Progestagen component in combined hormone replacement therapy in postmenopausal women and breast cancer risk: A debated clinical issue

References

• Lamb R, Harrison H, Clarke RB. Mammary development, carcinomas and progesterone: role of Wnt signalling. Ernst Schering Found Symp Proc 2007;1:1–23.
   Google Scholar
• Schindler AE, Campagnoli C, Druckmann R, Huber J, Pasqualini JR, Schweppe KW, Thijssen JH. Aspects of progestin activity on the breast: European Progestin Club. Maturitas 1998;29:61–65.
   PubMed Web of Science ®Google Scholar
• Gruber CJ, Tschugguel W, Schneeberger C, Huber JC. Production and actions of estrogens. N Engl J Med 2002;346:340–352.
   PubMed Web of Science ®Google Scholar
• Seeger H, Wallwiener D, Mueck AO. The effect of progesterone and synthetic progestins on serum- and estradiol-stimulated proliferation of human breast cancer cells. Horm Metab Res 2003;35:76–80.
   PubMed Web of Science ®Google Scholar
• Gadducci A, Biglia N, Sismondi P, Genazzani AR. Breast cancer and sex steroids: critical review of epidemiological, experimental and clinical investigations on etiopathogenesis, chemoprevention and endocrine treatment of breast cancer. Gynecol Endocrinol 2005;20:343–360.
   PubMed Web of Science ®Google Scholar
• Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and hormone replacement therapy: collaborative reanalysis of data from 51 epidemiological studies of 52705 women with breast cancer and 108411 without breast cancer. Lancet 1997;350:1047–1059.
   PubMed Web of Science ®Google Scholar
• Magnusson C, Baron JA, Correia N, Bergström R, Adami HO, Persson I. Breast-cancer risk following long-term oestrogen- and oestrogen-progestin-replacement therapy. Int J Cancer 1999;81:339–344.
   PubMed Web of Science ®Google Scholar
• Schairer C, Lubin J, Troisi R, Sturgeon S, Brinton L, Hoover R. Menopausal estrogen and estrogen-progestin replacement therapy and breast cancer risk. JAMA 2000;283:485–491.
   PubMed Web of Science ®Google Scholar
• Ross RK, Paganini-Hill A, Wan PC, Pike MC. Effect of hormone replacement therapy on breast cancer risk: estrogens versus estrogen plus progestin. J Natl Cancer Inst 2000;92:328–332.
   PubMed Web of Science ®Google Scholar
• Chen CL, Weiss NS, Newcomb P, Barlow W, White E. Hormone replacement therapy in relation to breast cancer. JAMA 2002;287:734–741.
   PubMed Web of Science ®Google Scholar
• Weiss LK, Burkman RT, Cushing-Haugen KL, Voigt LF, Simon MS, Daling JR, Norman SA, Bernstein L, Ursin G, Marchbanks PA, et al Hormone replacement therapy regimens and breast cancer risk. Obstet Gynecol 2002;100:1148–1158.
   PubMed Web of Science ®Google Scholar
• Rossouw JE, Anderson GL, Prentice RL, LaCroix AZ, Kooperberg C, Stefanick ML, Jackson RD, Beresford SA, Howard BV, Johnson KC, et al Writing Group for the Women's Health Initiative Investigators. Risks and benefits of estrogen plus progestin in healthy postmenopausal women: principal results from the Women's Health Initiative randomized controlled trial. JAMA 2002;288:321–333.
   PubMed Web of Science ®Google Scholar
• Daling JR, Malone KE, Doody DR, Voigt LF, Bernstein L, Coates RJ, Marchbanks PA, Norman SA, Weiss LK, Ursin G, et al Relation of regimens of combined hormone replacement therapy to lobular, ductal, and other histologic types of breast carcinoma. Cancer 2002;95:2455–2464.
   PubMed Web of Science ®Google Scholar
• Beral V. Million Women Study Collaborators. Breast cancer and hormone-replacement therapy in the Million Women Study. Lancet 2003;362:419–427.
   PubMed Web of Science ®Google Scholar
• Olsson HL, Ingvar C, Bladström A. Hormone replacement therapy containing progestins and given continuously increases breast carcinoma risk in Sweden. Cancer 2003;97:1387–1392.
   PubMed Web of Science ®Google Scholar
• Position Statement. Role of progestogen in hormone therapy for postmenopausal women: position statement of the North American Monopause Society. Menopause 2003;10:113–132.
