c-Myc Transforms Human Mammary Epithelial Cells through Repression of the Wnt Inhibitors DKK1 and SFRP1

ABSTRACT c-myc is frequently amplified in breast cancer; however, the mechanism of myc-induced mammary epithelial cell transformation has not been defined. We show that c-Myc induces a profound morphological transformation in human mammary epithelial cells and anchorage-independent growth. c-Myc suppresses the Wnt inhibitors DKK1 and SFRP1, and derepression of DKK1 or SFRP1 reduces Myc-dependent transforming activity. Myc-dependent repression of DKK1 and SFRP1 is accompanied by Wnt target gene activation and endogenous T-cell factor activity. Myc-induced mouse mammary tumors have repressed SFRP1 and increased expression of Wnt target genes. DKK1 and SFRP1 inhibit the transformed phenotype of breast cancer cell lines, and DKK1 inhibits tumor formation. We propose a positive feedback loop for activation of the c-myc and Wnt pathways in breast cancer.

[1]  M. Hung,et al.  β-Catenin, a novel prognostic marker for breast cancer: Its roles in cyclin D1 expression and cancer progression , 2000 .

[2]  A. Levine,et al.  WISP-1 is a Wnt-1- and beta-catenin-responsive oncogene. , 2000, Genes & development.

[3]  Harold E. Varmus,et al.  Many tumors induced by the mouse mammary tumor virus contain a provirus integrated in the same region of the host genome , 1982, Cell.

[4]  K. Brennan,et al.  Wnt Proteins in Mammary Development and Cancer , 2004, Journal of Mammary Gland Biology and Neoplasia.

[5]  Mitchell D Schnall,et al.  Conditional activation of Neu in the mammary epithelium of transgenic mice results in reversible pulmonary metastasis. , 2002, Cancer cell.

[6]  G. Evan,et al.  A modified oestrogen receptor ligand-binding domain as an improved switch for the regulation of heterologous proteins. , 1995, Nucleic acids research.

[7]  Robert D Cardiff,et al.  Impact of p53 loss on reversal and recurrence of conditional Wnt-induced tumorigenesis. , 2003, Genes & development.

[8]  A. Sparks,et al.  Identification of c-MYC as a target of the APC pathway. , 1998, Science.

[9]  L. Penn,et al.  Negative autoregulation of c‐myc transcription. , 1990, The EMBO journal.

[10]  Randall T Moon,et al.  A second canon. Functions and mechanisms of beta-catenin-independent Wnt signaling. , 2003, Developmental cell.

[11]  R. Cardiff,et al.  c-MYC induces mammary tumorigenesis by means of a preferred pathway involving spontaneous Kras2 mutations , 2001, Nature Medicine.

[12]  S. Fuchs,et al.  CRD-BP mediates stabilization of betaTrCP1 and c-myc mRNA in response to beta-catenin signalling. , 2006, Nature.

[13]  S. Aaronson,et al.  An autocrine mechanism for constitutive Wnt pathway activation in human cancer cells. , 2004, Cancer cell.

[14]  S. Fuchs,et al.  CRD-BP mediates stabilization of βTrCP1 and c-myc mRNA in response to β-catenin signalling , 2006, Nature.

[15]  S. Baylin,et al.  Epigenetic gene silencing in cancer – a mechanism for early oncogenic pathway addiction? , 2006, Nature Reviews Cancer.

[16]  Jonathan R Pollack,et al.  A transcriptional response to Wnt protein in human embryonic carcinoma cells , 2002, BMC Developmental Biology.

[17]  T. Kiyono,et al.  Both Rb/p16INK4a inactivation and telomerase activity are required to immortalize human epithelial cells , 1998, Nature.

[18]  Hans Clevers,et al.  The beta-catenin/TCF-4 complex imposes a crypt progenitor phenotype on colorectal cancer cells. , 2002, Cell.

[19]  Kathryn A. O’Donnell,et al.  The c-Myc target gene network. , 2006, Seminars in cancer biology.

[20]  Irina Klaman,et al.  Loss of SFRP1 is associated with breast cancer progression and poor prognosis in early stage tumors. , 2004, International journal of oncology.

[21]  M. Hung,et al.  Beta-catenin, a novel prognostic marker for breast cancer: its roles in cyclin D1 expression and cancer progression. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[22]  G Leclercq,et al.  Stable 'portrait' of breast tumors during progression: data from biology, pathology and genetics. , 2004, Endocrine-related cancer.

[23]  Jean Paul Thiery,et al.  Epithelial-mesenchymal transitions in development and pathologies. , 2003, Current opinion in cell biology.

[24]  Christof Niehrs,et al.  Kremen proteins are Dickkopf receptors that regulate Wnt/β-catenin signalling , 2002, Nature.

[25]  R. Nusse,et al.  Wnt signaling in disease and in development , 2005, Cell Research.

[26]  L. M. Facchini,et al.  Myc induces cyclin D1 expression in the absence of de novo protein synthesis and links mitogen-stimulated signal transduction to the cell cycle. , 1994, Oncogene.

