Cytogenetic alterations in eight mammary tumors and tumor-suppressor gene p53 mutation in one mammary tumor from dogs

OBJECTIVE

To identify mutations in canine mammary tumors.

ANIMALS

10 tumor-bearing dogs.

PROCEDURE

Culture of neoplastic cells originating from mammary tumors was performed, and trypsin-G banding was used for cytogenetic investigations. The same tumors were subjected to molecular genetic screening by use of DNA extraction, polymerase chain reaction, DNA elution, and DNA sequencing for ras oncogenes and the p53 tumor suppressor gene.

RESULTS

A broad spectrum of chromosome aberrations was observed, including trisomies, reciprocal translocations, and structural and numerical X-chromosome alterations and deletions. Molecular genetic analysis revealed a tumor suppressor p53 gene mutation in codon 249 of exon 7 in one instance. Interestingly, analyzed mammary tumors were free of mutations in N-ras, K-ras and H-ras, exons 1 and 2.

CONCLUSIONS

Chromosome alterations are wide-spread in canine mammary tumors, but no ras family mutations were detected in tumors from these 10 dogs.

CLINICAL RELEVANCE

Knowledge about chromosome, oncogene, and tumor suppressor gene damage could be helpful for diagnosis and prognosis of neoplastic diseases in dogs.

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.

Menin mutations in patients with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN-1) is a familial cancer syndrome with parathyroid, pituitary and enteropancreatic tumors. The disease phenotype segregates with markers on chromosome 11q13. Very recently a new gene was cloned from this region and was found to carry mutations in 14 of 15 unrelated MEN-1 patients. The gene was termed menin and is predicted to code for a tumor suppressor protein of 610 amino acids, but its precise function is totally unknown. To confirm this finding we used PCR from genomic DNA and direct sequencing to analyze exons 2 through 10 of the menin gene in eight patients from four pedigrees with MEN-1 syndrome or an affected relative. We identified four different heterozygous mutations, three of them are novel: one nonsense mutation, one large deletion of 32 bp and two insertions, all of them located in exon 2. Our results confirm that patients with MEN-1 carry mutations in the menin gene.

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.

Serum leptin levels following hypothalamic surgery

To study a potential alteration of hypothalamic centers involved in the negative feedback action of leptin on body weight, serum leptin levels were measured in relation to BMI in 18 patients following surgery for a hypothalamic craniopharyngioma (Ctx), and were compared to levels found in 21 patients operated for a pituitary adenoma (Ptx) or in healthy control subjects. All subjects with Ptx received rhGH replacement therapy (0.5 to 2 IU/m2/d), and serum leptin levels were followed in 3 months intervals over 24 months. Serum leptin levels in patients with Ptx were comparable to controls, whereas 7 of the 18 patients with Ctx had higher than expected concentrations for their BMI. GH treatment in Ptx subjects did not alter serum leptin levels. In 5 Ctx patients where preoperative samples were available, weight gain in parallel to an increase in serum leptin levels was observed but only minimal changes in 4 others. Our data support the role of leptin as an important marker of body weight. The rapid increase in serum leptin levels observed in some Ctx subjects suggests that early postoperative measurement of serum leptin levels may help to identify patients at risk of weight gain following hypothalamic destruction.

Serum leptin and weight reduction in female obesity

Leptin, an adipocyte-derived hormone, induces a decrease in food intake and increases energy expenditure via hypothalamic interactions. In animal models obesity can be caused by leptin deficiency or by a dysfunction of the hypothalamic leptin receptor. Using a radioimmunoassay for the determination of leptin in human serum, we measured serum leptin levels in 227 otherwise healthy normal weight (N = 78; body mass index = 16.1-27.7 kg/m2) or obese women (N = 149; body mass index = 27.8-56.7 kg/m2). Fifty-three subjects were followed over a period of 12 weeks under weight reduction (800 kcal/day) and a subgroup of 33 for another 13 weeks after termination of the diet. Body mass index and serum leptin concentrations were measured longitudinally and compared to female controls not under diet. Under baseline conditions, log serum leptin levels were positively related to body mass index with a best fit using a non-linear regression (p < 0.001), indicating an attenuated increase in serum leptin levels with high body mass index. No subgroup with low serum leptin levels could be identified. Weight reduction induced a rapid decrease in serum leptin levels within the first 3 weeks to levels significantly lower than in body mass index-matched controls under normal diet (p < 0.001). This pattern was consistent after 6 and 12 weeks. Serum leptin levels increased again after the end of the diet but remained significantly lower than in the controls despite unrestricted calorie intake over 7 weeks. The rapid and persistent decrease in serum leptin to lower levels than expected from matched controls may explain the pertinent difficulties of obese subjects to cope with weight reduction.

Cytogenetic variation between four cases of feline fibrosarcoma

Short term cultures of four feline fibrosarcomas were analysed cytogenetically. There was marked genetic heterogeneity between the four cats, each showing a different clonal abnormality. The aberrations detected were one deleted B2, one marker F1 and two reciprocal translocations, t (A2q; E3q) and t (A1q; B4p).