   PubMed Web of Science ®Google Scholar
• Anderson GL, Limacher M, Assaf AR, Bassford T, Beresford SA, Black H, Bonds D, Brunner R, Brzyski R, Caan B, et al Women's Health Initiative Steering Committee. Effects of conjugated equine estrogen in postmenopausal women with hysterectomy: the Women's Health Initiative randomized controlled trial. JAMA 2004;291:1701–1712.
   PubMed Web of Science ®Google Scholar
• Blake J. Menopause: evidence-based practice. Best Pract Res Clin Obstet Gynaecol 2006;20:799–839.
   PubMed Web of Science ®Google Scholar
• Beral V, Reeves G, Banks E. Current evidence about the effect of hormone replacement therapy on the incidence of major conditions in postmenopausal women. BJOG 2005;112:692–695.
   PubMed Web of Science ®Google Scholar
• Kenemans P. Postmenopausal hormone therapy and breast cancer: what is the problem? Maturitas 2005;51:75–82.
   PubMed Web of Science ®Google Scholar
• Tannen RL, Weiner MG, Xie D, Barnhart K. Estrogen affects post-menopausal women differently than estrogen plus progestin replacement therapy. Hum Reprod 2007;22:1769–1777.
   PubMed Web of Science ®Google Scholar
• Opatrny L, Dell'Aniello S, Assouline S, Suissa S. Hormone replacement therapy use and variations in the risk of breast cancer. BJOG 2008;115:169–175.
   PubMed Web of Science ®Google Scholar
• Cuzick J. Hormone replacement therapy and the risk of breast cancer. Eur J Cancer in press.
   Web of Science ®Google Scholar
• de Lignières B, de Vathaire F, Fournier S, Urbinelli R, Allaert F, Le MG, Kuttenn F. Combined hormone replacement therapy and risk of breast cancer in a French cohort study of 3175 women. Climacteric 2002;5:332–340.
   PubMed Web of Science ®Google Scholar
• Campagnoli C, Clavel-Chapelon F, Kaaks R, Peris C, Berrino F. Progestins and progesterone in hormone replacement therapy and the risk of breast cancer. J Steroid Biochem Mol Biol 2005;96:95–108.
   PubMed Web of Science ®Google Scholar
• Fournier A, Berrino F, Riboli E, Avenel V, Clavel-Chapelon F. Breast cancer risk in relation to different types of hormone replacement therapy in the E3N-EPIC cohort. Int J Cancer 2005;114:448–454.
   PubMed Web of Science ®Google Scholar
• Dinger JC, Heinemann LA, Mohner S, Thai do M, Assmann A. Breast cancer risk associated with different HRT formulations: a register-based case-control study. BMC Womens Health 2006;12:6–13.
   Google Scholar
• L'hermite M, Simoncini T, Fuller S, Genazzani AR. Could transdermal estradiol + progesterone be a safer postmenopausal HRT? A review. Maturitas 2008;60:185–201.
   PubMed Web of Science ®Google Scholar
• Fournier A, Berrino F, Clavel-Chapelon F. Unequal risks for breast cancer associated with different hormone replacement therapies: results from the E3N cohort study. Breast Cancer Res Treat 2008;107:103–111.
   PubMed Web of Science ®Google Scholar
• Yee D, Lee AV. Crosstalk between the insulin-like growth factors and estrogens in breast cancer. J Mammary Gland Biol Neoplasia 2000;5:107–115.
   PubMed Web of Science ®Google Scholar
• Cheskis BJ. Regulation of cell signalling cascades by steroid hormones. J Cell Biochem 2004;93:20–27.
   PubMed Web of Science ®Google Scholar
• Song RX, Zhang Z, Chen Y, Bao Y, Santen RJ. Estrogen signaling via a linear pathway involving insulin-like growth factor I receptor, matrix metalloproteinases, and epidermal growth factor receptor to activate mitogen-activated protein kinase in MCF-7 breast cancer cells. Endocrinology 2007;148:4091–4101.
   PubMed Web of Science ®Google Scholar
• Kyo S, Takakura M, Kanaya T, Zhuo W, Fujimoto K, Nishio Y, Orimo A, Inoue M. Estrogen activates telomerase. Cancer Res 1999;59:5917–5921.
   PubMed Web of Science ®Google Scholar
• Gao J, Chen D, Tian Y, Zhang J, Cai K. Effect of estrogen on telomerase activity in human breast cancer cells. J Huazhong Univ Sci Technol Med Sci 2003;23:286–287.
