The importance of intracrine estrogen action in hormone dependent diseases

Endometrial cancer and ovarian cancer, which represent a high percentage of all cancers in menopausal or postmenopausal women depend on steroid hormones. Since the progression of a great part of these cancers rely on estrogens, their application in the hormone-replacement therapy for the treatment of menopausal symptoms like hot flashes, night sweats and depression is highly controversial. Because such symptoms occur in as many as 80% of women and may last more than 7 years, phytoestrogens derived from various plants (e.g. soy, red clover or black cohosh) are marketed as a promising "natural" alternative to classical synthetic estrogens and are available as over-the- counter remidies in the United States and Europe. However, the possible risks and adverse effects of these natural compounds after long-term use concerning tumor growth and interference with endogenous estrogen levels and metabolism have not been studied yet in endometrial or ovarian cancers. Therefore, the proposed project will examine for the first time the possible influence of phytoestrogens on endogenous hormone levels and their hormone metabolism in human endometrial and ovarian cancer cells simultaneously quantifying the ten most important estrogens in the presence and absence of phytochemicals by using a highly sophisticated analysing system. Investigations will also emphasize on molecular transporters, which play an important role in the uptake and release of various hormone precursors, active hormones and their metabolites, as well as the assumed inhibitory effect of phytoestrogens on several enzymes involved in steroid hormone biosynthesis and metabolism. For all experiments, cells will be analysed with state-of-the-art molecular biological methods in the presence and absence of phytoestrogens. In order to compare the results of the previous cell culture and tissue sample experiments with the complex processes in patients, blood samples gained from postmenopausal women before and after treatment with phytoestrogens will be analysed and the hormone profiles monitored. These studies are intended to help to understand the interplay between endogenous hormones and therapeutically used natural phytoestrogens. I also aimed to provide more specific information on safety and adverse effects of phytoestrogen treatment, especially concerning hormone-sensitive diseases in postmenopausal women. The findings of this project may also lead to further rational design and synthesis of molecules that would interact with transporters or enzymes and would block proliferation or invasion of cancer cells.The proposed project will be performed in close collaboration between the University of Ljubljana (Faculty of Medicine) and the University of Vienna (Faculty of Life Sciences) in order to combine the expertise of both research groups.

The importance of intracrine estrogen action in hormone dependent diseases Estrogens play a pivotal role in human physiology inducing the progression of breast- and ovarian carcinomas. These hormone-dependent cancers develop mainly in meno- and postmenopausal women for whom treatment of menopausal symptoms with estrogens is of major concern. Women therefore take natural hormone replacement constituents from soy or black cohosh, which are widely available as dietary supplements. However, little is known, whether these supplements may induce tumor growth following continuous consumption. By using a newly established high-resolution mass spectrometry assay it was shown that incubation of human breast cancer cells with the soy isoflavones genistein and daidzein strongly inhibited glucuronidation and sulfation of estrogens even in micromolar or even sub-micromolar concentrations. This lead to a concomitant increase in the level of the most potent estrogen 17-estradiol and a stimulation of hormone-dependent breast cancer cell proliferation. Resveratrol, a chemopreventive phytoestrogen found in grapes, only revealed a modest inhibition of estrogens metabolism. Dietary supplements containing genistein and diazein should not be taken by women with hormone-dependent breast cancer; resveratrol on the other hand seems to be safe. By contrast, treatment of the same breast cancer cells with black cohosh extract and its major constituent actein revealed no changes in the conjugation of estrogens and cancer cell proliferation thereby suggesting that the use of black cohosh supplements by women diagnosed with breast cancer is safe. However, black cohosh extract and actein selectively inhibited sulfation of dehydroepiandrosterone which led to an increased formation of the androgens androstenedione and testosterone, possibly explaining an effect of black cohosh against climacteric vasomotor symptoms, especially hot flashes. Estrogen metabolomics may also be used as a marker to determine cancer resistance against platinum-based drugs as shown in carboplatin-sensitive and carboplatin-resistant ovarian cancer cell lines. Notably, significant inhibition of steroid metabolism was only observed in carboplatin-resistant cells. Altered metabolism of estrogen and androgens may not only be good markers for other tumor but also for hormone-dependent diseases like Crohn's disease.