title: Silibinin Inhibits Platelet-Derived Growth Factor-Driven Cell Proliferation via Downregulation of N-Glycosylation in Human Tenon's Fibroblasts in a Proteasome-Dependent Manner.
abstract: The objective of this study was to evaluate the effects of silibinin on cell proliferation in platelet-derived growth factor (PDGF)-treated human Tenon's fibroblasts (HTFs). The effect of silibinin on cell proliferation in PDGF-treated HTFs was determined by examining the expression of proliferating cell nuclear antigen (PCNA) and performing WST-1 assays. Cell cycle progression was evaluated using flow cytometry. The related cyclins and cyclin-dependent kinases (CDKs) were also analyzed using western blot. A modified rat trabeculectomy model was established to evaluate the effect of silibinin on cell proliferation in vivo. Western blot analysis was carried out to determine the effect of silibinin on the expression of PDGF receptor and on the downstream signaling pathways regulated by PDGF receptor. PDGF elevated the expression of PCNA in HTFs, and this elevation was inhibited by silibinin. The inhibitory effect of silibinin on cell proliferation was also confirmed via WST-1 assay. PDGF-stimulated cell cycle in HTFs was delayed by silibinin, and the related cyclin D1 and CDK4 were also suppressed by silibinin. In the rat model of trabeculectomy, silibinin reduced the expression of PCNA at the site of blebs in vivo. The effects of silibinin on PDGF-stimulated HTFs were mediated via the downregulation of PDGF receptor-regulated signaling pathways, such as ERKs and STATs, which may be partially caused by the downregulation of N-glycosylation of PDGF receptor beta (PDGFRβ). The effect of silibinin on modulation of N-glycosylation of PDGFRβ was mediated in a proteasome-dependent manner. Silibinin inhibited cell proliferation and delayed cell cycle progression in PDGF-treated HTFs in vitro. PDGF also modulated the process of N-glycosylation of the PDGFRβ in a proteasome-dependent manner. Our findings suggest that silibinin has potential therapeutic applications in glaucoma filtering surgery.
authors.affiliation: Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.|Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yi-Hao
authors.initials: YH
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.|Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ching-Long
authors.initials: CL
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.|Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Da-Wen
authors.initials: DW
authors.lastname: Lu
authors.affiliation: Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.|Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chang-Min
authors.initials: CM
authors.lastname: Liang
authors.affiliation: Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.|Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Ming-Cheng
authors.initials: MC
authors.lastname: Tai
authors.affiliation: Graduate Institute of Medical Science, National Defense Medical Center, Taipei, Taiwan.|Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Jiann-Torng
authors.initials: JT
authors.lastname: Chen
mesh_terms: D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects*; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D006031:Glycosylation / Q000187:drug effects; D006801:Humans; D007976:Leupeptins / Q000494:pharmacology; D009584:Nitrogen / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000378:metabolism; D000077385:Silybin; D012838:Silymarin / Q000494:pharmacology*; D058475:Tenon Capsule / Q000166:cytology*
chemical_list: D007976:Leupeptins; D010982:Platelet-Derived Growth Factor; D012838:Silymarin; D000077385:Silybin; D020797:Receptor, Platelet-Derived Growth Factor beta; D046988:Proteasome Endopeptidase Complex; D009584:Nitrogen; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde