Abstract 3051: Genome-wide microarray expression and genomic alteration by array-CGH analysis in neuroblastoma stem-like cells

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Neuroblastoma, the most common extracranial malignant solid tumor in childhood has a very diverse clinical behaviour: from spontaneous regression to a very aggressive malignant progression and resistance to chemotherapy. This heterogeneous clinical behaviour might be due to molecular differences in tumor cell subpopulations. The cancer stem cells (CSC) model proposes the existence of a subpopulation within the tumor with stem-like cell properties: a significant proliferation capacity, a unique self-renewal capacity, and therefore, a higher ability to form new tumors. We enriched the stem-like cell population content of two commercial neuroblastoma cell lines (SKNDZ and SIMA) by the use of conditioned cell culture media for neurospheres, and compared genome expression and genomic gains and losses appearing in neurospheres versus the alterations appearing in standard tumor cells, by microarray analysis and array-CGH, respectively. Array-CGH did not show any significant differences between standard and neurosphere-forming cell lines, both in SKNDZ and in SIMA. The microarray expression analysis highlighted some of the most relevant biological processes and molecular functions that might be responsible for the stem-cell like phenotype. As expected, some signalling pathways detected were involved in self-renewal of normal tissues (Wnt, Notch, Hedgehog and TGF-β) and seem to contribute to CSC phenotype when deregulated. Among them, we focused on the aberrant activation of Hedgehog and TGF-β signalling pathways. We confirmed the inhibition of repressors of TGF-β pathway, as SMAD6 and SMAD7 by quantitative PCR. The analysis of the Sonic Hedgehog pathway showed overexpression of PTCH1, GLI1 and SMO. We analyzed two CSC surface markers, and found overexpression of CD133 and CD15 in SIMA neurospheres, confirming that this cell line was particularly enriched in stem-like cells. This work shows a cross-talk of different pathways in neuroblastoma, and the importance of it in stem-like cells, as confirmed by the overexpression observed in JAG1, one of the targets of TGF-β and also the main activator of Notch signalling pathway. Further analysis based on this work could identify possible new targets for molecular CSC therapies against neuroblastoma, highlighting the importance of redirecting current cancer treatments towards CSC to achieve total elimination of tumor cell population and improve treatment effectiveness. Citation Format: Raquel Ordonez, Gabriel Gallo, Soledad Martinez, Sheila Legarra, Noemie Pata-Merci, Justine Guegan, Giselle Danglot, Xing Fan, Juan A. Rey, Alain Bernheim, Javier S. Castresana. Genome-wide microarray expression and genomic alteration by array-CGH analysis in neuroblastoma stem-like cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3051. doi:10.1158/1538-7445.AM2014-3051