Poster Presentation Advances in Neuroblastoma Research Congress 2016

Aldehyde dehydrogenases activity plays a key role in NB aggressive behavior (#232)

Marjorie Flahaut 1 , Nicolas Jauquier 1 , Nadja Chevalier 2 , Katya Nardou 1 , Katia Balmas-Bourloud 1 , Raffaele Renella 1 , Nicole Gross 1 , Annick Mühlethaler-Mottet 1
  1. University Hospital CHUV, Lausanne, Switzerland
  2. Physiology, University of Lausanne, Lausanne, Switzerland

Background: The successful targeting of neuroblastoma (NB) associated tumor-initiating cells (TICs) is a real challenge in developing new therapeutic strategies. By combining serial neurosphere (NS) passages with gene expression profiling, we have previously identified ALDH1A2 and ALDH1A3 as potential NB-TICs markers in patient-derived xenograft (PDX) tumors. ALDH1A2, ALDH1A3, with ALDH1A1, belonging to the subfamily of aldehyde dehydrogenases 1 (ALDH1) isoenzyme involved in the synthesis of retinoic acid, have been identified as functional stem cell markers in various cancers. In this study, we explored the involvement of ALDH1 isoforms and the related ALDH activity in NB aggressive properties.

Methods: ALDH activity and ALDH1A1/A2/A3 expression levels were measured using the ALDEFLUOR™ kit, and by real-time PCR, respectively. ALDH activity was inhibited using the specific ALDH inhibitor diethylaminobenzaldehyde (DEAB), and ALDH1A3 gene knock out was generated through the CRISPR/Cas9 technology.

Results: Here, we confirmed the enrichment of ALDH1A2 and ALDH1A3 mRNA expression in NB cell lines and PDX tumor during NS-passages. We found that ALDH1 expression was associated to less aggressive NB cell lines and correlated with better prognosis, while ALDH1A3 is more widely expressed in NB cell lines and is associated with poor survival and high-risk prognostic factors. We also observed an important ALDH activity in various NB cell lines and PDX tumors. Specific inhibition of ALDH activity with DEAB resulted in a strong reduction of NB cell clonogenicity, and self-renewal potential, and partially restored NB cells sensitivity to 4-hydroxycyclophosphamide. Finally, the specific knock out of the ALDH1A3 gene mediated a cell type-dependant inhibition of NB clonogenic and TICs self-renewal properties.

Conclusion: Altogether our data revealed that ALDH activity plays a key role in NB aggressive phenotype, and that the involvement of ALDH1A3 isoenzyme in this process is cell type-dependent, possibly due to the various expression profiles of other ALDH isoforms.