Mechanisms of the epithelial–mesenchymal transition by TGF-β
Abstract
The formation of epithelial cell barriers results from the defined spatiotemporal differentiation of stem cells into a specialized and polarized epithelium, a process termed mesenchymal–epithelial transition. The reverse process, epithelial–mesenchymal transition (EMT), is a metastable process that enables polarized epithelial cells to acquire a motile fibroblastoid phenotype. Physiological EMT also plays an essential role in promoting tissue healing, remodeling or repair in response to a variety of pathological insults. On the other hand, pathophysiological EMT is a critical step in mediating the acquisition of metastatic phenotypes by localized carcinomas. Although metastasis clearly is the most lethal aspect of cancer, our knowledge of the molecular events that govern its development, including those underlying EMT, remain relatively undefined. Transforming growth factor-β (TGF-β) is a multifunctional cytokine that oversees and directs all aspects of cell development, differentiation and homeostasis, as well as suppresses their uncontrolled proliferation and transformation. Quite dichotomously, tumorigenesis subverts the tumor suppressing function of TGF-β, and in doing so, converts TGF-β to a tumor promoter that stimulates pathophysiological EMT and metastasis. It therefore stands to reason that determining how TGF-β induces EMT in developing neoplasms will enable science and medicine to produce novel pharmacological agents capable of preventing its ability to do so, thereby improving the clinical course of cancer patients. Here we review the cellular, molecular and microenvironmental mechanisms used by TGF-β to mediate its stimulation of EMT in normal and malignant cells.
Papers of special note have been highlighted as: ▪ of interest ▪▪ of considerable interest
Bibliography
- 1 Baum B, Settleman J, Quinlan MP: Transitions between epithelial and mesenchymal states in development and disease. Semin. Cell Dev. Biol.19,294–308 (2008).
- 2 Yang J, Weinberg RA: Epithelial–mesenchymal transition: at the crossroads of development and tumor metastasis. Dev. Cell.14,818–829 (2008).
- 3 Elenbaas B, Weinberg RA: Heterotypic signaling between epithelial tumor cells and fibroblasts in carcinoma formation. Exp. Cell Res.264,169–184 (2001).
- 4 Moustakas A, Heldin CH: Signaling networks guiding epithelial–mesenchymal transitions during embryogenesis and cancer progression. Cancer Sci.98,1512–1520 (2007).
- 5 Zavadil J, Bottinger EP: TGF-β and epithelial-to-mesenchymal transitions. Oncogene24,5764–5774 (2005).
- 6 Thiery JP: Epithelial–mesenchymal transitions in development and pathologies. Curr. Opin. Cell Biol.15,740–746 (2003).
- 7 Shook D, Keller R: Mechanisms, mechanics and function of epithelial–mesenchymal transitions in early development. Mech. Dev.120,1351–1383 (2003).
- 8 Thiery JP: Epithelial–mesenchymal transitions in tumor progression. Nat. Rev. Cancer2,442–454 (2002).
- 9 Willis BC, Borok Z: TGF-β-induced EMT: mechanisms and implications for fibrotic lung disease. Am. J. Physiol. Lung Cell. Mol. Physiol.293,L525–L534 (2007).
- 10 Blobe GC, Schiemann WP, Lodish HF: Role of TGF-β in human disease. N. Engl. J. Med.342,1350–1358 (2000).
- 11 Galliher AJ, Neil JR, Schiemann WP: Role of TGF-β in cancer progression. Future Oncol.2,743–763 (2006).
- 12 Massague J, Gomis RR: The logic of TGF-β signaling. FEBS Lett.580,2811–2820 (2006).
- 13 Siegel PM, Massague J: Cytostatic and apoptotic actions of TGF-β in homeostasis and cancer. Nat. Rev. Cancer3,807–821 (2003).
- 14 Savagner P: Leaving the neighborhood: molecular mechanisms involved during epithelial–mesenchymal transition. Bioessays23,912–923 (2001).
- 15 Miettinen PJ, Ebner R, Lopez AR, Derynck R: TGF-β induced transdifferentiation of mammary epithelial cells to mesenchymal cells: involvement of type I receptors. J. Cell Biol.127,2021–2036 (1994).
- 16 Kaartinen V, Voncken JW, Shuler C et al.: Abnormal lung development and cleft palate in mice lacking TGF-β3 indicates defects of epithelial–mesenchymal interaction. Nature Genet.11,415–421 (1995).▪ Study established the critical role for transforming growth factor (TGF)-β3 in regulating developmental epithelial–mesenchymal transition (EMT).
- 17 Romano LA, Runyan RB: Slug is an essential target of TGF-β2 signaling in the developing chicken heart. Dev. Biol.223,91–102 (2000).
- 18 Saika S, Kono-Saika S, Ohnishi Y et al.: Smad3 signaling is required for epithelial–mesenchymal transition of lens epithelium after injury. Am. J. Pathol.164,651–663 (2004).
- 19 Saika S, Kono-Saika S, Tanaka T et al.: Smad3 is required for dedifferentiation of retinal pigment epithelium following retinal detachment in mice. Lab. Invest.84,1245–1258 (2004).
- 20 Sato M, Muragaki Y, Saika S, Roberts AB, Ooshima A: Targeted disruption of TGF-β1/Smad3 signaling protects against renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction. J. Clin. Invest.112,1486–1494 (2003).
- 21 Feng XH, Derynck R: Specificity and versatility in TGF-β signaling through Smads. Annu. Rev. Cell Dev. Biol.21,659–693 (2005).
- 22 Moustakas A, Heldin CH: Non-Smad TGF-β signals. J. Cell Sci.118,3573–3584 (2005).
- 23 Shi Y, Massague J: Mechanisms of TGF-β signaling from cell membrane to the nucleus. Cell113,685–700 (2003).
- 24 Tsukazaki T, Chiang TA, Davison AF, Attisano L, Wrana JL: SARA, a FYVE domain protein that recruits Smad2 to the TGF-β receptor. Cell95,779–791 (1998).▪ Identified sarA as a novel adapter molecule that facilitates Smad2/3 recruitment and activation by TGF-β receptors.
- 25 Miura S, Takeshita T, Asao H et al.: Hgs (Hrs), a FYVE domain protein, is involved in Smad signaling through cooperation with SARA. Mol. Cell Biol.20,9346–9355 (2000).
- 26 Hocevar BA, Smine A, Xu XX, Howe PH: The adaptor molecule Disabled-2 links the TGF-β receptors to the Smad pathway. EMBO J.20,2789–2801 (2001).
- 27 Hayashi H, Abdollah S, Qiu Y et al.: The MAD-related protein Smad7 associates with the TGF-β receptor and functions as an antagonist of TGF-β signaling. Cell89,1165–1173 (1997).▪ Identified Smad7 as an inhibitory molecule of the TGF-β signaling system.
