Europ..]. Cancer,Vol. 14, pp. 865-867
0014-2964/78/0801q)865502.00/0
© Pergamon Press Ltd. 1978. Printed in Great Britain
In Vitro Effects of Oestrogen on Testosterone Metabolism by Human Breast Cancers W. R. MILLER and A. P. M. FORREST Department of Clinical Surgery, Royal Infirmary, Edinburgh, EH3 9YW, United Kingdom Abstract--The effect of in vitro addition of oestradiol on the metabolism of 7o~3H
testosterone by 15 human breast cancers has been investigated. Oestradiol significantly inhibited metabolism and conversion to 5a dihydrotestosterone, 5~ androstanediol and A4 androstenedione.
shaking at 37°C in an atmosphere of oxygen for two hours. In two tumours oestradiol-3methyl ether (1.5#g/ml) was added to a further incubate as an additional control. The reaction was stopped by the addition of methanol (40ml) and the incubate stored at -- 10°C. Before extracting the metabolites, 500~g each of non-radioactive testosterone, 5a dihydrotestosterone (5a DHT), 5~ androstanediol, A4 androstenedione and oestradiol-17fl were added to each incubate to monitor recovery losses. Details of the methodology for steroid purification by thin layer chromatography and characterisation by chemical derivative formation have been described previously [7]. Metabolism of testosterone was determined by measuring the incorporation of radioactive label into the appropriate metabolites after correction for recovery losses. Statistical comparisons b e tween the results of incubates with and without added oestradiol were performed by paired ttests after logarithmic transformation of the data.
INTRODUCTION
HUMAN breast cancers can metabolise steroid precursors to active hormones such as 50~ dihydrotestosterone [1, 2] and oestradiol-17fl [3, 4]. Whilst the metabolism of testosterone by rat m a m m a r y tumours has been shown to be influenced by oestrogen both in vitro [5] and in vivo [6], little is known about the effects of hormones on steroidogenesis in human tumours. The aira of the present study was to determine in vitro the effect of oestradiol17fl on testosterone metabolism by human breast cancer. MATERIALS
AND METHODS
Tumours from 15 patients with proven cancer of the breast were studied: 10 subjects were at least 5yr postmenopausal, 4 were premenopausal and had regular menstrual periods at the time of investigation. One patient had undergone bilateral oophorectomy 15 months previou,dy. Following excision the tumours, 10 of which were primary carcinomas and 5 recurrence on the chest wall, were processed at 0°C. They were finely sliced and split into duplicate portions each weighing 0.5 g to which Krebs Ringer phosphate buffer pH 7.4 (5ml), an NADPH generating system and 20#Ci 7~3H testosterone (5.7 Ci/mmole from Radiochemical Centre, Amersham) were added. Incubation was then carried out either in the presence of oe,stradiol (1.5#g/ml) or its vehicle (propyleneglycol: ethanol 1 : 1 ) by
RESULTS
The results are presented in Table 1. All 15 cancers converted testosterone to 5a DHT, 50e androstanediol and A4 androstenedione but synthesis of oestradiol was detected in only 8 turnours. In certain tumours, these products represented only a small proportion of the total metabolites; uncharacterized highlypolar compounds being responsible for most of the unidentified material. The addition of oestradiol-17fl to the incubates caused significant inhibition of the metabolism of testosterone (P
0014-2964/78/0801q)865502.00/0
© Pergamon Press Ltd. 1978. Printed in Great Britain
In Vitro Effects of Oestrogen on Testosterone Metabolism by Human Breast Cancers W. R. MILLER and A. P. M. FORREST Department of Clinical Surgery, Royal Infirmary, Edinburgh, EH3 9YW, United Kingdom Abstract--The effect of in vitro addition of oestradiol on the metabolism of 7o~3H
testosterone by 15 human breast cancers has been investigated. Oestradiol significantly inhibited metabolism and conversion to 5a dihydrotestosterone, 5~ androstanediol and A4 androstenedione.
shaking at 37°C in an atmosphere of oxygen for two hours. In two tumours oestradiol-3methyl ether (1.5#g/ml) was added to a further incubate as an additional control. The reaction was stopped by the addition of methanol (40ml) and the incubate stored at -- 10°C. Before extracting the metabolites, 500~g each of non-radioactive testosterone, 5a dihydrotestosterone (5a DHT), 5~ androstanediol, A4 androstenedione and oestradiol-17fl were added to each incubate to monitor recovery losses. Details of the methodology for steroid purification by thin layer chromatography and characterisation by chemical derivative formation have been described previously [7]. Metabolism of testosterone was determined by measuring the incorporation of radioactive label into the appropriate metabolites after correction for recovery losses. Statistical comparisons b e tween the results of incubates with and without added oestradiol were performed by paired ttests after logarithmic transformation of the data.
INTRODUCTION
HUMAN breast cancers can metabolise steroid precursors to active hormones such as 50~ dihydrotestosterone [1, 2] and oestradiol-17fl [3, 4]. Whilst the metabolism of testosterone by rat m a m m a r y tumours has been shown to be influenced by oestrogen both in vitro [5] and in vivo [6], little is known about the effects of hormones on steroidogenesis in human tumours. The aira of the present study was to determine in vitro the effect of oestradiol17fl on testosterone metabolism by human breast cancer. MATERIALS
AND METHODS
Tumours from 15 patients with proven cancer of the breast were studied: 10 subjects were at least 5yr postmenopausal, 4 were premenopausal and had regular menstrual periods at the time of investigation. One patient had undergone bilateral oophorectomy 15 months previou,dy. Following excision the tumours, 10 of which were primary carcinomas and 5 recurrence on the chest wall, were processed at 0°C. They were finely sliced and split into duplicate portions each weighing 0.5 g to which Krebs Ringer phosphate buffer pH 7.4 (5ml), an NADPH generating system and 20#Ci 7~3H testosterone (5.7 Ci/mmole from Radiochemical Centre, Amersham) were added. Incubation was then carried out either in the presence of oe,stradiol (1.5#g/ml) or its vehicle (propyleneglycol: ethanol 1 : 1 ) by
RESULTS
The results are presented in Table 1. All 15 cancers converted testosterone to 5a DHT, 50e androstanediol and A4 androstenedione but synthesis of oestradiol was detected in only 8 turnours. In certain tumours, these products represented only a small proportion of the total metabolites; uncharacterized highlypolar compounds being responsible for most of the unidentified material. The addition of oestradiol-17fl to the incubates caused significant inhibition of the metabolism of testosterone (P
