IKAROS isoforms differentially control gene expression and differentiation of a B-cell acute lymphoblastic leukemia cell line.

B-cell acute lymphoblastic leukemia (B-ALL) is the most common malignancy occurring in children and a leading cause of cancer-related mortality, thus there is an urgent need for development of novel therapeutic strategies for high risk B-ALL patients. The significance of IKZF1 gene alterations in B-ALL cases is controversial, as some studies have shown those to be associated with poor prognosis, while others have reported that deletion of exons 4-7 of the IKZF1 gene, which results in generation of IKAROS isoform 6, is related favorable prognosis. For the present study, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 was employed for knockout of the IKZF1 gene and various IKAROS knockout lines were established, which allowed for investigation of precise functions of the gene by comparing four lines with different IKAROS isoform 1 and 6 statuses. The results clearly showed induction of significant differentiation and cell cycle progression in IKAROS isoform 6 knockout clones. Furthermore, knockout of IKAROS isoform 6 resulted in significant upregulation of the expression of IKAROS isoform 1 as well as signal transducer and activator of transcription 5 (STAT5) activity, which are considered to be related to the observed features. Further investigations are warranted to provide greater mechanistic insight regarding IKAROS-mediating pathways, which will lead to development of novel therapy for human B-ALL.