Collaborative ISL1/GATA3 interaction in controlling neuroblastoma oncogenic pathways overlapping with but distinct from MYCN

Abstract

<b>Background</b>: Transcription factor <i>ISL1</i> plays a critical role in sympathetic neurogenesis. Expression of <i>ISL1</i> has been associated with neuroblastoma, a pediatric tumor derived from sympatho-adrenal progenitors, however the role of <i>ISL1</i> in neuroblastoma remains unexplored. <b>Method</b>: Here, we knocked down <i>ISL1</i> (KD) in SH-SY5Y neuroblastoma cells and performed RNA-seq and ISL1 ChIP-seq analyses. <b>Results</b>: Analyses of these data revealed that <i>ISL1</i> acts upstream of multiple oncogenic genes and pathways essential for neuroblastoma proliferation and differentiation, including <i>LMO1</i> and <i>LIN28B</i>. <i>ISL1</i> promotes expression of a number of cell cycle associated genes, but represses differentiation associated genes including RA receptors and the downstream target genes <i>EPAS1</i> and <i>CDKN1A</i>. Consequently, Knockdown of <i>ISL1</i> inhibits neuroblastoma cell proliferation and migration in vitro and impedes tumor growth in vivo, and enhances neuronal differentiation by RA treatment. Furthermore, genome-wide mapping revealed a substantial co-occupancy of binding regions by ISL1 and GATA3, and ISL1 physically interacts with GATA3, and together they synergistically regulate the aforementioned oncogenic pathways. In addition, analyses of the roles of <i>ISL1</i> and <i>MYCN</i> in <i>MYCN</i>-amplified and <i>MYCN</i> non-amplified neuroblastoma cells revealed an epistatic relationship between <i>ISL1</i> and <i>MYCN</i>. <i>ISL1</i> and <i>MYCN</i> function in parallel to regulate common yet distinct oncogenic pathways in neuroblastoma. <b>Conclusion</b>: Our study has demonstrated that <i>ISL1</i> plays an essential role in neuroblastoma regulatory networks and may serve as a potential therapeutic target in neuroblastoma.