title: Altered Secretory Activity of APE1/Ref-1 D148E Variants Identified in Human Patients With Bladder Cancer.
abstract: OBJECTIVE
  Apurinic/apyrimidinic endonuclease 1/redox factor-1 (APE1/Ref-1) is a multifunctional protein involved in DNA repair and redox modulation. Recently, serum and urinary APE1/Ref-1 levels were reported to be increased in patients with bladder cancer. Genetic variations of APE/Ref-1 are associated with the risk of cancer. However, the effect of APE1/Ref-1 variants on its secretory activity is yet unknown.
  
  
  METHODS
  APE1/Ref-1 variants were evaluated by DNA sequencing analysis of reverse transcription polymerase chain reaction products in coding DNA sequences (CDS) of APE1/Ref-1 in bladder tissue samples from patients with bladder cancer (n=10). Secretory activity of APE1/Ref-1 variants was evaluated with immunoblot and enzyme-linked immunosorbent assay of the culture medium supernatants.
  
  
  RESULTS
  Four different substitution mutants (D148E, I64V/D148E, W67R/D148E, and E86G/D148E) of APE1/Ref-1 were identified in bladder cancer specimens. However, deletion mutants of APE1/Ref-1 CDS were not found. The secretory activity of the APE1/Ref-1 variants (D148E, I64V/D148E, and E86G/D148E) was increased compared to that of wild type APE1/Ref-1. Furthermore, the secretory activity in basal or hyperacetylated conditions was much higher than that in APE1/Ref-1 D148E-transfected HEK293 cells.
  
  
  CONCLUSIONS
  Taken together, our data suggest that the increased secretory activity of D148E might contribute to increased serum levels of APE1/Ref-1 in patients with bladder cancer.
authors.affiliation: Department of Physiology, Chungnam National University School of Medicine, Daejeon, Korea.|Department of Medical Science, Chungnam National University, Daejeon, Korea.
authors.forename: Yu Ran
authors.identifier: 0000-0002-1902-8818
authors.initials: YR
authors.lastname: Lee
authors.affiliation: Department of Urology, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Korea.
authors.forename: Jae Sung
authors.identifier: 0000-0003-4324-8148
authors.initials: JS
authors.lastname: Lim
authors.affiliation: Department of Urology, Chungnam National University Hospital, Chungnam National University College of Medicine, Daejeon, Korea.
authors.forename: Ju Hyun
authors.identifier: 0000-0001-5996-5876
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Department of Physiology, Chungnam National University School of Medicine, Daejeon, Korea.
authors.forename: Sunga
authors.identifier: 0000-0002-3358-7923
authors.initials: S
authors.lastname: Choi
authors.affiliation: Department of Physiology, Chungnam National University School of Medicine, Daejeon, Korea.
authors.forename: Hee Kyoung
authors.identifier: 0000-0002-2860-6448
authors.initials: HK
authors.lastname: Joo
authors.affiliation: Department of Physiology, Chungnam National University School of Medicine, Daejeon, Korea.|Department of Medical Science, Chungnam National University, Daejeon, Korea.
authors.forename: Byeong Hwa
authors.identifier: 0000-0002-3347-2739
authors.initials: BH
authors.lastname: Jeon
keywords: Apurinic/Apyrimidinic Endonuclease 1/Redox Factor-1 (APE1/Ref-1); Bladder Cancer; Enzyme-Linked Immunosorbent Assay; Point Mutation; Secretion