title: Tetramethylpyrazine induces G0/G1 cell cycle arrest and stimulates mitochondrial-mediated and caspase-dependent apoptosis through modulating ERK/p53 signaling in hepatic stellate cells in vitro.
abstract: Activation of hepatic stellate cells (HSCs) is a pivotal event in the pathogenesis of liver fibrosis. Pharmacological induction of HSC apoptosis could be a promising strategy for fibrosis regression. Natural product tetramethylpyrazine (TMP) exhibits potent antifibrotic activities in vivo. However, the molecular mechanisms remain to be defined. The present study aimed at investigating the anti-proliferative and pro-apoptotic effects of TMP on HSCs and elucidating the underlying mechanisms. Our results demonstrated that TMP had no apparent cytotoxic effects on hepatocytes, but significantly inhibited HSC proliferation and induced cell cycle arrest at the G0/G1 checkpoint. These effects were associated with TMP regulation of cyclin D1, p21, p27 and p53. Furthermore, we found that TMP disrupted mitochondrial functions and led to activation of caspase cascades in HSCs. Mechanistic investigations revealed that TMP selectively blocked the extracellular signal-regulated kinase (ERK) signaling and activated p53, which was required for TMP induction of caspase-dependent mitochondrial apoptosis in HSCs. Autodock simulations predicted that TMP could directly bind to ERK2 with two hydrogen bonds and low energy score, indicating that ERK2 could be a direct target molecule for TMP within HSCs. Moreover, TMP altered expression of some marker proteins relevant to HSC activation. These data collectively revealed that TMP modulation of ERK/p53 signaling led to mitochondrial-mediated and caspase-dependent apoptosis in HSCs in vitro. These studies provided mechanistic insights into the antifibrotic properties of TMP that may be exploited as a potential option for hepatic fibrosis.
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, Nanjing University of Chinese Medicine, 282 Hanzhong Road, Nanjing 210029, Jiangsu, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: De-Song
authors.initials: DS
authors.lastname: Kong
authors.forename: Zi-Li
authors.initials: ZL
authors.lastname: Zhang
authors.forename: Na
authors.initials: N
authors.lastname: Lei
authors.forename: Xiao-Jing
authors.initials: XJ
authors.lastname: Zhu
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.forename: Yin
authors.initials: Y
authors.lastname: Lu
authors.forename: Shi-Zhong
authors.initials: SZ
authors.lastname: Zheng
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D020169:Caspases / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D059585:G1 Phase Cell Cycle Checkpoints / Q000187:drug effects*; D055166:Hepatic Stellate Cells / Q000187:drug effects* / Q000473:pathology; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D008103:Liver Cirrhosis / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008297:Male; D008928:Mitochondria / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D011719:Pyrazines / Q000633:toxicity*; D051381:Rats; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
chemical_list: D011719:Pyrazines; D016159:Tumor Suppressor Protein p53; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D020169:Caspases; C017953:tetramethylpyrazine