We propose that this microenvironment is selective for more aggressive cancer phenotypes and is therefore a potential target for more advanced prognostics and novel therapeutics. O66 Newly Characterised ex vivo Colospheres as a Three-Dimensional Colon Cancer Cell Model of Tumour Aggressiveness Louis-Bastien Weiswald1, Sophie Richon1,

Pierre Validire2, Marianne Briffod3, René Lai-Kuen4, Fabrice P. Cordelières5, Françoise Bertrand3, Gerald Massonnet1, Elisabetta Marangoni6, Marc Pocard7,8, Ivan Bieche9, Marie-France Poupon6, Dominique Bellet1, Virginie Dangles-Marie 1 1 IFR 71 Sciences du Médicament, Faculté des Sciences Phamraceutiques et Biologiques buy GSK872 Paris Descartes, Paris, France, 2 Département d’Anatomie Pathologique, Institut Mutualiste Montsouris, Paris,

France, 3 Service d’Anatomie et de Cytologie Pathologiques, Centre René Huguenin, Saint Cloud, France, 4 Plateforme d’Imagerie Cellulaire et Moléculaire, IFR71 Sciences du Médicament, Faculté des Sciences Pharmaceutiques et Biologiques Paris Descartes, Paris, France, 5 Plateforme Imagerie Cellulaire et Tissulaire, LY2874455 solubility dmso Research Center, Institut Curie, Orsay, France, 6 Département du Transfert, Hôpital Institut Curie, Paris, France, 7 Département Médico-Chirurgical de Pathologie Digestive Chirurgie, Hôpital Lariboisière, Paris, France, 8 UMR U965 INSERM/Paris7 Université next Paris Diderot, Hôpital Lariboisière, Paris, France, 9 UMR745 INSERM, Faculté des Sciences Pharmaceutiques et Biologiques Paris Descartes, Paris, France New models continue

to be required to improve our understanding of colorectal cancer progression. The impact of microenvironment -like cell-cell interactions, extracellular matrix- on cell phenotype is now well described and multicellular three-dimensional tumour spheroids have been shown to closely mimic phenotype characteristics of in vivo solid tumours. In this context, we characterized here a three-dimensional multicellular tumour model we named colospheres, directly obtained from mechanically dissociated colonic primary tumours and correlated with metastatic potential. Colorectal primary tumours (n = 203) and 120 paired non-tumoral colon mucosa were mechanically disaggregated into small fragments for short-term cultures. Colospheres, exclusively formed by viable cancer cells, were obtained in only one day from 98 tumours (47%). Inversely, non-tumoral colonic mucosa never generated colospheres. The colosphere forming capacity was statistically significantly associated to tumour aggressiveness, according to AJCC stage analysis. Further characterization was performed using colospheres, generated from a human colon cancer xenograft, and spheroids, formed on agarose by the paired cancer cell line. Despite close morphology, colospheres displayed higher Mizoribine invasivity than spheroids.