- 28 Nakao A, Afrakht M, Moren A et al.: Identification of Smad7, a TGF-β-inducible antagonist of TGF-β signalling. Nature389,631–635 (1997).▪ Identified Smad7 as an inhibitory molecule of the TGF-β signaling system.
- 29 Souchelnytskyi S, Nakayama T, Nakao A et al.: Physical and functional interaction of murine and Xenopus Smad7 with bone morphogenetic protein receptors and TGF-β receptors. J. Biol. Chem.273,25364–25370 (1998).
- 30 Ebisawa T, Fukuchi M, Murakami G et al.: Smurf1 interacts with TGF-β type I receptor through Smad7 and induces receptor degradation. J. Biol. Chem.276,12477–12480 (2001).
- 31 Kavsak P, Rasmussen RK, Causing CG et al.: Smad7 binds to Smurf2 to form an E3 ubiquitin ligase that targets the TGF-β receptor for degradation. Mol. Cell6,1365–1375 (2000).
- 32 Datta PK, Moses HL: STRAP and Smad7 synergize in the inhibition of TGF-β signaling. Mol. Cell. Biol.20,3157–3167 (2000).
- 33 Ibarrola N, Kratchmarova I, Nakajima D et al.: Cloning of a novel signaling molecule, AMSH-2, that potentiates TGF-β signaling. BMC Cell Biol.5,2 (2004).
- 34 Koinuma D, Shinozaki M, Komuro A et al.: Arkadia amplifies TGF-β superfamily signalling through degradation of Smad7. EMBO J.22,6458–6470 (2003).
- 35 Liu FY, Li XZ, Peng YM, Liu H, Liu YH: Arkadiα-SMAd7-mediated positive regulation of TGF-β signaling in a rat model of tubulointerstitial fibrosis. Am. J. Nephrol.27,176–183 (2007).
- 36 Liu W, Rui H, Wang J et al.: Axin is a scaffold protein in TGF-β signaling that promotes degradation of Smad7 by Arkadia. EMBO J.25,1646–1658 (2006).
- 37 Bakin AV, Rinehart C, Tomlinson AK, Arteaga CL: p38 mitogen-activated protein kinase is required for TGF-β-mediated fibroblastic transdifferentiation and cell migration. J. Cell Sci.115,3193–3206 (2002).
- 38 Bakin AV, Tomlinson AK, Bhowmick NA, Moses HL, Arteaga CL: Phosphatidylinositol 3-kinase function is required for TGF-β-mediated epithelial to mesenchymal transition and cell migration. J. Biol. Chem.275,36803–36810 (2000).
- 39 Bhowmick NA, Zent R, Ghiassi M, McDonnell M, Moses HL: Integrin β1 signaling is necessary for TGF-β activation of p38MAPK and epithelial plasticity. J. Biol. Chem.276,46707–46713 (2001).
- 40 Lamouille S, Derynck R: Cell size and invasion in TGF-β induced epithelial to mesenchymal transition is regulated by activation of the mTOR pathway. J. Cell Biol.178,437–451 (2007).
- 41 Perlman R, Schiemann WP, Brooks MW, Lodish HF, Weinberg RA: TGF-β-induced apoptosis is mediated by the adapter protein Daxx that facilitates JNK activation. Nat. Cell Biol.3,708–714 (2001).
- 42 Zavadil J, Bitzer M, Liang D et al.: Genetic programs of epithelial cell plasticity directed by TGF-β. Proc. Natl Acad. Sci. USA98,6686–6691 (2001).
- 43 Galliher AJ, Schiemann WP: β3 integrin and Src facilitate TGF-β mediated induction of epithelial–mesenchymal transition in mammary epithelial cells. Breast Cancer Res.8,R42 (2006).
- 44 Galliher AJ, Schiemann WP: Src phosphorylates Tyr284 in TGF-β type II receptor and regulates TGF-β stimulation of p38 MAPK during breast cancer cell proliferation and invasion. Cancer Res.67,3752–3758 (2007).
- 45 Galliher-Beckley AJ, Schiemann WP: Grb2 binding to Tyr284 in TGF-β is essential for mammary tumor growth and metastasis stimulated by TGF-β. Carcinogenesis29,244–251 (2008).
- 46 Azuma M, Motegi K, Aota K, Yamashita T, Yoshida H, Sato M: TGF-β1 inhibits NF-κB activity through induction of IκBα expression in human salivary gland cells: a possible mechanism of growth suppression by TGF-β1. Exp. Cell Res.250,213–222 (1999).
- 47 Neil JR, Schiemann WP: Altered TAB1:IkB kinase interaction promotes TGF-β-mediated NF-κB activation during breast cancer progression. Cancer Res.68,1462–1470 (2008).▪ Together with [37–42], established various noncanonical TGF-β effectors as critical mediators of EMT and oncogenic signaling stimulated by TGF-β.
- 48 Arsura M, Panta GR, Bilyeu JD et al.: Transient activation of NF-κB through a TAK1//IKK kinase pathway by TGF-β1 inhibits AP-1//SMAD signaling and apoptosis: implications in liver tumor formation. Oncogene22,412–425 (2003).
- 49 Kim DW, Sovak MA, Zanieski G et al.: Activation of NF-κB/Rel occurs early during neoplastic transformation of mammary cells. Carcinogenesis21,871–879 (2000).
- 50 Park J-I, Lee M-G, Cho K et al.: TGF-β1 activates interleukin-6 expression in prostate cancer cells through the synergistic collaboration of the Smad2, p38-NF-κB, JNK, and Ras signaling pathways. Oncogene22,4314–4332 (2003).
- 51 Rayet B, Gelinas C: Aberrant Rel/NF-κB genes and activity in human cancer. Oncogene18,6938–6947 (1999).
- 52 Horowitz JC, Rogers DS, Sharma V et al.: Combinatorial activation of FAK and AKT by TGF-β1 confers an anoikis-resistant phenotype to myofibroblasts. Cell Signal.19,761–771 (2007).
- 53 Thannickal VJ, Lee DY, White ES et al.: Myofibroblast differentiation by TGF-β1 is dependent on cell adhesion and integrin signaling via focal adhesion kinase. J. Biol. Chem.278,12384–12389 (2003).
- 54 Park SS, Eom YW, Kim EH et al.: Involvement of c-Src kinase in the regulation of TGF-β1-induced apoptosis. Oncogene23,6272–6281 (2004).
- 55 Wang S, Wilkes MC, Leof EB, Hirschberg R: Imatinib mesylate blocks a non-Smad TGF-β pathway and reduces renal fibrogenesis in vivo. FASEB J.19,1–11 (2005).
- 56 Wilkes MC, Leof EB: TGF-β activation of c-Abl is independent of receptor internalization and regulated by phosphatidylinositol 3-kinase and PAK2 in mesenchymal cultures. J. Biol. Chem.281,27846–27854 (2006).
