Diallyl sulfide inhibits diethylstilbesterol-induced DNA adducts in the breast of female ACI rats
2005 Study Abstract
Diethylstilbestrol (DES) is metabolized to reactive intermediates that produce DNA adducts and ultimately cancer. Diallyl sulfide (DAS) has been shown to inhibit the metabolism of several procarcinogens.
The ability of DES to produce DNA adducts in microsomal, mitochondrial, and nuclear in vitro metabolic systems and in the breast of female ACI rats, as well as ability of DAS to inhibit DNA adducts were investigated.
Microsomes, mitochondria, and nuclei isolated from breast tissue of female ACI rats were used to catalyze oxidation reactions. Female ACI rats were treated i.p. as follows: (1) corn oil, (2) 200mg/kg DES, (3) 200mg/kg DES/200mg/kg of DAS, (4) 200mg/kg DES/400mg/kg DAS. DES produced DNA adducts in each metabolic system. The relative adduct levels were 2.1 x 10(-4), 6.2 x 10(-6), and 2.9 x 10(-7) in microsomal, mitochondrial, and nuclear reactions, respectively. DAS inhibited DNA adducts in each metabolic system. The percent inhibition ranged from 86% in microsomes to 93% in nuclei.
DES produced DNA adducts in mtDNA and nDNA. DAS completely inhibited the DES-induced mtDNA adducts and caused a dose dependent decrease in nDNA adduct formation.
These findings suggest that DAS could inhibit DES-induced breast cancer by inhibiting its metabolism.
Diallyl sulfide inhibits diethylstilbesterol-induced DNA adducts in the breast of female ACI rats, Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, NCBI PubMed PMID: 15989972, 2005 Sep.
In 1971, the US Food and Drug Administration contraindicated its use in pregnancy when DES was associated with the development of vaginal clear cell adenocarcinoma (CCA) in daughters exposed in utero.
In daughters whose mothers took DES during pregnancy, the drug has been associated with congenital malformations of the reproductive tract, fertility problems, a possible increased risk of cervical carcinoma in situ, and a presumed lifetime risk of vaginal and cervical CCA.
DES mothers have an increased risk of breast cancer (RR = 1.3).
DES sons have an increased prevalence of urogenital anomalies, and a possible increased risk of testicular cancer.
DES exposure and the aging woman: mothers and daughters, Current women’s health reports, NCBI PubMed PMID: 12215312, 2002 Oct.
Can estrogenic radicals, generated by lactoperoxidase, be involved in the molecular mechanism of breast carcinogenesis?
2000 Study Abstract
Mutations of regulatory genes, which perturb the mechanism of cell replication resulting in abnormal cell proliferation, are the main cause of cancer.
Many endogenous and exogenous chemicals (including estrogenic hormones) are known to represent a major carcinogenic risk for humans. 2-OH- and 4-OH-derivatives of estrogenic molecules have been shown to form stable adducts with purine DNA bases and act as ‘depurinating’ agents, thus altering gene transcription.
Lactoperoxidase (LPO), which is produced by mammary glands, is likely to be involved in breast carcinogenesis, because of its ability to interact with estrogenic hormones and oxidise them through two one-electron reaction steps.
We investigated the reactivity of LPO towards five molecules:
17-beta-estradiol (a natural hormone),
diethylstilbestrol (a synthetic drug, supplied to pregnant women for preventing spontaneous abortion),
exestrol (a synthetic antigonadotropic estrogen),
and 4-OH-estradiol (catabolic products of estradiol).
Enzymatically generated radical derivatives of such molecules were stabilized by spin-trapping or by chelation of a diamagnetic metal ion and characterized with EPR spectroscopy. A kinetic study of the oxidation process was carried out using EPR and UV-visible spectroscopy.
Can estrogenic radicals, generated by lactoperoxidase, be involved in the molecular mechanism of breast carcinogenesis?, Redox report : communications in free radical research, NCBI PubMed PMID: 10994878, 2000.
DES induces in HBEC phenotypic changes indicative of cell transformation, associated with significant genomic alterations
2001 Study Abstract
Epidemiological and clinical evidences indicate that breast cancer risk is associated with prolonged ovarian function that results in elevated circulating levels of steroid hormones. Principal among these is estrogen, which is associated with two important risk factors, early onset of menarche and late menopause.
However, up to now there is no direct experimental evidence that estrogens are responsible of the initiation of human breast cancer. We postulate that if estrogens are causative agents of this disease, they should elicit in human breast epithelial cells (HBEC) genomic alterations similar to those exhibited by human breast cancers, such as DNA amplification and loss of genetic material representing tumor suppressor genes. These effects could result from binding of the hormone to its nuclear receptors (ER) or from its metabolic activation to reactive metabolites.
