title: Mechanisms underlying regulation of cell cycle and apoptosis by hnRNP B1 in human lung adenocarcinoma A549 cells.
abstract: OBJECTIVE
  Overexpression of heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1), a nuclear RNA binding protein, has been reported to occur in early-stage lung cancer and in premalignant lesions. DNA-dependent protein kinase (DNA-PK) is known to be involved in the repair of double-strand DNA breaks. Reduced capacity to repair DNA has been associated with the risk of lung cancer.
  
  
  METHODS
  We investigated a link between hnRNP B1 and DNA-PK and their effects on proliferation, cell cycle, and apoptosis in the human lung adenocarcinoma cell line A549.
  
  
  RESULTS
  We found that hnRNP B1 and DNA-PK interact with each other in a complex fashion. Reducing hnRNP B1 expression in A549 cells with the use of RNAi led to upregulation of p53 activity through upregulation of DNA-PK activity but without inducing p53 expression. Further, suppression of hnRNP B1 in A549 cells slowed cell proliferation, promoted apoptosis, and induced cell cycle arrest at the G1 stage. The presence of NU7026 reduced the arrest of cells at the G1 stage and reduced the apoptosis rate while promoting cell growth.
  
  
  CONCLUSIONS
  Taken together, our results demonstrate that by regulating DNA-PK activity, hnRNP B1 can affect p53-mediated cell cycle progression and apoptosis, resulting in greater cell survival and subsequent proliferation.
authors.forename: Juan
authors.initials: J
authors.lastname: Han
authors.forename: Feng-ming
authors.initials: FM
authors.lastname: Tang
authors.forename: Dan
authors.initials: D
authors.lastname: Pu
authors.forename: Dan
authors.initials: D
authors.lastname: Xu
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Weimin
authors.initials: W
authors.lastname: Li
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism*; D000077192:Adenocarcinoma of Lung; D017209:Apoptosis; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D060888:Real-Time Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C109198:CIB1 protein, human; D002135:Calcium-Binding Proteins; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D016159:Tumor Suppressor Protein p53; C439768:hnRNP A2