title: Associations between the Expression of Mucins (MUC1, MUC2, MUC5AC, and MUC6) and Clinicopathologic Parameters of Human Breast Ductal Carcinomas.
abstract: OBJECTIVE
  Mucins are members of the glycoprotein family expressed in benign and malignant epithelial cells. The aim of this study is to evaluate the relationships between the expression of mucins in breast ductal carcinoma and clinicopathologic parameters.
  
  
  METHODS
  We constructed tumor microarrays based on 240 cases of invasive ductal carcinoma and 40 cases of ductal carcinoma in situ (DCIS) using formalin fixed, paraffin embedded tissues. We examined the expressions of MUC1, MUC2, MUC5AC, and MUC6 by immunohistochemistry.
  
  
  RESULTS
  MUC1 demonstrated cytoplasmic, membranous, apical, and combinative expressions. Other mucins demonstrated cytoplasmic expression. In invasive ductal carcinoma, MUC1, MUC2, MUC5AC, and MUC6 were expressed in 93.6%, 6.2%, 4.8%, and 12.4% of cases, respectively; these rates were slightly, but not significantly, higher than observed in cases of DCIS. MUC1 expression was associated with estrogen receptor (ER) expression and negative MUC1 expression was associated with triple negativity. MUC6 expression was correlated with higher histologic grade, lymphatic invasion, lymph node metastasis, and HER2 positivity. No associations with any other clinicopathologic parameters were observed.
  
  
  CONCLUSIONS
  Most invasive ductal carcinomas of the breast express MUC1, and this expression is associated with ER expression. MUC6 expression is correlated with some clinicopathologic parameters that are indicators of poor prognosis. To evaluate the role of MUC6 as a potential biomarker, further studies are warranted.
authors.affiliation: Department of Pathology, Breast and Thyroid Cancer Center, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Sung-Im
authors.initials: SI
authors.lastname: Do
authors.forename: Kyungeun
authors.initials: K
authors.lastname: Kim
authors.forename: Dong-Hoon
authors.initials: DH
authors.lastname: Kim
authors.forename: Seoung Wan
authors.initials: SW
authors.lastname: Chae
authors.forename: Yong Lai
authors.initials: YL
authors.lastname: Park
authors.forename: Chan Heun
authors.initials: CH
authors.lastname: Park
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Sohn
keywords: Breast neoplasms; Human MUC1 protein; Human MUC6 protein; Mucins