OBJECTIVETo evaluate the expression of microRNAs and reveal the regulatory mechanism of miRNA-708 in pediatric common acute lymphoblastic leukemia (ALL) (common-ALL).

METHODSThe expressions of microRNAs in common-ALL patients were detected by microarrays in 3 pediatric common-ALL samples, and then verified by stem-loop quantitative RT-PCR in 34 common-ALL samples. The target genes of miR-708 were found by bioinformatics software, and verified by dual-luciferases reporter assay, RT-PCR and Western blot.

RESULTSCompared to normal bone marrow samples, of all the 2006 detected miRNAs, the expression of miR-708, miR-181b and miR-210 were 16.886 ± 16.854, 5.710 ± 4.652, and 9.789 ± 1.178, retrospectively, being significantly up-regulated expressed than those in normal control (1.872 ± 0.339, 1.276 ± 0.531 and 1.005 ± 0.080, retrospectively) (P < 0.05), while miR-27b and miR-345 were the two most down-regulated ones (0.524 ± 0.085 and 0.675 ± 0.086, retrospectively) (normal control: 1.123 ± 0.066 and 1.204 ± 0.140, retrospectively) (P < 0.05). And the expression of miR-708 and miR-181b were significantly correlated with the clinical types in common-ALL. In high risk common-ALL, miR-708 and miR-181b were much higher than in standard and middle risk common-ALL (P < 0.05). The further verification research in 293 cell line showed that miR-708 decreased the expression level of its target genes CNTFR, NNAT and GNG12 by combining with 3'-UTR of the 3 genes, moreover, miR-708 combined with CNTFR 3'-UTR in 394 ∼ 400 bp sequence region.

CONCLUSIONMicroRNAs plays an important regulatory role during the occurrence and development of the pediatric common-ALL and miR-708 is an important factor for high risk common-ALL.