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(1/67) Urinary 2-hydroxyestrone/16alpha-hydroxyestrone ratio and risk of breast cancer in postmenopausal women.

BACKGROUND: It has been suggested that women who metabolize a larger proportion of their endogenous estrogen via the 16alpha-hydroxylation pathway may be at elevated risk of breast cancer compared with women who metabolize proportionally more estrogen via the 2-hydroxylation pathway. However, the supporting epidemiologic data are scant. Consequently, we compared the ratio of urinary 2-hydroxyestrone (2-OHE1) to 16alphahydroxyestrone (16alpha-OHE1) in postmenopausal women with breast cancer and in healthy control subjects. METHODS: Estrogen metabolites were measured in urine samples obtained from white women who had participated in a previous population-based, breast cancer case-control study at our institution. All P values are from two-sided tests. RESULTS: All of the urinary estrogens measured, with the exception of estriol, were higher in the 66 case patients than in the 76 control subjects. The mean value of urinary 2-OHE1 in case patients was 13.8% (P = .20) higher than that in control subjects, 16alpha-OHE1 was 12.1% (P = .23) higher, estrone was 20.9% higher (P = .14), and 17beta-estradiol was 12.0% higher (P = .36). The ratio of 2-OHE1 to 16alpha-OHE1 was 1.1% higher in the patients (P = .84), contrary to the hypothesis. Compared with women in the lowest third of the values for the ratio of urinary 2-OHE1 to 16alpha-OHE1, women in the highest third were at a nonstatistically significantly increased risk of breast cancer (odds ratio = 1.13; 95% confidence interval = 0.46-2.78), again contrary to the hypothesis. CONCLUSION: This study does not support the hypothesis that the ratio of the two hydroxylated metabolites (2-OHE1/16alpha-OHE1) is an important risk factor for breast cancer.  (+info)

(2/67) Reproducibility of plasma and urinary sex hormone levels in premenopausal women over a one-year period.

Although endogenous sex steroid hormones in premenopausal women may be associated with the risk of breast cancer and other illnesses, direct evidence to support this hypothesis is limited in large part by methodological issues in the conduct of relevant studies. One major unresolved issue is whether a single blood sample (such as is available in most epidemiological studies), collected in a specific phase of the menstrual cycle, reflects long-term levels in that phase. To address this issue, two sets of blood and urine samples were obtained from 87 premenopausal women over a 1-year period in both the follicular and luteal phases. Plasma estradiol, estrone, and estrone sulfate were measured in the blood samples obtained in both phases, whereas progesterone and urinary 2- and 16a-hydroxyestrone were measured in luteal-phase samples only. For all of the women combined, intraclass correlation coefficients (ICCs) ranged, with one exception, from 0.52 to 0.71 for the plasma estrogens and the urinary estrogen metabolites. The sole exception was for estradiol in the luteal phase (ICC = 0.19); inclusion of only women who were ovulatory in both cycles and who collected each sample 4-10 days before their next period resulted in a substantially higher ICC for estradiol in the luteal phase (ICC = 0.62; 95% confidence interval, 0.43-0.78). These data indicate that, for several plasma and urinary sex hormones, a single follicular- or luteal-phase measurement in premenopausal women is reasonably representative of hormone levels in that phase for at least a 1-year period.  (+info)

(3/67) A new ELISA kit for measuring urinary 2-hydroxyestrone, 16alpha-hydroxyestrone, and their ratio: reproducibility, validity, and assay performance after freeze-thaw cycling and preservation by boric acid.

There is considerable controversy regarding the role of estrogen metabolites in breast cancer risk, fueled in part by the development of a rapid ELISA that is suitable for large scale investigations. An earlier version of the ELISA could detect values of the 2-hydroxyestrone (2-OHE1) and 16alpha-hydroxyestrone (16alpha-OHE1) metabolites as low as 2 ng/ml and produce consistent results in premenopausal urines. However, reproducibility was problematic in postmenopausal urines where concentrations of these compounds are much lower. In response to our concern, a new ELISA was developed with a sensitivity of 0.625 ng/ml, which we evaluated using the same pre- and postmenopausal urine samples analyzed in the earlier ELISA. In this report, we present findings on the new kit with regard to reproducibility of the 2-OHE1 and 16alpha-OHE1 measurements, comparability of results with gas chromatography-mass spectroscopy values, and with regard to the stability of the metabolites after repeated freeze-thaw cycles and after preservation by boric acid. For the most part, we found the new ELISA to be reproducible, with assay coefficients of variation ranging from 10 to 20%, and intraclass correlation coefficients (ICCs) ranging from 80 to 95% in both the pre- and postmenopausal urines. ELISA results for 16alpha-OHE1 differed from 1 day (i.e., batch) to the next, and the absolute values of the metabolites obtained by the ELISA were consistently lower than but well correlated with those obtained by gas chromatography-mass spectroscopy. Values of the 2-OHE1:16alpha-OHE1 ratio also differed between the methods, but because the range of values was not large, the magnitude of these differences was not as great. For the ratio, the correlation between methods was excellent, and the ICCs were high for both groups of women. After preservation by boric acid, values of the ratio varied according to acid concentration but not in a linear fashion. Ratio values were similar in urine samples exposed to four different freeze-thaw cycle treatments, although values for all treatments were consistently lower in one batch. Because batch-to-batch variability was not negligible, it is advisable that matched cases and controls be analyzed in the same batch. Provided this is done, the relatively low assay coefficient of variation and high ICC demonstrate that the new ELISA kit can reliably measure the 2-OHE1:16alpha-OHE1 ratio and detect small case-control differences in large population-based studies, where rapid and relatively easy laboratory methods are critical.  (+info)

