Targeted blockage of RNA binding protein E2 by decoy RNA induces the granulocytic differentiation of K562 cells

OBJECTIVE: To use a decoy RNA targeted blockage of the RNA binding protein E2 (hnRNP E2) resulting in the CCAAT/enhancer-binding protein alpha (C/EBP alpha) gene's abnormal translation and investigate its effect on the granulocytic differentiation of K562 cells and the probable molecular mechanism. METHODS: The hnRNP E2 decoy RNA expression plasmid was constructed and transfected into K562 cells with cationic liposome, and stable expression cells were obtained by G418 selection. The changes of C/EBP alpha and granulocyte colony-stimulating factor receptor (G-CSFR) gene expression were detected by RT-PCR and Western blot. The morphologic changes were observed after Wright-Giemsa staining. The expression of granulocytic differentiation antigens CD13 and CD15 was studied by immunocytochemistry. RESULTS: The stably expressed pG cells were obtained. Its C/EBP alpha mRNA level remained unchanged, while 42kD-C/EBP alpha protein expression was increased by (49.7 +/- 5.5)% (P < 0.05); and G-CSFR mRNA was increased by (42.1 +/- 3.6)% (P < .05), and its protein was increased by (37.4 +/- 6.2)% (P < 0.05) compared to that in the K562 control cells. The characteristics of polymorphonuclear neutrophils appeared in pG cells and CD13 and CD15 positive cell ratios were (18.7 +/- 2.5)% and (26.3 +/- 2.9)% respectively. CONCLUSIONS: HnRNP E2 decoy RNA can induce granulocytic differentiation of K562 cells, and G-CSF promotes this effect. The mechanisms may be that decoy RNA specifically blocks hnRNP E2, hence regulates the translation of C/ EBP alpha mRNA, restores the expression of 42kD-C/EBP alpha, and then up-regulates the expression of G-CSFR gene.