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GSE144035: Loss of Ikaros promotes oncogene independence in a model of Lmo2-induced T-cell acute lymphoblastic leukemia

Bulk RNA sequencing

LMO2 is an oncogenic transcription factor that is frequently overexpressed due to chromosomal abnormalities in T-cell acute lymphoblastic leukemia (T-ALL). In transgenic mouse models, Lmo2 overexpression causes thymocyte self-renewal resulting in T-cell leukemia with long latency. However, the requirement for Lmo2 for leukemia maintenance is poorly understood. To study this, we developed a Tetracycline-regulated knock-in mouse model that reversibly expresses Lmo2 throughout the haematopoietic system. This led to a specific impairment of T-cell development and the development of self-renewing preleukemic stem cells (pre-LSCs) in the thymus, followed by the development of fully penetrant T-lymphoblastic leukemia resembling human T-ALL. In preleukemic mice, repression of Lmo2 overcame the LMO2-induced thymocyte developmental block, reversed Lmo2-induced gene expression changes and eliminated self-renewing pre-LSCs in vivo. In contrast, overt T-lymphoblastic leukemias arising in this model were either immature, Lmo2-dependent leukemias resembling human ETP-ALL, or mature leukemias which were Lmo2-independent. Genomic analyses identified frequent loss of tumour suppressor genes in Lmo2-independent T-ALLs. Deletion of one of these, Ikaros (Ikzf1), was sufficient to transform Lmo2-dependent tumours to Lmo2-independence. Together these results indicate an evolution of oncogene addiction in T-ALL and that loss of Ikaros can promote self-renewal of T-ALL lymphoblasts in the absence of initiating oncogenes. SOURCE: Nicholas,C,Wong (nick.wong@monash.edu) - Monash University

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