title: Baicalein Triggers Autophagy and Inhibits the Protein Kinase B/Mammalian Target of Rapamycin Pathway in Hepatocellular Carcinoma HepG2 Cells.
abstract: Baicalein (BA), isolated from the Chinese medicinal herb Scutellariae radix (Huangqin in Chinese), is a flavonoid with various pharmacological effects. Herein, we found that BA only slightly reduced the cell viability on HepG2 cells after 24-h treatment as determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. However, BA (50 μM) effectively blocked the colony formation. Meanwhile, BA remarkably induced the formation of autophagosomes after 24-h treatment as determined by immunofluorescence with monodansylcadaverine staining as well as transmission electron microscopy, respectively. Moreover, BA obviously up-regulated the expression of microtubule-associated protein 1A/1B-light chain 3-II in concentration-dependent and time-dependent manners in HepG2 cells. When combined with the autophagy inhibitor chloroquine and BA, the cell viability and colony formation were significantly decreased, indicating that BA triggered protective autophagy, which prevented cell death. Further study showed that BA concentration-dependently and time-dependently decreased the expression of p-AKT (S473), p-ULK1 (S757) and p-4EBP1 (T37 and S65), suggesting the involvement of protein kinase B (AKT)/mammalian target of rapamycin (mTOR) in BA-triggered autophagy.
authors: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macao, Macao, China.
authors: Ya-Fang
authors: YF
authors: Wang
authors: Ting
authors: T
authors: Li
authors: Zheng-Hai
authors: ZH
authors: Tang
authors: Lin-Lin
authors: LL
authors: Chang
authors: Hong
authors: H
authors: Zhu
authors: Xiu-Ping
authors: XP
authors: Chen
authors: Yi-Tao
authors: YT
authors: Wang
authors: Jin-Jian
authors: JJ
authors: Lu
mesh_terms: D001343:Autophagy / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D044950:Flavanones / Q000494:pharmacology*; D056945:Hep G2 Cells / Q000187:drug effects; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D044950:Flavanones; C093429:MAP1A protein, human; C475491:MAP1B protein, human; D008869:Microtubule-Associated Proteins; C006680:baicalein; C546842:MTOR protein, human; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases
keywords: AKT; ULK1; autophagy; baicalein; hepatocellular carcinoma