- 57 Ebnet K, Suzuki A, Ohno S, Vestweber D: Junctional adhesion molecules (JAMs): more molecules with dual functions? J. Cell Sci.117,19–29 (2004).
- 58 Schneeberger EE, Lynch RD: The tight junction: a multifunctional complex. Am. J. Physiol. Cell. Physiol.286,C1213–C1228 (2004).
- 59 Itoh M, Bissell MJ: The organization of tight junctions in epithelia: implications for mammary gland biology and breast tumorigenesis. J. Mammary Gland Biol. Neoplasia8,449–462 (2003).
- 60 Bose R, Wrana JL: Regulation of Par6 by extracellular signals. Curr. Opin. Cell Biol.18,206–212 (2006).
- 61 Ozdamar B, Bose R, Barrios-Rodiles M, Wang HR, Zhang Y, Wrana JL: Regulation of the polarity protein Par6 by TGF-β receptors controls epithelial cell plasticity. Science307,1603–1609 (2005).▪ Identified the novel interaction between Par6 and TGF-β receptors, which promote EMT via the ubiquitination and degradation of RhoA.
- 62 Takaishi K, Sasaki T, Kotani H, Nishioka H, Takai Y: Regulation of cell–cell adhesion by Rac and Rho small G proteins in MDCK Cells. J. Cell Biol.139,1047–1059 (1997).
- 63 Niessen CM: Tight junctions/adherens junctions: basic structure and function. J. Invest. Dermatol.127,2525–2532 (2007).
- 64 Ridley AJ, Hall A: The small GTP-binding protein Rho regulates the assembly of focal adhesions and actin stress fibers in response to growth factors. Cell70,389–399 (1992).
- 65 Bhowmick NA, Ghiassi M, Bakin A et al.: TGF-β1 mediates epithelial to mesenchymal transdifferentiation through a RhoA-dependent mechanism. Mol. Biol. Cell12,27–36 (2001).
- 66 Mueller MM, Fusenig NE: Friends or foes - bipolar effects of the tumour stroma in cancer. Nat. Rev. Cancer4,839–849 (2004).
- 67 Kaplan RN, Rafii S, Lyden D: Preparing the ‘soil’: the premetastatic niche. Cancer Res.66,11089–11093 (2006).
- 68 Tlsty TD, Coussens LM: Tumor stroma and regulation of cancer development. Annu. Rev. Pathol.1,119–150 (2006).
- 69 Park CC, Bissell MJ, Barcellos-Hoff MH: The influence of the microenvironment on the malignant phenotype. Mol. Med. Today6,324–329 (2000).
- 70 Egeblad M, Werb Z: New functions for the matrix metalloproteinases in cancer progression. Nat. Rev. Cancer2,161–174 (2002).
- 71 Mott JD, Werb Z: Regulation of matrix biology by matrix metalloproteinases. Curr. Opin. Cell Biol.16,558–564 (2004).
- 72 Duivenvoorden WC, Hirte HW, Singh G: TGF-β1 acts as an inducer of matrix metalloproteinase expression and activity in human bone-metastasizing cancer cells. Clin. Exp. Metastasis17,27–34 (1999).
- 73 Kim ES, Sohn YW, Moon A: TGF-β-induced transcriptional activation of MMP-2 is mediated by activating transcription factor (ATF)2 in human breast epithelial cells. Cancer Lett.252,147–156 (2007).
- 74 Coussens LM, Tinkle CL, Hanahan D, Werb Z: MMP-9 supplied by bone marrow-derived cells contributes to skin carcinogenesis. Cell103,481–490 (2000).
- 75 Paszek MJ, Weaver VM: The tension mounts: mechanics meets morphogenesis and malignancy. J. Mammary Gland Biol. Neoplasia.9,325–342 (2004).
- 76 Anderson AR, Weaver AM, Cummings PT, Quaranta V: Tumor morphology and phenotypic evolution driven by selective pressure from the microenvironment. Cell127,905–915 (2006).▪ Very interesting study that used a multiscale mathematical modeling approach to predict how altered microenvironmental factors and conditions impact tumor development and progression.
- 77 Sternlicht MD, Bissell MJ, Werb Z: The matrix metalloproteinase stromelysin-1 acts as a natural mammary tumor promoter. Oncogene19,1102–1113 (2000).
- 78 Sternlicht MD, Lochter A, Sympson CJ et al.: The stromal proteinase MMP3/stromelysin-1 promotes mammary carcinogenesis. Cell98,137–146 (1999).▪ Established the essential role of matrix metalloproteinases (MMPs) in regulating the interactions between cells and their microenvironments, and in stimulating EMT.
- 79 Radisky DC, Levy DD, Littlepage LE et al.: Rac1b and reactive oxygen species mediate MMP-3-induced EMT and genomic instability. Nature436,123–127 (2005).▪ Established the essential role of matrix metalloproteinases (MMPs) in regulating the interactions between cells and their microenvironments, and in stimulating EMT.
- 80 Radisky DC, Kenny PA, Bissell MJ: Fibrosis and cancer: do myofibroblasts come also from epithelial cells via EMT? J. Cell Biochem.101,830–839 (2007).
- 81 Huber MA, Kraut N, Beug H: Molecular requirements for epithelial–mesenchymal transition during tumor progression. Curr. Opin. Cell Biol.17,548–558 (2005).
- 82 Gotzmann J, Mikula M, Eger A et al.: Molecular aspects of epithelial cell plasticity: implications for local tumor invasion and metastasis. Mutat. Res.566,9–20 (2004).
- 83 Jechlinger M, Grunert S, Beug H: Mechanisms in epithelial plasticity and metastasis: insights from 3D cultures and expression profiling. J. Mammary Gland Biol. Neoplasia7,415–432 (2002).
- 84 Cavallaro U, Niedermeyer J, Fuxa M, Christofori G: N-CAM modulates tumour-cell adhesion to matrix by inducing FGF-receptor signalling. Nat. Cell Biol.3,650–657 (2001).
- 85 Lehembre F, Yilmaz M, Wicki A et al.: NCAM-induced focal adhesion assembly: a functional switch upon loss of E-cadherin. EMBO J.27,2603–2615 (2008).
- 86 Illman SA, Lehti K, Keski-Oja J, Lohi J: Epilysin (MMP-28) induces TGF-β mediated epithelial to mesenchymal transition in lung carcinoma cells. J. Cell Sci.119,3856–3865 (2006).
- 87 Illman SA, Lohi J, Keski-Oja J: Epilysin (MMP-28) – structure, expression and potential functions. Exp. Dermatol.17,897–907 (2008).
