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BMC Cancer
Published in: BMC Cancer 1/2013

Open Access 01-12-2013 | Research article

Equol enhances tamoxifen’s anti-tumor activity by induction of caspase-mediated apoptosis in MCF-7 breast cancer cells

Authors: Christiana Charalambous, Chara A Pitta, Andreas I Constantinou

Published in: BMC Cancer | Issue 1/2013

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Abstract

Background

Soy phytoestrogens, such as daidzein and its metabolite equol, have been proposed to be responsible for the low breast cancer rate in Asian women. Since the majority of estrogen receptor positive breast cancer patients are treated with tamoxifen, the basic objective of this study is to determine whether equol enhances tamoxifen’s anti-tumor effect, and to identify the molecular mechanisms involved.

Methods

For this purpose, we examined the individual and combined effects of equol and tamoxifen on the estrogen-dependent MCF-7 breast cancer cells using viability assays, annexin-V/PI staining, cell cycle and western blot analysis.

Results

We found that equol (>50 μM) and 4-hydroxy-tamoxifen (4-OHT; >100 nM) significantly reduced the MCF-7 cell viability. Furthermore, the combination of equol (100 μM) and 4-OHT (10 μM) induced apoptosis more effectively than each compound alone. Subsequent treatment of MCF-7 cells with the pan-caspase inhibitor Z-VAD-FMK inhibited equol- and 4-OHT-mediated apoptosis, which was accompanied by PARP and α-fodrin cleavage, indicating that apoptosis is mainly caspase-mediated. These compounds also induced a marked reduction in the bcl-2:bax ratio, which was accompanied by caspase-9 and caspase-7 activation and cytochrome-c release to the cytosol. Taken together, these data support the notion that the combination of equol and tamoxifen activates the intrinsic apoptotic pathway more efficiently than each compound alone.

