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Nathan Goodyear

Urinary Estrogens and Estrogen Metabolites and Subsequent Risk of Breast Cancer among P... - 0 views

cancerres.aacrjournals.org/...696.full

estrogen metabolites estrogen metabolism ER estrogen receptors ROS hormones cancer breast cancer

shared by Nathan Goodyear on 07 Oct 15 - No Cached
  • both 2- and 4-catechol estrogen metabolites bind to the ER with affinities comparable with estradiol, 4-catechol estrogen metabolites have lower dissociation rates than estradiol and an enhanced ability to upregulate ER-dependent processes
  • 2-catechol estrogen metabolites act as either weak mitogens (39) or weak inhibitors of cell proliferation
  • While 16α-hydroxyestrone binds to the ER with lower affinity than estradiol, it binds covalently (41) and leads to a constitutively activated ER
  • ...15 more annotations...
  • 4-hydroxyestradiol and 16α-hydroxyestrone increasing proliferation and decreasing apoptosis in a manner similar to estradiol; however, these effects were achieved only at concentrations 10-fold higher than estradiol (39). In contrast, 2-hydroxyestradiol did not have substantial proliferative or antiapoptotic effects
  • In our study, the associations with both 2-hydroxyestrone and 16α-hydroxyestrone were nonsignificantly inverse and we did not observe a consistent trend or significant associations between the 2-hydroxyestrone:16α-hydroxyestrone ratio and breast cancer risk
  • Ratios of the 3 hydroxylation pathways were not significantly associated with risk although the 2:16-pathway and 4:16-pathway ratios were suggestively inversely associated
  • a significant inverse association with the ratio of parent estrogens to estrogen metabolites
  • several potentially estrogenic and genotoxic mechanisms
  • Estrogen metabolites also can be genotoxic
  • Catechol estrogens can be oxidized into quinones and induce DNA damage directly through the formation of DNA adducts, or indirectly via redox cycling and generation of reactive oxygen species
  • the oxidized forms of the catechol estrogens differ in their ability to damage DNA through adducts, with oxidized 2-catechols forming stable and reversible DNA adducts and oxidized 4-catechols forming unstable adducts, which lead to depurination and mutations
  • 2- and 4-catechols have been shown to produce reactive oxygen species and induce oxidative DNA damage
  • act independently from the ER
  • 16α-Hydroxyestrone also may be genotoxic
  • While the catechol estrogens have estrogenic and genotoxic potential, the methylated catechol estrogens, which are catechol estrogens with one hydroxyl group methylated, have been hypothesized to lower the risk of breast cancer
  • The suggested mechanisms are indirect, by decreasing circulating levels of catechol estrogens and thereby the opportunity for catechols to exert genotoxic or proliferative effects, or direct, by inhibiting tumor growth and inducing apoptosis
  • the balance between phase I (oxidation) and phase II (methylation) metabolism of estrogen may be important in hormonally related cancer development.
  • Despite the estrogenic and genotoxic potential of many of the estrogen metabolites, we only observed a significantly increased breast cancer risk with one estrogen metabolite, 17-epiestriol, which has particularly strong estrogenic activity and binds to both ERα and ERβ with an affinity comparable with estradiol
  • Nathan Goodyear on 07 Oct 15
     
    review of estrogen metabolites and breast cancer risk in premenopausal women.
Nathan Goodyear

Circulating 2-hydroxy and 16-α hydroxy estrone levels and risk of breast canc... - 1 views

www.ncbi.nlm.nih.gov/...PMC2562592

estrogen metabolism menopause post-menopause post menopause estrogen metabolite 2-OH-estrone 16-alpha-OH-estrone 2:16alpha-OH estrone breast cancer risk hormone hormones

shared by Nathan Goodyear on 21 Aug 14 - No Cached
  • 2-OH estrogens bind to the estrogen receptor (ER) with affinity equivalent to or greater than estradiol
  • previous prospective studies have not observed any significant associations with either 2-OH or 16α-OH estrone or the ratio of the two metabolites and breast cancer risk overall.
    • Nathan Goodyear
      Nathan Goodyear on 08 Oct 15
       
