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

¹Institute of Endocrinology, Centre of Oncological Endocrinology, University of Milan, Via Balzaretti 9, 20133 Milan, Italy

²Unit of Genetics of Neurodegenerative and Metabolic Diseases, Fondazione IRCCS Istituto Neurologico Carlo Besta, Via Celoria 11, 20133 Milan, Italy

author email corresponding author email* Contributed equally

BMC Cancer 2008, 8:30doi:10.1186/1471-2407-8-30


Published:	29 January 2008

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.