   PubMedGoogle Scholar
• Bayne S, Liu JP. Hormones and growth factors regulate telomerase activity in ageing and cancer. Mol Cell Endocrinol 2005;240:11–22.
   PubMed Web of Science ®Google Scholar
• Martínez-Campa CM, Alonso-González C, Mediavilla MD, Cos S, González A, Sanchez-Barcelo EJ. Melatonin down-regulates hTERT expression induced by either natural estrogens (17beta-estradiol) or metalloestrogens (cadmium) in MCF-7 human breast cancer cells. Cancer Lett 2008;268:272–277.
   PubMed Web of Science ®Google Scholar
• Mitropoulou TN, Tzanakasis GN, Kletsas D, Kalofonos HP, Karamanos NK. Letrozole as a potent inhibitor of cell proliferation and expression of metalloproteinases (MMP-2 and MMP-9) by human epithelial breast cancer cells. Int J Cancer 2003;104:155–160.
   PubMed Web of Science ®Google Scholar
• Abdallah MA, Abdullah HI, Kang S, Taylor DD, Nakajima ST, Gercel-Taylor C. Effects of the components of hormone therapy on matrix metalloproteinases in breast-cancer cells: an in vitro study. Fertil Steril 2007;87:978–981.
   PubMed Web of Science ®Google Scholar
• Takei H, Lee ES, Jordan VC. In vitro regulation of vascular endothelial growth factor by estrogens and antiestrogens in estrogen-receptor positive breast cancer. Breast Cancer 2002;9:39–42.
   PubMedGoogle Scholar
• Garvin S, Nilsson UW, Huss FR, Kratz G, Dabrosin C. Estradiol increases VEGF in human breast studied by whole-tissue culture. Cell Tissue Res 2006;325:245–251.
   PubMed Web of Science ®Google Scholar
• Jordan VC. Biochemical pharmacology of antiestrogen action. Pharmacol Rev 1984;36:245–276.
   PubMed Web of Science ®Google Scholar
• Kawagoe J, Ohmichi M, Takahashi T, Ohshima C, Mabuchi S, Takahashi K, Igarashi H, Mori-Abe A, Saitoh M, Du B, Ohta T, et al Raloxifene inhibits estrogen-induced up-regulation of telomerase activity in a human breast cancer cell line. J Biol Chem 2003;278:43363–43372.
   PubMed Web of Science ®Google Scholar
• Gadducci A, Cosio S, Genazzani AR. Use of estrogen antagonists and aromatase inhibitors in breast cancer and hormonally sensitive tumors of the uterine body. Curr Opin Invest Drug 2004;5:1031–1044.
   PubMedGoogle Scholar
• Qu Z, Van Ginkel S, Roy AM, Westbrook L, Nasrin M, Maxuitenko Y, Frost AR, Carey D, Wang W, Li R, et al Vascular endothelial growth factor reduces tamoxifen efficacy and promotes metastatic colonization and desmoplasia in breast tumors. Cancer Res 2008;68:6232–6240.
   PubMed Web of Science ®Google Scholar
• Giretti MS, Fu XD, De Rosa G, Sarotto I, Baldacci C, Garibaldi S, Mannella P, Biglia N, Sismondi P, Genazzani AR, et al Extra-nuclear signalling of estrogen receptor to breast cancer cytoskeletal remodelling, migration and invasion. PLoS ONE 2008;21;3: e2238.
   Google Scholar
• Manni A, Badger B, Wright C, Ahmed SR, Demers LM. Effects of progestins on growth of experimental breast cancer in culture: interaction with estradiol and prolactin and involvement of the polyamine pathway. Cancer Res 1987;47:3066–3071.
   PubMed Web of Science ®Google Scholar
• Groshong SD, Owen GI, Grimison B, Schauer IE, Todd MC, Langan TA, Sclafani RA, Lange CA, Horwitz KB. Biphasic regulation of breast cancer cell growth by progesterone: role of the cyclin-dependent kinase inhibitors, p21 and p27(Kip1). Mol Endocrinol 1997;11:1593–1607.
   PubMed Web of Science ®Google Scholar
• Lange CA, Richer JK, Shen T, Horwitz KB. Convergence of progesterone and epidermal growth factor signaling in breast cancer. Potentiation of mitogen-activated protein kinase pathways. J Biol Chem 1998;273:31308–31316.