      whether that risk is increased or decreased
  • it has been hypothesized that metabolism favoring the 2-OH over the 16α-OH pathway may be inversely associated with breast cancer risk (28).
  • ...24 more annotations...
  • they may act as only weak mitogens (14, 15), or as inhibitors of proliferation
  • No significant associations have been observed between 2-OH estrone and breast cancer risk
  • While 16α-OH estrone binds to the ER with lower affinity than estradiol, it binds covalently (18-20) and once bound, fails to down-regulate the receptor (21). Thus, 16α-OH estrone stimulates cell proliferation in a manner comparable to estradiol in ER+ breast cancer cell lines
  • In this large prospective study of 2-OH and 16α-OH estrone metabolites and breast cancer risk, we did not observe any significant associations overall with either individual metabolite or with the ratio of the two metabolites
  • we observed positive associations with 2-OH estrone and the 2:16α-OH estrone ratio among women with lower BMI and women with ER-/PR-tumors,
  • To date, several epidemiologic studies have examined the association between the 2-OH and 16α-OH estrogen metabolites and breast cancer risk with inconclusive results.
  • circulating estrogen levels have been associated more strongly with ER+/PR+ tumors than with ER-/PR- tumors
  • our results do not support the hypothesis that metabolism favoring the 2-OH estrone pathway is more beneficial to breast cancer risk than that favoring the 16α-OH estrone pathway
  • we observed significant positive associations of both 2-OH estrone and the 2:16α-OH estrone ratio with ER-/PR-tumors
  • Three (30, 32, 33) of four (30-33) studies observed RRs above 1 for the association between 16α-OH estrone and breast cancer risk (range of RRs=1.23-2.47); none of the point estimates was statistically significant though one trend was suggestive
  • based on animal studies, 2-OH estrone and the 2:16α-OH estrone ratio have been hypothesized to be inversely associated with breast cancer risk
  • No significant associations have been observed between 2-OH estrone, 16α-OH estrone, or the 2:16α-OH estrone ratio and breast cancer risk and the direction of the estimates is not consistent across studies.
    • Nathan Goodyear
      Nathan Goodyear on 08 Oct 15
       
      better worded is no consistent, significant associations.   There are some studies that point to the 16 catecholestrogen and increased cancer risk; limited studies show negative effects of 2 catecholestrogens on cancer risk and prospective studies available pretty much dispel the idea that the 2:16 ratio has an risk predictability.
  • we observed a suggestive inverse association with 16α-OH estrone and a significant positive association with the 2:16α-OH estrone ratio among lean women, suggesting possible associations in a low estrogen environment.
  • 16α-OH estrone increases unscheduled DNA synthesis in mouse mammary cells (27) and hence also may be genotoxic
  • Although 2-OH estrogens are capable of redox cycling, the semiquinones and quinones (i.e., the oxidized forms) form stable DNA adducts that are reversible without DNA destruction
  • In our population of PMH nonusers, we observed no associations with ER+/PR+ tumors, but significant positive associations with 2-OH estrone and the 2:16α-OH estrone ratio among women with ER-/PR- tumors
    • Nathan Goodyear
      Nathan Goodyear on 08 Oct 15
       
      one of the few studies to find this association between 2 catecholestrogens and the 2:16 ratio and ER-/PR-tumors
  • Animal and in vitro studies have shown that hydroxy estrogens can induce DNA damage either directly, through the formation of quinones and DNA adducts, or indirectly, through redox cycling and the generation of reactive oxygen species
    • Nathan Goodyear
      Nathan Goodyear on 08 Oct 15
       
      genotoxic via directe DNA adducts and indirectly via ROS; this is in addition to the proliferative effect
  • we observed a significant positive association between the 2:16α-OH estrone ratio and breast cancer risk among lean women
  • No significant associations have been observed with the 2:16α-OH estrone ratio
  • In the Danish study, no associations were observed with either ER+ or ER- tumors among PMH nonusers
  • significant positive associations with 2-OH estrone and the 2:16α-OH estrone ratio were observed among PMH users with ER+, but not ER-, tumors
  • it is possible that the genotoxicity of 2-OH estrone plays a role in hormone receptor negative tumors
  • 4-OH estrogens have a greater estrogenic potential than 2-OH estrogens, given the lower dissociation rate from estrogen receptors compared with estradiol (61), and are potentially more genotoxic since the quinones form unstable adducts, leading to depurination and mutation in vitro and in vivo
  • the balance between the catechol (i.e., 2-OH and 4-OH) and methoxy (i.e., 2-Me and 4-Me) estrogens may impact risk
  • Nathan Goodyear on 21 Aug 14
     
    The risks of estrogen metabolism are not clear cut.  Likely never will be due to the complexity of individual metabolism.  This study found no correlation between 2OH-Estrone and 2OH:16alpha-Estrone and breast cancer risk in ER+/PR+ breast cancer.  Translated: no benefit in breast cancer risk in 2OH-Estrone metabolism or increased 2OH:16alpha estrone metabolism.  There was a positive association between 2OH-Estrone and 2:16alpha-Estrone in women with ER-/PR- tumors and low BMI.
  • anonymous on 28 Oct 15
     
