Fascin, a Novel Target of B-Catenin-TCF Signaling, Is Expressed at the Invasive Front of Human Colon Cancer Danijela Vignjevic, 1 Marie Schoumacher, 1 Nancy Gavert, 3 Klaus-Peter Janssen, 4 Gloria Jih, 3 Marick Lae ´, 2 Daniel Louvard, 1 Avri Ben-Ze’ev, 3 and Sylvie Robine 1 1 UMR 144 Centre National de la Recherche Scientifique and 2 Department of Pathology, Institut Curie, Paris, France; 3 Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot, Israel; and 4 Department of Surgery, Technical University of Munich, Munich, Germany Abstract Cancer cells become metastatic by acquiring a motile and invasive phenotype. This step requires remodeling of the actin cytoskeleton and the expression of exploratory, sensory organelles known as filopodia. Aberrant B-catenin-TCF target gene activation plays a major role in colorectal cancer development. We identified fascin1, a key component of filopodia, as a target of B-catenin-TCF signaling in colorectal cancer cells. Fascin1 mRNA and protein expression were increased in primary cancers in a stage-dependent manner. Fascin1 was exclusively localized at the invasive front of tumors also displaying nuclear B-catenin. Forced expression of fascin1 in colorectal cancer cells increased their migration and invasion in cell cultures and caused cell dissemination and metastasis in vivo , whereas suppression of fascin1 expression by small interfering RNA reduces cell invasion. Although expression of fascin1 in primary tumors correlated with the presence of metastases, fascin1 was not expressed in metastases. Our studies show that fascin1 expression is tightly regulated during development of colon cancer metastases and is a novel target of B-catenin-TCF signaling. We propose that transient up-regulation of fascin1 in colorectal cancer promotes the acquisition of migratory and invasive pheno- types that lead to metastasis. Moreover, the expression of fascin1 is down-regulated when tumor cells reach their metastatic destination where migration ceases and prolifera- tion is enhanced. Although metastasis to vital organs is often the cause of mortality, only limited success has been attained in developing effective therapeutics against metastatic dis- ease. We propose that genes involved in cell migration and invasion, such as fascin1 , could serve as novel targets for metastasis prevention. [Cancer Res 2007;67(14):6844–53] Introduction Colorectal carcinomas carry mutations in a variety of oncogenes and tumor suppressor genes that contribute to the pathogenesis of cancer. Loss of function mutation in the adenomatosis polyposis coli (APC ) tumor suppressor gene is an early event in colorectal carcinogenesis leading to activation of the Wnt/h-catenin signaling pathway (1). Later in tumorigenesis, there is an accumulation of additional mutations, in K-ras, p53, Rb , and genes encoding components of the transforming growth factor h signaling pathway (2). Although the effect of such mutations on cell cycle control and cell proliferation was extensively studied, much less is known about mutations that contribute to the formation of metastases. h-Catenin is a central player in the Wnt pathway having a dual function in epithelial cells. First, it is a component of adherens junctions that is essential to link the cytoplasmic tail of cadherins to the cytoskeleton (3). A process mediated by the APC/Axin/ glycogen synthase kinase-3h complex efficiently degrades un- bound, cytoplasmic h-catenin. However, on activation of the Wnt pathway, or by aberrations in the h-catenin degradation machinery, h-catenin accumulates in the nucleus where it does a second transcriptional role by interacting with the family of TCF/LEF factors (4, 5). Mutations in components of the h-catenin pathway generally occur early in colon cancer progression consistent with the ability of h-catenin to activate target genes that are involved in cell proliferation, such as cyclin D1 (6, 7) and c-myc (8). At this stage, tumor cells are still adherent to each other in an epithelial structure. h-Catenin accumulates to higher levels in the nuclei of cells at the tumor-host interface at later stages of tumor progression (9). At this stage, h-catenin is believed to activate the expression of genes involved in invasion and metastasis, such as matrix metalloproteinases (MMP) and the cell adhesion molecule L1 (9–11). A critical hallmark of the invasive phenotype in cancer cells is the abundant expression of exploratory, sensory organelles known as filopodia. Efficient bundling of actin filaments within filopodia is essential for filopodia formation both in vitro (12) and in cultured cells (13, 14). Fascin1 is currently the only actin bundling protein localized along the entire length of filopodia and its depletion by small interfering RNA (siRNA) leads to a substantially reduced number of filopodia (13). Moreover, several studies showed that fascin1 significantly increases cell migration in transfilter assays (15–17). Thus, by participating in filopodia formation, fascin1 may promote cell migration. Fascin1 is expressed predominantly in neuronal tissue and is absent from normal epithelial cells. However, high levels of fascin1 expression were reported in many types of cancer cells (refs. 18–25 and reviewed in ref. 26), including colon cancer (16, 27, 28). Fascin1 was also identified in a set of genes that mediate breast cancer metastasis to the lung and clinically correlated with the development of lung metastasis when expressed in primary breast cancer tissue (29). The role of fascin1 up-regulation in cancer and the mechanisms involved are currently unknown. Note: Supplementary data for this article are available at Cancer Research Online (http://cancerres.aacrjournals.org/). Requests for reprints: Danijela Vignjevic, Equipe de Morphogene`se et Signalisation Cellulaires, UMR 144 Centre National de la Recherche Scientifique/ Institut Curie, 25 rue d’Ulm, 75248 Paris Cedex 05, France. Phone: 33-1-42-34-63-61; Fax: 33-1-42-34-63-77; E-mail: danijela.vignjevic@curie.fr. I2007 American Association for Cancer Research. doi:10.1158/0008-5472.CAN-07-0929 Cancer Res 2007; 67: (14). July 15, 2007 6844 www.aacrjournals.org Research Article Research. on August 26, 2015. © 2007 American Association for Cancer cancerres.aacrjournals.org Downloaded from