CD44 splice isoform switching in human and mouse epithelium is essential for epithelial-mesenchymal transition and breast cancer progression.

Epithelial-mesenchymal transition (EMT) is a tightly regulated process that is critical for embryogenesis but is abnormally activated during cancer metastasis and recurrence. Here we show that a switch in CD44 alternative splicing is required for EMT. Using both in vitro and in vivo systems, we have demonstrated a shift in CD44 expression from variant isoforms (CD44v) to the standard isoform (CD44s) during EMT. This isoform switch to CD44s was essential for cells to undergo EMT and was required for the formation of breast tumors that display EMT characteristics in mice. Mechanistically, the splicing factor epithelial splicing regulatory protein 1 (ESRP1) controlled the CD44 isoform switch and was critical for regulating the EMT phenotype. Additionally, the CD44s isoform activated Akt signaling, providing a mechanistic link to a key pathway that drives EMT. Finally, CD44s expression was upregulated in high-grade human breast tumors and was correlated with the level of the mesenchymal marker N-cadherin in these tumors. Together, our data suggest that regulation of CD44 alternative splicing causally contributes to EMT and breast cancer progression.

[1]  Zhongzhou Yang,et al.  PDK1 Regulates Vascular Remodeling and Promotes Epithelial-Mesenchymal Transition in Cardiac Development , 2010, Molecular and Cellular Biology.

[2]  Frank Speleman,et al.  miR-9, a MYC/MYCN-activated microRNA, regulates E-cadherin and cancer metastasis , 2010, Nature Cell Biology.

[3]  Claude C. Warzecha,et al.  ESRP1 and ESRP2 are epithelial cell-type-specific regulators of FGFR2 splicing. , 2009, Molecular cell.

[4]  Lili Wan,et al.  RNA and Disease , 2009, Cell.

[5]  A. Lichtenstein,et al.  Aberrant splicing of the E-cadherin transcript is a novel mechanism of gene silencing in chronic lymphocytic leukemia cells. , 2008, Blood.

[6]  B. Frey,et al.  Deep surveying of alternative splicing complexity in the human transcriptome by high-throughput sequencing , 2008, Nature Genetics.

[7]  Eric T. Wang,et al.  Alternative Isoform Regulation in Human Tissue Transcriptomes , 2008, Nature.

[8]  Domenico Coppola,et al.  MicroRNA-155 Is Regulated by the Transforming Growth Factor β/Smad Pathway and Contributes to Epithelial Cell Plasticity by Targeting RhoA , 2008, Molecular and Cellular Biology.

[9]  R. Weinberg,et al.  Growth-Inhibitory and Tumor- Suppressive Functions of p53 Depend on Its Repression of CD44 Expression , 2008, Cell.

[10]  Robert A. Weinberg,et al.  Epithelial-mesenchymal transition: at the crossroads of development and tumor metastasis. , 2008, Developmental cell.

[11]  Wenjun Guo,et al.  The Epithelial-Mesenchymal Transition Generates Cells with Properties of Stem Cells , 2008, Cell.

[12]  G. Goodall,et al.  The miR-200 family and miR-205 regulate epithelial to mesenchymal transition by targeting ZEB1 and SIP1 , 2008, Nature Cell Biology.

[13]  A. Nath,et al.  Leptin affects endocardial cushion formation by modulating EMT and migration via Akt signaling cascades , 2008, The Journal of cell biology.

[14]  Sun-Mi Park,et al.  The miR-200 family determines the epithelial phenotype of cancer cells by targeting the E-cadherin repressors ZEB1 and ZEB2. , 2008, Genes & development.

[15]  L. Nelles,et al.  Activation of NF-κB by Akt upregulates Snail expression and induces epithelium mesenchyme transition , 2007, Oncogene.

[16]  Héctor Peinado,et al.  Snail, Zeb and bHLH factors in tumour progression: an alliance against the epithelial phenotype? , 2007, Nature Reviews Cancer.

[17]  P. Sharp,et al.  A positive feedback loop couples Ras activation and CD44 alternative splicing. , 2006, Genes & development.

[18]  A. Kornblihtt,et al.  The connection between splicing and cancer , 2006, Journal of Cell Science.

