Abstract
Hormonal regulation of plasminogen activator expression in 7,12-dimethylbenz[a]anthracene (DMBA)--induced rat mammary carcinomas was studied both in vivo and in vitro and was compared to that in DMBA-mammary dysplasia induced in neonatally androgenised rats. The plasminogen activator activity in DMBA-mammary carcinomas, but not in DMBA-mammary dysplasia, was regulated by oestrogen. This suggests that expression of this enzyme is hormonally regulated in carcinoma cells. Furthermore, in two of six DMBA-mammary carcinoma groups classified in terms of hormonal treatment, plasminogen activator activity was not under the control of oestrogen. Thus, the present results suggest that at the time of carcinogenesis, the hormonal milieu determines the hormone sensitivities of the malignant cells.
Highlights
The 7,12-dimethylbenz[a]anthracene (DMBA) - induced rat mammary tumour model is valuable for studying the hormonal dependence of breast cancer in humans
Three types of palpable mass were found in the mammary glands: mammary carcinomas, grossly visible cysts, and mammary dysplasia
Mammary dysplasia was characterised by heterogenous microscopic features including adenosis, fibrosis, duct papillomatosis and fibroadenoma-like lesions
Summary
The 7,12-dimethylbenz[a]anthracene (DMBA) - induced rat mammary tumour model is valuable for studying the hormonal dependence of breast cancer in humans In this model system, several studies have provided evidence that the oestrogen receptor is present in breast cancer cells (King et al, 1965; Mobbs, 1966). We studied this hypothesis by comparing the effect of oestrogen on plasminogen activator production in DMBA-induced rat mammary carcinomas to that in mammary dysplasia induced in NA rats. We demonstrate that this enzyme is produced in DMBA-induced carcinomas and that this enzyme is not necessarily regulated by oestrogen in some DMBA-induced carcinoma cells. We conclude that during carcinogenesis the hormonal milieu determines how plasminogen activator expression may be regulated in transformed cells
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