[27]  D. Liao,et al.  c-Myc in breast cancer. , 2000, Endocrine-related cancer.

[28]  T. Pramila,et al.  Interaction of Frizzled Related Protein (FRP) with Wnt Ligands and the Frizzled Receptor Suggests Alternative Mechanisms for FRP Inhibition of Wnt Signaling* , 1999, The Journal of Biological Chemistry.

[29]  Yoshiaki Kawano,et al.  Secreted antagonists of the Wnt signalling pathway , 2003, Journal of Cell Science.

[30]  L. Penn,et al.  The myc oncogene: MarvelouslY Complex. , 2002, Advances in cancer research.

[31]  B. Groner,et al.  Targeted c‐myc gene expression in mammary glands of transgenic mice induces mammary tumours with constitutive milk protein gene transcription. , 1988, The EMBO journal.

[32]  R. Assoian,et al.  Anchorage-dependent Cell Cycle Progression , 1997, The Journal of cell biology.

[33]  M. Mahadevappa,et al.  SARPs: a family of secreted apoptosis-related proteins. , 1997, Proceedings of the National Academy of Sciences of the United States of America.

[34]  Christof Niehrs,et al.  Kremen proteins are Dickkopf receptors that regulate Wnt/beta-catenin signalling. , 2002, Nature.

[35]  M. Cole,et al.  E-cadherin repression contributes to c-Myc-induced epithelial cell transformation , 2007, Oncogene.

[36]  D. Birnbaum,et al.  WNT pathway and mammary carcinogenesis: Loss of expression of candidate tumor suppressor gene SFRP1 in most invasive carcinomas except of the medullary type , 2001, Oncogene.

[37]  Hans Clevers,et al.  Caught up in a Wnt storm: Wnt signaling in cancer. , 2003, Biochimica et biophysica acta.

[38]  M. Cole,et al.  Mechanism of transcriptional activation by the Myc oncoproteins. , 2006, Seminars in cancer biology.

[39]  K. Alitalo,et al.  Repression of cyclin D1: a novel function of MYC. , 1994, Molecular and cellular biology.

[40]  P. Leder,et al.  Spontaneous mammary adenocarcinomas in transgenic mice that carry and express MTV/myc fusion genes , 1984, Cell.

[41]  R. Moon,et al.  Direct regulation of the Xenopus engrailed-2 promoter by the Wnt signaling pathway, and a molecular screen for Wnt-responsive genes, confirm a role for Wnt signaling during neural patterning in Xenopus , 1999, Mechanisms of Development.

[42]  M. Loda,et al.  Growth factor requirements and basal phenotype of an immortalized mammary epithelial cell line. , 2002, Cancer research.

[43]  Masafumi Nakamura,et al.  Pin1 regulates turnover and subcellular localization of β-catenin by inhibiting its interaction with APC , 2001, Nature Cell Biology.

[44]  R. Dickson,et al.  Of Mice and Myc: c-Myc and Mammary Tumorigenesis , 2004, Journal of Mammary Gland Biology and Neoplasia.

[45]  M. Eilers,et al.  Negative regulation of the mammalian UV response by Myc through association with Miz-1. , 2002, Molecular cell.

[46]  A. Børresen-Dale,et al.  TP53 and breast cancer , 2003, Human mutation.

[47]  Jeffrey D. Axelrod,et al.  A Second Canon , 2003 .

[48]  A. Bejsovec.  Wnt Pathway Activation New Relations and Locations , 2005, Cell.

[49]  A. Levine,et al.  WISP-1 is a Wnt-1- and β-catenin-responsive oncogene , 2000, Genes & Development.

[50]  B. Trock,et al.  C-myc amplification in breast cancer: a meta-analysis of its occurrence and prognostic relevance , 2000, British Journal of Cancer.

[51]  H. Varmus,et al.  Expression of the int-1 gene in transgenic mice is associated with mammary gland hyperplasia and adenocarcinomas in male and female mice , 1988, Cell.

[52]  R. Palmiter,et al.  Inhibition of mammary gland involution is associated with transforming growth factor alpha but not c-myc-induced tumorigenesis in transgenic mice. , 1995, Cancer research.

[53]  W. Hahn,et al.  Human breast cancer cells generated by oncogenic transformation of primary mammary epithelial cells. , 2001, Genes & development.

[54]  K. Kinzler,et al.  Constitutive Transcriptional Activation by a β-Catenin-Tcf Complex in APC−/− Colon Carcinoma , 1997, Science.

[55]  R. Nusse,et al.  The Wnt signaling pathway in development and disease. , 2004, Annual review of cell and developmental biology.

[56]  C. Conti,et al.  Lack of Cyclin-Dependent Kinase 4 Inhibits c-myc Tumorigenic Activities in Epithelial Tissues , 2004, Molecular and Cellular Biology.

[57]  C. Niehrs,et al.  Dickkopf-1 is a member of a new family of secreted proteins and functions in head induction , 1998, Nature.