Estrogen MetabolismRole in Oncology Tom Archie, MD SLWRMC Tumor Board June 19, 2008
50yo Caucasian Female • Early breast cancer – poorly differentiated • MRI negative for contralateral tumor • Receptor Status: • Triple Negative (ER, PR, HER2/neu) • Lumpectomy followed by Taxotere and Cytoxan
Estrogen Metabolism Testing • Identify high risk patients for new breast cancer • Others: prostate cancer, leukemia, olfactory tumors, and Parkinson’s Disease (probably more to come) • Identify high risk of recurrence in breast cancer patients (and other cancers) • Modify risk via modification of estrogen metabolism balance • Future: “pre-mammogram” biomarker
Catechol Estrogen Quinones to DNA Adducts • Endogenous Estrogens can become carcinogenic via formation of catechol estrogen quinones, which react with DNA to form specific depurinating estrogen-DNA adducts. • The mutations resulting from these adducts can lead to cell transformation and the initiation of breast cancer. • Irregardless of ER status • Mechanism: Sheer volume of DNA “apurinic” sites – DNA repair enzymes make mistakes, leading to single nucleotide polymorphisms (SNP)
Catechol Estrogen Quinones to DNA Adducts • 4-OH-estrone induces DNA Adduct formation in normal breast epithelium (MCF-10F cells) • Saeed M et al. Int J Cancer. 2007 Apr 15;120(8):1821-4.
Human Study of Urinary Estrogen Metabolites w/ and w/o Breast CA • Human study comparing healthy controls, breast cancer patients, and “high risk” patients (as determined by oncologists in study) • The levels of the ratios of depurinating DNA adducts to their respective estrogen metabolites/conjugates were significantly higher in high-risk women (p < 0.001) and women with breast cancer (p < 0.001) than in control subjects. • This mechanism represents the best understood and documented initiation step in the formation of any cancer. • Gaikwad NW et al. The molecular etiology of breast cancer: evidence from biomarkers of risk.Int J Cancer. 2008 May 1;122(9):1949-57.
COMT and CE (Catechol Estrogen) • Quantitatively, the most active CE conjugative pathway is methylation. CE methylation is catalyzed by COMT • Catechol-O-methyltransferase (COMT) a classical phase II enzyme, catalyzes the transfer of methyl groups from S-adenosyl methionine, the enzyme cofactor, to hydroxyl groups of a number of catechol substrates, including the CEs. • Under normal circumstances, CEs are, for the most part, promptly O-methylated by COMT to form 2- and 4-O-methylethers, which are then excreted. • While virtually all catechols are substrates for COMT, the highest affinities for the enzyme are exhibited by the CEs • Journal of the National Cancer Institute Monographs No. 27, 2000
Low Functioning COMT and Breast Cancer Risk • Genetic epidemiology studies have proposed a possible correlation between the low activity allele (COMTLL) and increased breast cancer risk • Lavigne JA, et al. An association between the allele coding for a low activity variant of catechol-O-methyltransferase and the risk for breast cancer. Cancer Res 1997;57:5493–5497. • Huang CS, et al. Breast cancer risk associated with genotype polymorphism of the estrogen metabolizing genes CYP17, CYP1A1, and COMT: A multigenic study on cancer susceptibility. Cancer Res 1999;59:4870–4875. • Yim D-S, et al. Relationship between the val158met polymorphism of catechol O-methyl transferase and breast cancer. Pharmacogenetics 2001;11:1–8.
COMT and Breast Cancer • COMT protects cells from the genotoxicity and cytotoxicity of catechol estrogens, by preventing their conversion to quinones • Adds methyl group (-CH3) at the -OH site that would otherwise be oxidized by peroxidase enzymes • Low activity of COMT leads to higher levels of depurinating estrogen-DNA adducts that can induce mutations and initiate cancer. • MCF-10F (human breast epithelial cells that are ER neg) • Estrogen-DNA adducts’ carcinogenicity independent of ER status • Zahid M et al. Free Radic Biol Med. 2007 Dec 1;43(11):1534-40. • Lu F et al.J Steroid Biochem Mol Biol. 2007 ; 105(1-5): 150–158.