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Nathan Goodyear

Urinary estrogen metabolites in women at high risk for breast cancer - 0 views

carcin.oxfordjournals.org/...1532.full

breast cancer CA estrogen metabolism 2:16 OHE 2-OH-estrone 16-alpha-OH-estrone

shared by Nathan Goodyear on 10 May 12 - No Cached
  • obesity has also been linked to preferential estrogen metabolism via the 16-alpha-hydroxylation pathway; thus, a prediction of the mechanism by which obesity could increase breast cancer risk would be through a lowering of the 2:16 ratio in favor of the 16 pathway
  • increased BMI was associated with a lower 2:16 OHE ratio
  • Our data show a significant association between alcohol use, defined as at least one drink per day or an average of seven per week, and 2:16 OHE ratio
  • ...10 more annotations...
  • An alcohol-induced rise in estrogens as a consequence of alcohol catabolism in the liver has been reported
  • The only study that looked at the association between alcohol and wine consumption in healthy women did not report a clear association
  • smoking has been reported to increase induction of the 2-hydroxylation metabolic pathway (24). However, the few epidemiological studies conducted on healthy women showed no difference in estrogen metabolites with smoking status (22) or smoking dose (20), in line with our findings.
  • Family history of a first-degree family member with breast cancer confers a 2- to 4-fold risk of developing breast cancer
  • 16% of breast cancers are due to unidentified hereditary factors
  • Estrogen metabolism occurs through enzymes whose activity is determined by the presence of specific genetic polymorphisms, thus can be defined as unique to each individual.
  • the metabolism is also influenced by a number of environmental factors, which change over a lifetime
  • significantly lower 2:16 OHE ratio in women who have known breast cancer risk factors compared with healthy women
  • There was an additional significant association specifically with BMI and alcohol use, which also supports the evidence that these factors affect estrogen metabolism
  • Profiling estrogen metabolites may identify women who are more likely to develop breast cancer within a population of women with known risk factors
  • Nathan Goodyear on 10 May 12
     
    urinary estrogen metabolites shown to provide insight into breast cancer risk.  This study suggested that a low 2:16 OHE ratio increase breast cancer risk.
Nathan Goodyear

Oral estrogen antagonizes the metabolic actions of growth hormone in growth hormone-def... - 0 views

ajpendo.physiology.org/...E1191.long

oral estrogen oral estrogen HGH human growth hormone growth hormone IGF-1 hormone hormones therapy

shared by Nathan Goodyear on 19 Feb 13 - No Cached
  • Nathan Goodyear on 19 Feb 13
     
    One really wonders if estrogen should ever be given orally at all.  Though this study is small, this is consistent with other studies that show that estrogen therapy, particularly oral therapy interferes with growth hormone signaling and thus action.  Oral estrogen decreases IGF-1, increases growth hormone binding protein, lowers metabolism and reduces protein metabolism as monitored by leucine turnover.
Nathan Goodyear

Progesterone metabolites in breast cancer - 1 views

erc.endocrinology-journals.org/...717.full

progesterone metabolism tumor tumorigenesis cancer risk growth hormone hormones 5-beta-pregnanediol 5-alpha-pregnanediol 4-pregnenediol 5-alpha reductase

