The role of long noncoding RNAs in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is genetically heterogeneous and can be classified into genetic subclasses based on protein coding gene expression profiles. Thus far, long noncoding RNAs (lncRNAs), representing one of the largest fractions of the human transcriptome, remained unexplored as genetics markers for distinct T-ALL subtypes. Therefore, we here determined, for the first time, lncRNA expression profiles in lymphoblasts of 64 T-ALL patients and identified a robust set of lncRNAs that discriminate previously established genetic subtypes of human T-ALL. Half of these lncRNAs were positively correlated with the expression levels of neighboring protein coding genes located in their immediate vicinity, hinting towards cis-regulatory functions. In addition, gene set enrichment analysis showed that these lncRNA signatures were also recapitulated in human T-ALL cell lines representative for the different genetic subclasses, suggesting that these tumor lines could serve as valuable in vitro cellular model systems for further functional lncRNA studies. Finally, comparison of T-ALL lncRNA signatures with those from stage-specific normal developing human thymocytes revealed multiple ectopically expressed, putative oncogenic lncRNAs. Our data identify lncRNAs novel genetic markers in T-ALL biology and warrant further in depth investigations towards landscaping of their specific role in thymopoiesis and leukemogenesis. Gene expression profiles of 10 different T-ALL cell lines