Enzyme patterns of glucose catabolism in hormone-dependent and -independent mammary tumours of GR mice

Abstract

Mammary tumours were induced in ovariectomized GR female mice according to the method of van Nie, by feeding estrone in the drinking water and giving weekly injections of progesterone pellets. The tumour incidence was 90% after 14 weeks of treatment. More than 90% of the induced tumours proved to be hormone dependent, and remained so for the next few serial transplantations after which they changed into hormone independent tumours. The determination of hexokinase, phosphofructokinase, pyruvate kinase, and lactate dehydrogenase activity of hormone dependent tumours showed a consistent increase as compared to virgin, though not to lactating mammary gland. However, only hexokinase activity was further increased by the transition to autonomy. In agreement with this, lactate accumulation was significantly higher in autonomous compared to hormone dependent tumours. The activity of glucose- 6-phosphate dehydrogenase was found to be significantly lower in autonomous tumours as compared to hormone dependent as well as to virgin mammary gland. No increase in activity could be induced in autonomous tumour tissue by administering estrone.