title: Expression of Bmi-1 protein in tumor tissues is associated with favorable prognosis in breast cancer patients.
abstract: OBJECTIVE
  Abnormal expression of the cell cycle regulatory protein Bmi-1 has been studied in breast cancer, but the clinical relevance has not been fully elucidated. We studied the expression of Bmi-1 protein in breast cancer patients to define its clinical significance in breast cancer.
  
  
  METHODS
  Tissue microarrays were performed to evaluate the expression of Bmi-1 by immunohistochemistry in tumor tissues from 960 patients with stage I-III breast cancer. We assessed the relationship between the expression of Bmi-1 and pathologic prognostic indices as well as clinical long-term follow up outcome.
  
  
  RESULTS
  Bmi-1 was expressed in 53.2% of breast cancer patients by immunohistochemistry, and the expression of Bmi-1 was significantly correlated with favorable prognostic indices at diagnosis. In univariate analysis, patients with Bmi-1 expression showed favorable relapse-free survival (88.6+/-2.7% vs. 72.3+/-4.3%, P=0.041) and favorable overall survival (93.5+/-2.2% vs. 82.6+/-3.5%, P<0.001) than patients without Bmi-1 expression. According to multivariate analyses, Bmi-1 expression was identified as independent prognostic factor for overall survival with a statistical significance (hazard ratio of Bmi-1 (-) patients compared to Bmi-1 (+) patients, 1.744; 95% CI, 1.013-3.003; P=0.045). This correlation of Bmi-1 expression with favorable overall survival was maintained in patients underwent uniform chemotherapy, regardless of undergoing adjuvant chemotherapy. In a subset analysis according to ER status, Bmi-1 expression associated with favorable overall survival only in ER-positive patients.
  
  
  CONCLUSIONS
  Bmi-1 expression assessed with Immunohistochemistry may be associated with favorable overall survival in breast cancer patients, especially in patients with ER-positive breast cancer.
authors.affiliation: Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Ilwon-dong 50, Gangnam-gu, Seoul 135-710, Korea.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Choi
authors.forename: Yoon La
authors.initials: YL
authors.lastname: Choi
authors.forename: Eun Yoon
authors.initials: EY
authors.lastname: Cho
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shin
authors.forename: Ki Woong
authors.initials: KW
authors.lastname: Sung
authors.forename: Yu Kyeong
authors.initials: YK
authors.lastname: Hwang
authors.forename: Sang Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Gu
authors.initials: G
authors.lastname: Kong
authors.forename: Jeong Eon
authors.initials: JE
authors.lastname: Lee
authors.forename: Jee Soo
authors.initials: JS
authors.lastname: Kim
authors.forename: Jung Han
authors.initials: JH
authors.lastname: Kim
authors.forename: Jung-Hyun
authors.initials: JH
authors.lastname: Yang
authors.forename: Seok Jin
authors.initials: SJ
authors.lastname: Nam
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D002453:Cell Cycle; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D009154:Mutation; D009367:Neoplasm Staging; D009687:Nuclear Proteins / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D063150:Polycomb Repressive Complex 1; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012334:RNA, Neoplasm / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016896:Treatment Outcome
chemical_list: C069077:BMI1 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1