Canine Mammary Carcinomas Research Articles

Amyloid in canine mammary tumors.

In canine mammary carcinomas, amyloid was present as amyloid-containing corpora amylacea and as local deposits between neoplastic epithelial cells or in stromal tissue. Histochemical staining methods revealed that this amyloid was not of the AA-type amyloid and contained tryptophan. The possible pathogenesis of this amyloid deposition is discussed.

Studies of three canine mammary carcinoma cell lines—I. In vitro properties

Three cells lines, REM 134, 111 and 367, have been derived from canine mammary carcinomas and their morphological characteristics in vitro are described. They are tumorigenic in athymic nude mice, have no demonstrable fibronectin on their cell surfaces and exhibit a varied pattern of lectin binding. They can be cloned in semi-solid agar. One line, REM 134, responds to oestrogen and luteotropic hormone in vitro, although none of the three had demonstrable oestrogen receptors.

Studies of three canine mammary cell lines—II. In Vivo properties

Three cell lines, REM 134, 111 and 367, derived from canine mammary carcinomas have been used to induce tumours in athymic nude mice after subcutaneous injection. The histopathology of the tumours was compared and each was found to resemble closely the original tumour. This did not change after serial in vivo passage. Metastasis never occurred. Injection of REM 134 cells intracranially resulted in a fast-growing tumour which also did not metastasize; injection intrapleurally resulted in growths most commonly on the mediastinum with confinement to the chest cavity. Fibronectin was present in the subcutaneous tumours. Two of the cell lines were cloned in semi-solid agar. When tested, these clones induced tumours identical histologically to the uncloned ones. Finally, male and female mice were injected subcutaneously with the same number of cells from each of the three lines but the rate of tumour growth did not differ significantly between the two sexes.

Cytoplasmic steroid effects on nuclear RNA polymerase activity in canine mammary carcinomas

DNA-dependent RNA polymerase activity has been studied in isolated nuclei from canine mammary tumours. Initial experiments showed high levels of RNase activity in this tissue; accordingly, routine assays were terminated before loss of acid-precipitable radioactivity was evident. RNA polymerase A and B activity in isolated nuclei were shown to be increased by addition of receptor-containing cytosol previously incubated with oestradiol-17β, dihydrotestosterone or R5020. Where no receptor was present, as measured by saturation binding assays and sucrose density gradient analysis, there was no corresponding increase in polymerase activity. The steroid antagonists tamoxifen and cyproterone did not elicit any response even when their corresponding steroids produced a 1- to 2-fold stimulation of polymerase activity. Steroid-induced effects proved to be dose-dependent, with half maximal responses for oestradiol-17β 8 × 10 −8 M, R5020 2 × 10 −6 M and dihydrotestosterone 9 × 10 −6 M.

Agglutination reactions of spontaneous canine tumour cells, induced by concanavalin a, demonstrated by an isotopic assay

Quantitative assessment of the agglutination of 51Cr labelled canine cell suspensions to canine kidney cell monolayers has been performed over a range of concanavalin A concentrations. Agglutination was observed with all cell cultures tested, comprising four spontaneous canine melanomas, two canine mammary carcinomas, a benign mammary tumour and a contact-inhibited kidney cell line. The melanomas tested showed strong specific inhibition of concanavalin A agglutination by 10(-2)M alpha-methyl-D-glucopyranoside. Inhibition of agglutination of mammary tumour and kidney cells was weaker and less specific. Agglutination was inhibited at 4degrees C. Reduced agglutination to glutaraldehyde-fixed mono-layers was observed in the case of mammary tumours but was absent when contact-inhibited kidney cells were tested. The specificity of the reaction for transformed cells and the parameters involved are discussed.