Researchers have discovered a potential therapeutic target for T-cell acute lymphoblastic leukemia (T-ALL), according to a paper published in Cell.
The team first identified long, non-coding strands of RNA (lncRNA) that were active in T cells from patients with T-ALL but not in the healthy T cells of subjects without the disease.
Further analysis revealed that inhibiting 1 of these lncRNAs, LUNAR1 (leukemia-induced non-coding activator RNA-1), stalled T-ALL growth in vitro and in vivo.
The study offers preliminary evidence that drugs targeting LUNAR1 could treat T-ALL, and LUNAR1 could aid in diagnosing the disease, said Iannis Aifantis, PhD, of NYU Langone Medical Center in New York.
“Our study shows that LUNAR1 is highly specific for T-cell acute lymphoblastic leukemia and plays a key role in how this cancer develops,” he noted, adding that overproduction of LUNAR1 was recorded in almost all (90%) of the leukemia patients analyzed.
To make these discoveries, Dr Aifantis and his colleagues performed ultra-high-depth RNA sequencing of human T-ALL cell lines and primary leukemia samples.
They used the resulting data to generate the most comprehensive T-ALL transcriptome assembly to date and then isolated putative lncRNA genes. This revealed 6023 lncRNAs that are active in T-ALL, 60% of which had not been identified before.
The researchers zeroed in on LUNAR1 by pinpointing the lncRNAs that were active in the NOTCH1 pathway, which is active in at least half of T-ALL patients. LUNAR1 stood out right away, the team said, as the most highly expressed lncRNA.
The researchers also found that LUNAR1 does not produce cancerous proteins on its own. However, its production proved essential to the cell-to-cell signaling action of another protein, IGF-1R (insulin-like growth factor 1 receptor), which is tied to many cancers, including leukemia.
Additional experiments showed that the gene coding for LUNAR1 is near the gene for IGF-1R and located toward the end of the chromosome. When activated, LUNAR1’s position allows it to chemically loop back and, in turn, bind to and activate IGF-1R.
According to Dr Aifantis, this research shows that T-ALL could simply be described as a condition of “too much errant signaling.” He noted that, in normal T cells, lncRNAs such as LUNAR1 are not transcribed, NOTCH1 is inactive, and there is no looping back of LUNAR1 to activate IGF-1R.
To confirm their findings, the researchers also transplanted human leukemia T cells into mice and inhibited LUNAR1 in some of the animals. Tumor growth stalled only in those mice in which LUNAR1 was inactivated.
The researchers said their next step is to develop a more effective inhibitor of LUNAR1, preferably something that would precisely target 1 or more of its 200-plus component nucleotides.
