Responsiveness of mouse mammary tumours to pregnancy

For many years we have maintained in this laboratory a number of inbred strains of mice including the so-called high-mammary-tumor strains C3H, C3H-AVY, DD, and A, all of which have the mammary tumor virus (MTV) and two low-mammary-tumor strains C57BL and BALB/c in which MTV has not been demonstrated. There are certain differences among the high-mammarytumor strains. C3H-AVY is so designated because it bears the AvY mutation that arose in C3H and has been shown to increase suceptibility to a number of tumors including mammary gland tumors. DD can be expected to differ from the other strains since it came from Japan and is unrelated to the other strains. Strain A is unusual in that, while the breeding females have a relatively high incidence of mammary tumors, the incidence in the virgins is very low. Even the lines of MTV carried by these strains are somewhat different. There is also a great difference in the two low-tumor strains. C57BL not only does not have the MTV but is genetically very resistant to it, whereas BALB/c is very susceptible to MTV.Various combinations of these mouse strains and the lines of MTV have been made by transferring the lines of virus to mouse strains other than their original host strain through foster nursing in order to observe how this might alter the development and incidence of mammary tumors. In addition, the milk-transmitted MTV

“…Deringer (1969) has also observed them in RIII. They are similar to the mammary tumors that occur in strain GR studied by the Amsterdam group (Miihlbock, 1965;Van Nie and Thung, 1965).…”

Section: Test For Mtv and M T V Antigen In Milk Samplesmentioning

confidence: 72%

Mammary tumors, plaques, and hyperplastic alveolar nodules in various combinations of mouse inbred strains and the different lines of the mammary tumor virus

Heston

Vlahakis

1971

“…Simultaneous investigations of other endocrine parameters of ovarian function would be necessary to answer this question completely. Similar time-limited phases of hormone dependency were described with regard to the effect of pregnancy in mice on progression of tumor growth (Foulds, 1954;van Nie et al, 1965) and also in rats bearing chemically induced mammary cancers (Huggins et al, 1959;Shay et al, 1961Shay et al, , 1964Williams, 1965;Davis et al, 1966).…”

Section: Discussionmentioning

confidence: 70%

Biological and chemotherapeutic studies on primary mammary tumors in C3H and C3HO mice

Gelzer¹,

Loustalot²

1967

A reproducible chemotherapy assay system using primary mammary tumors in C3H and C3HO mice is described. These tumors, although possibly hormone-dependent to a minor extent, are not steroid-sensitive and their response to accepted anti-cancer compounds follows in general that of classical transplantable rodent tumors.Primary tumors in mice (Moulton, 1945;Hoag, 1963) growing autochthonously in their hosts are not only considered similar to human cancer in respect of their mode of occurrence, but their growth in, as a rule, highly inbred animals minimizes the development of qualitative and quantitative alterations in properties due to immunological mechanisms (Foulds, 1954;Milgrom, 1961). Moreover, certain primary mammary tumors were found to be at least partially hormone-dependent (Shimkin, 1945;Scholler, 1958), thus serving as a model for human mammary cancer (Boyd, 1900).The main difficulty encountered in the use of primary tumors for quantitative tumor studies has been the wide variation in tumor growth. Accordingly, chemotherapeutic studies on a systematic basis are relatively rare in such systems (Dyer, 1945;Scholler et al., 1956).The purpose of this study was to ascertain whether a suitable assay system with primary mammary tumors of C3H and C3HO mice could be developed. Attempts to analyze the status of relative hormone-dependency and the chemotherapeutic sensitivity of these tumors will be described. MATERIAL AND METHODS AnimalsTumor-bearing C3H and C3HO mice of either sex were obtained at weekly intervals by airfreight from the " International Center for the Provision and Study of Tumor-Bearing Animals " (Prof. 0. Muhlbock, Amsterdam). The animals were 7-8 months old and weighed 25-30 g. Female mice were either virgins or "forced breeders ". The males had been castrated at an early age and then treated with approximately 10 pg estrogen daily (i.e. 2 mg estrogen per 1 1 drinking water).The animals, placed in plastic cages, were kept in air-conditioned quarters at a constant temperature and maintained on mouse peIlets (Nafag A.G., Gossau, Switzerland) and water ad libitum. Body-weights were recorded at weekly intervals. TumorsInbred C3H and C3HO mice are known to show a 90-100% incidence of spontaneous mammary tumors (Moulton, 1945;Hoag, 1963). These occur along the milk crest in both females and castrated males (Muhlbock, 1956) and histologically are predominantly of the adenocarcinomatous type. C3H and C3HO hybrid animals harbor the milk agent (MTA) (Moore et al., 1963). In preliminary experiments it was established that there was no significant difference in the rate of growth of tumors either between the castrated male and female animals or between tumors on C3H and hybrid C3HO mice. Thus, in the experiments to be reported, all mice of each

“…This strain is a high mammary cancer strain with pregnancydependent mammary tumors. Thus, during the first pregnancies small mammary tumors might develop and regress again, while in later pregnancies palpable mammary tumors might appear and fail to regress (van Nie and Thung, 1965).…”

Section: Resultsmentioning

confidence: 99%

Mammary tumor virus (MTV) antigens in normal and mammary tumor‐bearing mice

Hilgers

Theuns

Nie

1973

Quantitative itrimunofluorescence tests were used to study M TV-antigen production in normal and mammary tumor-bearing mice ojtwo low (BALBIc and C3Hf) and two high (C3H and G R ) as well as in the MTV-induced tumors o f t h e BALBlc strain, but low in G R-strain tumors. Sera from mice bearing MTV-antigen producing mammary tumors (as well as from some pregnant and lactating G R mice) contained excess M T Vantigens. Spleens of BALBIc mice bearing MTV-antigen-induced tumors often contained detectable amounts of MTV-antigens, while normal and mammary tumor-bearing