title: Correlation of cyclin D1 and Rb gene expression with apoptosis in invasive breast cancer.
abstract: BACKGROUND
  In vitro studies have shown that amplification and overexpression of the cyclin D1 gene can accelerate the progress of cells through the G1 phase. Therefore, cyclin D1 may have an apoptosis inhibiting effect. The retinoblastoma (Rb) gene was shown recently to be an important regulator of apoptosis.
  
  
  OBJECTIVE
  To evaluate whether expression of the cyclin D1 and Rb genes correlated with apoptotic counts in a group of 97 invasive breast cancers.
  
  
  METHODS
  Expression of the cyclin D1 and Rb genes was detected by standard immunnohistochemistry using paraffin wax embedded sections. Apoptotic cells were counted according to a strict protocol, in 10 fields of vision systematically spread over the most poorly differentiated area of the tumour, at a magnification of x630. Apoptotic cells counts were expressed as apoptotic cells/mm2.
  
  
  RESULTS
  Cyclin D1 overexpression was found in 49% of cases. Loss of Rb expression was found in 44% of cases, and occurred particularly in poorly differentiated tumours. Cyclin D1 and Rb expression showed a positive correlation (p = 0.003). Apoptotic counts varied from 1 to 62/mm2. There were no significant correlations between cyclin D1 overexpression and apoptotic counts in the total group or in the retinoblastoma protein (pRb) positive tumours. Loss of Rb expression also showed no correlation with apoptotic counts.
  
  
  CONCLUSIONS
  Cyclin D1 is frequently overexpressed in pRb positive tumours, but no evidence has been found for an anti-apoptotic effect of cyclin D1 overexpression or Rb expression in invasive breast cancer.
authors.affiliation: Department of Pathology, Free University Hospital, Amsterdam, Netherlands.
authors.forename: J S
authors.initials: JS
authors.lastname: de Jong
authors.forename: P J
authors.initials: PJ
authors.lastname: van Diest
authors.forename: R J
authors.initials: RJ
authors.lastname: Michalides
authors.forename: P
authors.initials: P
authors.lastname: van der Valk
authors.forename: C J
authors.initials: CJ
authors.lastname: Meijer
authors.forename: J P
authors.initials: JP
authors.lastname: Baak
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D019938:Cyclin D1 / Q000378:metabolism*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000378:metabolism*; D016160:Retinoblastoma Protein / Q000378:metabolism*
chemical_list: D009363:Neoplasm Proteins; D016160:Retinoblastoma Protein; D019938:Cyclin D1