- 88 Harbeck N, Kates RE, Schmitt M et al.: Urokinase-type plasminogen activator and its inhibitor type 1 predict disease outcome and therapy response in primary breast cancer. Clin. Breast Cancer5,348–352 (2004).
- 89 Duffy MJ, Duggan C: The urokinase plasminogen activator system: a rich source of tumor markers for the individualized management of patients with cancer. Clin. Biochem.37,541–548 (2004).
- 90 Mitra SK, Lim ST, Chi A, Schlaepfer DD: Intrinsic focal adhesion kinase activity controls orthotopic breast carcinoma metastasis via the regulation of urokinase plasminogen activator expression in a syngenetic tumor model. Oncogene25,4429–4440 (2006).
- 91 Lin SW, Ke FC, Hsiao PW, Lee PP, Lee MT, Hwang JJ: Critical involvement of ILK in TGF-β1-stimulated invasion/migration of human ovarian cancer cells is associated with urokinase plasminogen activator system. Exp. Cell Res.313,602–613 (2007).
- 92 Lester RD, Jo M, Montel V, Takimoto S, Gonias SL: uPAR induces epithelial mesenchymal transition in hypoxic breast cancer cells. J. Cell Biol.178,425–436 (2007).
- 93 Santibanez JF: JNK mediates TGF-β1-induced epithelial mesenchymal transdifferentiation of mouse transformed keratinocytes. FEBS Lett.580,5385–5391 (2006).
- 94 Whitley BR, Church FC: Wound-induced migration of MDA-MB-435 and SKOV-3 cancer cells is regulated by plasminogen activator inhibitor-1. Int. J. Oncol.27,749–757 (2005).
- 95 Binder BR, Christ G, Gruber F et al.: Plasminogen activator inhibitor 1: physiological and pathophysiological roles. News Physiol. Sci.17,56–61 (2002).
- 96 Shetty S, Shetty P, Idell S, Velusamy T, Bhandary YP, Shetty RS: Regulation of plasminogen activator inhibitor-1 expression by tumor suppressor protein p53. J. Biol. Chem.283,19570–19580 (2008).
- 97 Kortlever RM, Bernards R: Senescence, wound healing and cancer: the PAI-1 connection. Cell Cycle5,2697–2703 (2006).
- 98 Whitley BR, Palmieri D, Twerdi CD, Church FC: Expression of active plasminogen activator inhibitor-1 reduces cell migration and invasion in breast and gynecological cancer cells. Exp. Cell Res.296,151–162 (2004).
- 99 Descotes F, Riche B, Saez S et al.: Plasminogen activator inhibitor type 1 is the most significant of the usual tissue prognostic factors in node-negative breast ductal adenocarcinoma independent of urokinase-type plasminogen activator. Clin. Breast Cancer8,168–177 (2008).
- 100 Wienke D, Davies GC, Johnson DA et al.: The collagen receptor Endo180 (CD280) is expressed on basal-like breast tumor cells and promotes tumor growth in vivo. Cancer Res.67,10230–10240 (2007).
- 101 Kim ES, Kim MS, Moon A: TGF-β in conjunction with H-Ras activation promotes malignant progression of MCF10A breast epithelial cells. Cytokine29,84–91 (2005).
- 102 Ignotz RA, Massague J: TGF-β stimulates the expression of fibronectin and collagen and their incorporation into the extracellular matrix. J. Biol. Chem.261,4337–4345 (1986).
- 103 Xie L, Law B, Aakre M et al.: TGF-β-regulated gene expression in a mouse mammary gland epithelial cell line. Breast Cancer Res.5,R187–R198 (2003).
- 104 Maschler S, Wirl G, Spring H et al.: Tumor cell invasiveness correlates with changes in integrin expression and localization. Oncogene24,2032–2041 (2005).
- 105 Kang Y, Massague J: Epithelial–mesenchymal transitions: Twist in development and metastasis. Cell118,277–279 (2004).
- 106 Bremnes RM, Veve R, Hirsch FR, Franklin WA: The E-cadherin cell–cell adhesion complex and lung cancer invasion, metastasis, and prognosis. Lung Cancer36,115–124 (2002).
- 107 Graff JR, Greenberg VE, Herman JG et al.: Distinct patterns of E-cadherin CpG island methylation in papillary, follicular, Hurthle’s cell, and poorly differentiated human thyroid carcinoma. Cancer Res.58,2063–2066 (1998).
- 108 Comijn J, Berx G, Vermassen P et al.: The two-handed E box binding zinc finger protein SIP1 downregulates E-cadherin and induces invasion. Mol. Cell7,1267–1278 (2001).
- 109 Peinado H, Olmeda D, Cano A: Snail, Zeb and bHLH factors in tumour progression: an alliance against the epithelial phenotype? Nat. Rev. Cancer7,415–428 (2007).
- 110 Cano A, Perez-Moreno MA, Rodrigo I et al.: The transcription factor snail controls epithelial–mesenchymal transitions by repressing E-cadherin expression. Nat. Cell Biol.2,76–83 (2000).
- 111 Thuault S, Valcourt U, Petersen M, Manfioletti G, Heldin CH, Moustakas A: TGF-β employs HMGA2 to elicit epithelial–mesenchymal transition. J. Cell Biol.174,175–183 (2006).
- 112 Hazan RB, Phillips GR, Qiao RF, Norton L, Aaronson SA: Exogenous expression of N-cadherin in breast cancer cells induces cell migration, invasion, and metastasis. J. Cell Biol.148,779–790 (2000).
- 113 Gravdal K, Halvorsen OJ, Haukaas SA, Akslen LA: A switch from E-cadherin to N-cadherin expression indicates epithelial to mesenchymal transition and is of strong and independent importance for the progress of prostate cancer. Clin. Cancer Res.13,7003–7011 (2007).
- 114 Pyo SW, Hashimoto M, Kim YS et al.: Expression of E-cadherin, P-cadherin and N-cadherin in oral squamous cell carcinoma: correlation with the clinicopathologic features and patient outcome. J. Craniomaxillofac. Surg.35,1–9 (2007).
- 115 Yang L, Huang J, Ren X et al.: Abrogation of TGF-β signaling in mammary carcinomas recruits Gr-1+CD11b+ myeloid cells that promote metastasis. Cancer Cell.13,23–35 (2008).
- 116 Nam JS, Terabe M, Mamura M et al.: An anti-TGF-β antibody suppresses metastasis via cooperative effects on multiple cell compartments. Cancer Res.68,3835–3843 (2008).
- 117 Grunert S, Jechlinger M, Beug H: Diverse cellular and molecular mechanisms contribute to epithelial plasticity and metastasis. Nat. Rev. Mol. Cell Biol.4,657 (2003).
- 118 Masszi A, Di Ciano C, Sirokmany G et al.: Central role for Rho in TGF-β1-induced α-smooth muscle actin expression during epithelial–mesenchymal transition. Am. J. Physiol. Renal Physiol.284,F911–F924 (2003).
