Tyrosine Kinase Receptor Expression in Canine Liposarcoma.

The expression of tyrosine kinase receptors is attracting major interest in human and veterinary oncological pathology because of their role as targets for adjuvant therapies. Little is known about tyrosine kinase receptor (TKR) expression in canine liposarcoma (LP), a soft tissue sarcoma. The aim of this study was to evaluate the immunohistochemical expression of the TKRs fibroblast growth factor receptor 1 (FGFR1) and platelet-derived growth factor receptor-ß (PDGFRß); their ligands, fibroblast growth factor 2 (FGF2) and platelet-derived growth factor B (PDGFB); and c-kit in canine LP. Immunohistochemical labeling was categorized as high or low expression and compared with the mitotic count and MIB-1-based proliferation index. Fifty canine LPs were examined, classified, and graded. Fourteen cases were classified as well differentiated, 7 as myxoid, 25 as pleomorphic, and 4 as dedifferentiated. Seventeen cases were grade 1, 26 were grade 2, and 7 were grade 3. A high expression of FGF2, FGFR1, PDGFB, and PDGFRß was identified in 62% (31/50), 68% (34/50), 81.6% (40/49), and 70.8% (34/48) of the cases, respectively. c-kit was expressed in 12.5% (6/48) of the cases. Mitotic count negatively correlated with FGF2 ( R = -0.41; P < .01), being lower in cases with high FGF2 expression, and positively correlated with PDGFRß ( R = 0.33; P < .01), being higher in cases with high PDGFRß expression. No other statistically significant correlations were identified. These results suggest that the PDGFRß-mediated pathway may have a role in the progression of canine LP and may thus represent a promising target for adjuvant cancer therapies.

Validation of tissue microarray for molecular profiling of canine and feline mammary tumours.

Tissue microarray (TMA) is a high-throughput method adopted for simultaneous molecular profiling of tissue samples from large patient cohorts. The aim of this study was to validate the TMA method for the molecular classification of canine and feline mammary tumours. Twelve samples, five feline and five canine mammary tumours and two canine haemangiosarcomas, were collected. TMA construction was based on Kononen's method of extracting a cylindrical core of paraffin wax-embedded 'donor' tissue and inserting it into a 'recipient' wax block. Seven consecutive sections from each tissue array block were subjected to immunohistochemistry (IHC) using primary antibodies specific for oestrogen receptor (OR), progesterone receptor (PR), c-erbB-2, cytokeratin (CK) 5/6, CK14, CK19 and p63. The same panel of antibodies was applied to the full sections from all cases. Comparison between full sections and TMA scores revealed different results depending on the antibodies. Labelling for OR, PR, CK19 and p63 showed total concordance, c-erbB2 (score +2, +3) was concordant in nine out of ten cases, CK5/6 and CK14 in eight out of ten cases. The TMA platform preserves the molecular profile of canine and feline mammary tumour markers, representing a useful tool for rapid and cost-effective analysis for the first phenotypic screening using OR, PR and c-erbB2 antibodies. Basal cytokeratin, used for triple negative identification, shows a multifocal 'niche' expression pattern, for which IHC of the full section or multiple core array is recommended.

Enhanced virulence of the Escherichia coli O157:H7 spinach-associated outbreak strain in two animal models is associated with higher levels of Stx2 production after induction with ciprofloxacin.

Shiga toxin (Stx)-producing Escherichia coli (STEC) causes hemorrhagic colitis and the hemolytic-uremic syndrome (HUS). STEC strains may produce Stx1a and/or Stx2a or variants of either toxin. A 2006 spinach-associated outbreak of STEC O157:H7 resulted in higher hospitalization and HUS rates than previous STEC outbreaks. The spinach isolate, strain K3995, contains both stx2a and stx2c. We hypothesized that the enhanced virulence of K3995 reflects the combination of stx2 alleles (carried on lysogenic phages) and/or the amount of Stx2 made by that strain. We compared the virulence of K3995 to those of other O157:H7 isolates and an isogenic Stx2 mutant in rabbits and mice. We also measured the relative levels of Stx2 produced from those strains with or without induction of the stx-carrying phage. Some rabbits infected with K3995 exhibited intestinal pathology and succumbed to infection, while none of those infected with O157:H7 strain 2812 (Stx1a(+) Stx2a(+)) died or showed pathological signs. Rabbits infected with the isogenic Stx2a mutant K3995 stx2a::cat were not colonized as well as those infected with K3995 and exhibited no signs of disease. In the streptomycin-treated mouse model, more animals infected with K3995 died than did those infected with O157:H7 strain 86-24 (Stx2a(+)). Additionally, K3995 produced higher levels of total Stx2 and toxin phage DNA in cultures after phage induction than did 86-24. Our results demonstrate the greater virulence of K3995 compared to other O157:H7 strains in rabbits and mice. We conclude that this enhanced virulence is linked to higher levels of Stx2 expression as a consequence of increased phage induction.

CD117 expression influences proliferation but not survival in canine mammary tumours.

CD117 is a transmembrane tyrosine kinase receptor encoded by the c-Kit proto-oncogene. The immunohistochemical expression of CD117 was examined in 49 specimens of canine mammary glands (eight normal/hyperplastic, 11 benign tumours and 30 malignant tumours). Expression was assessed as: (1) presence or absence of CD117; (2) membrane, cytoplasmic, or both, distributions; and (3) percentage of CD117-labelled cells. None of these three immunohistochemical parameters was correlated with the type of mammary tissue (i.e. normal, benign or malignant), histotypes or histological stage of malignant tumours, or survival. An association was observed between Ki67 index and all three CD117 labelling parameters only for malignant tumours, with a significant increase in proliferative activity in tumours expressing CD117, mainly with both cytoplasmic and membrane expression.