shared by Nathan Goodyear on 20 Feb 12 - No Cached
  • P metabolites produced within breast tissues might be independently active hormones functioning as cancer-promoting or -inhibiting regulatory agents
  • these P metabolites function as independent pro-or anti-cancer autocrine/paracrine hormones that regulate cell proliferation, adhesion, apoptosis and cytoskeletal, and other cell status molecules via novel receptors located in the cell membrane and intrinsically linked to cell signaling pathways
  • only a fraction of all breast cancer patients respond to this estrogen-based therapy and the response is only temporary
  • ...30 more annotations...
  • P serves as the precursor for the major steroid hormones (androgens, estrogens, corticosteroids) produced by the gonadal and adrenal cortical tissues.
  • 5α-pregnane, 5β-pregnane, and 4-pregnene metabolites of P
  • These P-metabolizing enzymes included 5α-reductase, 5β-reductase, 3α-hydroxysteroid oxido-reductase (3α-HSO), 3β-HSO, 20α-HSO, 20β-HSO, 6α(β)-, 11β-, 17-, and 21-hydroxylase, and C17–20-lyase
  • Reduction of P to 5α-pregnanes is catalyzed by 5α-reductase and the direct 5α-reduced metabolite of P is 5α-pregnane-3,20-dione (5αP). The 5α-reductase reaction is irreversible
  • The two 4-pregnenes resulting from direct P conversion are 4-pregnen-3α-ol-20-one (3αHP) and 4-pregnen-20α-ol-3-one (20αHP), catalyzed by the actions of 3α-HSO and 20α-HSO respectively
  • the P-metabolizing enzyme activities identified in human breast tissues and cell lines were: 5α-reductase, 3α-HSO, 3β-HSO, 20α-HSO, and 6α-hydroxylase
  • In normal breast tissue, conversion to 4-pregnenes greatly exceeded the conversion to 5α-pregnanes, whereas in tumorous tissue, conversion to 5α-pregnanes greatly exceeded that to 4-pregnenes
  • The results indicated that P 5α-reductase activity is significantly higher, whereas P 3α-HSO and 20α-HSO activities are significantly lower in tumor than in normal tissues
  • he results showed that production of 5α-pregnanes was higher and that of 4-pregnenes was lower in tumorigenic (e.g. MCF-7) than in nontumorigenic (e.g. MCF-10A) cells (Fig. 3c⇑), while differences in ER/P status did not appear to play a role
  • The 5α-pregnane-to-4-pregnene ratios were 7- to 20-fold higher in the tumorigenic than in the nontumorigenic cell lines
  • altered direction in P metabolism, and hence in metabolite ratios, was due to significantly elevated 5α-reductase and depressed 3α- and 20α-HSO activities in breast tumor tissues and tumorigenic cells. It appeared, therefore, that changes in P-metabolizing enzyme activities might be related to the shift toward mammary cell tumorigenicity and neoplasia
  • In vivo, changes in enzyme activity can result from changes in levels of the enzyme due to changes in expression of the mRNA coding for the enzyme, or from changes in the milieu in which the enzyme operates (such as temperature and pH, and concentrations of cofactors, substrates, products, competitors, ions, phospholipids, and other molecules)
  • Overall, the enzyme activity and expression studies strongly suggest that 5α-reductase stimulation and 3α- and 20α-HSO suppression are associated with the transition from normalcy to cancer of the breast
  • The level of expression of 5α-reductase is up-regulated by estradiol and P in the uterus (Minjarez et al. 2001) and by 5α-dihydrotestosterone (DHT) in the prostate
  • 3αHP inhibited whereas 5αP-stimulated proliferation
  • Stimulation in cell numbers was also observed when cells were treated with other 5α-pregnanes, such as 5α-pregnan-3α-ol-20-one, 5α-pregnan-20α-ol-3-one, and 5α-pregnane-3α,20α-diol, whereas other 4-pregnenes such as 20α-HP and 4-pregnene-3α,20α-diol resulted in suppression of cell proliferation
  • Stimulation of cell proliferation with 5αP and inhibition with 3αHP were also observed in all other breast cell lines examined, whether ER/P-negative (MCF-10A, MDA-MB-231) or ER/P-positive (T47D, ZR-75-1) and whether requiring estrogen for tumorigenicity (MCF-7, T47D) or not (MDA-MB-231), or whether they are nontumorigenic (
  • αHP resulted in significant increases in apoptosis and decreases in mitosis, leading to significant decreases in total cell numbers. In contrast, treatment with 5αP resulted in decreases in apoptosis and increases in mitosis.
  • The opposing actions of 5αP and 3αHP on both cell anchorage and proliferation strengthen the hypothesis that the direction of P metabolism in vivo toward higher 5α-pregnane and lower 4-pregnene concentrations could promote breast neoplasia and lead to malignancy.
  • he effects on proliferation and adhesion were not due to P, but due to the 5α-reduced metabolites
  • The studies showed that binding of 5αP or 3αHP occurs in the plasma membrane fractions, but not in the nuclear or cytosolic compartments
  • separate high-specificity, high-affinity, low- capacity receptors for 5αP and 3αHP that are distinct from each other and from the well-studied nuclear/cytosolic P, estrogen, and androgen and corticosteroid receptors
  • The studies thus provided the first demonstration of the existence of specific P metabolite receptors
  • the receptor results suggest that the putative tumorigenic actions of 5αP may be significantly augmented by the estradiol-induced increases in 5αP binding and decreases in 3αHP binding.
  • Estradiol and 5αP resulted in significant dose-dependent increases, whereas 3αHP and 20αHP each resulted in dose-dependent decreases in total ER
  • In combination, estradiol + 5αP or 3αHP + 20αHP resulted in additive increases or decreases respectively in ER numbers.
  • The data suggest that the action of 5αP on breast cancer cells involves modulation of the MAPK signaling pathway
  • current evidence does not appear to support the notion that increased 5α-reductase activity/ expression might significantly alter androgen influences on breast tumor growth.
  • both testosterone and DHT inhibit cell growth more or less to the same extent
  • Note that 5α-reductase reaction is not reversible
  • Nathan Goodyear on 20 Feb 12
     
    Fantastic read on the effects of progesterone metabolism on tumor and cancer growth.  Tumorigenesis is not just about the hormone, hormone balance, but about the metabolism of hormones.  This is why premarin is so carcinogenic: it is primarily metabolized by the 4-OH estrone pathway.
Nathan Goodyear

Associations of the Fecal Microbiome With Urinary Estrogens and Estrogen Metabolites in... - 0 views

press.endocrine.org/...jc.2014-2222

gut flora gut microbiome gut microbiota estrogen metabolites metabolism hormone hormones women gut

shared by Nathan Goodyear on 06 May 15 - No Cached
  • Nathan Goodyear on 06 May 15
     
    women with increased gut microbiome diversity found to have increased estrogen metabolites compared to parent estrogen i.e. gut microbiome diversity in women effects estrogen metabolism. 
Nathan Goodyear