Conclusions

Consequently, equol may be used therapeutically in combination treatments and clinical studies to enhance tamoxifen’s effect by providing additional protection against estrogen-responsive breast cancers.
Appendix
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Literature
1.
McPherson K, Steel CM, Dixon JM: ABC of breast diseases. Breast cancer-epidemiology, risk factors, and genetics. BMJ. 2000, 321 (7261): 624-628. 10.1136/bmj.321.7261.624.CrossRefPubMedPubMedCentral
2.
Jin S, Zhang QY, Kang XM, Wang JX, Zhao WH: Daidzein induces MCF-7 breast cancer cell apoptosis via the mitochondrial pathway. Ann Oncol. 2010, 21 (2): 263-268. 10.1093/annonc/mdp499.CrossRefPubMed
3.
Chan K, Morris GJ: Chemoprevention of breast cancer for women at high risk. Semin Oncol. 2006, 33 (6): 642-646. 10.1053/j.seminoncol.2006.08.017.CrossRefPubMed
4.
Jemal A, Thomas A, Murray T, Thun M: Cancer statistics, 2002. CA Cancer J Clin. 2002, 52 (1): 23-47. 10.3322/canjclin.52.1.23.CrossRefPubMed
5.
Adlercreutz H: Phyto-oestrogens and cancer. Lancet Oncol. 2002, 3 (6): 364-373. 10.1016/S1470-2045(02)00777-5.CrossRefPubMed
6.
Mitchell JH, Gardner PT, McPhail DB, Morrice PC, Collins AR, Duthie GG: Antioxidant efficacy of phytoestrogens in chemical and biological model systems. Arch Biochem Biophys. 1998, 360 (1): 142-148. 10.1006/abbi.1998.0951.CrossRefPubMed
7.
Arora A, Nair MG, Strasburg GM: Antioxidant activities of isoflavones and their biological metabolites in a liposomal system. Arch Biochem Biophys. 1998, 356 (2): 133-141. 10.1006/abbi.1998.0783.CrossRefPubMed
8.
Choi EJ, Ahn WS, Bae SM: Equol induces apoptosis through cytochrome c-mediated caspases cascade in human breast cancer MDA-MB-453 cells. Chem Biol Interact. 2009, 177 (1): 7-11. 10.1016/j.cbi.2008.09.031.CrossRefPubMed
9.
Lampe JW, Karr SC, Hutchins AM, Slavin JL: Urinary equol excretion with a soy challenge: influence of habitual diet. Proc Soc Exp Biol Med. 1998, 217 (3): 335-339.CrossRefPubMed
10.
Setchell KD, Brown NM, Lydeking-Olsen E: The clinical importance of the metabolite equol-a clue to the effectiveness of soy and its isoflavones. J Nutr. 2002, 132 (12): 3577-3584.PubMed
11.
Treeck O, Juhasz-Boess I, Lattrich C, Horn F, Goerse R, Ortmann O: Effects of exon-deleted estrogen receptor beta transcript variants on growth, apoptosis and gene expression of human breast cancer cell lines. Breast Cancer Res Treat. 2008, 110 (3): 507-520. 10.1007/s10549-007-9749-7.CrossRefPubMed
12.
Treeck O, Lattrich C, Springwald A, Ortmann O: Estrogen receptor beta exerts growth-inhibitory effects on human mammary epithelial cells. Breast Cancer Res Treat. 2010, 120 (3): 557-565. 10.1007/s10549-009-0413-2.CrossRefPubMed
13.
Paruthiyil S, Parmar H, Kerekatte V, Cunha GR, Firestone GL, Leitman DC: Estrogen receptor beta inhibits human breast cancer cell proliferation and tumor formation by causing a G2 cell cycle arrest. Cancer Res. 2004, 64 (1): 423-428. 10.1158/0008-5472.CAN-03-2446.CrossRefPubMed
14.
Choi EJ, Kim T: Equol induced apoptosis via cell cycle arrest in human breast cancer MDA-MB-453 but not MCF-7 cells. Mol Med Report. 2008, 1 (2): 239-244.
15.
Magee PJ, Raschke M, Steiner C, Duffin JG, Pool-Zobel BL, Jokela T, Wahala K, Rowland IR: Equol: a comparison of the effects of the racemic compound with that of the purified S-enantiomer on the growth, invasion, and DNA integrity of breast and prostate cells in vitro. Nutr Cancer. 2006, 54 (2): 232-242. 10.1207/s15327914nc5402_10.CrossRefPubMed
16.
Schmitt E, Dekant W, Stopper H: Assaying the estrogenicity of phytoestrogens in cells of different estrogen sensitive tissues. Toxicol In Vitro. 2001, 15 (4–5): 433-439.CrossRefPubMed
