title: The prognostic significance and value of cyclin D1, CDK4 and p16 in human breast cancer.
abstract: BACKGROUND
  Loss of the retinoblastoma protein tumor suppressor gene (RB) coding for a nuclear phosphoprotein that regulates the cell cycle is found in many human cancers and probably leads to disruption of the p16-cyclin D1-CDK4/6-RB pathway. Cyclin D1 is known to activate CDK4, which then phosphorylates the RB protein, leading to cell cycle progression. p16 inhibits CDK4, keeping RB hypophosphorylated and preventing cell cycle progression. The significance of these three markers, cyclin D1, CDK4 and p16, for breast cancer and carcinogenesis is nevertheless still controversial.
  
  
  METHODS
  The material consisted of 102 formalin-fixed human breast cancer samples, in which cyclin D1, CDK4 and p16 expression was evaluated immunohistochemically. The amounts of cyclin D1 mRNA present were analyzed by quantitative real time PCR.
  
  
  RESULTS
  High cyclin D1 expression statistically significantly correlated with lower tumor grade, estrogen and progesterone receptor positivity and lower proliferation activity in breast tumors and increased breast cancer-specific survival and overall survival. Tumors with high cyclin D1 protein had 1.8 times higher expression of cyclin D1 mRNA. CDK4 expression did not correlate with cyclin D1 expression or the survival data. p16 expression was associated with Human Epidermal Growth Factor Receptor 2 (HER2) negativity and increased breast cancer-specific survival and disease-free survival. No statistical correlations between cyclin D1, CDK4 and p16 were found.
  
  
  CONCLUSIONS
  Cyclin D1 was associated with a good breast cancer prognosis but functioned independently of CDK4. High cyclin D1 expression may be partially due to increased CCND1 transcription. p16 correlated with a better prognosis and may function without CDK4. In conclusion, it appears that cyclin D1, CDK4 and p16 function independently in human breast cancer.
authors: Emmi
authors: E
authors: Peurala
authors: Peppi
authors: P
authors: Koivunen
authors: Kirsi-Maria
authors: KM
authors: Haapasaari
authors: Risto
authors: R
authors: Bloigu
authors: Arja
authors: A
authors: Jukkola-Vuorinen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D019938:Cyclin D1 / Q000096:biosynthesis*; D051358:Cyclin-Dependent Kinase 4 / Q000096:biosynthesis*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000096:biosynthesis*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins
chemical_list: C530104:CCND1 protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D025521:Tumor Suppressor Proteins; D019938:Cyclin D1; C495900:CDK4 protein, human; D051358:Cyclin-Dependent Kinase 4