Benign mixed tumor of canine mammary gland showing an r(X) and trisomy 5 as the only clonal abnormalities

cDNA microarray profiles of canine mammary tumour cell lines reveal deregulated pathways pertaining to their phenotype

Mammary cancer is the most common type of cancer in female dogs with a lifetime risk of over 24% when dogs are not spayed. The elucidation of the complete canine genome opens new areas for development of cancer therapies. These should be tested first by in vitro models such as cell lines. However, to date, no canine mammary cell lines have been characterized by expression profiling. In this study, canine mammary tumour cell lines with histologically distinct primary tumours of origin were characterized using a newly developed canine cDNA microarray. Comparisons of gene expression profiles showed enrichment for distinct biological pathways and were related to biological properties of the cell lines such as growth rate and in vitro tumourigenicity. Additionally, gene expression profiles of cell lines also showed correspondence to their tumour of origin. Major differences were found in Wnt, cell cycle, cytokine/Rho-GTPase, alternative complement and integrin signalling pathways. Because these pathways show an overlap at the molecular level with those found in human breast cancer, the expression profiling of spontaneous canine mammary cancer may also function as a biological sieve to identify conserved gene expression or pathway profiles of evolutionary significance that are involved in tumourigenesis. These results are the basis for further characterization of canine mammary carcinomas and development of new therapies directed towards specific pathways. In addition these cell lines can be used to further investigate identified deregulated pathways and characterize until now unannotated genes.

Cytogenetic analysis of three oropharyngeal malignant melanomas in dogs

Three cases of histologically confirmed oropharyngeal malignant melanomas in dogs are presented including clinical examinations and cytogenetic analysis. Case one showed a hyperdiploid karyotype. Case two, a recurrent tumour, had a highly hypodiploid karyotype with supernumerary meta- and submetacentric chromosomes in all metaphases analysed. In the third case, a clonal fusion of chromosome 1 and 25 was observed. Comparing these results with another case of canine cutaneous melanoma as well as with human malignant melanomas reported in the literature, these tumours obviously often show cytogenetic aberrations like aneuploidy and centric fusions.

Ring chromosome 4 as the sole cytogenetic anomaly in a chondroblastoma: a case report and review of the literature

Chromosome analysis of a chondroblastoma of the right distal femur in a 31-year-old male patient revealed a ring chromosome 4 in approximately one-third of the analyzed cells. The remaining cells had a normal karyotype. These findings were subsequently confirmed by fluorescence in situ hybridization (FISH) with a chromosome-4-specific library. FISH with cosmids pC847.351 (4p16.3) and cT171 (4q35) revealed that fewer than 300 kilobase pairs (kbp) are deleted. To our knowledge, ring chromosome 4 has never been reported in this type of neoplasm. There are, however, several reports of chondroblastoma with other chromosome abnormalities, but the relation of these anomalies to this tumor specifically is unclear. In this report, we also provide a review of the literature concerning cytogenetic studies in chondroblastoma. The possible significance of ring chromosome 4 in this type of tumor is discussed.

Trisomy 1 in a canine acute leukemia indicating the pathogenetic importance of polysomy 1 in leukemias of the dog

We report on a canine acute myeloid leukemia showing a trisomy 1 and a t(X;8) as clonal cytogenetic abnormalities. Comparing these results with similar cases of canine leukemias reported in the literature, one realizes that trisomy 1 is a recurrent cytogenetic finding in canine acute leukemia. Trisomy 1 may be a specific anomaly associated with either etiology or progression of this disease. As with comparable human neoplasms, cytogenetic investigations could be of diagnostic and prognostic significance for canine hematopoietic diseases. Moreover, as trisomies are recurrent cytogenetic findings in human leukemias, as well, comparative gene mapping in future studies may help to focus the etiologic basis of the disease to particular chromosomal segments instead of whole chromosomes.