wogonin and Neuroblastoma

Alzheimer's disease (AD) is a progressive neurodegenerative disorder. Many molecular lesions have been detected in AD, of which the most commonly observed is the accumulation of misfolded proteins, including β-amyloid (Aβ40 and Aβ42) and tau, in the aging brain. The mammalian target of rapamycin (mTOR) pathway mediates Aβ clearance through autophagy and regulates tau phosphorylation via glycogen synthase kinase-3β (GSK3β). Thus, mTOR becomes an important therapeutic target for AD. However, no mTOR inhibitor has yet been marketed to treat AD. Here, we discovered a natural product, wogonin, which could potently promote Aβ clearance in the primary neural astrocytes and significantly decrease Aβ secretion in SH-SY5Y-APP and BACE1 cells [SH-SY5Y cells stably expressing the human amyloid precursor protein (APP) and β-secretase (BACE1)] through the mTOR/autophagy signaling pathway. Additionally, further research revealed that wogonin inhibited the activity of GSK3β via mTOR inhibition, finally leading to tau phosphorylation reduction in SH-SHY5Y cells and primary neural astrocytes. In conclusion, our study identified a small molecule, wogonin, which could effectively promote Aβ clearance and decrease tau phosphorylation, and highlighted its therapeutic potential for AD treatment.

Topics: Amyloid beta-Peptides; Animals; Astrocytes; Autophagy; Cells, Cultured; Dose-Response Relationship, Drug; Embryo, Mammalian; Flavanones; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Green Fluorescent Proteins; Humans; Microscopy, Confocal; Neuroblastoma; Peptide Fragments; Phosphorylation; Signal Transduction; tau Proteins; TOR Serine-Threonine Kinases; Transfection

Wogonin, a flavonoid isolated from Scutellaria baicalensis Georgi, has been reported to exhibit a variety of biological effects including anti-cancer effects. It has a pro-apoptotic role in many cancer types. However, the molecular mechanisms of wogonin in treating neuroblastoma remain elusive. In the present study, two malignant neuroblastoma cell lines (SK-N-BE2 and IMR-32 cells) were treated with different doses of wogonin (0-150 μM). Wogonin showed significant cytotoxic effects in SK-N-BE2 and IMR-32 cells in a dose- and time-dependent manner. Treatment of SK-N-BE2 and IMR-32 cells with 75 μΜ wogonin for 48 h significantly promoted apoptosis, the release of cytochrome c, altered the expression of certain members of Bcl-2 family (Bcl-2, Bax and Bid), and increased the activation of caspase-3, caspase-8, caspase-9, and PARP-1, which demonstrated that the cytotoxic effect of wogonin in SK-N-BE2 and IMR-32 cells is mediated by mitochondrial dysfunction. Moreover, wogonin induced the expression of endoplasmic reticulum (ER) stress-related proteins (GRP78/Bip and GRP94/gp96) and activation of caspase-12 and caspase-4 in SK-N-BE2 and IMR-32 cells. In addition, wogonin increase the expression of IRE1α and TRAF2, and phosphorylation of ASK1 and JNK in SK-N-BE2 and IMR-32 cells. Knockdown of IRE1α by siRNA not only markedly inhibited wogonin-induced up-regulation of IRE1α and TRAF2, and phosphorylation of ASK1 and JNK but also reduced wogonin-induced cytotoxic effects and mitochondrial dysfunction in SK-N-BE2 and IMR-32 cells. These results indicated that wogonin could induce apoptosis, mitochondrial dysfunction, and ER stress in SK-N-BE2 and IMR-32 cells by modulating IRE1α-dependent pathway.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Endoribonucleases; Flavanones; Humans; MAP Kinase Kinase 4; MAP Kinase Kinase Kinase 5; Mitochondria; Neuroblastoma; Protein Serine-Threonine Kinases; TNF Receptor-Associated Factor 2