title: p63: a novel myoepithelial cell marker in canine mammary tissues.
abstract: Several immunohistochemical markers have been used to demonstrate the presence of myoepithelial cells in order to determine their role in the histogenesis of mammary tumors. p63, a recently characterized p53 homologue, is consistently expressed in myoepithelial cells of the human breast; however, no assessment of its immunoreactivity has been reported so far in canine mammary tissues. We investigated p63 immunohistochemical expression, as a novel myoepithelial cell nuclear marker, in 81 samples of normal (n = 2), hyperplastic (n = 11), and neoplastic (n = 68) canine mammary tissues. Myoepithelial phenotype was confirmed by using complementary monoclonal antibodies: alpha-smooth muscle actin, cytokeratin 14, cytokeratin AE1/AE3, and vimentin. p63 expression was observed in 91.4% (74/81) of the samples evaluated. Normal mammary glands, mammary hyperplasias, and benign tumors showed 100% immunoreactivity, with p63 expression restricted to myoepithelial cell nuclei. In general, benign mixed tumors showed a basal cell compartment immunoreactive to p63, with a gradual decrease of its expression during myoepithelial transformation. p63 expression was found in 72% of malignant tumors, allowing myoepithelial or basal cell identification in spindle-cell carcinomas (2/2), tubulopapillary carcinomas (8/9), solid carcinomas (7/10), and carcinosarcomas (1/3). The osteosarcoma analyzed was p63 negative. In our series, stromal components were consistently nonreactive to p63. In conclusion, the present study reveals p63 as a sensitive and highly specific marker of myoepithelial cells in canine mammary tissues, and the authors suggest p63 as an additional marker for defining myoepithelial histogenesis.
authors.affiliation: Department of Pathology and Veterinary Clinics, University of Trás os Montes e Alro Douro, Vila Real, Portugal.
authors.forename: A
authors.initials: A
authors.lastname: Gama
authors.forename: A
authors.initials: A
authors.lastname: Alves
authors.forename: F
authors.initials: F
authors.lastname: Gartner
authors.forename: F
authors.initials: F
authors.lastname: Schmitt
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D004283:Dog Diseases / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D004285:Dogs; D005260:Female; D007150:Immunohistochemistry; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D015674:Mammary Neoplasms, Animal / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D008565:Membrane Proteins; D009208:Myoepithelioma / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology / Q000662:veterinary*; D010750:Phosphoproteins / Q000032:analysis*; D015534:Trans-Activators / Q000032:analysis*
chemical_list: D015415:Biomarkers; C081876:CKAP4 protein, human; D008565:Membrane Proteins; D010750:Phosphoproteins; D015534:Trans-Activators