- 119 Yazhou C, Wenlv S, Weidong Z, Licun W: Clinicopathological significance of stromal myofibroblasts in invasive ductal carcinoma of the breast. Tumour Biol.25,290–295 (2004).
- 120 Cary LA, Guan JL: Focal adhesion kinase in integrin-mediated signaling. Front. Biosci.4,D102–D113 (1999).
- 121 Cary LA, Han DC, Guan JL: Integrin-mediated signal transduction pathways. Histol. Histopathol.14,1001–1009 (1999).
- 122 Schwartz MA, Ginsberg MH: Networks and crosstalk: integrin signalling spreads. Nat. Cell Biol.4,E65–E68 (2002).
- 123 Hood JD, Cheresh DA: Role of integrins in cell invasion and migration. Nat. Rev. Cancer.2,91–100 (2002).
- 124 Ginsberg MH, Partridge A, Shattil SJ: Integrin regulation. Curr. Opin. Cell Biol.17,509–516 (2005).
- 125 Guo W, Giancotti FG: Integrin signalling during tumour progression. Nat. Rev. Mol. Cell Biol.5,816–826 (2004).
- 126 Sieg DJ, Hauck CR, Ilic D et al.: FAK integrates growth-factor and integrin signals to promote cell migration. Nat. Cell Biol.2,249–256 (2000).
- 127 Chen SY, Chen HC: Direct interaction of focal adhesion kinase (FAK) with Met is required for FAK to promote hepatocyte growth factor-induced cell invasion. Mol. Cell. Biol.26,5155–5167 (2006).
- 128 Mizejewski GJ: Role of integrins in cancer: survey of expression patterns. Proc. Soc. Exp. Biol. Med.222,124–138 (1999).
- 129 Sheppard D, Cohen DS, Wang A, Busk M: TGF-β differentially regulates expression of integrin subunits in guinea pig airway epithelial cells. J. Biol. Chem.267,17409–17414 (1992).
- 130 Kumar NM, Sigurdson SL, Sheppard D, Lwebuga-Mukasa JS: Differential modulation of integrin receptors and extracellular matrix laminin by TGF-β1 in rat alveolar epithelial cells. Exp. Cell Res.221,385–394 (1995).
- 131 Wang A, Yokosaki Y, Ferrando R, Balmes J, Sheppard D: Differential regulation of airway epithelial integrins by growth factors. Am. J. Respir. Cell Mol. Biol.15,664–672 (1996).
- 132 Munger JS, Huang X, Kawakatsu H et al.: The integrin αvβ6 binds and activates latent TGF-β1: a mechanism for regulating pulmonary inflammation and fibrosis. Cell96,319–328 (1999).▪ First established the importance of integrins in promoting the activation of latent TGF-β complexes.
- 133 Jenkins RG, Su X, Su G et al.: Ligation of protease-activated receptor 1 enhances αvβ6 integrin-dependent TGF-β activation and promotes acute lung injury. J. Clin. Invest.116,1606–1614 (2006).
- 134 Neurohr C, Nishimura SL, Sheppard D: Activation of TGF-β by the integrin αvβ8 delays epithelial wound closure. Am. J. Respir. Cell Mol. Biol.35,252–259 (2006).
- 135 Morris DG, Huang X, Kaminski N et al.: Loss of integrin αvβ6-mediated TGF-β activation causes MMP12-dependent emphysema. Nature422,169–173 (2003).
- 136 Mu D, Cambier S, Fjellbirkeland L et al.: The integrin αvβ8 mediates epithelial homeostasis through MT1-MMP-dependent activation of TGF-β1. J. Cell Biol.157,493–507 (2002).
- 137 Knight PA, Wright SH, Brown JK, Huang X, Sheppard D, Miller HR: Enteric expression of the integrin αvβ6 is essential for nematode-induced mucosal mast cell hyperplasia and expression of the granule chymase, mouse mast cell protease-1. Am. J. Pathol.161,771–779 (2002).
- 138 Kim KK, Kugler MC, Wolters PJ et al.: Alveolar epithelial cell mesenchymal transition develops in vivo during pulmonary fibrosis and is regulated by the extracellular matrix. Proc. Natl Acad. Sci. USA103,13180–13185 (2006).
- 139 Bates RC, Bellovin DI, Brown C et al.: Transcriptional activation of integrin β6 during the epithelial–mesenchymal transition defines a novel prognostic indicator of aggressive colon carcinoma. J. Clin. Invest.115,339–347 (2005).
- 140 Ma LJ, Yang H, Gaspert A et al.: TGF-β-dependent and -independent pathways of induction of tubulointerstitial fibrosis in β6(-/-) mice. Am. J. Pathol.163,1261–1273 (2003).
- 141 Owens DM, Broad S, Yan X, Benitah SA, Watt FM: Suprabasal α5β1 integrin expression stimulates formation of epidermal squamous cell carcinomas without disrupting TGF-β signaling or inducing spindle cell tumors. Mol. Carcinog.44,60–66 (2005).
- 142 Kostenuik PJ, Singh G, Orr FW: TGF-β upregulates the integrin-mediated adhesion of human prostatic carcinoma cells to type I collagen. Clin. Exp. Metastasis15,41–52 (1997).
- 143 Giannelli G, Fransvea E, Marinosci F et al.: TGF-β1 triggers hepatocellular carcinoma invasiveness via α3β1 integrin. Am. J. Pathol.161,183–193 (2002).
- 144 Giannelli G, Bergamini C, Fransvea E, Sgarra C, Antonaci S: Laminin-5 with TGF-β1 induces epithelial to mesenchymal transition in hepatocellular carcinoma. Gastroenterology129,1375–1383 (2005).
- 145 Sloan EK, Pouliot N, Stanley KL et al.: Tumor-specific expression of αvβ3 integrin promotes spontaneous metastasis of breast cancer to bone. Breast Cancer Res.8,R20 (2006).
- 146 Bandyopadhyay A, Agyin JK, Wang L et al.: Inhibition of pulmonary and skeletal metastasis by a TGF-β type I receptor kinase inhibitor. Cancer Res.66,6714–6721 (2006).
- 147 Nakamura K, Yano H, Schaefer E, Sabe H: Different modes and qualities of tyrosine phosphorylation of Fak and Pyk2 during epithelial–mesenchymal transdifferentiation and cell migration: analysis of specific phosphorylation events using site-directed antibodies. Oncogene20,2626–2635 (2001).
- 148 Liu S, Shi-wen X, Kennedy L et al.: FAK is required for TGF-β-induced JNK phosphorylation in fibroblasts: implications for acquisition of a matrix-remodeling phenotype. Mol. Biol. Cell.18,2169–2178 (2007).
