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Background Gliomas remain among the most difficult cancers to treat, with a 5-year overall survival no greater than 5%. Many saponins showed a wide spectrum of anti-cancer activities at low concentration. Polyphyllin II is one of the common saponins from Paris polyphylla. However, the effect of Polyphyllin II on glioma cells has not been evaluated. Objective of the present study was to investigate whether Polyphyllin II have inhibition on glioma cells, and the possible mechanisms. Methods The viability of U87 and U251 cells was detected by cell counting kit-8, cell counting real time cellular analysis and cell clone formation methods. Transwell was used to estimate the aggression of U87 and U251. The cell apoptosis rate was tested by flow cytometry. The morphological change was determined by transmission electron microscopy. The levels of AKT, phosphorylation of AKT, Bax, Bcl-2, cytochrome c, and cleaved caspase 3 proteins were assessed by Western blot. N-acetyl-L-cysteine was used to check the role of ROS in polyphyllin II inhibition to glioma cells. Results Polyphyllin II showed significant suppress to proliferation and aggression of U87 and U251 in a dose- and time- dependent manner. Result of flow cytometry confirmed that Polyphyllin II induced apoptosis to U87 and U251 cells. Transmission electron microscopy observation revealed majority of the glioma cells treated with Polyphyllin II had turgidity of mitochondrion, disarrangement, diminution and vacuolization, those refer to mitochondrial apoptosis. Western blot indicated that Polyphyllin II promoted cyt-c, Bax, caspase 3 and cleaved-caspase 3, and decreased Bcl-2, AKT and p-AKT. Rescue experiments using N-acetyl-L-cysteine, a reactive oxygen species scavenger, reversed the levels of Bax and cyt-c, and the inhibition in Polyphyllin II-treated U87 and U251 cells. Conclusions The present findings revealed that polyphyllin II may be a potential drug against glioma.

Glioblastoma is one of the most difficult cancers to treat with a 5-year overall survival rate less than 5%. Temozolomide (TMZ) is an effective drug for prolonging the overall survival time of patients, while drug-resistance is an important clinical problem at present. Pennogenin-3-α-L-rhamnopyranosyl-(1→4)-[α-Lrhamno-pyranosyl-(1→2)]- β-D-glucopyranoside (N45), a steroidal saponin, was isolated from the rhizomes of Paris vietnamensis (Takht.), which is used as a Traditional Chinese Medicine and has been reported to possess preclinical anticancer efficacy in various cancer types. However, the mechanism of the inhibition of N45 on glioblastoma cells and its possible application in the treatment of chemotherapy-resistant glioblastoma cells are still unknown. In this study, we use cellular methodological experiments including cell counting kit-8 (CCK-8) assay, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining assay, flow cytometry assay, transmission electron microscopy (TEM) and Western blot. The results show that N45 significantly suppresses the proliferation of glioblastoma cells and TMZ-resistant glioblastoma cells (U87R) by inducing mitochondrial apoptosis through reactive oxygen species (ROS)/phosphoinositide 3-kinase (PI3K)/Akt signal pathway, and the N-acetyl-L-cysteine (NAC) combined with N45 effectively reduced N45-mediated apoptosis and reversed the inhibition of PI3K/Akt signal pathway. In addition, N45 decreased the drug-resistance by down-regulation of nuclear factor kappa-B p65 (NF-κB p65) to attenuate O6-methylguanine-DNA methyltransferase (MGMT) in TMZ-resistant glioblastoma cells (U87R). Our findings proved that N45 might be a potential therapeutic agent against glioblastoma and TMZ-resistant glioblastoma, promising to be a potential agent to reduce drug resistance.

Many glioma patients develop resistance to temozolomide (TMZ) treatment, resulting in reduced efficacy and survival rates. TMZ-resistant cell lines SHG44R and U87R, which highly express O

Recently we isolated CN-3, a new asterosaponin from starfish