In this study, we show that loss of CDKN1B increased the prevalence of cell cycle regulator defects in immature T-ALL, usually only ascribed to CDKN2A/B deletions, and that CDKN1B deletions frequently coincide with expression of MEF2C, considered as one of the driving oncogenes in immature early T-cell precursor (ETP) ALL.
Using human T-ALL and BaF3 cell lines with high expression levels of MEF2C, the present study tested whether the BCL2 inhibitor (ABT-737) restores the sensitivity to prednisolone (PSL), because MEF2C causes PSL resistance, possibly by augmenting the anti-apoptotic activity of BCL2.
Three distinct immature T-cell acute lymphoblastic leukemia entities have been described including cases that express an early T-cell precursor immunophenotype or expression profile, immature MEF2C-dysregulated T-cell acute lymphoblastic leukemia cluster cases based on gene expression analysis (immature cluster) and cases that retain non-rearranged TRG@ loci.
Specifically, high MEF2C expression has been linked to mixed lineage leukemia-rearranged acute myeloid leukemia as well as to the immature subgroup of T-cell acute lymphoblastic leukemia.
Lacking comma: Chromosomal deletion of the STAT5 binding site in LOUCY cells reduced protein levels of STAT5 in some MEF2C-positve T-ALL cell lines, and the presence of inhibitory IL7-JAK-STAT5 signaling highlighted the repressive impact of this factor in MEF2C regulation.