- 149 Cicchini C, Laudadio I, Citarella F et al.: TGF-β-induced EMT requires focal adhesion kinase (FAK) signaling. Exp. Cell Res.314,143 (2008).
- 150 Wendt MK, Schiemann WP: Therapeutic targeting of the focal adhesion complex prevents oncogenic TGF-β signaling and metastasis. Breast Cancer Res.11(5),R68 (2009).
- 151 Kim W, Seok Kang Y, Soo Kim J, Shin N-Y, Hanks SK, Song WK: The integrin-coupled signaling adaptor p130Cas suppresses Smad3 function in TGF-β signaling. Mol. Biol. Cell.19,2135–2146 (2008).
- 152 Cabodi S, Tinnirello A, Di Stefano P et al.: p130Cas as a new regulator of mammary epithelial cell proliferation, survival, and HER2-Neu oncogene-dependent breast tumorigenesis. Cancer Res.66,4672–4680 (2006).
- 153 Tumbarello DA, Brown MC, Hetey SE, Turner CE: Regulation of paxillin family members during epithelial–mesenchymal transformation: a putative role for paxillin δ. J. Cell Sci.118,4849–4863 (2005).
- 154 Fujimoto N, Yeh S, Kang HY et al.: Cloning and characterization of androgen receptor coactivator, ARA55, in human prostate. J. Biol. Chem.274,8316–8321 (1999).
- 155 Guerrero-Santoro J, Yang L, Stallcup MR, DeFranco DB: Distinct LIM domains of Hic-5/ARA55 are required for nuclear matrix targeting and glucocorticoid receptor binding and coactivation. J. Cell Biochem.92,810–819 (2004).
- 156 Yang L, Guerrero J, Hong H, DeFranco DB, Stallcup MR: Interaction of the Tau2 transcriptional activation domain of glucocorticoid receptor with a novel steroid receptor coactivator, Hic-5, which localizes to both focal adhesions and the nuclear matrix. Mol. Biol. Cell.11,2007–2018 (2000).
- 157 Tumbarello DA, Turner CE: Hic-5 contributes to epithelial–mesenchymal transformation through a RhoA/ROCK-dependent pathway. J. Cell Physiol.211,736–747 (2007).
- 158 Mok SC, Wong KK, Chan RK et al.: Molecular cloning of differentially expressed genes in human epithelial ovarian cancer. Gynecol. Oncol.52,247–252 (1994).
- 159 Mok SC, Chan WY, Wong KK et al.: DOC-2, a candidate tumor suppressor gene in human epithelial ovarian cancer. Oncogene16,2381–2387 (1998).
- 160 Prunier C, Hocevar BA, Howe PH: Wnt signaling: physiology and pathology. Growth Factors22,141–150 (2004).
- 161 Prunier C, Howe PH: Disabled-2 (Dab2) is required for TGF-β-induced epithelial to mesenchymal transition (EMT). J. Biol. Chem.280,17540–17548 (2005).
- 162 Hocevar BA, Prunier C, Howe PH: Disabled-2 (Dab2) mediates TGF-β-stimulated fibronectin synthesis through TGF-β-activated kinase 1 and activation of the JNK pathway. J. Biol. Chem.280,25920–25927 (2005).
- 163 Sorrentino A, Thakur N, Grimsby S et al.: The type I TGF-β receptor engages TRAF6 to activate TAK1 in a receptor kinase-independent manner. Nat. Cell Biol.10,1199–1207 (2008).▪ Demonstrates the importance of TRAF6 to interact physically with TGF-β receptors, leading to the activation of MAP kinases via ubiquitination of TAK1.
- 164 Yamashita M, Fatyol K, Jin C, Wang X, Liu Z, Zhang YE: TRAF6 mediates Smad-independent activation of JNK and p38 by TGF-β. Mol. Cell31,918–924 (2008).▪ Demonstrates the importance of TRAF6 to interact physically with TGF-β receptors, leading to the activation of MAP kinases via ubiquitination of TAK1.
- 165 Gal A, Sjoblom T, Fedorova L, Imreh S, BeugH, Moustakas A: Sustained TGF-β exposure suppresses Smad and non-Smad signalling in mammary epithelial cells, leading to EMT and inhibition of growth arrest and apoptosis. Oncogene27,1218–1230 (2008).
- 166 Hall A: Rho GTPases and the control of cell behaviour. Biochem. Soc. Trans.33,891–895 (2005).
- 167 Hall A, Nobes CD: Rho GTPases: molecular switches that control the organization and dynamics of the actin cytoskeleton. Philos. Trans. R. Soc. Lond. B. Biol. Sci.355,965–970 (2000).
- 168 Sander EE, ten Klooster JP, van Delft S, van der Kammen RA, Collard JG: Rac downregulates Rho activity: reciprocal balance between both GTPases determines cellular morphology and migratory behavior. J. Cell Biol.147,1009–1022 (1999).
- 169 Cho HJ, Yoo J: Rho activation is required for TGF-β-induced epithelial–mesenchymal transition in lens epithelial cells. Cell Biol. Int.31,1225–1230 (2007).
- 170 Massague J: How cells read TGF-β signals. Nat. Rev. Mol. Cell. Biol.1,169–178 (2000).
- 171 Murillo MM, del Castillo G, Sanchez A, Fernandez M, Fabregat I: Involvement of EGF receptor and c-Src in the survival signals induced by TGF-β1 in hepatocytes. Oncogene24,4580–4587 (2005).
- 172 Jechlinger M, Sommer A, Moriggl R et al.: Autocrine PDGFR signaling promotes mammary cancer metastasis. J. Clin. Invest.116,1561–1570 (2006).
- 173 Dedhar S, Williams B, Hannigan G: Integrin-linked kinase (ILK): a regulator of integrin and growth-factor signalling. Trends. Cell Biol.9,319–323 (1999).
- 174 Hannigan G, Troussard AA, Dedhar S: Integrin-linked kinase: a cancer therapeutic target unique among its ILK. Nat. Rev. Cancer.5,51–63 (2005).
- 175 Hehlgans S, Haase M, Cordes N: Signalling via integrins: implications for cell survival and anticancer strategies. Biochim. Biophys. Acta.1775,163–180 (2007).
- 176 White DE, Cardiff RD, Dedhar S, Muller WJ: Mammary epithelial-specific expression of the integrin-linked kinase (ILK) results in the induction of mammary gland hyperplasias and tumors in transgenic mice. Oncogene20,7064–7072 (2001).
- 177 Somasiri A, Howarth A, Goswami D, Dedhar S, Roskelley CD: Overexpression of the integrin-linked kinase mesenchymally transforms mammary epithelial cells. J. Cell Sci.114,1125–1136 (2001).
- 178 Lee YI, Kwon YJ, Joo CK: Integrin-linked kinase function is required for TGF-β-mediated epithelial to mesenchymal transition. Biochem. Biophys. Res. Commun.316,997–1001 (2004).
