title: Axl receptor tyrosine kinase expression in breast cancer.
abstract: OBJECTIVE
  Triple-negative breast cancer comprises a clinically aggressive group of invasive carcinomas. We examined a published gene expression screen of a panel of breast cancer cell lines to identify a potential triple-negative breast cancer-specific gene signature, and attempted to verify our findings by performing immunohistochemical analysis on tissue microarrays containing a large cohort of invasive breast carcinomas.
  
  
  METHODS
  The microarray dataset for a panel of human breast cancer cell lines was interrogated for triple-negative breast cancer-specific genes. Membranous immunohistochemical expression of the protein product of the AXL gene was assessed semiquantitatively in 569 invasive breast carcinomas grouped according to molecular subgroup by immunohistochemistry.
  
  
  RESULTS
  AXL was significantly upregulated in triple-negative/basal B cell lines compared with luminal or basal A cell lines. No significant difference was observed in the level of immunohistochemical expression of Axl protein between triple-negative breast cancers and other molecular subgroups (p=0.257). Axl expression was significantly associated with lymphovascular invasion (LVI) in all subgroups combined (p=0.033), and within the luminal A (p=0.002) and triple-negative breast cancer subgroups (p=0.026).
  
  
  CONCLUSIONS
  Despite preferential upregulation of AXL in triple-negative/basal B cell lines, analysis of Axl protein expression in a large series of patients' breast tumours revealed no association between Axl expression and triple-negative breast cancer or other subtype. The association of Axl expression with LVI supports previous work that implicates Axl as a promoter of invasiveness in breast cancer cell lines. Further studies are necessary to explore whether Axl expression of individual breast cancer tumours can be clinically useful.
authors.affiliation: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, USA.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: D'Alfonso
authors.affiliation: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Hannah
authors.affiliation: Department of Public Health, Weill Cornell Medical College, New York, USA.
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, USA.
authors.forename: Yifang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, USA.
authors.forename: Pengbo
authors.initials: P
authors.lastname: Zhou
authors.affiliation: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, USA.
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shin
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D064726:Triple Negative Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D000094963:Axl Receptor Tyrosine Kinase
chemical_list: D014408:Biomarkers, Tumor; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D000094963:Axl Receptor Tyrosine Kinase; C000722289:AXL protein, human
keywords: Breast Cancer; Breast Pathology; Immunohistochemistry; Tumour Markers