Jadwiga Szymczak

Concentration of sex steroids in adipose tissue after menopause.

Adipose tissue is a site of uptake, storage, action, and metabolism of sex steroids. After menopause aromatization of androgens to estrogens in adipose tissue is one of the most important sources of estrogen in the circulation and for peripheral tissues. The aim of this study was to estimate local sex steroid concentrations in breast and abdominal subcutaneous (s.c.) adipose tissue, to compare them with plasma concentrations and to investigate possible correlations with body mass index (BMI). The patients were postmenopausal women undergoing surgery for non-oncological reasons (Group A; n = 35) and breast cancer patients (group B; n = 19). The concentrations of estrone, 17 beta-estradiol, estrone sulfate, 17 beta-estradiol sulfate, androstenedione, androstenediol (androst-5-ene-3 beta, 17 beta-diol), testosterone and dehydroepiandrosterone were measured. The method was based on frozen tissue homogenization, extraction with ethanol: acetone, delipidation, extraction of estrogens with ether, and of androgens with iso-octane in toluene, followed by RIA. The mean levels of steroids were higher in fat than in plasma, apart from testosterone. Levels of sulfates of estrogens and androstenediol were higher in breast than abdominal adipose tissue, and levels of estradiol lower. Positive correlations were found between BMI and tissue and plasma concentration of both estrone and androstenedione.

Intratumoral levels of estrogens in breast cancer

Breast cancer tissue is an endocrine organ and particularly the estrogen biosynthetic properties of this tissue have been well studied. The concentration of estradiol in breast cancer tissue from postmenopausal patients is considerably higher than that in the circulation and appears to depend largely on local production. Androgenic precursor steroids are abundantly present, but estrogen storage pools like fatty acid derivatives appear to be less important than initially thought. New, potent and highly specific aromatase inhibitors effectively inhibit peripheral conversion of androgens to estrogens (Cancer Res. 53: 4563, 1993) as well as intratumour aromatase, median aromatase activity being 89% lower in the tissue from patients pretreated with aromatase inhibitor 7 days prior to surgery (P < 0.001). Also the intratissue concentrations of estrogens were decreased (64% and 80% reduction, respectively for estrone and estradiol; P = 0.001 and <0.05; Cancer Res. 57: 2109, 1997). These results illustrate that intratissue estrogen biosynthesis is effectively inhibited by the new generation of aromatase inhibitors. The pathophysiological consequences of this finding are currently under study.

Plasma adiponectin concentration in relation to severity of coronary atherosclerosis and cardiovascular risk factors in middle-aged men.

Adiponectin, an adipocyte-derived protein, seems to be a link between obesity, insulin resistance, and atherosclerosis. The present study investigated the association between adiponectin and coronary artery disease in middle-aged men. Material and methods: We examined 48 men (aged 40–60) with angiographically confirmed coronary atherosclerosis and 19 healthy men, matched by age, as a control group. Concentrations of glucose and lipids were estimated with enzymatic methods. Plasma level of adiponectin, total and free testosterone, estradiol, estrone, DHEA-S, and insulin were estimated with RIA commercial kits. Results: Men with coronary atherosclerosis had lower plasma adiponectin level than controls (16.2±9.2 vs 20.5±6.7 µg/mL; p<0.05). However, after including BMI and waist as covariate data in ANCOVA, the difference in adiponectin levels between men with CAD and controls lost statistical significance (respectively for BMI and waist: p=0.4 and p=0.7). Moreover, although not significant, adiponectin levels decreased as a function of the number of significantly narrowed coronary arteries. In a priori comparison the lowest adiponectin plasma concentration was in men with three-vessel coronary artery disease (14.3±9.8 µg/mL) and the highest in controls (20.5±6.8 µg/mL; p=0.09). Adiponectin plasma level correlated negatively (p<0.05) with BMI, waist, percentage of total fat, fasting-insulin-resistance index (FIRI), total cholesterol and triglycerides, and positively with quantitative insulin sensitivity check index (QUICKI), HDL cholesterol, total testosterone, and total testosterone/estradiol ratio. Conclusions: Our data suggest that low plasma adiponectin level is connected with insulin resistance syndrome and atherogenic lipid profile. It seems that adiponectin plays a role in pathogenesis of coronary atherosclerosis, especially in obese and insulin-resistant subjects.

Estrogens in plasma and fatty tissue from breast cancer patients and women undergoing surgery for non-oncological reasons

Breast cancer tissue is able to maintain the tissue estradiol level in spite of the massive decrease in plasma estradiol associated with menopause, whereas fatty tissue from breasts with malignancies more closely reflects the changes in plasma. In the present study estrone and estradiol levels in fatty tissues from different origins were compared to evaluate the capacity of distant fatty tissues to act as estrogen reservoirs. Abdominal fat was obtained from 25 premenopausal and 20 postmenopausal women who underwent surgery for non-oncological reasons. Estrone and estradiol levels in these tissues were compared to those in breast fatty tissue from breast cancer patients. Plasma estrogen levels were not different in the two groups. In both groups, median plasma estradiol levels dropped sharply with menopause (from 363 to 40 pmol/l in breast cancer patients; from 280 to 45 pmol/l in the non-oncological patients; p less than 0.002), whereas a significant decrease in plasma estrone was observed only in the breast cancer patients (from 238 to 140 pmol/l; p less than 0.02). In premenopausal women, median estrone and estradiol levels in breast fatty tissue (1135 and 375 fmol/g, respectively) and abdominal tissue (1390 and 470 fmol/g, respectively) were not different. In postmenopausal women, however, significantly higher estrone levels (663 vs. 508 fmol/g; p less than 0.01) and estradiol levels (245 vs. 187 fmol/g; p less than 0.02) were found in abdominal fatty tissue. In view of the absolute estrogen levels in breast and abdominal fatty tissue and in plasma, we conclude, however, that it is unlikely that remote fat contributes substantially to the maintenance of estrogen levels in breast cancer tissue.