Breast cancer: a comparison of response to endocrine therapy and oestrogen excretion patterns including unusual metabolites

Nutrition, aging and cancer: lessons from dietary intervention studies

There is convincing epidemiological and clinical evidence that, independent of aging, lifestyle and, notably, nutrition are associated with development or progression of major human cancers, including breast, prostate, colorectal tumors, and an increasingly large collection of diet-related cancers. Mechanisms underlying this association are mostly related to the distinct epigenetic effects of different dietary patterns. In this context, Mediterranean diet has been reported to significantly reduce mortality rates for various chronic illnesses, including cardiovascular diseases, neurodegenerative diseases and cancer. Although many observational studies have supported this evidence, dietary intervention studies using a Mediterranean dietary pattern or its selected food components are still limited and affected by a rather large variability in characteristics of study subjects, type and length of intervention, selected end-points and statistical analysis. Here we review data of two of our intervention studies, the MeDiet study and the DiMeSa project, aimed at assessing the effects of traditional Mediterranean diet and/or its component(s) on a large panel of both plasma and urine biomarkers. Both published and unpublished results are presented and discussed.

Estrogen and prostate cancer: an eclipsed truth in an androgen-dominated scenario

Prostate cancer is the commonest non-skin cancer in men. Incidence and mortality rates of this tumor vary strikingly throughout the world. Although several factors have been implicated to explain this remarkable variation, lifestyle and dietary factors may play a dominant role, with sex hormones behaving as intermediaries between exogenous factors and molecular targets in development and progression of prostate cancer. Human prostate cancer is generally considered a paradigm of androgen-dependent tumor; however, estrogen role in both normal and malignant prostate appears to be equally important. The association between plasma androgens and prostate cancer remains contradictory and mostly not compatible with the androgen hypothesis. Similar evidence apply to estrogens, although the ratio of androgen to estrogen in plasma declines with age. Apart from methodological problems, a major issue is to what extent circulating hormones can be considered representative of their intraprostatic levels. Both nontumoral and malignant human prostate tissues and cells are endowed with key enzymes of steroid metabolism, including 17betahydroxysteroid dehydrogenase (17betaHSD), 5beta-reductase, 3alpha/3betaHSD, and aromatase. A divergent expression and/or activity of these enzymes may eventually lead to a differential prostate accumulation of steroid derivatives having distinct biological activities, as it occurs for hydroxylated estrogens in the human breast. Locally produced or metabolically transformed estrogens may differently affect proliferative activity of prostate cancer cells. Aberrant aromatase expression and activity has been reported in prostate tumor tissues and cells, implying that androgen aromatization to estrogens may play a role in prostate carcinogenesis or tumor progression. Interestingly, many genes encoding for steroid enzymes are polymorphic, although only a few studies have supported their relation with risk of prostate cancer. In animal model systems estrogens, combined with androgens, appear to be required for the malignant transformation of prostate epithelial cells. Although the mechanisms underlying the hormonal induction of prostate cancer in experimental animals remain uncertain, there is however evidence to support the assumption that long term administration of androgens and estrogens results in an estrogenic milieu in rat prostates and in the ensuing development of dysplasia and cancer. Both androgen and estrogen have been reported to stimulate proliferation of cultured prostate cancer cells, primarily through receptor-mediated effects. As for estrogens, the two major receptor types, ERalpha and ERbeta, are expressed in both normal and diseased human prostate, though with a different cellular localization. Since these two receptors are different in terms of ligand binding, heterodimerization, transactivation, and estrogen response element activity, it is likely that an imbalance of their expression may be critical to determine the ultimate estrogen effects on prostate cancer cells. In prostate cancer, ERbeta activation appears to limit cell proliferation directly or through ERalpha inhibition, and loss of ERbeta has been consistently associated with tumor progression. Several splicing variants of both ERalpha and ERbeta exist. Little is known about their expression and function in the human prostate, although reciprocal regulation and interaction with gene promoter both warrant further investigation. In summary, although multiple consistent evidence suggests that estrogens are critical players in human prostate cancer, their role has been only recently reconsidered, being eclipsed for years by an androgen-dominated interest.