Estrogen Metabolism and Breast Cancer : Epidemiology - 0 views

journals.lww.com/...lism_and_Breast_Cancer.15.aspx

estrogen metabolism estrogen metabolism estrogen metabolite metabolite metabolites breast cancer 2-OH-estrone 16alpha-OH-estrone 2:16alpha-OHE1

shared by Nathan Goodyear on 21 Aug 14 - No Cached
  • Nathan Goodyear on 21 Aug 14
     
    Maybe the risks of estrogen metabolism is age dependent?  This Long Island Breast Cancer Study Project found that an increased 2:16alphOH-estrone ratio was associated with a reduced premenopausal, invasive breast cancer risk.  This association declined when looked at in postmenopausal women.
Nathan Goodyear

Cigarette smoking and hormones : Current Opinion in Obstetrics and Gynecology - 0 views

journals.lww.com/...te_smoking_and_hormones.3.aspx

smoking tobacco CYP1A1 CYP1B1 estrogen hormones estrogen metabolism estrogen metabolites

shared by Nathan Goodyear on 05 Dec 16 - No Cached
  • Epidemiologic studies worldwide have established that exposure to cigarette smoke is an important cause of estrogen deficiency.
  • Nathan Goodyear on 05 Dec 16
     
    tobacco smoke alters estrogen metabolism.  Increase in CYP1B1 and CYP1B1 are the result of tobacco smoke.
Nathan Goodyear

A randomized, open-label, crossover study ... [Menopause. 2007 Nov-Dec] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...17507833

BHRT HRT estrogen oral transdermal therapy treatment hormones TBG thyroid liver metabolism

shared by Nathan Goodyear on 16 Nov 11 - No Cached
  • Nathan Goodyear on 16 Nov 11
     
    oral estrogen is a bad choice as it relates to BHRT or HRT for that matter.  Compared to transdermal estrogen, oral estrogen through increasing TBG and slowed liver metabolism results in decreased thyroid hormone production.  
Nathan Goodyear

Associations of the Fecal Microbiome With Urinary Estrogens and Estrogen Metabolites in... - 0 views

press.endocrine.org/...jc.2014-2222

estrogen metabolites gut flora gut microbiome gut microbiota hormones cancer breast cancer microbiome estrogen

shared by Nathan Goodyear on 16 Jul 15 - No Cached
  • Nathan Goodyear on 16 Jul 15
     
    Post-menopause women with increased gut microbiome diversity found to be associated with increased urinary excretion of estrogen metabolites compared to parent estrogens.  This relationship has been shown to be associated with a reduced breast cancer risk.
Nathan Goodyear

Role of Polymorphic Human Cytochrome P450 Enzymes in Estrone Oxidation - 0 views

cebp.aacrjournals.org/...551.long

estrogen metabolism estrogen metabolites cytochrome P450 estrogen estrone hormones detoxification metabolites

shared by Nathan Goodyear on 11 Sep 15 - No Cached
  • CYP1A1 and CYP1B1 are not expressed in any significant quantity in the liver. Therefore, they would not be expected to contribute to the overall systemic metabolism of estrone. However, both enzymes have been identified in breast tissue
  • CYP1A1 displayed relatively high activity for all three hydroxylations, suggesting that it may play an important role in extrahepatic tissues where it is expressed
  • CYP1A1 was more active with regard to 2-hydroxylation and 4-hydroxylation, it also displayed one of the greatest 16α-hydroxylating activities of the CYP enzymes tested.
  • ...4 more annotations...
  • CYP1B1 displayed a high affinity for estrone and preferentially catalyzed 4-hydroxylation over 2-hydroxylation
  • CYP1B1 did not seem to contribute to 16α-hydroxylation.
  • CYP1B1 was shown to preferentially catalyze 4-hydroxylation, whereas CYP1A1 was shown to preferentially catalyze 2-hydroxylation
  • Among the CYP enzymes expressed in the liver, CYP1A2 was the most active with regard to 2-hydroxylation
  • Nathan Goodyear on 11 Sep 15
     
    good discussion of estrogen metabolism and the P450 enzymes.
Nathan Goodyear

Association of testosterone with estrogen abolishes the beneficial effects of estrogen ... - 0 views

ajpheart.physiology.org/...ajpheart.00681.2014

Testosterone Estrogen CVD cardiovascular health disease heart hormone hormones women female

shared by Nathan Goodyear on 02 Feb 15 - No Cached
  • Nathan Goodyear on 02 Feb 15
     
    Testosterone reduced the vascular benefits of Estrogen (conjugated equine Estrogen) in female rat model.  Testosterone is seeing widespread use in women with very little positive data.  In fact, the majority of data points to poor metabolic effects and poor outcomes.
Nathan Goodyear