17.
Sathyamoorthy N, Wang TT: Differential effects of dietary phyto-oestrogens daidzein and equol on human breast cancer MCF-7 cells. Eur J Cancer. 1997, 33 (14): 2384-2389. 10.1016/S0959-8049(97)00303-1.CrossRefPubMed
18.
Tonetti DA, Zhang Y, Zhao H, Lim SB, Constantinou AI: The effect of the phytoestrogens genistein, daidzein, and equol on the growth of tamoxifen-resistant T47D/PKC alpha. Nutr Cancer. 2007, 58 (2): 222-229. 10.1080/01635580701328545.CrossRefPubMed
19.
20.
Kandaswami C, Lee LT, Lee PP, Hwang JJ, Ke FC, Huang YT, Lee MT: The antitumor activities of flavonoids. In Vivo. 2005, 19 (5): 895-909.PubMed
21.
Le Marchand L: Cancer preventive effects of flavonoids–a review. Biomed Pharmacother. 2002, 56 (6): 296-301. 10.1016/S0753-3322(02)00186-5.CrossRefPubMed
22.
Ren W, Qiao Z, Wang H, Zhu L, Zhang L: Flavonoids: promising anticancer agents. Med Res Rev. 2003, 23 (4): 519-534. 10.1002/med.10033.CrossRefPubMed
23.
de Lemos ML: Effects of soy phytoestrogens genistein and daidzein on breast cancer growth. Ann Pharmacother. 2001, 35 (9): 1118-1121.CrossRefPubMed
24.
Gercel-Taylor C, Feitelson AK, Taylor DD: Inhibitory effect of genistein and daidzein on ovarian cancer cell growth. Anticancer Res. 2004, 24 (2B): 795-800.PubMed
25.
Guo JM, Xiao BX, Liu DH, Grant M, Zhang S, Lai YF, Guo YB, Liu Q: Biphasic effect of daidzein on cell growth of human colon cancer cells. Food Chem Toxicol. 2004, 42 (10): 1641-1646. 10.1016/j.fct.2004.06.001.CrossRefPubMed
26.
Fisher B, Costantino JP, Wickerham DL, Redmond CK, Kavanah M, Cronin WM, Vogel V, Robidoux A, Dimitrov N, Atkins J, et al: Tamoxifen for prevention of breast cancer: report of the National Surgical Adjuvant Breast and Bowel Project P-1 Study. J Natl Cancer Inst. 1998, 90 (18): 1371-1388. 10.1093/jnci/90.18.1371.CrossRefPubMed
27.
McKeon VA: The breast cancer prevention trial: should women at risk take tamoxifen?. J Obstet Gynecol Neonatal Nurs. 1999, 28 (6 Suppl 1): 34-38.PubMed
28.
Radmacher MD, Simon R: Estimation of tamoxifen’s efficacy for preventing the formation and growth of breast tumors. J Natl Cancer Inst. 2000, 92 (1): 48-53. 10.1093/jnci/92.1.48.CrossRefPubMed
29.
Kallio A, Zheng A, Dahllund J, Heiskanen KM, Harkonen P: Role of mitochondria in tamoxifen-induced rapid death of MCF-7 breast cancer cells. Apoptosis. 2005, 10 (6): 1395-1410. 10.1007/s10495-005-2137-z.CrossRefPubMed
30.
Mandlekar S, Hebbar V, Christov K, Kong AN: Pharmacodynamics of tamoxifen and its 4-hydroxy and N-desmethyl metabolites: activation of caspases and induction of apoptosis in rat mammary tumors and in human breast cancer cell lines. Cancer Res. 2000, 60 (23): 6601-6606.PubMed
31.
Mandlekar S, Kong AN: Mechanisms of tamoxifen-induced apoptosis. Apoptosis. 2001, 6 (6): 469-477. 10.1023/A:1012437607881.CrossRefPubMed
32.
Salami S, Karami-Tehrani F: Biochemical studies of apoptosis induced by tamoxifen in estrogen receptor positive and negative breast cancer cell lines. Clin Biochem. 2003, 36 (4): 247-253. 10.1016/S0009-9120(03)00007-9.CrossRefPubMed
33.
Couldwell WT, Hinton DR, He S, Chen TC, Sebat I, Weiss MH, Law RE: Protein kinase C inhibitors induce apoptosis in human malignant glioma cell lines. FEBS Lett. 1994, 345 (1): 43-46. 10.1016/0014-5793(94)00415-3.CrossRefPubMed
34.
Gelmann EP: Tamoxifen for the treatment of malignancies other than breast and endometrial carcinoma. Semin Oncol. 1997, 24 (1 Suppl 1): S1-S65. S61-70PubMed
35.
Constantinou AI, Lantvit D, Hawthorne M, Xu X, van Breemen RB, Pezzuto JM: Chemopreventive effects of soy protein and purified soy isoflavones on DMBA-induced mammary tumors in female Sprague–Dawley rats. Nutr Cancer. 2001, 41 (1–2): 75-81.CrossRefPubMed