   PubMed Web of Science ®Google Scholar
• Moore MR, Conover JL, Franks KM. Progestin effects on long-term growth, death, and Bcl-xL in breast cancer cells. Biochem Biophys Res Commun 2000;277:650–654.
   PubMed Web of Science ®Google Scholar
• Shen T, Horwitz KB, Lange CA. Transcriptional hyperactivity of human progesterone receptors is coupled to their ligand-dependent down-regulation by mitogen-activated protein kinase-dependent phosphorylation of serine 294. Mol Cell Biol 2001;21:6122–6131.
   PubMed Web of Science ®Google Scholar
• Moore MR. A rationale for inhibiting progesterone-related pathways to combat breast cancer. Curr Cancer Drug Targets 2004;4:183–189.
   PubMed Web of Science ®Google Scholar
• Sitruk-Ware R, Plu-Bureau G. Exogenous progestogens and the human breast. Maturitas 2004;49:58–66.
   PubMed Web of Science ®Google Scholar
• Jeng MH, Parker CJ, Jordan VC. Estrogenic potential of progestins in oral contraceptives to stimulate human breast cancer cell proliferation. Cancer Res 1992;52:6539–6546.
   PubMed Web of Science ®Google Scholar
• Markiewicz L, Hochberg RB, Gurpide E. Intrinsic estrogenicity of some progestagenic drugs. J. Steroid Biochem Mol Biol 1992;41:53–58.
   PubMed Web of Science ®Google Scholar
• Gadducci A, Genazzani AR. Steroid hormones in endometrial and breast cancer. Eur J Gynaecol Oncol 1997;18:371–378.
   PubMed Web of Science ®Google Scholar
• Rabe T, Bohlmann MK, Rehberger-Schneider S, Prifti S. Induction of estrogen receptor-alpha and -beta activities by synthetic progestins. Gynecol Endocrinol 2000;14:118–126.
   PubMed Web of Science ®Google Scholar
• Pasqualini JR, Chetrite GS. Endocrine, paracrine and intracrine mechanisms of growth regulation in normal and malignant breast epithelium. In: Hormone replacement therapy and cancer. The Current status of research and practice, Genazzani AR, editors. Boca Raton: Parthenon Publishing, 2002. pp 44–53.
   Google Scholar
• Sutherland RL, Prall OWJ, Watts CKW, Musgrove EA. Estrogen and progestin regulation of cell cycle progression. J Mammary Gland Biol Neoplasia 1998;3:63–72.
   PubMed Web of Science ®Google Scholar
• Musgrove EA, Lee CS, Cornish AL, Swarbrick A, Sutherland RL. Antiprogestin inhibition of cell cycle progression in T-47D breast cancer cells is accompanied by induction of the cyclin-dependent kinase inhibitor p21. Mol Endocrinol 1997;11:54–66.
   PubMedGoogle Scholar
• Lange CA, Richer JK, Horwitz KB. Hypothesis: progesterone primes breast cancer cells for cross-talk with proliferative or antiproliferative signals. Mol Endocrinol 1999;13:829–836.
   PubMed Web of Science ®Google Scholar
• Musgrove EA, Lee CS, Sutherland RL. Progestins both stimulate and inhibit breast cancer cell cycle progression while increasing expression of transforming growth factor α, epidermal growth factor receptor, c-fos, and c-myc genes. Mol Cell Biol 1991;11:5032–5043.
   PubMed Web of Science ®Google Scholar
• Hurd C, Khattree N, Alban P, Nag K, Jhanwar SC, Dinda S, Moudgil VK. Hormonal regulation of the p53 tumor suppressor protein in T47D human breast carcinoma cell line. J Biol Chem 1995;270:28507–28510.
   PubMed Web of Science ®Google Scholar
• Migliaccio A, Piccolo D, Castoria G, Di Domenico M, Bilancio A, Lombardi M, Gong W, Beato M, Auricchio F. Activation of the Src/p21ras/Erk pathway by progesterone receptor via cross-talk with estrogen receptor. EMBO J 1998;17:2008–2018.
   PubMed Web of Science ®Google Scholar
• Castoria G, Barone MV, Di Domenico M, Bilancio A, Ametrano D, Migliaccio A, Auricchio F. Non-transcriptional action of oestradiol and progestin triggers DNA synthesis. EMBO J 1999;18:2500–2510.
   PubMed Web of Science ®Google Scholar
• Ballare C, Uhrig M, Bechtold T, Sancho E, Di Domenico M, Migliaccio A, Auricchio F, Beato M. Two domains of the progesterone receptor interact with the estrogen receptor and are required for progesterone activation of the c-Src/Erk pathway in mammalian cells. Mol Cell Biol 2003;23:1994–2008.
