BMC Cancer Research article Retinoic acid reduces human neuroblastoma cell migration and invasiveness: effects on DCX, LIS1, neurofilaments-68 and vimentin expression Elio Messi*†1, Maria C Florian†1, Claudio Caccia2, Mariarosa Zanisi1 and Roberto Maggi1 BioMed Central Open Access Address: 1Institute of Endocrinology, Centre of Oncological Endocrinology, University of Milan, Via Balzaretti 9, 20133 Milan, Italy and 2Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy Email: Elio Messi* - elio.messi@unimi.it; Maria C Florian - maria.florian@unimi.it; Claudio Caccia - claudio.caccia@alice.it; Mariarosa Zanisi - mariarosa.zanisi@unimi.it; Roberto Maggi - roberto.maggi@unimi.it * Corresponding author †Equal contributors Published: 29 January 2008 BMC Cancer 2008, 8:30 doi:10.1186/1471-2407-8-30 This article is available from: http://www.biomedcentral.com/1471-2407/8/30 Received: 13 July 2007 Accepted: 29 January 2008 © 2008 Messi et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: Neuroblastoma is a severe pediatric tumor, histologically characterised by a variety of cellular phenotypes. One of the pharmacological approaches to neuroblastoma is the treatment with retinoic acid. The mechanism of action of retinoic acid is still unclear, and the development of resistance to this differentiating agent is a great therapy problem. Doublecortin, a microtubule-associated protein involved in neuronal migration, has recently been proposed as a molecular marker for the detection of minimal residual disease in human neuroblastoma. Nevertheless, no information is available on the expression of doublecortin in the different cell-types composing human neuroblastoma, its correlation with neuroblastoma cell motility and invasiveness, and the possible modulations exerted by retinoic acid treatment. Methods: We analysed by immunofluorescence and by Western blot analysis the presence of doublecortin, lissencephaly-1 (another protein involved in neuronal migration) and of two intermediate filaments proteins, vimentin and neurofilament-68, in SK-N-SH human neuroblastoma cell line both in control conditions and under retinoic acid treatment. Migration and cell invasiveness studies were performed by wound scratch test and a modified microchemotaxis assay, respectively. Results: Doublecortin is expressed in two cell subtypes considered to be the more aggressive and that show high migration capability and invasiveness. Vimentin expression is excluded by these cells, while lissencephaly-1 and neurofilaments-68 are immunodetected in all the cell subtypes of the SK-N-SH cell line. Treatment with retinoic acid reduces cell migration and invasiveness, down regulates doublecortin and lissencephaly-1 expression and up regulates neurofilament-68 expression. However, some cells that escape from retinoic acid action maintain migration capability and invasiveness and express doublecortin. Conclusion: a) Doublecortin is expressed in human neuroblastoma cells that show high motility and invasiveness; b) Retinoic acid treatment reduces migration and invasiveness of the more aggressive cell components of SK-N-SH cells; c) The cells that after retinoic acid exposure show migration and invasive capability may be identified on the basis of doublecortin expression. Page 1 of 12 (page number not for citation purposes)