This hypothesis was tested by treating with the natural estrogen 17beta-estradiol (E2) and the synthetic steroid diethylstilbestrol (DES) MCF-10F cells, a HBEC line that is negative for ER. Cells treated with the chemical carcinogen benzo (a) pyrene (BP) served as a positive control of cell transformation.
BP-, E2-, and DES-treated MCF-10F cells showed increases in survival efficiency and colony efficiency in agar methocel, and loss of ductulogenic capacity in collagen gel. The largest colonies were formed by BP-treated cells, becoming progressively smaller in DES- and E2-treated cells. The loss of ductulogenic capacity was maximal in BP-, and less prominent in E2- and DES-treated cells. Genomic analysis revealed that E2- and DES-treated cells exhibited loss of heterozygosity in chromosomes 3 and 11, at 3p21, 3p21-21.2, 3p21.1-14.2, and 3p14.2 14.1, and at 11q23.3 and 11q23.1-25 regions, respectively. It is noteworthy that these loci are also affected in breast lesions, such as ductal hyperplasia, carcinoma in situ, and invasive carcinoma.
Our data are the first ones to demonstrate that estrogens induce in HBEC phenotypic changes indicative of cell transformation and that those changes are associated with significant genomic alterations that might unravel new pathways in the initiation of breast cancer.
Carcinogenicity of estrogens in human breast epithelial cells, APMIS : acta pathologica, microbiologica, et immunologica Scandinavica, NCBI PubMed PMID: 11297193, 2001 Jan.
Experimental study on relationship between exogenous estrogen and breast cancer risk
1997 Study Abstract
OBJECTIVE To investigate the relationship between exogenous estrogen and breast cancer risk.
METHODS Female rats were randomly divided into three groups, namely diethylstilbestrol (DES), norethindrone compositae (CoNET) and control group. The histological structure and ultrastructural changes of mammae were observed. The levels of sexual hormones in serum were determined and the AgNOR counts, DNA contents and steroid receptor contents in mammary epithelium were also detected.
RESULTS In DES group, the level of progesterone (10.38 ng/ml) was obviously lower than that in the control group (13.37 ng/ml); the incidence of hyperplasia of mammary gland (73.33%) was significantly higher than that in the control group (7.69%); and the degree of hyperplasia was obviously more serious than that in the control group. Moreover, there were 13.33% of rats with atypical hyperplasia in DES group. The DNA contents, AgNOR counts and estrogen receptor (ER) positive rate were markedly higher in DES group (95.60, 2.43 and 71.71% respectively) than in the control group (83.07, 1.88 and 40% respectively). However, in CoNET group, there were no obvious influences on ER, AgNOR and DNA in mammary epithelium.
CONCLUSIONS Exogenous estrogen (DES) could affect the levels of sexual hormones in serum, accelerate the DNA duplication, increase the AgNOR counts and ER contents, and induce atypical hyperplasia and ultrastructural changes of mammary gland, hence becoming a latent risk factor of breast cancer. However, the results failed to suggest that the contraceptive, CoNET, could increase the risk of breast cancer.
Experimental study on relationship between exogenous estrogen and breast cancer risk, Chinese medical journal, NCBI PubMed PMID: 9594309, 1997 May.
Diethylstilbestrol and risk of fatal breast cancer in a prospective cohort of US women
1996 Study Abstract
The authors examined the association between the use of diethylstilbestrol during pregnancy and the risk of subsequent fatal breast cancer in a large prospective study of US adults.
After 9 years of follow-up, 1,574 cases of fatal breast cancer were observed among 501,536 gravid women who reported no prior history of cancer in 1982.
Results from Cox proportional hazards models showed a positive association between a history of diethylstilbestrol exposure (reported by 3.9% of all women) and fatal breast cancer (adjusted rate ratio = 1.34, 95% confidence interval 1.06-1.69). This excess risk did not increase over time; women who were exposed more than 35 years ago (rate ratio = 1.35, 95% confidence interval 0.97-1.87) were not at greater risk than women who were exposed within the past 35 years (rate ratio = 1.39, 95% confidence interval 1.01-1.93). The positive association was not observed in women who used diethylstilbestrol before age 25 years but was seen at all other ages. The age of study participants did not modify the association between exposure and breast cancer, and there were no significant interactions between ever use of diethylstilbestrol and any of the other potential risk factors included in the analysis.
These findings are consistent with those of several other studies of diethylstilbestrol exposure and breast cancer.
Diethylstilbestrol and risk of fatal breast cancer in a prospective cohort of US women, American journal of epidemiology, NCBI PubMed PMID: 8823060, 1996 Oct 1.
The most common cancer in US women and the 2nd leading cause of cancer death is breast cancer.