   PubMed Web of Science ®Google Scholar
• Myoui A, Nishimura R, Williams PJ, Hiraga T, Tamura D, Michigami T, Mundy GR, Yoneda T. C-SRC tyrosine kinase activity is associated with tumor colonization in bone and lung in an animal model of human breast cancer metastasis. Cancer Res 2003;63:5028–5033.
   PubMed Web of Science ®Google Scholar
• Tan M, Li P, Klos KS, Lu J, Lan KH, Nagata Y, Fang D, Jing T, Yu D. ErbB2 promotes Src synthesis and stability: novel mechanisms of Src activation that confer breast cancer metastasis. Cancer Res 2005;65:1858–1867.
   PubMed Web of Science ®Google Scholar
• Rucci N, Recchia I, Angelucci A, Alamanou M, Del Fattore A, Fortunati D, Susa M, Fabbro D, Bologna M, Teti A. Inhibition of protein kinase c-Src reduces the incidence of breast cancer metastases and increases survival in mice: implications for therapy. J Pharmacol Exp Ther 2006;318:161–172.
   PubMed Web of Science ®Google Scholar
• Hiscox S, Morgan L, Green TP, Barrow D, Gee J, Nicholson RI. Elevated Src activity promotes cellular invasion and motility in tamoxifen resistant breast cancer cells. Breast Cancer Res Treat 2006;297:263–274.
   Google Scholar
• Summy JM, Gallick GE. Src family kinases in tumor progression and metastasis. Cancer Metastasis Rev 2003;22:337–358.
   PubMed Web of Science ®Google Scholar
• Shupnik MA. Crosstalk between steroid receptors and the c-Src-receptor tyrosine kinase pathways: implications for cell proliferation. Oncogene 2004;23:7979–7989.
   PubMed Web of Science ®Google Scholar
• Carnevale RP, Proietti CJ, Salatino M, Urtreger A, Peluffo G, Edwards DP, Boonyaratanakornkit V, Charreau EH, Bal de Kier Joffé E, Schillaci R, et al Progestin effects on breast cancer cell proliferation, proteases activation, and in vivo development of metastatic phenotype all depend on progesterone receptor capacity to activate cytoplasmic signaling pathways. Mol Endocrinol 2007;21:1335–1358.
   PubMed Web of Science ®Google Scholar
• Fu XD, Giretti MS, Baldacci C, Garibaldi S, Flamini M, Sanchez AM, Gadducci A, Genazzani AR, Simoncini T. Extra-nuclear signaling of progesterone receptor to breast cancer cell movement and invasion through the actin cytoskeleton. PLoS ONE 2008;3:e2790.
   PubMed Web of Science ®Google Scholar
• Foidart JM, Colin C, Denoo X, Desreux J, Be'liard A, Fournier S, de Lignieres B. Estradiol and progesterone regulate the proliferation of human breast epithelial cells. Fertil Steril 1998;69:963–969.
   PubMed Web of Science ®Google Scholar
• Chang KJ, Lee TTY, Linares-Cruz G, Fournier S, de Lignieres B. Influences of percutaneous administration of estradiol and progesterone of human breast epithelial cell cycle in vivo. Fertil Steril 1995;63:785–791.
   PubMed Web of Science ®Google Scholar
• Xu B, Kitawaki J, Koshiba H, Ishihara H, Kiyomizu M, Teramoto M, Kitaoka Y, Honjo H. Differential effects of progestogens, by type and regimen, on estrogen-metabolizing enzymes in human breast cancer cells. Maturitas 2007;56:142–152.
   PubMed Web of Science ®Google Scholar
• Wood CE, Register TC, Lees CJ, Chen H, Kimrey S, Cline JM. Effects of estradiol with micronized progesterone or medroxyprogesterone acetate on risk markers for breast cancer in postmenopausal monkeys. Breast Cancer Res Treat 2007;101:125–134.
   PubMed Web of Science ®Google Scholar
• Wood CE, Register TC, Cline JM. Transcriptional profiles of progestogen effects in the postmenopausal breast. Breast Cancer Res Treat in press.
   Web of Science ®Google Scholar
• Campagnoli C, Abbà C, Ambroggio S, Peris C. Differential effects of progestins on the circulating IGF-I system. Maturitas 2003;46S:S39–S44.