(4/67) Increased urinary excretion of 2-hydroxyestrone but not 16alpha-hydroxyestrone in premenopausal women during a soya diet containing isoflavones.

Asian diets high in soy are associated with lower risk for breast cancer compared with Western diets. Moreover, higher levels of two putative carcinogenic metabolites of 17beta-estradiol, 4- and 16alpha-hydroxyestrogen, and lower amounts of anticarcinogenic metabolites, 2-hydroxyestrogens, have been associated with greater breast cancer risk. In this study, we tested the hypothesis that consumption of a soya diet containing the weakly estrogenic isoflavones genistein and daidzein may alter the metabolism of 17beta-estradiol to 2- and 16alpha-hydroxylated products. Eight pre-menopausal women were placed on a soya-containing, constant diet in a metabolic unit. The diet provided 400 kilocalories from soymilk and 113-202 mg/day (158 +/- 26 mg/day, mean +/- SD) isoflavones daily for a complete menstrual cycle. After a washout period of 4 months, the subjects consumed the same diet, but with soymilk that contained <4.5 mg/day isoflavones ("isoflavone-free"). Urine samples were collected for 24 h daily for the entire cycle during each soya diet period for the analysis of daidzein, genistein, and 2- and 16alpha-hydroxyestrone. Subjects excreted measurable amounts of daidzein (11.6-39.2 mg/day) and genistein (2.9-18.2 mg/day) during the isoflavone-rich soya diet but not during the isoflavone-free soya diet. The diet rich in isoflavones increased the cycle mean daily urinary excretion of 2-hydroxyestrone (averaged over the entire cycle) from 11.6 +/- 2.06 to 17.0 +/- 2.96 nmol/12-h (P = 0.03), a 47% increase. However, the mean daily excretion of 16alpha-hydroxyestrone did not change (7.0 +/- 1.14 nmol/12-h during the isoflavone-free and 7.7 +/- 1.25 nmol/12-h during the isoflavone-rich diet; P = 0.36). The ratio of 2-hydroxyestrone to 16alpha-hydroxyestrone was higher during the isoflavone-rich soya diet (2.6 +/- 0.34) than during the isoflavone-free diet (2.0 +/- 0.32; P = 0.01), a 27% increase. These results suggest that soya isoflavones increase the metabolism of endogenous estrogens to the protective 2-hydroxylated estrogens in women, and this may play an important role in lowering 17beta-estradiol levels and the long-term risk for breast cancer.  (+info)

(5/67) Brassica vegetable consumption shifts estrogen metabolism in healthy postmenopausal women.

Previous studies suggest that the estrogen metabolite 16alpha-hydroxyestrone acts as a breast tumor promoter. The alternative product of estrogen metabolism, 2-hydroxyestrone, does not exhibit estrogenic properties in breast tissue, and lower values of the ratio 2-hydroxyestrone:16alpha-hydroxyestrone (2:16) in urine may be an endocrine biomarker for greater breast cancer risk. Vegetables of the Brassica genus, such as broccoli, contain a phytochemical, which may shift estrogen metabolism and increase the 2:16 ratio. Adding 500 g/day of broccoli to a standard diet shifts 2:16 values upward in humans; however, it is unknown as to whether healthy women are able to consume a sufficient quantity of Brassica to affect breast cancer risk through this mechanism. In this study, 34 healthy postmenopausal women participated in an intensive intervention designed to facilitate the addition of Brassica to the daily diet. The diet was measured by repeated 24-h recall, and estrogen metabolites were measured by enzyme immunoassay in 24-h urine samples. In a crude analysis, there was a nonsignificant increase in the urinary 2:16 ratio associated with greater Brassica consumption. With adjustment for other dietary parameters, Brassica vegetable consumption was associated with a statistically significant increase in 2:16 values, such that for each 10-g/day increase in Brassica consumption, there was an increase in the 2:16 ratio of 0.08 (95% confidence interval, 0.02-0.15). To the extent that the 2:16 ratio, as measured in urine, is associated with breast cancer risk, future research should consider Brassica vegetable consumption as a potentially effective and acceptable dietary strategy to prevent breast cancer.  (+info)

(6/67) Differential effects of estrone and estrone-3-O-sulfamate derivatives on mitotic. Arrest, apoptosis, and microtubule assembly in human breast cancer cells.