Estrogen Metabolism and Risk of Breast Cancer in Postmenopausal Women - 0 views

www.ncbi.nlm.nih.gov/...PMC3283536

estrogen metabolism estrogen metabolism breast cancer breast cancer

shared by Nathan Goodyear on 14 Oct 13 - No Cached
  • The ratio of the 2-hydroxylation pathway to parent estrogens was associated with a statistically significantly decreased risk of breast cancer
  • In this study, this ratio was more strongly associated with the risk of breast cancer compared with the ratio of 2-hydroxylation pathway to 16-hydroxylation pathway or unconjugated estradiol alone
  • 2-hydroxylation pathway catechols have relatively low affinities for estrogen receptors (4) and are rapidly cleared from circulation
  • ...6 more annotations...
  • In this study, the ratio of the 2-hydroxylation pathway to the 16-hydroxylation pathway was associated with a non-statistically significantly decreased risk of breast cancer
  • In this study, the ratio of catechols to methylated catechols in the 4-hydroxylation pathway was associated with statistically significantly increased risk of breast cancer.
  • This result is consistent with the hypothesis that mutagenic quinones derived from 4-hydroxylation pathway catechols contribute to pathogenesis of postmenopausal breast cancer.
  • Catechols in both the 2- and 4-hydroxylation pathways can be oxidized to form quinones; these reactive electrophiles can then react with DNA to form a variety of adducts
  • Methylation of the catechols prevents their conversion to reactive quinones
  • the most common DNA adducts derived from 4-hydroxylation pathway catechols are depurinating and highly mutagenic (7,40), most of those derived from 2-hydroxylation pathway catechols are stable and can be repaired with little error
  • Nathan Goodyear on 14 Oct 13
     
    Lower 2-OH estrone metabolism associated with lower risk of breast cancer, but 4-OH estrone associated with increased risk of breast cancer.
Nathan Goodyear

Circulating Estrogen Metabolites and Risk for Breast Cancer in Premenopausal Women - 0 views

cebp.aacrjournals.org/...2273.short

estrogen metabolism estrogen metabolite estrogen metabolism breast cancer 2-OH-estrone 16alpha-OH-estrone estrone metabolite metabolites

shared by Nathan Goodyear on 21 Aug 14 - No Cached
  • Nathan Goodyear on 21 Aug 14
     
    Epidemiologic study finds no association between increased 2OH-estrone metabolism and increased 2OH:16alphaOH-estrone metabolism and a reduction in breast cancer risk.
Nathan Goodyear

Estrogen Metabolism and Risk of Breast Cancer in Postmenopausal Women - 0 views

jnci.oxfordjournals.org/...326.full

estrogen metabolism cancer breast cancer estrogen metabolites

shared by Nathan Goodyear on 16 Jul 15 - No Cached
  • Nathan Goodyear on 16 Jul 15
     
    Get article on estrogen metabolism/metabolites and their effects on the risk of breast cancer in post menopause women.  This article brings to light new information: 2:16alpha estrone ratio is not a great predicted of risk, 2-OH and 4-OH metabolites can form quinone intermediates...
Nathan Goodyear

The 4-Pregnene and 5α-Pregnane Progesterone Metabolites Formed in Nontumorous... - 0 views

cancerres.aacrjournals.org/...936.full

progesterone metabolism cancer risk 4-pregnene 5alpha-pregnane

shared by Nathan Goodyear on 17 Feb 12 - No Cached
  • We report here the first evidence that tumorous breast tissue exhibits elevated 5α-reductase activity, which promotes significant increases in 5α-pregnanes, especially 5αP,4 whereas the normal (nontumorous) breast tissue produces more 4-pregnenes, especially 3αHP
  • 3αHP and other 4-pregnenes inhibit, whereas 5αP and other 5α-pregnanes stimulate, breast cell proliferation and detachment
  • it is evident that breast tissue can convert progesterone into two classes of metabolites: the δ-4-pregnenes (which retain the C4–5 double bond), and the 5α-reduced 21-carbon steroids (5α-pregnanes)
  • ...12 more annotations...
  • irreversible action of 5α-reductase
  • in normal (nontumorous) breast tissue, the 4-pregnene metabolites of progesterone greatly exceeded the 5α-pregnanes, whereas in tumorous tissue, 5α-pregnanes exceeded 4-pregnenes.
  • These differences in 5α-pregnane and 4-pregnene amounts were largely attributable to differences in 5αP and 3αHP production in tumorous and nontumorous tissues
  • the metabolic activities were in general similar, regardless of the age and ER state of the patient or whether she was pre- or postmenopausal.
  • These findings suggest greatly elevated 5α-reductase activity in tumorous, as compared with nontumorous, breast tissue.
  • progesterone metabolites that retain the C-4 double bond (i.e., the 4-pregnenes) exert an antiproliferative effect in the three cell lines that were tested, whereas the 5α-pregnanes stimulate breast cell line proliferation.
  • the degree of mitogenicity would be determined by the ratio of 5α-pregnanes:4-pregnenes. Tissues with a high 4-pregnene:5α-pregnane ratio would maintain a higher degree of normalcy, whereas those with a high 5α-pregnane:4-pregnene ratio would tend toward tumorigenicity
  • The observations that progesterone metabolites affect both ER-positive and ER-negative cells as well as tumorigenic (MCF-7) and nontumorigenic (MCF-10A) cells strengthen the argument that these factors may be endocrinologically relevant for all forms of breast cancer.
  • progesterone metabolites as the active endocrine/paracrine/autocrine factors
  • Estrogen-based therapies elicit responses in only one-third of all breast cancer patients, and most of these show relapse.
  • the metabolic activities were in general similar, regardless of the age and ER state of the patient or whether she was pre- or postmenopausal.
    • Nathan Goodyear
      Nathan Goodyear on 27 Jan 14
       