   Google Scholar
• Hankinson SE, Willett WC, Colditz GA, Hunter DJ, Michaud DS, Deroo B, Rosner B, Speizer FE, Pollak M. Circulating concentrations of insulin-like growth factor-I and risk of breast cancer. Lancet 1998;351:1393–1396.
   PubMed Web of Science ®Google Scholar
• Toniolo P, Bruning PF, Akhmedkhanov A, Bonfrer JM, Koenig KL, Lukanova A, Shore RE, Zeleniuch-Jacquotte A. Serum insulin-like growth factor-I and breast cancer. Int J Cancer 2000;88:828–832.
   PubMed Web of Science ®Google Scholar
• Campagnoli C, Biglia N, Lanza MG, Lesca L, Peris C, Sismondi P. Androgenic progestogens oppose the decrease of insulin-like growth factor I serum level induced by conjugated oestrogens in postmenopausal women. Preliminary report. Maturitas 1994;19:25–31.
   PubMed Web of Science ®Google Scholar
• Fonseca E, Ochoa R, Galván R, Hernández M, Mercado M, Zárate A. Increased serum levels of growth hormone and insulin-like growth factor-I associated with simultaneous decrease of circulating insulin in postmenopausal women receiving hormone replacement therapy. Menopause 1999;6:56–60.
   PubMed Web of Science ®Google Scholar
• Heald A, Selby PL, White A, Gibson JM. Progestins abrogate estrogen-induced changes in the insuline-like growth factor axis. Am J Obstet Gynecol 2000;183:593–600.
   PubMed Web of Science ®Google Scholar
• Posaci C, Altunyurt S, Islekel H, Onvural A. Effects of HRT on serum levels of IGF-I in postmenopausal women. Maturitas 2001;40:69–74.
   PubMed Web of Science ®Google Scholar
• Campagnoli C, Colombo P, De Aloysio D, Gambacciani M, Grazioli I, Nappi C, Serra GB, Genazzani AR. Positive effects on cardiovascular and breast metabolic markers of oral estradiol and dydrogesterone in comparison with transdermal estradiol and norethisterone acetate. Maturitas 2002;41:299–311.
   PubMed Web of Science ®Google Scholar
• Chlebowski RT, Hendrix SL, Langer RD, Stefanick ML, Gass M, Lane D, Rodabough RJ, Gilligan MA, Cyr MG, Thomson CA, et al WHI Investigators. Influence of estrogen plus progestin on breast cancer and mammography in healthy postmenopausal women: the Women's Health Initiative Randomized Trial. JAMA 2003;289:3243–3253.
   PubMed Web of Science ®Google Scholar
• Horwitz KB, Sartorius CA. Progestins in hormone replacement therapies reactivate cancer stem cells in women with preexisting breast cancers: a hypothesis. J Clin Endocrinol Metab 2008;93:3295–3298.
   PubMed Web of Science ®Google Scholar
• Perou CM, Sorlie T, Eisen MB, van de Rijn M, Jeffrey SS, Rees CA, Pollack JR, Ross DT, Johnsen H, Akslen LA, et al Molecular portraits of human breast tumours. Nature 2000;406:747–752.
   PubMed Web of Science ®Google Scholar
• Reya T, Morrison SJ, Clarke MF, Weissman IL. Stem cells, cancer, and cancer stem cells. Nature 2001;414:105–111.
   PubMed Web of Science ®Google Scholar
• Al-Hajj M, Wicha MS, Benito-Hernandez A, Morrison SJ, Clarke MF. Prospective identification of tumorigenic breast cancer cells. Proc Natl Acad Sci USA 2003;100:3983–3988.
   PubMed Web of Science ®Google Scholar
• Sartorius CA, Harvell DM, Shen T, Horwitz KB. Progestins initiate a luminal to myoepithelial switch in estrogen-dependent human breast tumors without altering growth. Cancer Res 2005;65:9779–9788.
   PubMed Web of Science ®Google Scholar
• Clarke RB. Ovarian steroids and the human breast: regulation of stem cells and cell proliferation. Maturitas 2006;54:327–334.
   PubMed Web of Science ®Google Scholar
• Horwitz KB, Dye WW, Harrell JC, Kabos P, Sartorius CA. Rare steroid receptor-negative basal-like tumorigenic cells in luminal subtype human breast cancer xenografts. Proc Natl Acad Sci USA 2008;105:5774–5779.
   PubMed Web of Science ®Google Scholar