Low Functioning COMT Common • 25% of US Caucasians are homozygous for the val108/158met polymorphism in the COMT gene • Lachman HM, et al. Pharmacogenetics 1996;6:243–250. • Scanlon PD, et al. Science 1979;203:63–65. • 27% Chinese Americans and 34% Japanese Americans • Wu A et al. Cancer Res 2003;63: 7526–7529 • Val108/158Met SNP associated with 3-4x reduction in functional enzymatic rate of COMT. • Zhu BT. Curr Drug Metab 2002;3: 321–349
E2:E16 Ratio - Breast Cancer Risk • Prospective Study 10,786 women aged 34-69 with 5 ½ yr followup • Measured urinary estrogen metabolites • 144 breast cancer pts w/ 4 matched controls for each cancer • Highest quintile E2:E16 ratio • Premenopausal: OR 0.58 (42% risk red) • Postmenopausal: OR 1.29 (29% risk inc) Muti et al. Epidemiology. 2000 Nov;11(6):635-40
Broccoli increases E2:E16 ratio • Increase E2:E16 ratio 29.5% with broccoli 500gr/day • Cruciferous vegetables cause the upregulation of Cyp1A2 (19%) and Cyp1A1 and inhibit Cyp2E1 • Indole 3 Carbinol (glucocinolate) • Sulforaphane (isothiocyanate) • Diindolylmethane (glucocinolate) • Calcium D Glucarate
Interpretation • Low 2-Hydroxyestrone/16α-Hydroxyestrone Ratio • Premenopausal female • Increased risk of ongoing carcinogensis leading to treatment failure
Interpretation • Poor methylation capacity – she is a “slow methylator” • 4-Methoxyestrone is undetectable • 4-Hydroxyestrone is not being methylated adequately. • 4-Hydroxyestrone level is high. • This is associated with increased levels of 4-catechol estrogen DNA adducts, which are strongly associated with the initiation of breast and prostate cancer. • COMT is likely genetically slow • Principal agent for eliminating catechol estrogens
Interpretation • Interestingly, the methylation of 2OHE is adequate, whereas methylation of 4OHE is not • I find no literature citing methylation preferences for 2OHE vs. 4OHE • Fact remains that additional methylation support is needed
Treatment Goals • Enhance methylation • Decrease Cyp1B1 activity • Increase E2:E16 ratio • Cruciferous vegetables
Improve Methylation • Increase substrate for COMT (SAMe) • Add methyl donors • Folate, methylcobalamin (B12) • Trimethylglycine (Betaine) • Vit B6 (to discourage the accumulation of homocysteine and encourage the formation of glutathione via synthesis of cysteine) • There is no physiological mechanism to suggest an adverse interaction between methylation and the metabolism of either taxotere or cytoxan
Improve Methylation COMT
Cyp1B1 inhibition (ie: reduction of DNA adducts) • Reduce xenobiotic pollutant exposure • N-acetyl Cysteine • Sulforaphane (glucosinolate from broccoli) induces quinone reductase, which takes CEQs back to catechol estrogens, reducing the potential for the creating of DNA adducts. • Hwang. J Med Food. 2005 Summer;8(2):198-203 • Glutathione conjugates are not playing much of a role in protecting against DNA adducts.
Cyp 1B1 Inhibition to decrease DNA Adduct Formation • Increased methylation of catechol estrogens leads to feedback inhibition of Cyp1B1 • Dawling et al. Cancer Res. 2003 Jun 15;63 (12):3127-32.
Cyp 1B1 Inhibition to decrease DNA Adduct Formation • Reduced Lipoic Acid • N-acetyl Cysteine • Resveratrol • Melatonin (minimal but positive effect) • Zahid M. et al. Inhibition of depurinating estrogen-DNA adduct formation by natural compounds. Chem Res Toxicol. 2007 Dec;20(12):1947-53. Epub 2007 Nov • Chen et al. Resveratrol inhibits TCDD-induced expression of CYP1A1 and CYP1B1 and catechol estrogen-mediated oxidative DNA damage in cultured human mammary epithelial cells Carcinogenesis vol.25 no.10 pp.2005--2013, 2004 doi:10.1093/carcin/bgh183
Synergism b/t Paclitaxel and Broccoli Glucosinolate • Diindolylmethane in combination with paclitaxel synergistically inhibits growth of Her2 / neu human breast cancer cells through G2M phase cell-cycle arrest and induction of apoptosis / necrosis • McGuire KP, et al. J Surg Res. 2006 May 15;132(2):208-13. Epub 2006 Mar 31.
Broccoli and Antitumor Effects • Sulforaphane inhibits breast cancer growth and induces Quinone Reductase • Hwang. J Med Food. 2005 Summer;8(2):198-203. • I3C induces Br CA cell cycle arrest
Potential Risk • Uncertain effect on Cyp3A4 • (60% of drugs) • Sulforaphane inhibtis • Diindolylmethane has no effect • Could affect concentration of these drugs and theoretically increase adverse drug events or decrease efficacy • Taxotere metabolized by Cyp3A4 • Consider avoiding near time of infusion
Prostate CA • Small study of urine estrogen metabolites in men with prostate cancer vs. benign urological d/o vs. healthy controls • 4-OHE1-DNA Adducts detected at higher levels in samples from subjects with prostate cancer and benign urological conditions compared to healthy males • This is the first demonstration that CEQ-derived DNA adducts are present in urine samples from subjects with prostate cancer. • Markushkin Y et al. Potential biomarker for early risk assessment of prostate cancer. Prostate. 2006 Oct 1;66(14):1565-71
Extension to Other Cancers • This mechanism is also involved in • Initiation of leukemia by benzene • Rat olfactory tumors by naphthalene • Neurodegenerative diseases such as Parkinson's disease by dopamine. • Estrogens and Human Diseases. Volume 1089 published November 2006 Ann. N.Y. Acad. Sci. 1089: 286–301 (2006). doi: 10.1196/annals.1386.042
Conclusion • No human intervention trials on manipulation of estrogen metabolism in patients w/ active breast cancer • Epidemiologic studies support cruciferous vegetables and methyl donors to decrease breast cancer risk • In vitro studies showing anticancer effects of brassica • Risk of non-action vs. action? • Enhance methylation now • Increase E2:E16 ratio now but reduce likelihood of possible interaction w/ metabolism of taxotere by avoiding for 1 week prior and 2 days after administration of taxotere • Inhibit Cyp1B1 now
One Last Thought for Future Discussion Multifocal Angiostatic Therapy
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