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Local aromatase activity in human breast tissues
J H Thijssen1, J Daroszewski, A Milewicz
1Department of Endocrinology, University Hospital, Utrecht, The Netherlands.
Summary
High intra-tissue oestradiol concentrations fuel malignant breast tumor growth. This study investigated local aromatase activity and steroid levels, but the precise mechanisms regulating breast tissue oestradiol remain elusive.
Area of Science:
- Endocrinology
- Oncology
- Biochemistry
Background:
- Oestradiol presence in malignant breast cells promotes tumor growth.
- Local intra-tissue oestradiol concentrations, independent of plasma levels, are critical.
- In situ oestrogen biosynthesis is implicated in local oestradiol accumulation.
Purpose of the Study:
- To investigate the regulation of local oestradiol concentrations in breast tissues.
- To measure local aromatase activities and steroid concentrations in fatty and tumor tissues.
- To determine the localization of aromatase and steroid levels in different breast quadrants.
Main Methods:
- Measurement of aromatase activities in vitro.
- Quantification of androgen and oestrogen concentrations in dissected adipose and tumor tissues.
- Analysis of steroid concentrations and aromatase activity in various breast tissue quadrants.
Main Results:
- Small variations in steroid concentrations were found in adipose tissues.
- No tumor-directed gradients of androgens or oestrogens were detected in adipose tissue.
- No consistent pattern in aromatase activity was observed between tumor-bearing and non-affected breast quadrants.
- No correlations were found between in vitro aromatase activity and in vivo product concentrations.
Conclusions:
- The mechanisms responsible for regulating local oestradiol levels in breast tissues are currently unknown.
- Further research is needed to elucidate the complex factors controlling intra-tissue oestradiol concentrations in breast cancer.