- 179 Karin M: NF-κB in cancer development and progression. Nature441,431 (2006).
- 180 Huber MA, Azoitei N, Baumann B et al.: NF-κB is essential for epithelial–mesenchymal transition and metastasis in a model of breast cancer progression. J. Clin. Invest.114,569–581 (2004).
- 181 Chua HL, Bhat-Nakshatri P, Clare SE, Morimiya A, Badve S, Nakshatri H: NF-κB represses E-cadherin expression and enhances epithelial to mesenchymal transition of mammary epithelial cells: potential involvement of ZEB-1 and ZEB-2. Oncogene26,711 (2006).
- 182 Sovak MA, Arsura M, Zanieski G, Kavanagh KT, Sonenshein GE: The inhibitory effects of TGF-β1 on breast cancer cell proliferation are mediated through regulation of aberrant NF-κB/Rel expression. Cell Growth Differ.10,537–544 (1999).
- 183 Neil JR, Johnson KM, Nemenoff RA, Schiemann WP: Cox-2 inactivates Smad signaling and enhances EMT stimulated by TGF-β through a PGE2-dependent mechanisms. Carcinogenesis29,2227–2235 (2008).
- 184 Xie L, Law BK, Chytil AM, Brown KA, Aakre ME, Moses HL: Activation of the ERK pathway is required for TGF-β1-induced EMT in vitro. Neoplasia6,603–610 (2004).
- 185 Atfi A, Djelloul S, Chastre E, Davis R, Gespach C: Evidence for a role of Rho-like GTPases and stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) in TGF-β-mediated signaling. J. Biol. Chem.272,1429–1432 (1997).
- 186 Hocevar BA, Brown TL, Howe PH: TGF-β induces fibronectin synthesis through a c-Jun N-terminal kinase-dependent, Smad4-independent pathway. EMBO J.18,1345–1356 (1999).
- 187 Shintani Y, Wheelock MJ, Johnson KR: Phosphoinositide-3 kinase-Rac1-c-Jun NH2-terminal kinase signaling mediates collagen I-induced cell scattering and up-regulation of N-cadherin expression in mouse mammary epithelial cells. Mol. Biol. Cell.17,2963–2975 (2006).
- 188 Ke Z, Lin H, Fan Z et al.: MMP-2 mediates ethanol-induced invasion of mammary epithelial cells over-expressing ErbB2. Int. J. Cancer119,8–16 (2006).
- 189 Buck MB, Knabbe C: TGF-β signaling in breast cancer. Ann. NY Acad. Sci.1089,119–126 (2006).
- 190 Hanahan D, Weinberg RA: The hallmarks of cancer. Cell100,57–70 (2000).
- 191 Moreno-Bueno G, Portillo F, Cano A: Transcriptional regulation of cell polarity in EMT and cancer. Oncogene27,6958–6969 (2008).
- 192 Ikenouchi J, Matsuda M, Furuse M, Tsukita S: Regulation of tight junctions during the epithelium-mesenchyme transition: direct repression of the gene expression of claudins/occludin by Snail. J. Cell Sci.116,1959–1967 (2003).
- 193 Alexandrow MG, Kawabata M, Aakre M, Moses HL: Overexpression of the c-Myc oncoprotein blocks the growth-inhibitory response but is required for the mitogenic effects of TGF-β. Proc. Natl Acad. Sci. USA92,3239–3243 (1995).▪ Established c-Myc as an a molecule that possesses anti-TGF-β activity during tumorigenesis.
- 194 Chen CR, Kang Y, Massague J: Defective repression of c-Myc in breast cancer cells: a loss at the core of the TGF-β growth arrest program. Proc. Natl Acad. Sci. USA98,992–999 (2001).
- 195 Smith AP, Verrecchia A, Faga G et al.: A positive role for Myc in TGF-β-induced Snail transcription and epithelial-to-mesenchymal transition. Oncogene28,422–430 (2008).
- 196 Bromberg JF, Wrzeszczynska MH, Devgan G et al.: Stat3 as an oncogene. Cell98,295–303 (1999).
- 197 Yang Y, Pan X, Lei W et al.: Regulation of TGF-β1-induced apoptosis and epithelial-to-mesenchymal transition by protein kinase A and signal transducers and activators of transcription 3. Cancer Res.66,8617–8624 (2006).
- 198 Zhao S, Venkatasubbarao K, Lazor JW et al.: Inhibition of STAT3Tyr705 phosphorylation by Smad4 suppresses TGF-β-mediated invasion and metastasis in pancreatic cancer cells. Cancer Res.68,4221–4228 (2008).
- 199 Lo HW, Hsu SC, Xia W et al.: Epidermal growth factor receptor cooperates with signal transducer and activator of transcription 3 to induce epithelial–mesenchymal transition in cancer cells via up-regulation of TWIST gene expression. Cancer Res.67,9066–9076 (2007).
- 200 Ali S, Coombes RC: Endocrine-responsive breast cancer and strategies for combating resistance. Nat. Rev. Cancer2,101–112 (2002).
- 201 Coombes RC, Gibson L, Hall E, Emson M, Bliss J: Aromatase inhibitors as adjuvant therapies in patients with breast cancer. J. Steroid Biochem. Mol. Biol.86,309–311 (2003).
- 202 Fujita N, Jaye DL, Kajita M, Geigerman C, Moreno CS, Wade PA: MTA3, a Mi-2/NuRD complex subunit, regulates an invasive growth pathway in breast cancer. Cell113,207–219 (2003).
- 203 Dhasarathy A, Kajita M, Wade PA: The transcription factor snail mediates epithelial to mesenchymal transitions by repression of estrogen receptor-α. Mol. Endocrinol.21,2907–2918 (2007).
- 204 Silveri L, Tilly G, Vilotte JL, Le Provost F: MicroRNA involvement in mammary gland development and breast cancer. Reprod. Nutr. Dev.46,549–556 (2006).
- 205 Croce CM, Calin GA: miRNAs, cancer, and stem cell division. Cell122,6–7 (2005).
- 206 Iorio MV, Ferracin M, Liu CG et al.: MicroRNA gene expression deregulation in human breast cancer. Cancer Res.65,7065–7070 (2005).
- 207 Blenkiron C, Miska EA: miRNAs in cancer: approaches, etiology, diagnostics and therapy. Hum. Mol. Genet.16,R106–R113 (2007).
- 208 Dalmay T, Edwards DR: MicroRNAs and the hallmarks of cancer. Oncogene25,6170–6175 (2006).
- 209 Blenkiron C, Goldstein LD, Thorne NP et al.: MicroRNA expression profiling of human breast cancer identifies new markers of tumor subtype. Genome Biol.8,R214 (2007).
