INTRODUCTION Continual renewal of intestinal epithelium is ensured by the proliferation of stem cell populations confined to the crypt region. As cell migration proceeds from crypt base to villus tip, the undifferentiated cells acquire morphological and biochemical features of polarized cells. Among these cells, the absorptive enterocytes carry the digestive enzymes located at the apical brush border membrane. Cell adhesion to the underlying basement membrane is thought to be critical in the regulation of these migration/differentiation events. This hypothesis is strengthened by the observation that changes in the spatial/developmental distribution of basement membrane molecules are concomitant to the morphogenetic processes and compartmentalization in the adult organ (for reviews see Simon-Assmann et al., 1995, 1998). Among the basement membrane components, laminins display a wide array of biological activities such as cell adhesion, migration and differentiation. It has been shown that a subset of epithelial basement membranes contains the laminin-5 variant (Verrando et al., 1987; Rousselle et al., 1991). This adhesion ligand has been isolated from keratinocytes and squamous carcinoma cells. In these cells, laminin-5 (α3β3γ2) is initially synthesized as a cellular heterotrimeric precursor comprising the 200 kDa (α3 precursor), 155 kDa (γ2 precursor) and 140 kDa (β3) polypeptides (Marinkovich et al., 1992a; Rousselle and Aumailley, 1994). The laminin α3 chain is immunologically related to a distinct 190 kDa laminin α chain interacting with the β1 and γ1 chains to form the laminin-6 variant (Marinkovich et al., 1992b) and with β2 and γ1 chains to form the laminin-7 variant (Champliaud et al., 1996). Laminin-5 and laminin-1 (α1β1γ1) are expressed in the intestine and display a differential localization according to the crypt-to-villus positioning (for review see Simon-Assmann et al., 1998). In particular, laminin-5 presents a gradient of intensity increasing from the base to the tip of the villus (Leivo et al., 1996; Orian- Rousseau et al., 1996). This expression pattern is consistent with that of HD1, a protein of the hemidesmosmal plaque, and integrin α6β4 (Simon-Assmann et al., 1994a; Orian-Rousseau et al., 1996) and suggests a possible role of laminin-5 in differentiation and/or migration of intestinal cells. To date, models of normal intestinal cell culture displaying the same properties as the enterocytes of the crypt-villus axis, are not available for further in vitro studies. This is the reason 1993 Journal of Cell Science 111, 1993-2004 (1998) Printed in Great Britain © The Company of Biologists Limited 1998 JCS9736 In the mature gut, laminin-5 is expressed at the basal aspect of the differentiating epithelial cells. In vitro, we show that three more or less differentiated human colonic cancer HT29 cell lines produce and deposit laminin-5; they predominantly synthesize and secrete the 440 kDa form of laminin-5 that comprises the unprocessed 155 kDa γ2 chain, as determined by immunoprecipitation analysis. In contrast, the highly differentiated colon carcinoma Caco-2 cells produce almost no laminin-5. Using anti-integrin antibodies, we show that adhesion of the two colonic cancer cell lines to laminin-5 is mediated by multiple integrin receptors including those for α3β1, α6β1 and α6β4 integrins like in other cell types. In addition, the implication of integrin α2β1 in this adhesion process is demonstrated for the first time. This has been shown by cell adhesion inhibition experiments, solid phase assays and confocal analysis. Together with previous in situ observations, these data provide a baseline knowledge for the understanding of the regulation of laminin-5 in normal and pathological intestine. Key words: Intestine, Epithelial cell, Basement membrane, Differentiation, Integrin SUMMARY Human colonic cancer cells synthesize and adhere to laminin-5. Their adhesion to laminin-5 involves multiple receptors among which is integrin α2β1 Véronique Orian-Rousseau 1, *, Daniel Aberdam 2 , Patricia Rousselle 3 , Anthea Messent 4 , Jelena Gavrilovic 4 , Guerrino Meneguzzi 2 , Michèle Kedinger 1 and Patricia Simon-Assmann 1,‡ 1 INSERM U.381, 3 Avenue Molière, 67200 Strasbourg, France 2 INSERM U.385, Faculté de Médecine, Avenue de Valombrose, 06107 Nice Cédex 2, France 3 Institut de Biologie et Chimie des Protéines, CNRS, 69367 Lyon Cédex 07, France 4 School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK *Present address: Forschungszentrum Karlsruhe, Institute of Genetics, 76021 Karlsruhe, Germany ‡ Author for correspondence (e-mail: patricia.simon-assmann@inserm.u-strasbg.fr) Accepted 6 May; published on WWW 30 June 1998