13q14.3 chromosomal region contains miR-15 and miR-16 and deletion of this region is a commonly reported aberration in chronic lymphoblastic leukemia (CLL), suggesting miRNAs involvement in CLL pathogenesis.
MicroRNAs, specifically miR-21-5p and a 23 nucleotide long 5'-phosphorylated miRNA with 3'-uridylation (iso-miR-16-5p), were only detected in the CLL patients.
In CLLs with 13q deletions the miR-15a/miR-16-1 cluster directly targeted TP53 (mean luciferase activity for miR-15a vs scrambled control, 0.68 relative light units (RLU) [95% confidence interval {CI}, 0.63-0.73]; P = .02; mean for miR-16 vs scrambled control, 0.62 RLU [95% CI, 0.59-0.65]; P = .02) and its downstream effectors.
Some human miRNAs are linked to leukemias: the miR-15a/miR-16 locus is frequently deleted or down-regulated in patients with B-cell chronic lymphocytic leukemia and miR-142 is at a translocation site found in a case of aggressive B-cell leukemia.