Identification and purification of a family of dimeric major cold shock protein homologs from the psychrotrophic Bacillus cereus WSBC 10201

Whole-cell protein patterns of a psychrotrophic Bacillus cereus strain from cultures grown at 7 and 30 degrees C were compared. This analysis revealed that at least three major proteins are expressed at a significantly higher rate at 7 degrees C than at 30 degrees C. The most abundant of these cold-induced proteins was a small polypeptide of 7.5 kDa, designated CspA, of B. cereus. In addition, four small proteins very similar in size to CspA were seen on both 7 degrees C and 30 degrees C two-dimensional protein gels. Immunoblot analysis using B. cereus anti-CspA antibodies indicated that the five proteins described above plus an additional sixth protein not visible on silver-stained two-dimensional gels are members of a B. cereus cold shock protein family. This hypothesis was corroborated by cloning and sequencing of the genes encoding five proteins of this family. The protein sequences deduced are highly similar and show homology to small procaryotic cold shock proteins and to the cold shock domain of eucaryotic Y-box proteins. Besides CspA, only one of the additional five CspA homologs was slightly cold inducible. In the presence of 100 mM NaCl, the two purified members of the protein family (CspA and CspE) elute as dimers at an apparent molecular mass of 15 kDa from a gel filtration column. At higher salt concentrations, they dissociate into their monomers. Their ability to bind to the ATTGG motif of single-stranded oligonucleotides was demonstrated by band shift analysis.

[Present state of preclinical research on the efficacy and safety of para immunity inducers from poxviruses. A study of the literature]

The investigations on the "systemic level" after parenteral application of pox-inducers to man and animal have proved the preparations to be harmless and surprisingly effective with regard to certain indications. The clinical data correlate to laboratory parameters to serve as proof for the efficacy. The challenge models (VSV, Aujeszky) verify a dosis-efficacy relationship. The evaluation of the efficacy of the pox-inducers in isolated blood- and liver-cells respectively cell cultures (cellular "in vitro" level) provide a unified picture: increase of the phagocytosis, of the NK-cells and the thymidinkinase activity in liver cells. The investigations on the "cytokine release" illustrate that pox-inducers promote the release respectively the production of diverse cytokines important for the regulation of the immune system. This has been proved for interferon alpha and gamma, the interleukin 1, 2 and 12 as well as for CSF and TNF. To conclude, a regulative effect is ascribed to the poxvirus inducers in the network of paraspecific defence in regard to stimulating as well as inhibiting effects. The endogenous medication by way of pox-inducers (paramunization) is diametrically opposed to the exogenous application of cytokines.

Mutations in tumour suppressor gene p53 in two feline fibrosarcomas

Exons 5-7 of the tumour suppressor gene p53 were investigated in genomic DNA of tumours of domestic cats. In one fibrosarcoma investigated we observed a mutation GAG-->AAG (glutamic acid-->lysine) in codon 180; in another there was a mutation CGG-->TGG (arginine-->tryptophane) in codon 248.

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.

Cytogenetic characterization of a fibroma and three haemangiopericytomas in domestic dogs

Cytogenetic evaluation of tumour cells taken from an 11-year-old mixed breed birth with a fibroma, showed trisomy 1 (2n = 79) and often the presence of a third copy of chromosome 4. In a 13-year-old mixed breed Boxer bitch with a haemangiopericytoma, trisomy 9 (2n = 79) was present. In contrast, another haemangiopericytoma (in a 15-year-old rough-haired Dachshund bitch) showed a deleted chromosome 1, several centric fusions and trisomy 2. Trisomy 2 and trisomy 29 were detected in a third haemangiopericytoma from an 11-year-old rough-haired Dachshund bitch.

The influence of proteins on silver staining of nucleic acids following polyacrylamide gel electrophoresis

The influence, on silver staining, of proteins and restriction enzymes in polymerase chain reaction (PCR) products was studied in 12-20% polyacrylamide gels. For small DNA fragments (74, 41 and 33 bp) best results were achieved using 20% polyacrylamide gels. In 12% gels, restriction enzymes and also proteins used for PCR (bovine serum albumin, Taq-DNA polymerase) interfere with silver staining of nucleic acids.

Sequence of an exon of tumour suppressor p53 gene--a comparative study in domestic animals: mutation in a feline solid mammary carcinoma

Partial sequence determinations were performed on exon 8 of tumour suppressor gene p53 of cattle, sheep, goat, horse and pig. High sequence homology between these species and other species including dog, cat, chicken and man is demonstrated. A mutation CGG-->TGG (arginine-->tryptophan) was detected in a feline solid carcinoma of the mammary gland.

Cytogenetic analyses of four solid tumours in dogs

Four solid tumours (one haemangiopericytoma, one haemangioendothelioma, one spindle-cell sarcoma and one mammary carcinoma) in dogs were analysed cytogenetically. In the haemangiopericytoma, an additional small chromosomal segment was present. Very complex changes including centric fusions and symmetric meta-centrics 1, 6, 10 and 12 were conspicuous in the highly unbalanced karyotype of the haemangioendothelioma. Complex changes, particularly many centric fusions and a tandem translocation 4/14, were features of the spindle-cell sarcoma. One centric fusion and a symmetric metacentric 13 were present in the mammary carcinoma.

Trisomy D1, marker F1: new cytogenetic findings in two cases of feline fibrosarcoma

An 11-year-old female cat and a 12-year-old male cat developed fibrosarcomas. Trisomy D1 was observed in a high percentage (20%) of the tumour cells of the female patient while a large marker chromosome F1 was present in 25% of the tumour cells of the male patient.

Sequence of an exon of the canine p53 gene--mutation in a papilloma

Exon 8 of tumour suppressor gene p53 was sequenced in domestic dogs. Ten nucleotide differences were revealed in a comparison with the feline sequence. A mutation ACT-->TCT (threonine-->serine) in codon 284 was detected in a papilloma of the oral mucosa.