Tn and Sialyl-Tn antigens in canine gastric tissues

Malignant transformation is often associated with abnormal protein glycosylation expressed, amongst others, by the accumulation of simple mucin-type carbohydrates namely Tn and Sialyl-Tn (STn) antigens. These are usually limited in normal tissues and their increased expression has been associated with cancer progression and poor prognosis. This study aims to evaluate the role of Tn and STn antigens in the neoplastic transformation of the canine gastric mucosa and to correlate their putative immunoexpression alterations with some pathological features. Tn and STn antigens expression were immunohistochemically evaluated in canine normal gastric mucosa (n = 3), gastric polyps (n = 9) and gastric carcinomas (n = 25), neoplastic emboli (n = 12) and metastases (n = 8). In normal gastric mucosa, Tn antigen was detected in the gastric epithelial cells, while STn antigen was absent. Similarly, all gastric polyps expressed Tn antigen, but none displayed STn antigen immunostaining. In carcinomas, Tn antigen was expressed in 96% of the cases and STn antigen in 68% of the neoplasms. STn antigen was significantly higher in carcinomas compared with normal mucosa (P < .05). No correlation was found between each antigen and the different subtypes of tumours according to WHO classification, tumour differentiation, lymph vascular invasion or metastasis. All neoplastic emboli expressed both antigens, and the expression score was similar or higher than that displayed by the neoplastic cells of the primary tumour. The high prevalence of STn antigen in gastric carcinomas compared with normal mucosa highlights the cancer-associated nature of this antigen. Our results link STn antigen expression to neoplastic transformation and suggest that it may be a useful marker of gastric cancer progression in dogs.

Caracterización de la expresión de galectina-3 mediante inmunohistoquímica en lesiones intraepiteliales de glándula mamaria de perras sin evidencia de tumor

Las lesiones intraepiteliales (LIEs) son anormalidades morfológicas locales de los ductosy los lobulillos de la glándula mamaria que incrementan el riesgo de cáncer. Los programasde detección temprana de cáncer de seno han incrementado la identificaciónde LIEs. En este sentido, en perras se ha propuesto las LIEs como modelo comparativocon humanos. La galectina-3 está involucrada con la progresión del cáncer en mujeresy hembras caninas pero su papel en el comportamiento biológico de las neoplasias escontradictorio según la célula de origen. El objetivo de este trabajo fue caracterizar laexpresión de la galectina-3 por medio de inmunohistoquímica en 19 glándulas mamarias(GM) de seis perras sin evidencia de tumor que contenían 50 tipos de LIEs y 7 carcinomasinvasivos, teniendo en cuenta el porcentaje de células positivas y la intensidaddel color de la inmunoreacción. No hubo inmunomarcación para galectina-3 en lasadenosis, las hiperplasias ductales usuales, la hiperplasia lobular atípica, las lesiones decélulas columnares, los carcinomas complejos o las hiperplasias complejas. Un papiloma/adenoma con hiperplasia de acinos tuvo inmunomarcación multifocal en 11–50% delas células con moderada intensidad. Dos carcinomas in situ del subtipo lobular (unode grado histológico nuclear intermedio y el otro de alto grado) tuvieron marcación en10% de las células, pero uno tuvo intensidad baja y el otro, intensidad moderada. Loshallazgos sugieren que el papel de la galectina-3 es poco importante en la iniciación delas LIEs, pero sugieren que es una proteína de interés en la progresión de estas lesionesque posiblemente interactúa en el comportamiento biológico de esta enfermedad.

Aberrant expression of sLex and sLea as candidate prognostic factors for feline mammary gland tumour

Expression of the carbohydrate antigens sialyl Lewis x (sLe(x)) and a (sLe(a)) was evaluated in feline mammary gland tumours (FMGT). Immunohistochemical analysis of tissues from 21 FMGT patients and 11 healthy cats revealed significantly higher sLe(x) and sLe(a) antigen expression in adenocarcinoma tissues compared with that of normal mammary tissues (P <0.01). Serum concentration of sLe(x) was evaluated using an enzyme-linked immunosorbent assay and was significantly higher in the 11 FMGT patients (4.71 ± 10.1 U/ml) than the 22 patients with other disease (2.69 ± 1.59 U/ml) (P = 0.03) and the 22 healthy cats (3.71 ± 1.10 U/ml), although the latter difference was not significant. Although the number of cases examined in this study was small, our findings suggest that aberrant expression of sLe antigens may be induced by tumourigenesis in FMGT and that sLe antigens are potential prognostic tumour markers for FMGT.

Molecular carcinogenesis of canine mammary tumors: news from an old disease

Studies focusing on the molecular basis of canine mammary tumors (CMT) have long been hampered by limited numbers of molecular tools specific to the canine species. The lack of molecular information for CMT has impeded the identification of clinically relevant tumor markers beyond histopathology and the introduction of new therapeutic concepts. Additionally, the potential use for the dog as a model for human breast cancer is debatable until questions are answered regarding cellular origin, mechanisms, and cellular pathways. During the past years, increasing numbers of canine molecular tools have been developed on the genomic, RNA, and protein levels, and an increasing number of studies have shed light on specific aspects of canine carcinogenesis, particularly of the mammary gland. This review summarizes current knowledge on the molecular carcinogenesis of CMT, including the role of specific oncogenes, tumor suppressors, regulators of apoptosis and DNA repair, proliferation indices, adhesion molecules, circulating tumor cells, and mediators of angiogenesis in CMT progression and clinical behavior. Whereas the data available are far from complete, knowledge of molecular pathways has a significant potential to complement and refine the current diagnostic and therapeutic approach to this tumor type. Furthermore, current data show that significant similarities and differences exist between canine and human mammary tumors at the molecular level. Clearly, this is only the beginning of an understanding of the molecular mechanisms of CMT and their application in clinical patient management.