There is considerable interest in the potential use of estrogen derivatives for the treatment and prevention of breast cancer. We demonstrated previously that the sulfamoylated estrone derivative 2-methoxyestrone-3-O-sulfamate (2-MeOEMATE) induced G2-M cell cycle arrest and modest levels of apoptosis in breast cancer cells in vitro, whereas the parent estrone derivative, 2-methoxyestrone, did not. 2-MeOEMATE also induced breast tumor regression in vivo in intact rats. To further explore the significance of sulfamoylation on the anticancer activity of estrone derivatives and to elucidate their mechanism of action, we synthesized two additional agents, 2-ethylestrone and 2-ethylestrone-3-O-sulfamate (2EtEMATE). 2-MeOEMATE and 2-EtEMATE inhibited the growth of a panel of estrogen receptor-negative and -positive breast cancer cell lines in vitro, induced mitotic arrest and apoptosis, and suppressed the long-term clonogenic potential of MCF7 and CAL51 breast cancer cells. In each assay, the sulfamoylated estrone derivatives were >10-fold more potent than their parent compounds. The sulfamoylated estrone derivatives were also significantly more potent inhibitors of cell growth than the previously studied endogenous estradiol metabolite 2-methoxyestradiol. 2-MeOEMATE and 2-EtEMATE functioned as antimicrotubule agents and inhibited the ability of paclitaxel to promote tubulin assembly in vitro. Like other antimicrotubule agents, the sulfamoylated estrone derivatives induced BCL-2 and BCL-XL phosphorylation and increased p53 expression. 2-MeOEMATE and 2-EtEMATE are novel antimicrotubule agents that have potent anticancer activity in breast cancer cells in vitro and may be beneficial as anticancer agents in vivo.  (+info)

(7/67) The catechol estrogen, 4-hydroxyestrone, has tissue-specific estrogen actions.

Recent data indicate that the catechol estrogen, 2-hydroxyestrone (2-OHE(1)), has no effect on any target tissue including bone, whereas 16 alpha-hydroxyestrone (16 alpha-OHE(1)) exerts tissue-selective estrogen agonist activity. The effect of the catechol estrogen, 4-hydroxyestrone (4-OHE(1)), putatively associated with tumorigenesis, has not been studied in the skeleton. The purpose of this study was to assess the effect of 4-OHE(1) on tibia, uterine and mammary gland histology and blood cholesterol in ovariectomized (OVX'd) growing rats. Ten-week-old female Sprague-Dawley rats were injected subcutaneously with 200 microg/kg BW per day with 4-OHE(1), 17 beta-estradiol (E(2)) or vehicle for three weeks. OVX resulted in uterine atrophy, increased body weight, radial bone growth and cancellous bone turnover, and hypercholesterolemia. E(2) prevented these changes with the expected exception that the subcutaneous infusion of this high dose of estrogen did not prevent the hypercholesterolemia. 4-OHE(1) prevented the increase in blood cholesterol and the increase in body weight. 4-OHE(1) appeared to have partial estrogen activity in the uterus; uterine weight and epithelial cell height were significantly greater than the OVX rats but significantly less (twofold) than the E(2) animals. Analysis of variance indicated that 4-OHE(1) slightly decreased the periosteal mineral apposition rate (P<0.05) compared with vehicle-treated rats but had no effect on double-labeled perimeter or bone formation rate. Similarly, 4-OHE(1) was a partial estrogen agonist on cancellous bone turnover. The data suggest that the catechol estrogen, 4-OHE(1), unlike 2-OHE(1), has estrogen activity. Furthermore, the profile of activity differs from that of 16 alpha-OHE(1). Our results suggest that estrogen metabolites may selectively influence estrogen-target tissues and, concomitantly, modulate estrogen-associated disease risk.  (+info)

(8/67) Oestrogen and progesterone increase the levels of apoptosis induced by the human papillomavirus type 16 E2 and E7 proteins.

Human papillomavirus (HPV) type 16 infects the genital tract and is generally acknowledged to be a causative agent of cervical cancer. HPV infection alone is not sufficient to induce cervical cancer and other factors such as steroid hormones are thought to play a role in the establishment and/or progression of this disease. The HPV-16 E2 protein is required for virus replication and modulates viral gene expression whereas the HPV-16 E7 protein is required for cell transformation. We and others have shown that both the E2 and E7 proteins can induce apoptotic cell death in HPV-transformed and non-HPV transformed cell lines. Here we show that the steroid hormones oestrogen and progesterone can both increase the levels of E2- and E7-induced apoptosis. The oestrogen metabolite 16 alpha-hydroxyoestrone also increases E2- and E7-induced cell death and the dietary component indole-3-carbinol, which reduces the formation of 16alpha-hydroxyoestrone from oestrogen, blocks the effects of oestrogen. Thus the metabolism of oestrogen to 16 alpha-hydroxyoestrone appears to be required for the effects of this hormone on E2- and E7-induced cell death. We also show that the oestrogen receptor antagonist 3-hydroxytamoxifen blocks the effects of oestrogen on E2- and E7-induced cell death, whereas the anti-progesterone RU486 blocks the effects of both progesterone and oestrogen. We discuss these results in terms of the origin and progression of cervical cancer.  (+info)