B. Mayr

Novel p53 tumour suppressor mutations in cases of spindle cell sarcoma, pleomorphic sarcoma and fibrosarcoma in cats

Twenty feline neoplasms were sequenced in the region from exons 5 to 8 for the presence of tumour suppressor gene p53 mutations. In a spindle cell sarcoma of the bladder, a missense mutation (codon 164 AAG→GAG, lysine→glutamic acid) in exon 5 was detected. In a pleomorphic sarcoma, a 23 bp deletion involving the splicing junction between intron 5 and exon 6 was observed. In a fibrosarcoma, a 6 bp deletion of p53 covering 2 bp of exon 7 and 4 bp of intron 7, including the splicing junction, was found. The study demonstrates three new p53 mutations in different types of sarcomas in cats.

Canine Tumour Suppressor Gene p53 - Mutation in a Case of Adenoma of Circumanal Glands

Highly conserved regions of the tumour suppressor gene p53, including the typical human tumour hot spots (codons 175, 245, 248, 249, 273 and 282), were investigated in various canine neoplasms. A mutation CGG → TGG (arginine → tryptophan) was detected in codon 249 in an adenoma of the circumanal gland.

Analysis of complex cytogenetic alterations in three canine mammary sarcomas

Cells of mammary sarcomas in three dogs were analysed cytogenetically. In an osteoidsarcoma, hyperdiploidy with a range of 92 to 98 chromosomes, and several structural aberrations (for example, a derivative chromosome 1, isochromosome 13 and several bi-armed markers) were observed. Isochromosome 13 was also present in a case of an osteoidchondrosarcoma. In a case of chondro-osteosarcoma both hypodiploidy with a chromosome range of 60 to 66 and hyperdiploidy with a range of 115 to 128 and several centric fusions were observed.

Characterisation of complex karyotype changes in two canine bone tumours

Two dogs developed osteosarcomas. In both cases, the cytogenetic analysis revealed the presence of numerically and structurally altered karyotypes. The chromosome ranges were 90 to 99 and 65 to 67, respectively. Centric fusions frequently identified were 1/3, 1/30 and 2/9 in one case, 3/19, 12/18 and 13/17 in the other.

Cytogenetic alterations in four feline soft-tissue tumours

Four mesenchymal neoplasms (two malignant fibroblastic histiocytomas, one fibrosarcoma, one fibroma) were investigated cytogenetically. Although no specific alterations were present, the frequent nonrandom involvement of chromosome E1 became clearly evident. Karyotypic alterations involving unrelated clonal changes were also present in the fibroma.

Chromosomal hyperdiploidy in a feline sarcoma

An eight-year-old male cat developed a sarcoma. The cytogenetic evaluation of the tumour cells showed the presence of hyperdiploidy (range 40 to 46 chromosomes). This hyperdiploidy was encountered in all the cells examined. Extra-chromosomes numbers C1, C2, B4, D4 and E3 were mainly responsible for the hyperdiploid chromosomal complements. There was a high incidence of monosomy E3.

Absence of p21 WAF1 and p27 Kip1 Gene Mutations in Various Feline Tumours

The coding regions of tumour suppressor and cell cycle regulatory genes p21 WAF1 and p27 Kip1 were investigated in 101 feline tumours of various types. No damaging mutations were present in the analysed areas of the genes

Novel canine tumour suppressor gene p53 mutations in cases of skin and mammary neoplasms.

Exons 4 to 8 of the tumour suppressor gene p53 were analysed in 25 skin and 25 mammary tumours of 50 dogs. A 1 bp deletion (ACC→AC) was detected in codon 89 in exon 4 in a squamous cell carcinoma. A missense mutation CGC→CAC (arginine→histidine) was present in codon 162 in exon 5 in a mammary adenocarcinoma. Moreover, a silent mutation occurred in codon 103 (serine) of exon 4 in a mammary adenoma. The somatic nature of the three mutations was demonstrated.

Loss of chromosome B2-material in three cases of feline mammary tumours

Tumour cells in three cases of mammary gland neoplasms in cats were analysed cytogenetically. There was a loss of chromosome B2-material in all the cases, and a loss of chromosome E3-material in two of them.

Characterisation of complex karyotype changes in a canine thyroid adenoma

A 14-year-old German shepherd dog developed an alveolar adenoma of the thyroid. The cytogenetic evaluation of the tumour cells showed two ranges of chromosome numbers. Centric fusions 2/32, 5/26, 6/11, 8/11, 9/23 and 14/31 were G-band identified in this complex change of karyotype.