Synthesis of Dna and Lecithin in Tissue Culture and Oestrogen Receptor Activity in Rat Mammary Tumours Dependent on and Independent of the Ovary

Abstract

Dimethylbenz(alpha)anthracene (DMBA)-induced and transplanted rat mammary tumours (2 lines) were examined for oestrogen receptor activity, and for sensitivity to hormones in vivo (by ovariectomy) and in vitro (by tissue culture). In vivo, the growth of all tumours induced by the administration of DMBA in random-bred Sprague-Dawley rats was found to be dependent on the ovary, whilst in all transplanted tumours (12 TG-3 and six TG-5 lines), maintained in an inbred strain of Sprague-dawley rats, growth was found to be independent of the ovary. In vitro, the capacity for DNA synthesis in DMBA-induced tumours was better maintained after 24 h when insulin (10 microgram/ml) and corticosterone (5 microgram/ml) or insulin, corticosterone and prolactin (each 5 microgram/ml) were present in the medium (five out of 12 and eight out of 11 tumours respectively); no effect of hormones in the media was detected after 48 h. In the transplanted tumours, no effect of hormones on DNA synthesis was detected after either 24 or 48 h of culture. Synthesis of lecithin was not detectably influenced by the presence of hormones in either DMBA-induced or transplanted tumours. Oestrogen receptor concentrations were, on average, significantly higher in the DMBA-induced tumours than in either line of transplanted tumour. For 22 DMBA-induced tumours and 15 transplanted tumours, the effect of hormones in vitro ('response') was directly correlated with receptor concentration at time 0 (Spearman's rho = +0.59) and inversely correlated with the rate of DNA synthesis ('basal') at time 0 (Spearman's rho = -0.62). No single parameter or pair of parameters permitted accurate distinction between the tumour types.

Endogenous peroxidase: an alternative to oestrogen receptor in the management of breast cancer?

“…It is known that not all DMBAinduced tumours are hormone-dependent and it might be postulated that the one such tumour in which no RP could be detected might have belonged to the hormone-independent minority of DMBAinduced tumours. This study revealed no overlap in RE levels between the two groups but it should be noted that in earlier generations of the TG3 and TG5 lines higher RE concentrations were found, and the distinction between the groups was less clear-cut (Hawkins et al, 1978;Scott et al, 1979).…”

“…Previous work in our department has shown that over 80% of such tumours regress after oophorectomy (Hawkins et al, 1978;Scott et al, 1979). Twenty-four such tumours were examined in this study.…”

Oestrogen receptor activity and intranuclear translocation of oestradiol in rat and human mammary tumours

“…These were tumours induced in randombred Sprague-Dawley rats by the administration of dimethylbenz(a)anthracene (DMBA) as previously described (Hawkins, Drewitt, Freedman, Killen, Jenner & Cameron, 1976) and two lines of transplantable tumours (TG/3 and TG/5) originally derived from tumours induced by DMBA in an inbred strain of Sprague-Dawley rats (Hawkins, Hill, Freedman, Killen & Miller, 1978). At the time of study, the latter two types of tumour were ovary independent whilst more than 80% of the former tumours were ovary dependent as previously reported (Scott, Murphy & Hawkins, 1979). Tumours were harvested when approximately 1-5 1-5 cm in size, by excision of the tumour after exsanguination of the animal under ether anaesthesia.…”