Oral Presentation Advances in Neuroblastoma Research Congress 2016

The ALK-F1174L activating mutation mediates the upregulation of gene cluster located in the 15qD1 genomic region including the Myc locus in tumors derived from murine neural crest progenitor cells (#7)

Katia Balmas-Bourloud 1 , Nicolas Jauquier 1 , Jean-Marc Joseph 1 , Isabelle Janoueix-Lerosey 2 , Nicole Gross 1 , Annick Mühlethaler-Mottet 1
  1. University Hospital CHUV, Lausanne, Switzerland
  2. Institut Curie, Paris, France

Introduction: The anaplastic lymphoma kinase (ALK) is overexpressed, mutated or amplified in most neuroblastoma (NB). The ALK-F1174L mutation mediates an enhanced activation of its downstream signaling cascade and an increased oncogenic potential relative to other ALK mutations. However, the precise molecular mechanisms remain unresolved.

Methods: To identify genes and pathways specifically activated by the ALK-F1174L mutation, human ALK-F1174L, ALK-R1275Q, or ALK-wt were stably expressed the murine neural crest progenitor cell (NCPC) line JoMa1. Transduced JoMa1 cells were injected orthotopically in adrenal gland of athymic Swiss nude mice and the transcriptomes of the resulting tumors were analyzed by Affymetrix microarrays. 

Results: As expected, the ALK-F1174L activating mutation displayed a significantly enhanced oncogenic potential relative to ALK-R1275Q and ALK-wt in NCPC. Comparison of the whole gene expression profile of these tumors revealed 1179 or 645 differentially expressed probe sets (FC>2) between ALK-wt and ALK-F1174L, or ALK-wt and ALK-R1275Q tumors, respectively. Surprisingly, despite strong difference in tumor growth, ALK-F1174L and ALK-R1275Q-derived tumors displayed only 19 differentially expressed probe sets. Interestingly, among the 11 overexpressed genes in the ALK-F1174L group, 6 genes, including Pvt1, Mtss1, Nsmce2, are located on the chromosome 15qD1 region close to the Myc locus. Although Myc was not identified among the differentially expressed genes, overexpression of Myc, as well as Pvt1, Mtss1, and Nsmce2 was validated by real-time PCR in ALK-F1174L-expressing tumors relative to ALK-R1275Q and ALK-wt groups, as well as in tumor-derived cell lines. Moreover, we confirmed using the ALK inhibitor TAE684 that the upregulation of these genes is directly dependent on ALK-F1174L activity.

Conclusion: These results suggest that the strong oncogenic potential mediated by the ALK-F1174L activating mutation may be caused by the upregulation a cluster of genes located in the 15qD1 genomic region. Further work will allow us to elucidate the precise regulatory mechanisms and to identify the respective role of these genes on tumor initiation and growth.