined. In the present study, quercetin nanoparticle induced cell autophagy and apoptosis in human neuroglioma cell was investigated. Quercetin nanoparticle administrated to animals displayed suppressed role in tumor growth. The cell viability was deterined through CCK8 assay. Transmission electron microscopy was utilized to observe the formation of autophagosome. The cell apoptosis was assessed by annexin V-PI staining. The protein expression of cell autophagy regulators and tumor suppressors were analyzed via western blot and RT-PCR. Treatment of human neuroglioma cell with quercetin nanoparticle induced cell death in a dose-and time-dependent manner. The flow cytometry results showed that the proportion of the apoptosis cells had gained after quercetin nanoparticle treatment compared to untreatment group. Moreover, the expression of activated PI3K/AKT and Bcl-2 were down-regulated upon quercetin nanoparticle treatment in human neuroglioma cells. The expression level of LC3 and ERK as well as cytoplasm p53, cleaved Caspase-3 and PARP was positively correlated with the concentration of quercetin nanoparticle. In addition, p-mTOR and GAIP were obviously down-regulated by quercetin nanoparticle treatment in a dose-dependent manner. These results indicated that quercetin nanoparticle could induce autophagy and apoptosis in human neuroglioma cells, the underlying molecular mechanisms, at least partly, through activation LC3/ERK/Caspase-3 and suppression AKT/mTOR signaling.