title: Characterization of a novel anti-fatty acid synthase (FASN) antiserum in breast tissue.
abstract: Fatty acid synthase (FASN) expression has been reported in many different tumors, including breast cancer. In gene microarray studies, the fatty acid synthase gene co-clustered with cytokeratins 5 and 17 and other genes that defined the basal-like subset of breast cancers. To define the use of this marker in breast pathology, a rabbit polyclonal antiserum (S143) to a peptide fragment of this gene was produced and compared with a commercially available monoclonal antibody by immunohistochemistry on various tissue microarrays and whole tissue sections. The tissue microarrays included 1090 breast cancers and 244 normal breast tissues. Whole tissue sections consisted of benign and malignant tissues from breast resection specimens. In contrast to other 'basal' markers identified by gene expression profiling data, the fatty acid synthase (FASN) expression pattern in normal breast was notable for its expression in only a small subset of basal and suprabasal cells. Dual staining experiments revealed that the subpopulation of cells labeling with FASN did not coexpress myoepithelial markers CK5/6 or p63, but did coexpress e-cadherin. In addition to staining a subset of basal and suprabasal cells, the antiserum highlighted apocrine differentiation, and stained 106/144 (74%) cases of columnar cell lesions and five of five cases of flat epithelial atypia. Despite its association with basal keratins in gene array studies, FASN expression did not correlate significantly with the outcome in breast cancer. We describe an expression pattern that highlights only a subset of basal and suprabasal cells in normal breast ducts and we show by dual expression studies that this subset of cells is different from myoepithelial and basal cytokeratin-positive cells. In addition, FASN expression is described in apocrine metaplasia, columnar cell lesions, and flat epithelial atypia.
authors.affiliation: Department of Pathology, Stanford University Medical Center, Stanford, CA 94305, USA. kjensen1@stanford.edu
authors.forename: Kristin C
authors.initials: KC
authors.lastname: Jensen
authors.forename: David F
authors.initials: DF
authors.lastname: Schaeffer
authors.forename: Maggie
authors.initials: M
authors.lastname: Cheang
authors.forename: Kelli
authors.initials: K
authors.lastname: Montgomery
authors.forename: Robert B
authors.initials: RB
authors.lastname: West
authors.forename: C Blake
authors.initials: CB
authors.lastname: Gilks
authors.forename: Doug
authors.initials: D
authors.lastname: Ross
authors.forename: Gulisa
authors.initials: G
authors.lastname: Turashvili
authors.forename: Stuart
authors.initials: S
authors.lastname: Schnitt
authors.forename: Matt
authors.initials: M
authors.lastname: van de Rijn
mesh_terms: D000818:Animals; D000906:Antibodies; D014408:Biomarkers, Tumor / Q000032:analysis*; D001940:Breast / Q000201:enzymology*; D001943:Breast Neoplasms / Q000201:enzymology* / Q000473:pathology*; D064429:Fatty Acid Synthases / Q000276:immunology*; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D011817:Rabbits; D046888:Tissue Array Analysis
chemical_list: D000906:Antibodies; D014408:Biomarkers, Tumor; D064429:Fatty Acid Synthases