title: 3-Methylcholanthrene, an AhR agonist, caused cell-cycle arrest by histone deacetylation through a RhoA-dependent recruitment of HDAC1 and pRb2 to E2F1 complex.
abstract: We previously showed that treating vascular endothelial cells with 3-methylcholanthrene (3MC) caused cell-cycle arrest in the Go/G1 phase; this resulted from the induction of p21 and p27 and a decreased level and activity of the cyclin-dependent kinase, Cdk2. We further investigated the molecular mechanisms that modulate cell-cycle regulatory proteins through the aryl-hydrocarbon receptor (AhR)/Ras homolog gene family, member A (RhoA) dependent epigenetic modification of histone. AhR/RhoA activation mediated by 3MC was essential for the upregulation of retinoblastoma 2 (pRb2) and histone deacetylase 1 (HDAC1), whereas their nuclear translocation was primarily modulated by RhoA activation. The combination of increased phosphatase and tensin homolog (PTEN) activity and decreased phosphatidylinositide 3-kinase (PI3K) activation by 3MC led to the inactivation of the Ras-cRaf pathway, which contributed to pRb2 hypophosphorylation. Increased HDAC1/pRb2 recruitment to the E2F1 complex decreased E2F1-transactivational activity and H3/H4 deacetylation, resulting in the downregulation of cell-cycle regulatory proteins (Cdk2/4 and Cyclin D3/E). Co-immunoprecipitation and electrophoretic mobility shift assay (EMSA) results showed that simvastatin prevented the 3MC-increased binding activities of E2F1 proteins in their promoter regions. Additionally, RhoA inhibitors (statins) reversed the effect of 3MC in inhibiting DNA synthesis by decreasing the nuclear translocation of pRb2/HDAC1, leading to a recovery of the levels of cell-cycle regulatory proteins. In summary, 3MC decreased cell proliferation by the epigenetic modification of histone through an AhR/RhoA-dependent mechanism that can be rescued by statins.
authors.affiliation: Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chih-Cheng
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Department of Nephrology, Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan.
authors.forename: Yuh-Mou
authors.initials: YM
authors.lastname: Sue
authors.affiliation: Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Nian-Jie
authors.initials: NJ
authors.lastname: Yang
authors.affiliation: Institute of Physiology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Shu-Hui
authors.initials: SH
authors.lastname: Juan
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000378:metabolism; D050687:E2F1 Transcription Factor / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation; D056284:Histone Deacetylase 1 / Q000378:metabolism*; D006657:Histones / Q000378:metabolism*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D042541:Intracellular Space / Q000378:metabolism; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D051379:Mice; D046912:Multiprotein Complexes / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D011485:Protein Binding; D021381:Protein Transport; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists; D050717:Retinoblastoma-Like Protein p130 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D050687:E2F1 Transcription Factor; D006657:Histones; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D046912:Multiprotein Complexes; D018336:Receptors, Aryl Hydrocarbon; D050717:Retinoblastoma-Like Protein p130; D008748:Methylcholanthrene; D019869:Phosphatidylinositol 3-Kinases; D019908:Proto-Oncogene Proteins c-raf; D051059:PTEN Phosphohydrolase; D056284:Histone Deacetylase 1; D016283:Proto-Oncogene Proteins p21(ras); D020742:rhoA GTP-Binding Protein