Sera of C3H/Z/Dm mice bearing spontaneous mam mary tumors, sera of apparently normal C3H/Z/Dm mice at different ages, and a serum of an A/Dm mouse with spontaneous breast cancer were tested by the indirect immunoperoxidase method against cells of C3H/HeJ spon taneous mammary tumor line constantly producing type B or mouse mammary tumor virus particles. The sera were also tested against cells of...

The phosphatidylinositol 3-kinase (PI3K)/Akt survival pathway is often dysregulated in cancer. Our previous studies have shown that coexpression of activated Akt1 with activated ErbB2 or polyoma virus middle T antigen uncoupled from the PI3K pathway (PyVmT Y315/322F) accelerates mammary tumor development but cannot rescue the metastatic phenotype associated with these models. Here, we report th...

BACKGROUND Mammary tumors are the most common tumor type in intact female dogs. Recently, the breast cancer 2 early onset (BRCA2) gene was proposed to be associated with tumorigenesis in dogs. The expression level of BRCA2 is important for its DNA repair function in mammalian cells, and its expression level is linked to tumorigenesis in mammary tissue. However, the expression of canine BRCA2 in...

Subcutaneous epithelial Ehrlich ascites tumor (EAT) transplants stimulate adja cent mammary duct epithelium in C57BL mice. Present data describe a similar effect for Sarcoma 180, which is of connective tissue origin. Increased mitotic activity, with peak value on the 2d day of tumor growth, occurred in the epithelial cells of mam mary ducts located in a 1-mm. area around the tumor nodule. Inwar...

Mammary tumorigenesis in genetic crosses between the high mammary tumor incidence GR and the low incidence C57BL mouse strains is highly correlated with murine mammary tumor virus expression in milk. Although the F1 and first backcross females had a mammary tumor incidence which was consistent with a single dominant gene segregation, the tumor incidence in the critical second backcross segregan...

We have previously demonstrated that (guanine-2-)-methyltransferase activity in extracts from 9,10-dimethyl-1,2-benzanthracene-induced rat mammary tumors differs from that of nonneoplastic mammary tissue. In this report, we explore further the nature of these differences by purification and characterization of the two major transfer RNA (tRNA) (guanine-2-)-methyltransferases from transplantable...

Lymphocytes from BALB/cCrgl mice react to mouse mammary tumor virus-associated antigen(s) when tested in in vitro blastogenic transformation assays. These mice have a low incidence (less than 1%) of spontaneous mammary tumors and are free from complete mammary tumor virions. We have studied the nature of the lymphoid cells mediating the lymphocyte transformation reaction to purified mammary tum...

Mouse mammary tumors grow preferentially upon transplantation into intact mammary glands compared to cleared mammary fat-pads. Both sites provide stroma of the orthotopic site, but the latter lacks epithelial elements. If epithelium from enzymatically dissociated normal mammary glands is added to the tumor cells prior to injection into cleared fat-pads, tumor growth is comparable to that seen i...

Breast cancer is the most frequent tumor type among women in the United States and in individuals with Li-Fraumeni syndrome. The p53 tumor suppressor gene is altered in a large proportion of both spontaneous breast malignancies and Li-Fraumeni breast cancers. This suggests that loss of p53 can accelerate breast tumorigenesis, yet p53-deficient mice rarely develop mammary tumors. To evaluate the...