title: Gene expression profiles in canine mammary carcinomas of various grades of malignancy.
abstract: BACKGROUND
  The frequency of mammary malignancies in canine patients is even three times over than in human. In various types of cancer different intracellular signalling pathways are perturbed, thus the patients with pathologically the same type of cancer often have dissimilar genetic defects in their tumours and respond in a heterogeneous manner to anticancer treatment. That is why the objective of the hereby study was to assess the gene expression profiles in canine mammary carcinomas (in unsupervised manner) classified by pathologists as grade 1 (well differentiated), grade 2 (moderately differentiated) and grade 3 (poorly differentiated) and compare their molecular and pathological classifications.
  
  
  RESULTS
  Our unsupervised analysis classified the examined tissues into three groups. The first one significantly differed from the others and consisted of four carcinomas of grade 3 and one carcinoma of grade 2. The second group consisted of four grade 1 carcinomas. The very heterogeneous (based on their pathological parameters) group was the last one which consisted of two grade 1 carcinomas, two grade 3 carcinomas and five grade 2 carcinomas. Hierarchical dendrogram showed that the most malignant tumour group had significantly distinct gene expression.
  
  
  CONCLUSIONS
  Molecular classification of canine mammary tumours is not identical with pathological classification. In our opinion molecular and pathological characterization of canine mammary malignancy can complement one another. However, furthers studies in this field are required.
authors.affiliation: Department of Physiological Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences-WULS, Nowoursynowska 159, Warsaw, 02-776, Poland.
authors.forename: Karol M
authors.initials: KM
authors.lastname: Pawłowski
authors.forename: Henryk
authors.initials: H
authors.lastname: Maciejewski
authors.forename: Izabella
authors.initials: I
authors.lastname: Dolka
authors.forename: Jan A
authors.initials: JA
authors.lastname: Mol
authors.forename: Tomasz
authors.initials: T
authors.lastname: Motyl
authors.forename: Magdalena
authors.initials: M
authors.lastname: Król
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D004283:Dog Diseases / Q000378:metabolism* / Q000473:pathology; D004285:Dogs; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D008321:Mammary Glands, Animal / Q000378:metabolism / Q000473:pathology; D015674:Mammary Neoplasms, Animal / Q000378:metabolism* / Q000473:pathology; D009367:Neoplasm Staging / Q000662:veterinary; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D059467:Transcriptome