36.
Constantinou AI, Mehta RG, Vaughan A: Inhibition of N-methyl-N-nitrosourea-induced mammary tumors in rats by the soybean isoflavones. Anticancer Res. 1996, 16 (6A): 3293-3298.PubMed
37.
Constantinou AI, White BE, Tonetti D, Yang Y, Liang W, Li W, van Breemen RB: The soy isoflavone daidzein improves the capacity of tamoxifen to prevent mammary tumours. Eur J Cancer. 2005, 41 (4): 647-654. 10.1016/j.ejca.2004.12.005.CrossRefPubMed
38.
Hwang J, Wang J, Morazzoni P, Hodis HN, Sevanian A: The phytoestrogen equol increases nitric oxide availability by inhibiting superoxide production: an antioxidant mechanism for cell-mediated LDL modification. Free Radic Biol Med. 2003, 34 (10): 1271-1282. 10.1016/S0891-5849(03)00104-7.CrossRefPubMed
39.
Rufer CE, Kulling SE: Antioxidant activity of isoflavones and their major metabolites using different in vitro assays. J Agric Food Chem. 2006, 54 (8): 2926-2931. 10.1021/jf053112o.CrossRefPubMed
40.
Pink JJ, Bilimoria MM, Assikis J, Jordan VC: Irreversible loss of the oestrogen receptor in T47D breast cancer cells following prolonged oestrogen deprivation. Br J Cancer. 1996, 74 (8): 1227-1236. 10.1038/bjc.1996.521.CrossRefPubMedPubMedCentral
41.
Mosmann T: Rapid colorimetric assay for cellular growth and survival: application to proliferation and cytotoxicity assays. J Immunol Methods. 1983, 65 (1–2): 55-63.CrossRefPubMed
42.
Batsi C, Markopoulou S, Kontargiris E, Charalambous C, Thomas C, Christoforidis S, Kanavaros P, Constantinou AI, Marcu KB, Kolettas E: Bcl-2 blocks 2-methoxyestradiol induced leukemia cell apoptosis by a p27(Kip1)-dependent G1/S cell cycle arrest in conjunction with NF-kappaB activation. Biochem Pharmacol. 2009, 78 (1): 33-44. 10.1016/j.bcp.2009.03.017.CrossRefPubMedPubMedCentral
43.
44.
Wang KK, Posmantur R, Nath R, McGinnis K, Whitton M, Talanian RV, Glantz SB, Morrow JS: Simultaneous degradation of alphaII- and betaII-spectrin by caspase 3 (CPP32) in apoptotic cells. J Biol Chem. 1998, 273 (35): 22490-22497. 10.1074/jbc.273.35.22490.CrossRefPubMed
45.
Li P, Nijhawan D, Budihardjo I, Srinivasula SM, Ahmad M, Alnemri ES, Wang X: Cytochrome c and dATP-dependent formation of Apaf-1/caspase-9 complex initiates an apoptotic protease cascade. Cell. 1997, 91 (4): 479-489. 10.1016/S0092-8674(00)80434-1.CrossRefPubMed
46.
47.
Mohamad N, Gutierrez A, Nunez M, Cocca C, Martin G, Cricco G, Medina V, Rivera E, Bergoc R: Mitochondrial apoptotic pathways. Biocell. 2005, 29 (2): 149-161.PubMed
48.
Choi EJ, Kim GH: Anticancer mechanism of equol in 7,12-dimethylbenz(a)anthracene-treated animals. Int J Oncol. 2011, 39 (3): 747-754.PubMed
49.
Widyarini S, Husband AJ, Reeve VE: Protective effect of the isoflavonoid equol against hairless mouse skin carcinogenesis induced by UV radiation alone or with a chemical cocarcinogen. Photochem Photobiol. 2005, 81 (1): 32-37. 10.1562/2004-06-02-RA-183.1.CrossRefPubMed
50.
Gaddy VT, Barrett JT, Delk JN, Kallab AM, Porter AG, Schoenlein PV: Mifepristone induces growth arrest, caspase activation, and apoptosis of estrogen receptor-expressing, antiestrogen-resistant breast cancer cells. Clin Cancer Res. 2004, 10 (15): 5215-5225. 10.1158/1078-0432.CCR-03-0637.CrossRefPubMed
51.
Nigam M, Ranjan V, Srivastava S, Sharma R, Balapure AK: Centchroman induces G0/G1 arrest and caspase-dependent apoptosis involving mitochondrial membrane depolarization in MCF-7 and MDA MB-231 human breast cancer cells. Life Sci. 2008, 82 (11–12): 577-590.CrossRefPubMed
52.
