Role of adhesion molecules and proliferation hyperplasic, pre neoplastic and neoplastic lesions in canine prostate.

E-cadherin and beta-catenin are component of adherens junctions in epithelial cells. Loss of these proteins have been associated with progression of prostatic diseases. We performed immunohistochemistry for E-cadherin, beta-catenin and Ki-67 on canine prostatic lesions. We analyzed the expression of these antibodies in benign prostatic hyperplasia (BPH, n = 22), in pre neoplastic lesions Prostatic Intra-epithelial Neoplasia (PIN), n = 3 and Prostatic Inflammatory Atrophy (PIA), n = 7 and prostate carcinoma (PC, n = 10). In this study, a membranous expression of E-cadherin and beta-catenin and nuclear expression of Ki-67 antigen were demonstrated. The proliferative index was statistically different between carcinomas and BPH and carcinomas and pre-neoplastic lesions. Like in men, the reduction of E-cadherin and increase of Ki-67 expression in neoplastic lesions in dog prostate may be related to the carcinogenic process in this gland.

Prognostic studies of canine and feline mammary tumours: the need for standardized procedures.

For several years, veterinary oncologists have been struggling with the prognosis of mammary tumours in dogs and cats. Translation of tumour characteristics into prognostic information is an invaluable tool for the use of the most appropriate therapies, as well as for planning innovative therapeutic trials. Moreover, canine and feline spontaneous mammary gland tumours are good models for the study of human breast cancer. Collecting and interpreting information regarding the prognosis of canine and feline mammary tumours is difficult due to the fact that different methods have been applied to study various components and characteristics. This review identifies some of the challenges of prognostic studies of spontaneous canine and feline mammary tumours and suggests standardized procedures to overcome these challenges and facilitate reproducibility and assessment of results.

Fibroblast-dependent tumorigenicity of melanoma xenografts in athymic mice.

Two human melanoma cell lines, UCT-Mel 2 and UCT-Mel 3, were invariably tumorigenic in nude mice when inoculated s.c. in doses of 10(6) cells or higher; 10(5) cells or less did not give rise to tumours. In this report we show that otherwise sub-tumorigenic inocula developed into vigorously growing tumour xenografts when co-inoculated with normal fibroblasts. Fibroblasts derived from adult, neonatal or embryonic tissues all functioned as complementing cells, as did cells of human or murine origin. There was, however, a requirement for complementing cell viability, since ethanol-killed fibroblasts were inefficacious. The fibroblast effect was dose-dependent and was not observed if injections of fibroblasts and melanoma cells were separated anatomically or temporally. We have shown, by titrating admixtures of melanoma cells and fibroblasts, that fibroblasts are, in quantitative terms, more efficacious than melanoma cells as complementing cells. The system we describe provides a useful model for the study of stromal-cell regulation of tumour growth.

Unusual growth characteristics of human melanoma xenografts in the nude mouse: a model for desmoplasia, dormancy and progression.

When human melanoma cells are injected into nude mice they usually give rise to tumours that grow progressively and do not elicit a prominent host response. We have recently developed a melanoma cell line, UCT-Mel 7, that did not show these characteristics. In the first place UCT-Mel 7 showed a consistently unusual, phasic growth pattern. After a short initial period of limited growth (phase 1), the tumour ceased growing and remained static for 2-3 months (phase 2). The tumour then regressed (phase 3) to enter a second period of quiescence (phase 4) which was eventually broken by the emergence of a rapidly growing lethal tumour (phase 5). Of particular interest was the fact that the rate at which the tumours grew correlated closely with their collagen content. During the prolonged, phase 2 plateau, the tumours were intensely desmoplastic; rapidly growing phase 5 tumours, that had escaped from dormancy, contained very little collagen and virtually no reticulin. This cell line helps to fill an important need for an experimental system for the study of desmoplasia, dormancy and progression.

Metastasis of a human melanoma cell line in the nude mouse.

A human melanoma cell line has been established which when inoculated subcutaneously into nude mice, is consistently metastatic. In order to document blood-borne spread, it was necessary to excise the primary tumour so prolonging the life of the animal and allowing metastases to become apparent. Macroscopically detectable metastatic spread at autopsy was reliably indicated by weight loss of the animals. Metastases were widespread and involved the lungs, abdominal cavity and organs and the gonads. The size of the primary tumour at the time of its removal, and not the period of s.c. growth, determined the incidence of metastatic disease. Removal of tumours weighing less than 0.6 g prevented metastasis, whereas all of the animals showed widely disseminated disease if the tumour was allowed to attain a size of 1.6 g before excision.