- 210 Hurteau GJ, Carlson JA, Spivack SD, Brock GJ: Overexpression of the microRNA Hsa-miR-200c leads to reduced expression of transcription factor 8 and increased expression of E-cadherin. Cancer Res.67,7972–7976 (2007).
- 211 Korpal M, Lee ES, Hu G, Kang Y: The miR-200 family inhibits epithelial–mesenchymal transition and cancer cell migration by direct targeting of E-cadherin transcriptional repressors ZEβ1 and ZEB2. J. Biol. Chem.283,14910–14914 (2008).
- 212 Gregory PA, Bert AG, Paterson EL et al.: The miR-200 family and miR-205 regulate epithelial to mesenchymal transition by targeting ZEβ1 and SIP1. Nat. Cell Biol.10,593–601 (2008).▪ Provide the first evidence linking altered microRNA expression to EMT stimulated by TGF-β.
- 213 Park SM, Gaur AB, Lengyel E, Peter ME: The miR-200 family determines the epithelial phenotype of cancer cells by targeting the E-cadherin repressors ZEβ1 and ZEB2. Genes Dev.22,894–907 (2008).▪ Provide the first evidence linking altered microRNA expression to EMT stimulated by TGF-β.
- 214 Burk U, Schubert J, Wellner U et al.: A reciprocal repression between ZEβ1 and members of the miR-200 family promotes EMT and invasion in cancer cells. EMBO Rep.9,582–589 (2008).▪ Provide the first evidence linking altered microRNA expression to EMT stimulated by TGF-β.
- 215 Ma L, Teruya-Feldstein J, Weinberg RA: Tumour invasion and metastasis initiated by microRNA-10b in breast cancer. Nature449,682–688 (2007).
- 216 Kong W, Yang H, He L et al.: MicroRNA-155 is regulated by the TGF-β/Smad pathway and contributes to epithelial cell plasticity by targeting RhoA. Mol. Cell. Biol.28,6773–6784 (2008).
- 217 Si ML, Zhu S, Wu H, Lu Z, Wu F, Mo YY: miR-21-mediated tumor growth. Oncogene26,2799–2803 (2007).
- 218 Zhu S, Si ML, Wu H, Mo YY: MicroRNA-21 targets the tumor suppressor gene tropomyosin 1 (TPM1). J. Biol. Chem.282,14328–14336 (2007).
- 219 Zhu S, Wu H, Wu F, Nie D, Sheng S, Mo YY: MicroRNA-21 targets tumor suppressor genes in invasion and metastasis. Cell Res.18,350–359 (2008).
- 220 Zavadil J, Narasimhan M, Blumenberg M, Schneider RJ: TGF-β and microRNA: mRNA regulatory networks in epithelial plasticity. Cells Tissues Organs185,157–161 (2007).
- 221 Bakin AV, Safina A, Rinehart C, Daroqui C, Darbary H, Helfman DM: A critical role of tropomyosins in TGF-β regulation of the actin cytoskeleton and cell motility in epithelial cells. Mol. Biol. Cell15,4682–4694 (2004).
- 222 Varga AE, Stourman NV, Zheng Q et al.: Silencing of the tropomyosin-1 gene by DNA methylation alters tumor suppressor function of TGF-β. Oncogene24,5043–5052 (2005).
- 223 Zheng Q, Safina A, Bakin AV: Role of high-molecular weight tropomyosins in TGF-β-mediated control of cell motility. Int. J. Cancer122,78–90 (2008).
- 224 Lombaerts M, van Wezel T, Philippo K et al.: E-cadherin transcriptional downregulation by promoter methylation but not mutation is related to epithelial-to-mesenchymal transition in breast cancer cell lines. Br. J. Cancer94,661 (2006).
- 225 Reynolds PA, Sigaroudinia M, Zardo G et al.: Tumor suppressor p16INK4A regulates polycomb-mediated DNA hypermethylation in human mammary epithelial cells. J. Biol. Chem.281,24790–24802 (2006).
- 226 Dumont N, Wilson MB, Crawford YG, Reynolds PA, Sigaroudinia M, Tlsty TD: Sustained induction of epithelial to mesenchymal transition activates DNA methylation of genes silenced in basal-like breast cancers. Proc. Natl Acad Sci. USA105,14867–14872 (2008).
- 227 Singh M, Spoelstra NS, Jean A et al.: ZEβ1 expression in type I versus type II endometrial cancers: a marker of aggressive disease. Mod. Pathol.21,912 (2008).
- 228 Shackleton M, Vaillant F, Simpson KJ et al.: Generation of a functional mammary gland from a single stem cell. Nature439,84–88 (2006).
- 229 Stingl J, Raouf A, Eirew P, Eaves CJ: Deciphering the mammary epithelial cell hierarchy. Cell Cycle5,1519–1522 (2006).
- 230 Villadsen R, Fridriksdottir AJ, Ronnov-Jessen L et al.: Evidence for a stem cell hierarchy in the adult human breast. J. Cell Biol.177,87–101 (2007).
- 231 Mishra L, Derynck R, Mishra B: TGF-β signaling in stem cells and cancer. Science310,68–71 (2005).
- 232 Ben-Porath I, Thomson MW, Carey VJ et al.: An embryonic stem cell-like gene expression signature in poorly differentiated aggressive human tumors. Nat. Genet.40,499–507 (2008).
- 233 Mani SA, Guo W, Liao MJ et al.: The epithelial–mesenchymal transition generates cells with properties of stem cells. Cell133,704–715 (2008).▪ Provides the first evidence linking EMT to the acquisition of ‘stemness’. Importantly, TGF-β signaling plays a major role in overseeing EMT and the appearance of cancer stem cells.
- 234 Morel AP, Lievre M, Thomas C, Hinkal G, Ansieau S, Puisieux A: Generation of breast cancer stem cells through epithelial–mesenchymal transition. PLoS ONE3,e2888 (2008).▪ Provides the first evidence linking EMT to the acquisition of ‘stemness’. Importantly, TGF-β signaling plays a major role in overseeing EMT and the appearance of cancer stem cells.
- 235 Shipitsin M, Campbell LL, Argani P et al.: Molecular definition of breast tumor heterogeneity. Cancer Cell11,259–273 (2007).▪ Provides the first evidence linking EMT to the acquisition of ‘stemness’. Importantly, TGF-β signaling plays a major role in overseeing EMT and the appearance of cancer stem cells.
- 236 Farina AR, Coppa A, Tiberio A et al.: TGF-β1 enhances the invasiveness of human MDA-MB-231 breast cancer cells by up-regulating urokinase activity. Int. J. Cancer.75,721–730 (1998).
- 237 Piek E, Ju WJ, Heyer J et al.: Functional characterization of TGF-β signaling in Smad2- and Smad3-deficient fibroblasts. J. Biol. Chem.276,19945–19953 (2001).