The early studies of Murray (11) suggested that male mice that had been castrated and trans planted with ovaries developed mammary cancer with approximately the same frequency as did virgin female mice of the same strain. Later, Loeb et al. (10), in a preliminary report in which no data were presented, stated that “aftertransplantation of ovaries into castrate male mice, the cancer rate and p...

Many risk factors for breast cancer are associated with hormonally regulated events. Although numerous mouse models of mammary cancer exist, few address the roles of hormones in spontaneous tumor formation. Here we report that transgenic mice that overexpress LH, resulting in ovarian hyperstimulation, undergo precocious mammary gland development. A significant increase in proliferation leads to...

Breast cancer (BC) is the most frequently malignancy in women. Therefore, establishment of an animal model for the development of preventative measures and effective treatment for tumors is required. A novel heterogeneous spontaneous mammary tumor animal model of Kunming mice was generated. The purpose of this study was to characterize the spontaneous mammary tumor model. Histopathologically, i...

C3H and C3H backcross mice were given repeated injections of preparations from strain-specific or strain-related mammary tumors of recent spontaneous origin together with Freund's adjuvant. The effect of the course of injections on spontaneous mammary tumor development was studied. Pre t rea tment with mammary tumor tissue did not lead to a significant reduction in spontaneous mammary tumor inc...

Chronic social isolation is linked to increased mammary tumor growth in rodent models of breast cancer. In the C3(1)/SV40 T-antigen FVB/N (TAg) mouse model of "triple-negative" breast cancer, the heightened stress response elicited by social isolation has been associated with increased expression of metabolic genes in the mammary gland before invasive tumors develop (i.e., during the in situ ca...

Defective autophagy has been implicated in mammary tumorigenesis, as the gene encoding the essential autophagy regulator BECN1 is deleted in human breast cancers and Becn1(+/-) mice develop mammary hyperplasias. In agreement with a recent study, which reports concurrent allelic BECN1 loss and ERBB2 amplification in a small number of human breast tumors, we found that low BECN1 mRNA correlates w...

Breast cancer continues to be a major challenge for public health, since it is the most common cancer of women in the Western world, and its prevalence is still increasing. In order to achieve better results in the prevention and treatment of breast cancer it is crucial to identify the mechanisms behind its initiation, i.e. the changes and deviations that have occurred in the mammary gland grow...

The relationship of ovarian hormones to the development of the breast and, logically, to mammary cancer appeared clearly outlined in the results of early castration experiments on mice. Prepuberty ovariectomy inhibited normal growth of the breast, with the consequence that females of strains with mammary tissue highly susceptible by heredity to spontaneous malignant alteration failed to develop...

Acquired resistance to TGFβ is a key step in the early stages of tumorigenesis. Mutations in TGFβ signaling components are rare, and little is known about the development of resistance in breast cancer. On the other hand, an activated Notch pathway is known to play a substantial role in promoting breast cancer development. Here, we present evidence of crosstalk between these two pathways throug...

Autophagy is a catabolic process involving self-digestion of cellular organelles during starvation as a means of cell survival; however, if it proceeds to completion, autophagy can lead to cell death. Autophagy is also a haploinsufficient tumor suppressor mechanism for mammary tumorigenesis, as the essential autophagy regulator beclin1 is monoallelically deleted in breast carcinomas. However, t...