Otto AM, Paddenberg R, Schubert S, Mannherz HG: Cell-cycle arrest, micronucleus formation, and cell death in growth inhibition of MCF-7 breast cancer cells by tamoxifen and cisplatin. J Cancer Res Clin Oncol. 1996, 122 (10): 603-612. 10.1007/BF01221192.CrossRefPubMed
53.
Sutherland RL, Hall RE, Taylor IW: Cell proliferation kinetics of MCF-7 human mammary carcinoma cells in culture and effects of tamoxifen on exponentially growing and plateau-phase cells. Cancer Res. 1983, 43 (9): 3998-4006.PubMed
54.
Allred CD, Twaddle NC, Allred KF, Goeppinger TS, Churchwell MI, Ju YH, Helferich WG, Doerge DR: Soy processing affects metabolism and disposition of dietary isoflavones in ovariectomized BALB/c mice. J Agric Food Chem. 2005, 53 (22): 8542-8550. 10.1021/jf051246w.CrossRefPubMed
55.
Uckun FM, Evans WE, Forsyth CJ, Waddick KG, Ahlgren LT, Chelstrom LM, Burkhardt A, Bolen J, Myers DE: Biotherapy of B-cell precursor leukemia by targeting genistein to CD19-associated tyrosine kinases. Science. 1995, 267 (5199): 886-891. 10.1126/science.7531365.CrossRefPubMed
56.
Boldin MP, Goncharov TM, Goltsev YV, Wallach D: Involvement of MACH, a novel MORT1/FADD-interacting protease, in Fas/APO-1- and TNF receptor-induced cell death. Cell. 1996, 85 (6): 803-815. 10.1016/S0092-8674(00)81265-9.CrossRefPubMed
57.
Muzio M, Chinnaiyan AM, Kischkel FC, O’Rourke K, Shevchenko A, Ni J, Scaffidi C, Bretz JD, Zhang M, Gentz R, et al: FLICE, a novel FADD-homologous ICE/CED-3-like protease, is recruited to the CD95 (Fas/APO-1) death–inducing signaling complex. Cell. 1996, 85 (6): 817-827. 10.1016/S0092-8674(00)81266-0.CrossRefPubMed
58.
Hu CC, Tang CH, Wang JJ: Caspase activation in response to cytotoxic Rana catesbeiana ribonuclease in MCF-7 cells. FEBS Lett. 2001, 503 (1): 65-68. 10.1016/S0014-5793(01)02691-6.CrossRefPubMed
59.
Janicke RU, Sprengart ML, Wati MR, Porter AG: Caspase-3 is required for DNA fragmentation and morphological changes associated with apoptosis. J Biol Chem. 1998, 273 (16): 9357-9360. 10.1074/jbc.273.16.9357.CrossRefPubMed
60.
Waterhouse NJ, Finucane DM, Green DR, Elce JS, Kumar S, Alnemri ES, Litwack G, Khanna K, Lavin MF, Watters DJ: Calpain activation is upstream of caspases in radiation-induced apoptosis. Cell Death Differ. 1998, 5 (12): 1051-1061. 10.1038/sj.cdd.4400425.CrossRefPubMed
61.
Berstein LM, Yue W, Wang JP, Santen RJ: Isolated and combined action of tamoxifen and metformin in wild-type, tamoxifen-resistant, and estrogen-deprived MCF-7 cells. Breast Cancer Res Treat. 2011, 128 (1): 109-117. 10.1007/s10549-010-1072-z.CrossRefPubMed
62.
Nazarewicz RR, Zenebe WJ, Parihar A, Larson SK, Alidema E, Choi J, Ghafourifar P: Tamoxifen induces oxidative stress and mitochondrial apoptosis via stimulating mitochondrial nitric oxide synthase. Cancer Res. 2007, 67 (3): 1282-1290. 10.1158/0008-5472.CAN-06-3099.CrossRefPubMed
63.
Fattman CL, An B, Sussman L, Dou QP: p53-independent dephosphorylation and cleavage of retinoblastoma protein during tamoxifen-induced apoptosis in human breast carcinoma cells. Cancer Lett. 1998, 130 (1–2): 103-113.CrossRefPubMed
64.
Ko YM, Wu TY, Wu YC, Chang FR, Guh JY, Chuang LY: Annonacin induces cell cycle-dependent growth arrest and apoptosis in estrogen receptor-alpha-related pathways in MCF-7 cells. J Ethnopharmacol. 2011, 137 (3): 1283-1290. 10.1016/j.jep.2011.07.056.CrossRefPubMed
Metadata
Title
Equol enhances tamoxifen’s anti-tumor activity by induction of caspase-mediated apoptosis in MCF-7 breast cancer cells
Authors
Christiana Charalambous
Chara A Pitta
Andreas I Constantinou
Publication date
01-12-2013
Publisher
BioMed Central
Published in
BMC Cancer / Issue 1/2013
Electronic ISSN: 1471-2407
DOI
https://doi.org/10.1186/1471-2407-13-238

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