title: Breast cancer expression of YKL-40 correlates with tumour grade, poor differentiation, and other cancer markers.
abstract: BACKGROUND
  Serum levels of a secreted glycoprotein YKL-40 are elevated in patients with a wide range of cancers including breast, colorectal, and ovarian cancers. Furthermore, these increased levels correlate with poorer survival of cancer patients, suggesting that serum levels of YKL-40 might be a prognostic biomarker. However, the tissue expression of YKL-40 and its relationship with clinical outcomes and other potential markers are poorly understood.
  
  
  METHODS
  Tissue samples from invasive breast cancers, breast ductal carcinoma in situ (DCIS), and cancer-free reduction mammoplasty were enrolled. YKL-40 expression was measured using immunohistochemistry and evaluated by a semi-quantification assay. Statistical analyses explored the relationship of YKL-40 with clinical outcome and other breast cancer biomarkers.
  
  
  RESULTS
  Breast ductal carcinoma in situ expressed low and moderate levels of YKL-40. In the subset of 203 patients with invasive cancer, YKL-40 levels were positively correlated with tumour grade (P<0.0001) and Her2/neu (P<0.01), but negatively correlated with oestrogen (P<0.0001) and progesterone receptor (P<0.0001). YKL-40 levels were inversely correlated with expressions of GATA3 (P=0.0137) and E-cadherin (P=0.0417).
  
  
  CONCLUSIONS
  These data demonstrate that expression levels of YKL-40 are associated with tumour grade, poor differentiation, and other breast cancer markers, highlighting that tissue levels of YKL-40 serve as a valuable biomarker for breast cancer diagnosis and prognosis.
authors.affiliation: Pioneer Valley Life Sciences Institute, 3601 Main Street, Springfield, MA 01199, USA. rong.shao@bhs.org
authors.forename: R
authors.initials: R
authors.lastname: Shao
authors.forename: Q J
authors.initials: QJ
authors.lastname: Cao
authors.forename: R B
authors.initials: RB
authors.lastname: Arenas
authors.forename: C
authors.initials: C
authors.lastname: Bigelow
authors.forename: B
authors.initials: B
authors.lastname: Bentley
authors.forename: W
authors.initials: W
authors.lastname: Yan
mesh_terms: D054392:Adipokines / Q000097:blood* / Q000276:immunology; D000328:Adult; D000918:Antibody Specificity; D014408:Biomarkers, Tumor / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000097:blood*; D002454:Cell Differentiation; D000071451:Chitinase-3-Like Protein 1; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D037102:Lectins / Q000097:blood* / Q000276:immunology; D008875:Middle Aged; D016612:Paraffin Embedding; D012189:Retrospective Studies
chemical_list: D054392:Adipokines; D014408:Biomarkers, Tumor; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D037102:Lectins