Abstract 2007: Transcriptional regulatory program controlled by the oncogenic transcription factor LMO1 in neuroblastoma

Neuroblastoma is an embryonal tumor of the peripheral sympathetic nervous system, accounting for 15% of all childhood cancer deaths. Both overexpression of the transcription factor LMO1 and the polymorphisms within this gene locus are associated with the susceptibility to neuroblastoma, but the oncogenic roles of LMO1 in neuroblastoma pathogenesis have not been elucidated. The roles of LMO1 in T-cell acute lymphoblastic leukemia (T-ALL) are better understood, and these suggest that some of its effects may be similar between the two malignancies. Here we identify the transcriptional regulatory program controlled by LMO1 in neuroblastoma and T-ALL cells. Knockdown of LMO1 induces apoptotic cell death in both tumor types. ChIP-seq and microarray analyses demonstrate that LMO1 frequently co-occupies its target genes with GATA3 and regulates gene expression in a tissue-specific manner. LMO1 positively regulates genes involved in neuronal development, tumor invasion and metastasis in neuroblastoma cells, whereas it regulates genes involved in lymphopoiesis and immune function in T-ALL cells. Gene set enrichment analysis reveals that many genes bound by LMO1 and GATA3 are significantly downregulated upon MYCN knockdown in the MYCN-amplified neuroblastoma cells. Importantly, LMO1 binds at the CDK6 gene locus, which is associated with a super-enhancer both in neuroblastoma and T-ALL cells. The mRNA expression of CDK6 is positively correlated with LMO1 expression in primary neuroblastoma samples. Knockdown of LMO1 downregulates CDK6 protein expression, whereas overexpression of LMO1 upregulates CDK6 expression. CDK6 knockdown induces apoptosis both in neuroblastoma and T-ALL cells. Our results indicate that CDK6 is a critical downstream target that is directly activated by LMO1 and is required for cell survival in neuroblastoma and T-ALL cells. Citation Format: Takaomi Sanda, Koshi Akahanse, Brian J. Abraham, Nina Weichert, Adam Durbin, Lars Anders, Shi Hao Tan, Alice Wei Yee Yam, Lee N. Lawton, Richard A. Young, John M. Maris, A Thomas Look. Transcriptional regulatory program controlled by the oncogenic transcription factor LMO1 in neuroblastoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2007.