      Interesting that the effect of progesterone metabolites were found to be independent from ER status, age, and pre/post menopause
  • Nathan Goodyear on 17 Feb 12
     
    Different progesterone metabolites shown to have different tumor effects.  Implications are that, just as estrogen metabolism effects cancer risk, so does progesterone metabolism.
Nathan Goodyear

Progesterone metabolites regulate induction, growth, and suppression of estrogen- and p... - 0 views

www.ncbi.nlm.nih.gov/...PMC3706910

progesterone metabolites metabolite 5-alpha pregnene 5-alpha pregnenes 5alpha-dihydroprogesterone 4-pregnene 4-pregnenes 3alpha-dihydroprogesterone breast cancer ER PR hormone hormones receptors estrogen

shared by Nathan Goodyear on 28 Jan 14 - No Cached
  • in vitro studies had shown that the progesterone metabolites, 5α-dihydroprogesterone (5αP) and 3α-dihydroprogesterone (3αHP), respectively, exhibit procancer and anticancer effects on receptor-negative human breast cell lines
  • Onset and growth of ER/PR-negative human breast cell tumors were significantly stimulated by 5αP and inhibited by 3αHP
  • When both hormones were applied simultaneously, the stimulatory effects of 5αP were abrogated by the inhibitory effects of 3αHP and vice versa
  • ...31 more annotations...
  • Treatment with 3αHP subsequent to 5αP-induced tumor initiation resulted in suppression of further tumorigenesis and regression of existing tumors
  • Tumorigenesis of ER/PR-negative breast cells is significantly enhanced by 5αP and suppressed by 3αHP, the outcome depending on the relative concentrations of these two hormones in the microenvironment in the breast regions
  • The findings show that the production of 5αP greatly exceeds that of 3αHP in ER/PR-negative tumors and that treatment with 3αHP can effectively block tumorigenesis and cause existing tumors to regress
  • hypothesis that a high 3αHP-to-5αP concentration ratio in the microenvironment may foster normalcy in noncancerous breast regions.
  • a large proportion (about 30% to 60%) of breast tumors are ER and/or PR negative
  • about 90% of normal proliferating breast epithelial cells are receptor negative
  • Our previous in vitro studies had shown that breast tissues and cell lines readily convert progesterone to 5α-pregnanes, such as 5αP, and delta-4-pregnenes, such as 3αHP (Figure ​(Figure1),1), and that tumorous breast tissues [15] and tumorigenic breast cell lines [16] produce higher levels of 5αP and lower levels of 3αHP than do normal breast tissues and nontumorigenic cell lines
  • The progesterone metabolism studies suggested that increases in 5αP and decreases in 3αHP production accompany the shift toward breast cell neoplasia and tumorigenicity
  • In vitro studies on five different human breast cell lines showed that cell proliferation and detachment are significantly increased by 5αP and decreased by 3αHP
  • the prevailing theory of hormonal regulation of breast cancer, as well as hormone-based therapies, revolves around estrogen and/or progesterone and ER/PR-positive breast cells and tumors.
  • Not only do these "receptor-negative" breast cancers fail to benefit from current hormonal therapies, but they also generally exhibit more-aggressive biologic behaviors and poorer prognosis than the receptor-positive ones
  • The results of the studies reported here show for the first time that the progesterone metabolites, 5αP and 3αHP, act as hormones that regulate ER/PR-negative breast tumor formation, growth, and regression
  • The onset of the ER/PR-negative human breast cell tumors in mice was considerably accelerated, and the growth significantly stimulated, by just one or two applications of 5αP
  • In contrast, 3αHP retarded onset of tumor formation, suppressed tumor growth, and inhibited or regressed existing 5αP-induced tumors
  • When both hormones were administered simultaneously, the effects of one were abrogated by the effects of the other.
  • The 5αPR and 3αHPR (which are associated with the plasma membranes of both ER/PR-positive [19] and ER/PR-negative [29] cells) are distinct from each other and from known ER, PR, androgen, and corticosteroid receptors, and lack affinity for other steroids, such as progesterone, estrogen, androgens, corticosteroids, and other progesterone metabolites
  • Levels of 5αPR are upregulated by 5αP itself and estradiol, and downregulated by 3αHP in both ER/PR-positive and -negative cells
  • ndications are that 5αP acts via the surface receptor-linked mitogen-activated protein kinase (MAPK; Erk1/2) pathway; 5αP significantly stimulates activation of Erk1/2 [30], increases the Bcl-2/Bax expression ratio [18] and actin depolymerization [31], and decreases expression of actin and adhesion plaque-associated vinculin [31], resulting in decreased apoptosis and increased mitosis and cell detachment
  • 3αHP appears to suppress protein kinase C (PKC), phospholipase C (PLC), Ca2+ mobilization (unpublished observations), and the Bcl-2/Bax expression ratio [18], and increases expression of the cell-cycle inhibitor p21 [18], resulting in increased apoptosis and decreased proliferation and detachment of breast cell lines.
  • serum from mice with tumors had significantly more 5αP than 3αHP
  • the tumors, which on average had about threefold higher concentrations of 5αP than the respective sera, and >10-fold higher 5αP than 3αHP levels
  • Previous in vitro metabolism studies showed that human breast tumor tissues convert significantly more progesterone to 5α-pregnanes like 5αP and less to 4-pregnenes like 3αHP than do paired normal (nontumorous) tissues
  • Similar differences in progesterone metabolism and enzyme gene expressions were observed between tumorigenic and nontumorigenic breast cell lines
  • breast carcinomas are able to synthesize progesterone
  • The current findings, along with the previous in vitro studies, suggest that the relative concentrations of 5αP and 3αHP in the breast microenvironment constitute important autocrine/paracrine determinants not only for tumorigenesis but also for potential regression of tumors and the maintenance of normalcy of ER/PR-negative breast cells/tissues.
  • Evidence presented here shows that a high concentration of 5αP, relative to 3αHP in the microenvironment, promotes initiation and growth of tumors, whereas a higher concentration of 3αHP, relative to 5αP, suppresses tumorigenesis and promotes normalcy
  • 5α-reductase and 5αPR levels are upregulated by 5αP
  • in the 3αHP-treated mice, the elevated 3αHP levels, relative to 5αP, in the microenvironment could have opposed progression to xenograft neoplasia by its inherent anticancer actions and the suppression of 5αP synthesis and 5αPR expression
  • the opposing actions of the progesterone metabolites also appear to exert some control over the estrogen-regulated effects on breast cancer by their ability to modulate ER numbers in ER-positive cells
  • because both ER/PR-negative and ER/PR-positive, as well as normal and tumorigenic human breast cell lines, have been shown to respond to 5αP and 3αHP in vitro, it is suggested that these endogenously produced progesterone metabolites may also play regulatory hormonal roles in ER/PR-positive breast cancers, as well as in the maintenance of normalcy in nontumorous breast tissues.
  • The in vivo data provide further evidence that progesterone metabolites, such as 5αP and 3αHP, deserve to be considered as active hormones in their own right, rather than inactive waste products
  • Nathan Goodyear on 28 Jan 14
     
