title: The role of BUB and CDC proteins in low-grade breast cancers.
abstract: BACKGROUND
  The drivers of neoplasia within low-grade luminal breast cancers remain undelineated. The BUB and CDC family are among kinase genes known recently to help to identify luminal breast cancers with poorer prognosis. Additionally, other CDC kinase genes (CDC42) are associated with luminal A breast cancers with good prognosis. We aimed to investigate the role of these kinases at the protein level within low-grade luminal breast cancers.
  
  
  METHODS
  The Nottingham Tenovus Primary Breast Cancer Series (n=1858) microarrays were immunostained for BUB (BUB1, BUB1B, BUB3) and CDC proteins (CDC2, CDC42) and expression correlated with clinicopathological and molecular variables and patient outcome (SPSS, version 22).
  
  
  RESULTS
  On χ(2) analysis, cytoplasmic BUB1 and nuclear BUB3 were negatively associated with grade including pleomorphism, mitosis, and Nottingham Prognostic Index, whereas BUB1B was positively associated (p=0·05). BUB1 and BUB3 expression was positively correlated with oestrogen and progesterone receptor expression whereas BUB1B was negatively correlated (p=0·01). CDC42 had strong associations with tumour morphology within the low-grade luminal breast cancers, tubular and lobular (p=0·02). CDC42 nuclear expression revealed negative correlations with basal (CK5) and HER family biomarkers (p=0·02). By contrast, cytoplasmic CDC2 overexpression was associated with high-grade tumours (p=0·01). BUB1, BUB1B, and CDC42 showed significant associations (p=0·04) with breast-cancer-specific survival even at the 15-20-year range, indicating their long-term prognostic potential.
  
  
  CONCLUSIONS
  These results suggest that BUB1, BUB3, and CDC42 are key kinases for low-grade luminal tumours whereas BUB1B and CDC2 kinases are preferentially expressed in high-grade disease. High protein expression of BUB1, BUB3, and CDC42 in low-grade breast cancers was associated with longer overall survival whereas lower expression resulted in poorer outcome.
  
  
  BACKGROUND
  Pathological Society of Great Britain and Northern Ireland, National Institute for Health Research.
authors: University of Nottingham, Nottingham, UK; Nottingham University Hospitals NHS Trust, Nottingham, UK. Electronic address: drabhikmukherjee@hotmail.com.
authors: Abhik
authors: A
authors: Mukherjee
authors: University of Nottingham, Nottingham, UK.
authors: Chitra
authors: C
authors: Joseph
authors: University of Nottingham, Nottingham, UK.
authors: Madeleine
authors: M
authors: Craze
authors: University of Nottingham, Nottingham, UK.
authors: Eleni
authors: E
authors: Chrysanthou
authors: University of Nottingham, Nottingham, UK; Nottingham University Hospitals NHS Trust, Nottingham, UK.
authors: Ian O
authors: IO
authors: Ellis