[19]  J. Venables.  Unbalanced alternative splicing and its significance in cancer , 2006, BioEssays : news and reviews in molecular, cellular and developmental biology.

[20]  J. Thiery,et al.  Complex networks orchestrate epithelial–mesenchymal transitions , 2006, Nature Reviews Molecular Cell Biology.

[21]  Phillip A. Sharp,et al.  Regulation of CD44 Alternative Splicing by SRm160 and Its Potential Role in Tumor Cell Invasion , 2006, Molecular and Cellular Biology.

[22]  J. Testa,et al.  AKT signaling in normal and malignant cells , 2005, Oncogene.

[23]  Alfonso Bellacosa,et al.  Epithelial–mesenchymal transition in development and cancer: role of phosphatidylinositol 3′ kinase/AKT pathways , 2005, Oncogene.

[24]  Robert D Cardiff,et al.  The transcriptional repressor Snail promotes mammary tumor recurrence. , 2005, Cancer cell.

[25]  J. López,et al.  CD44 attenuates metastatic invasion during breast cancer progression. , 2005, Cancer research.

[26]  M. Nieto,et al.  The Snail genes as inducers of cell movement and survival: implications in development and cancer , 2005, Development.

[27]  G. Berx,et al.  DeltaEF1 is a transcriptional repressor of E-cadherin and regulates epithelial plasticity in breast cancer cells , 2005, Oncogene.

[28]  S. Ramaswamy,et al.  Twist, a Master Regulator of Morphogenesis, Plays an Essential Role in Tumor Metastasis , 2004, Cell.

[29]  Alfonso Bellacosa,et al.  The protein kinase Akt induces epithelial mesenchymal transition and promotes enhanced motility and invasiveness of squamous cell carcinoma lines. , 2003, Cancer research.

[30]  M. Fraga,et al.  The transcription factor Slug represses E-cadherin expression and induces epithelial to mesenchymal transitions: a comparison with Snail and E47 repressors , 2003, Journal of Cell Science.

[31]  P. Herrlich,et al.  Signal-dependent regulation of splicing via phosphorylation of Sam68 , 2002, Nature.

[32]  J. Sleeman,et al.  CD44 is required for two consecutive steps in HGF/c-Met signaling. , 2002, Genes & development.

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

[34]  T. Mak,et al.  Absence of the CD44 gene prevents sarcoma metastasis. , 2002, Cancer research.

[35]  G. Berx,et al.  The two-handed E box binding zinc finger protein SIP1 downregulates E-cadherin and induces invasion. , 2001, Molecular cell.

[36]  H. Moses,et al.  Phosphatidylinositol 3-Kinase Function Is Required for Transforming Growth Factor β-mediated Epithelial to Mesenchymal Transition and Cell Migration* , 2000, The Journal of Biological Chemistry.

[37]  N. Ratner,et al.  Cd44 Enhances Neuregulin Signaling by Schwann Cells , 2000, The Journal of cell biology.

[38]  F. Hilberg,et al.  CD44-deficient mice develop normally with changes in subpopulations and recirculation of lymphocyte subsets. , 1999, Journal of immunology.

[39]  M. Hung,et al.  Interaction between the Adhesion Receptor, CD44, and the Oncogene Product, p185 HER2 , Promotes Human Ovarian Tumor Cell Activation* , 1997, The Journal of Biological Chemistry.

[40]  T. Mak,et al.  CD44 regulates hematopoietic progenitor distribution, granuloma formation, and tumorigenicity. , 1997, Blood.

[41]  Bruce A. Roe,et al.  Alternative splicing of RNAs transcribed from the human abl gene and from the bcr-abl fused gene , 1986, Cell.

[42]  M. Yaniv,et al.  The human SWI/SNF subunit Brm is a regulator of alternative splicing , 2006, Nature Structural &Molecular Biology.

[43]  P. Herrlich,et al.  CD44: From adhesion molecules to signalling regulators , 2003, Nature Reviews Molecular Cell Biology.

[44]  P. Rigby,et al.  Activation of a Qa/Tla class I major histocompatibility antigen gene is a general feature of oncogenesis in the mouse , 1983, Nature.