    Progesterone metabolites and breast cancer
Nathan Goodyear

Association between urinary levels of bisp... [Sci Total Environ. 2014] - PubMed - NCBI - 0 views

www.ncbi.nlm.nih.gov/...23954212

bisphenol A Bisphenol-A BPA estrogen metabolism hormone hormones xenoestrogens xenoestrogen

shared by Nathan Goodyear on 19 Jun 14 - No Cached
  • Nathan Goodyear on 19 Jun 14
     
    Bisphenol A (BPA) negatively effects estrogen metabolism. Bisphenol A preferentially increases 4OH-estrone which is the most toxic estrogen metabolite.
Nathan Goodyear

CYP1A1 and CYP1B1 polymorphisms and their association with estradiol and estrogen metab... - 0 views

www.ncbi.nlm.nih.gov/...16949388

estrogen metabolites estrogen metabolism menopause estrogen hormones

shared by Nathan Goodyear on 11 Sep 15 - No Cached
  • Nathan Goodyear on 11 Sep 15
     
    estrogen metabolites and associated risk.
Nathan Goodyear

Revealing Estrogen's Secret Role In Obesity - 0 views

www.sciencedaily.com/...070820145348.htm

estrogen obesity

shared by Nathan Goodyear on 07 Jun 11 - No Cached
  • researchers showed how estrogen receptors located in the hypothalamus serve as a master switch to control food intake, energy expenditure and body fat distribution.
  • This research seems to support a link between estrogen and regulation of obesity
  • ventromedial nucleus or VMN, is a key center for energy regulation.
  • ...2 more annotations...
  • When estrogen levels in the VMN dipped, the animals' metabolic rate and energy levels also plummeted
  • The findings suggested that the ER-alpha in this region plays an essential role in controlling energy balance, body fat distribution and normal body weight.
  • Nathan Goodyear on 07 Jun 11
     
    estrogen plays role in obesity in menopausal women.
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