peoniflorin and Brain-Neoplasms

Paeoniflorin (PF), a natural compound isolated from Paeoniae radix, has been shown to exert antitumor effects in various types of human cancers including glioma. However, the mechanism of action is not well understood. S-phase kinase-associated protein (Skp)2 functions as an oncogene in many cancers. In the present study, we investigated whether Skp2 mediates the anti-glioma activity of PF. We found that PF inhibited glioma cell proliferation, migration and invasion, and induced G2/M arrest and apoptosis. Skp2 expression was downregulated in glioma cells treated with PF. PF-induced antitumor effects in glioma cells were abolished by Skp2 overexpression but were enhanced by RNA interference of Skp2. Moreover, PF treatment inhibited U87 cell-derived tumor growth in a xenograft mouse model. These results demonstrate that PF exerts its antitumor effects in part by inhibiting Skp2 expression in glioma cells and could be a promising therapeutic agent for glioma therapy.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Biomarkers, Tumor; Brain Neoplasms; Cell Cycle; Cell Proliferation; Female; Glioma; Glucosides; Humans; Mice; Mice, Nude; Monoterpenes; S-Phase Kinase-Associated Proteins; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Paeoniflorin (PF) is a polyphenolic compound derived from Radix Paeoniae Alba thathas anti-cancer activities in a variety of human malignancies including glioblastoma. However, the underlying mechanisms have not been fully elucidated. Epithelial to mesenchymal transition (EMT), characterized as losing cell polarity, plays an essential role in tumor invasion and metastasis. TGFβ, a key member of transforming growth factors, has been demonstrated to contribute to glioblastoma aggressiveness through inducing EMT. Therefore, the present studies aim to investigate whether PF suppresses the expression of TGFβ and inhibits EMT that plays an important role in anti-glioblastoma. We found that PF dose-dependently downregulates the expression of TGFβ, enhances apoptosis, reduces cell proliferation, migration and invasion in three human glioblastoma cell lines (U87, U251, T98G). These effects are enhanced in TGFβ siRNA treated cells and abolished in cells transfected with TGFβ lentiviruses. In addition, other EMT markers such as snail, vimentin and N-cadherin were suppressed by PF in these cell lines and in BALB/c nude mice injected with U87 cells. The expression of MMP2/9, EMT markers, are also dose-dependently reduced in PF treated cells and in U87 xenograft mouse model. Moreover, the tumor sizes are reduced by PF treatment while there is no change in body weight. These results indicate that PF is a potential novel drug target for the treatment of glioblastoma by suppression of TGFβ signaling pathway and inhibition of EMT.

Topics: Animals; Brain Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Epithelial-Mesenchymal Transition; Female; Gene Expression Regulation, Neoplastic; Glioblastoma; Glucosides; Humans; Mice, Nude; Monoterpenes; Neoplasm Invasiveness; Transforming Growth Factor beta

Paeoniflorin is one of the active ingredients of the commonly used herbal medicine derived from Paeonia, which exhibits anticancer properties. MicroRNA-16 (miR-16) is upregulated in CD133(-) cells, but downregulated in CD133(+) cells from glioma tissue. Matrix metalloproteinase-9 (MMP-9) expression in glioma tissue samples is significantly higher than that in healthy brain tissue samples. Therefore, miR-16 and MMP-9 expression may be associated with glioma pathogenesis. In the present study, the effects of paeoniflorin on glioma were analyzed. U87 cells were treated with paeoniflorin at 0, 5, 10 and 20 μΜ concentrations. The results suggested that paeoniflorin inhibited U87 cell proliferation and accelerated cell apoptosis. In the present study paeoniflorin treatment increased miR-16 expression and reduced MMP-9 protein expression in U87 cells. Additionally, the results of the present study suggested that miR-16 may regulate MMP-9 expression in miR-16-transfected U87 cells. Furthermore, anti-miR-16 antibodies were used in order to investigate the apoptotic effects of paeoniflorin on U87 cells. The results demonstrated that paeoniflorin inhibits proliferation and induces apoptosis of human glial cells, via miR-16 upregulation and MMP-9 downregulation.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Brain; Brain Neoplasms; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Gene Expression Regulation, Neoplastic; Glioma; Glucosides; Humans; Matrix Metalloproteinase 9; MicroRNAs; Monoterpenes; Paeonia; Up-Regulation

We investigated the underlying mechanism for the potent proapoptotic effect of paeoniflorin (PF) on human glioma cells in vitro, focusing on signal transducer and activator of transcription 3 (STAT3) signaling. Significant time- and dose-dependent apoptosis and inhibition of proliferation were observed in PF-treated U87 and U251 glioma cells. Expression of STAT3, its active form phosphorylated STAT3 (p-STAT3), and several downstream molecules, including HIAP, Bcl-2, cyclin D1, and Survivin, were significantly downregulated upon PF treatment. Overexpression of STAT3 induced resistance to PF, suggesting that STAT3 was a critical target of PF. Interestingly, rapid downregulation of STAT3 was consistent with its accelerated degradation, but not with its dephosphorylation or transcriptional modulation. Using specific inhibitors, we demonstrated that the prodegradation effect of PF on STAT3 was mainly through the ubiquitin-proteasome pathway rather than via lysosomal degradation. These findings indicated that PF-induced growth suppression and apoptosis in human glioma cells through the proteasome-dependent degradation of STAT3.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Brain Neoplasms; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Glioma; Glucosides; Humans; Monoterpenes; Phosphorylation; Proteasome Endopeptidase Complex; Proteolysis; Signal Transduction; STAT3 Transcription Factor; Time Factors; Transfection; Ubiquitin; Ubiquitination