title: Therapeutic Targeting of RNA Polymerase I With the Small-Molecule CX-5461 for Prevention of Arterial Injury-Induced Neointimal Hyperplasia.
abstract: OBJECTIVE
  RNA polymerase I (Pol I)-dependent rRNA synthesis is a determinant factor in ribosome biogenesis and thus cell proliferation. The importance of dysregulated Pol I activity in cardiovascular disease, however, has not been recognized. Here, we tested the hypothesis that specific inhibition of Pol I might prevent arterial injury-induced neointimal hyperplasia.
  
  
  RESULTS
  CX-5461 is a novel selective Pol I inhibitor. Using this tool, we demonstrated that local inhibition of Pol I blocked balloon injury-induced neointima formation in rat carotid arteries in vivo. Neointimal development was associated with augmented rDNA transcriptional activity as evidenced by the increased phosphorylation of upstream binding factor-1. The beneficial effect of CX-5461 was mainly mediated by inducing G2/M cell cycle arrest of proliferating smooth muscle cells without obvious apoptosis. CX-5461 did not induce p53 stabilization but increased p53 phosphorylation and acetylation and activated the ataxia telangiectasia mutated/ataxia telangiectasia and Rad3-related (ATR) pathway. Inhibition of ATR, but not of ataxia telangiectasia mutated, abolished the cytostatic effect of CX-5461 and p53 phosphorylation. In addition, inhibition of p53 or knockdown of the p53 target GADD45 mimicked the effect of ATR inhibition. In vivo experiments showed that the levels of phospho-p53 and acetyl-p53, and activity of the ataxia telangiectasia mutated/ATR pathway were all augmented in CX-5461-treated vessels.
  
  
  CONCLUSIONS
  Pol I can be therapeutically targeted to inhibit the growth of neointima, supporting that Pol I is a novel biological target for preventing arterial restenosis. Mechanistically, Pol I inhibition elicited G2/M cell cycle arrest in smooth muscle cells via activation of the ATR-p53 axis.
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Qing
authors.initials: Q
authors.lastname: Ye
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Shu
authors.initials: S
authors.lastname: Pang
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Wenjing
authors.initials: W
authors.lastname: Zhang
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Xiaotong
authors.initials: X
authors.lastname: Guo
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Jianli
authors.initials: J
authors.lastname: Wang
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Yongtao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.).
authors.forename: Xiao
authors.initials: X
authors.lastname: Wu
authors.affiliation: From the School of Basic Medicine, Shandong University, Jinan, Shandong Province, China (Q.Y., S.P., W.Z., X.G., J.W., Y.L., F.J.); Key Laboratory of Cardiovascular Remodeling and Function Research & The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong, China (X.W.); and Department of Cardiology, Qing Dao Central Hospital, Qing Dao, Shandong Province, China (Y.Z.). fjiang@sdu.edu.cn.
authors.forename: Fan
authors.initials: F
authors.lastname: Jiang
mesh_terms: D000107:Acetylation; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D052160:Benzothiazoles / Q000494:pharmacology*; D020212:Carotid Artery Injuries / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D017536:Carotid Artery, Common / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D006965:Hyperplasia; D008297:Male; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D009287:Naphthyridines / Q000494:pharmacology*; D058426:Neointima; D010766:Phosphorylation; D012318:RNA Polymerase I / Q000037:antagonists & inhibitors* / Q000378:metabolism; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D052160:Benzothiazoles; C557717:CX 5461; D004791:Enzyme Inhibitors; D009287:Naphthyridines; D016159:Tumor Suppressor Protein p53; C576887:ataxia telangiectasia and Rad3-related kinase, rat; D064007:Ataxia Telangiectasia Mutated Proteins; D012318:RNA Polymerase I
keywords: RNA polymerase I; ataxia telangiectasia; cell cycle checkpoints; muscle, smooth; neointima