Between 1980-1987 in the US. age-adjusted incidence rates of breast cancer rose rapidly. They are also rising rapidly in several Asian countries (e.g., in Japan) which have the lowest incidence rates. These rapid increases may mean that environmental factors are responsible.
Incidence rates rise greatly with age until the late 40s. US women at highest risk of breast cancer are Jewish women, urban women, single women, and women living in the northern US. Women at lowest risk include Mormon and Seventh-Day Adventist women, Hispanic and Asian women, rural women, women living in the southern US, and married women.
Factors that have a relative risk greater than 2 are
mother and sister with history of breast cancer, especially if diagnoses at an early age;
atypical epithelial cells in nipple aspirate fluid;
nodular densities on the mammogram;
history of cancer in 1 breast;
mother or sister with history of breast cancer;
biopsy-confirmed benign proliferative breast disease;
hyperplastic epithelial cells without atypia in nipple aspirate fluid;
and radiation to chest in moderate to high doses.
Ovarian hormones appear to stimulate cell division in the breast, thus elevated levels may be risk factors.
Exogenous hormones may also increase the risk. Women are exposed to these exogenous hormones through
Postmenopausal obesity increases the risk while premenopausal obesity decreases the risk. A high fat diet in childhood and adolescence may increase the risk. Alcohol drinking may also increase the risk.
Older, white, and nulliparous women are more likely to have estrogen receptor-positive cancers.
Breast cancer in males tends to share the same risk factors as well as its own unique factors.
Prevention of postmenopausal obesity is the only established primary prevention effort. Screening is the only secondary prevention means.
Breast cancer epidemiology: summary and future directions, Epidemiologic reviews, NCBI PubMed PMID: 8405209, 1993.
European journal of cancer (Oxford, England : 1990)
Diethylstilboestrol is still used as an adjunct palliative treatment in certain patients with breast and prostate cancer. Its pharmacological, toxicological and carcinogenic properties are reviewed.
In addition to the usual untoward effects following subacute or chronic administration of oestrogens, treatment with diethylstilboestrol has been associated with serious cardiovascular sequelae.
Most characteristic are, however, the carcinogenic properties of this drug.
Many epidemiological data provide evidence that prenatal exposure to diethylstilboestrol is causally associated with vaginal and cervical clear-cell adenocarcinomas, a very rare type of cancer in the unexposed female population.
The intrauterine exposure of males leads to an increased risk of testicular cancer, although the data are less conclusive in this respect.
There is some evidence that administration of diethylstilboestrol in large doses to adult women during pregnancy increases the risk of subsequent breast cancer
and it probably increases the incidence of endometrial carcinoma, as has been shown with other similar oestrogens given chronically for menopausal symptoms.
Diethylstilboestrol: I, Pharmacology, Toxicology and carcinogenicity in humans, European journal of cancer, NCBI PubMed PMID: 1627392, 1992.
Long-term follow-up of mothers who received high doses of stilboestrol and ethisterone in pregnancy
1980 Study Abstract
The report by Dr Valerie Beral and Linda Colwell linking oestrogen therapy during pregnancy with later appearance (after 18-22 years) of breast cancer prompted us to review studies on oral contraceptives. …
… The data in the table indicate an increased risk of breast cancer among women with a positive history of oral contraceptive use but only after they have passed into their fifth or sixth decade. Breast cancer is common in women in their later years; a small increase in risk would therefore mean a large increase in the absolute number of cases. Most oral contraceptive users have not yet reached the critical age. Future studies should address this potential problem.
Full text (free access) : Long-term follow-up of mothers who received high doses of stilboestrol and ethisterone in pregnancy, British medical journal, NCBI PubMed PMC1715108, 1980 Dec.
Randomised trial of high doses of stilboestrol and ethisterone in pregnancy: long-term follow-up of mothers
1980 Study Abstract
In 1950 a trial was set up to evaluate the effects of large doses of stilboestrol and ethisterone on rates of fetal loss in pregnant diabetic women. Eighty women were allocated at random to receive the hormonal treatment and 76 to receive inactive tablets of identical appearance.
At follow-up 27 years later, information was obtained about 97% of the women, all but four being traced. All respondents were unaware of who had received hormones.
The overall mortality was 4.5 times that of women of comparable age in England and Wales, most deaths being from complications of diabetes.
More tumours, mainly benign, of the reproductive tract were reported in the hormone-exposed than the non-exposed group (14 (18%) and two (3%) respectively).
Four cases of malignant breast disease were reported in the hormone-exposed women and none in the non-exposed.
These findings support other evidence linking oestrogen treatment and breast cancer and suggesting that the latent period before the tumour becomes clinically apparent may be 15 years or longer.
Full text (free access) : Randomised trial of high doses of stilboestrol and ethisterone in pregnancy: long-term follow-up of mothers, British medical journal, NCBI PubMed PMC1714571, 1980 Oct.