Overexpression of miR-708 and its targets in the childhood common precursor B-cell ALL

The critical function of microRNAs in the pathogenesis and prognosis of hematopoietic cancer has become increasingly apparent. However, only a few miRNAs have been reported to be altered in acute lymphocytic leukemia (ALL).

To uncover aberrantly expressed miRNAs in pediatric B-cell ALL, our study employed genome-wide miRNA microarray analysis and stem-loop real-time quantitative polymerase chain reaction (qRT-PCR) to examine common precursor B-cell ALL samples. The target genes of miRNA-708 were then identified and verified by bioinformatics, dual-luciferase reporter assay, qRT-PCR, and Western blot.

Significant upregulation of miR-708, miR-210, and miR-181b, and downregulation of miR-345 and miR-27a were observed in common precursor B-cell ALL (common-ALL) samples (P < 0.05). In addition, elevated expression of miR-708 and miR-181b were found in high-risk common-ALL compared to standard and intermediate ones. miR-708 inhibited luciferase reporter activity by binding to the 3'-untranslated regions (3'-UTRs) of CNTFR, NNAT, and GNG12 mRNA in HEK-293 cell line and suppressed the protein levels of CNTFR, NNAT, and GNG12 in Jurkat cells. In addition, mRNA levels of CNTFR and NNAT, but not of GNG12, were found to be downregulated in high risk common-ALL samples. Mutational analysis revealed that miR-708 binds to the 394-400 bp sequence region of the 3'-UTR of CNTFR mRNA.

The expression level of miR-708 reflects differences among the clinical types of common-ALL, and CNTFR, NNAT, and GNG12 were identified as targets of miR-708.