A traditional Mediterranean diet decreases endogenous estrogens in healthy postmenopausal women

Breast cancer incidence and mortality rates are markedly lower in the south than in the north of Europe. This has been ascribed to differences in lifestyle and, notably, dietary habits across European countries. However, little information exists on the influence of different dietary regimens on estrogens and, hence, on breast cancer risk. Here we report results of our MeDiet Project, a randomized, dietary intervention study aimed to assess the effect of a Mediterranean diet on the profiles of endogenous estrogens in healthy postmenopausal women. Out of the 230 women who initially volunteered to participate in the study, 115 were found to be eligible and were enrolled. Women were then randomly assigned into an intervention (n = 58) and a control (n = 57) group. Women in the intervention group adhered to a traditional, restricted Mediterranean diet for 6 mo, whereas women in the control group continued to follow their regular diet. Women in the intervention group changed their dietary regimen substantially, and this eventually led to a shift from a prevalent intake of animal fat and proteins to a prevalent intake of vegetable fat and proteins. Regarding urinary estrogens, no significant difference was observed between the intervention and control groups at baseline. After 6 mo, however, control women did not show any major change but women in the intervention group exhibited a significant decrease (over 40%) of total estrogen levels (P < 0.02). The largest part of this modification was based on a marked decrease of specific estrogen metabolites, including hydroxy- and keto-derivatives of estradiol or estrone. To our knowledge, this is the first report to show that a traditional Mediterranean diet significantly reduces endogenous estrogen. This may eventually lead to identify selected dietary components that more effectively decrease estrogens levels and, hence, provide a basis to develop dietary preventive measures for breast cancer.

Oxidative and reductive pathways of estrogens in hormone responsive and non-responsive human breast cancer cells in vitro

In order to measure the formation and degradation rates of estradiol by human breast cancer cells, after assessing the biochemical basis of hormone responsiveness and growth response to estrogens, we considered both responsive, estrogen receptor (ER) positive, and non-responsive, ER-negative, breast cancer cell lines, i.e. MCF7, ZR75-1 and MDA-MB231. To this end, we employed a novel "intact cell" approach which allows us, after 24 h incubation, to analyze several enzyme activities in sequence, concurrently with the monitoring of labeled precursor degradation. Our investigations led to the following evidence: (a) the reductive activity of the 17 beta-hydroxysteroid oxoreductase (17 beta-HSOR) appears to be higher than the oxidative only in responsive, ER-rich MCF7 and ZR75-1 cells, as also previously observed by others; (b) this activity is, on the contrary, much lower in MDA-MB231 cells and other unresponsive, ER-poor breast cancer cell lines; (c) conversely, the oxidative activity shows an opposite pattern, being limited in MCF7 and ZR75-1 cells and much higher in MDA-MB231 cells. Overall, a 17 beta-HSOR reductive pathway prevails in both MCF7 and ZR75-1 cells, whilst the oxidative pathway is prevalent in MDA-MB231 cells, leading to a large formation of estrone that is no further metabolized, at least in the experimental conditions used. Our results may provide a likely explanation of previous data on the different estrogen content of breast tumor tissues.

Steroid profiles and optimization of high-performance liquid chromatographic analytic procedure

This paper presents a short review of the results obtained to date in our laboratory, with respect to the studies of steroid excretion profiles in both breast and endometrial cancer patients, by using gas-liquid chromatographic analysis. These data demonstrate the importance of minor estrogens, including catechol estrogens, and of their ratios with the classical ones, in studies of steroid metabolism in both breast and endometrial cancer. New data concerning postmenopausal endometrial cancer are consistent with our previous observations and demonstrate the necessity of measuring these steroids directly in tumors and examining patterns of metabolism in vitro. In order to analyze steroid metabolic patterns in vitro, however, high-performance liquid chromatography rather than gas-liquid chromatography methods are preferable on account of their selectivity, specificity, sensitivity and capacity to handle labile materials. With the aim of providing methods suitable for the complete resolution and analysis of these complex natural mixtures a method of computer-aided optimization of HPLC has been developed and its practical utility has been tested.

Modulation of oestrogen excretion profiles by adjuvant chemotherapy in pre- and postmenopausal breast cancer

Modulation of steroid status by conventional chemotherapy was studied in 31 breast cancer patients receiving CMF and in 31 age-matched breast cancer patients without any therapy, taken as controls. This was achieved through the study of oestrogen excretion profiles using previously identified parameters and referring not only to classical but also to the "other", namely catechol and unusual, oestrogen metabolites. After CMF treatment the premenopausal patients exhibit a modified excretion pattern, mainly concerning a marked and significant reduction of classical oestrogens, as shown by pattern indices. Because there is evidence that oestriol metabolism is not markedly affected by CMF treatment, such a significant decrease in classical oestrogens must be attributed to the secretory function, presumably ovarian ab origine. To the contrary, after treatment, pattern indices show significantly higher median values in postmenopausal patients. Mean oestriol ratio values also display a significant increase, thus supporting the hypothesis that conventional cytotoxic drugs may act by enhancing oestrogen metabolic rates. In fact, the postmenopausal treated subgroup proved to have significantly higher excretion levels of most of the oestrogens considered to date. Surprisingly, E1 + E1-S fractions were strongly reduced in this subgroup and this leads to the suggestion of an increased steroid metabolic rate by CMF treatment. However, comparing 9 breast cancer patients, when having had both short-term and non-short-term CMF treatment, the effects on steroid excretion patterns appear to arise at an early stage.