MiR-146a Expression Level As a Molecular Marker in Acute Promyleocytic Leukemia

Zhong, Hua; Wang, Chun; Fangyuan, Chen; Xu, Lan; Zhong, Jihua; Jiong, HU

doi:10.1182/blood.V120.21.4821.4821

Abstract

Abstract 4821

MiR-146a which is located on chromosomes 5 may be involved in normal hemtopoisis and the pathogenesis of several hematopoietic diseases through inhibiting the expression of its targets. Acute promyelocytic leukemia (APL) cell line NB₄ was taken as research model to find out whether miR-146a expression was associated to cell differentiation and proliferation. The miR-146a expression level of NB₄ cells decreased after ATRA treatment, meanwhile the expression level of its predicted target gene Smad4 increased simultaneously.

MiR-146a expression plasmid, no related negative control sequence plasmid and recombined luciferase reporter gene vector containing the miR-146a complementary combined site on Smad4 plasmid were constructed by DNA recombination technical. Both recombined plasmids were transiently co-transfected into 293T cells with control plasmid pRL-TK. The interaction between miR-146a and its predicted target gene Smad4 was confirmed by the relative activities of dual luciferase detection.

This interaction relationship was further confirmed by liposome entrapment transfection of miR-146a and its antisense molecular in NB₄ cells. The expression level of miR-146a in NB₄ cells did no influence on Smad4 gene expression but Smad4 protein expression levels (fig 1).

The changes of NB₄ cells on biological behaviors were observed by cell morphology, proliferation curve and flow cytometry methods under different miR-146a expression status. The results showed that cell proliferation ratio decreased and cell apoptosis ratio increased after miR-146a expression suppression in NB₄ cells.

The investigation of miR-146a expression levels in mononuclear cells of APL patients' bone marrow and clinical data were carried out. It was showed that the expression levels of miR-146a were higher in APL patients than normal controls. The expression level of miR-146a was positive correlated with peripheral blood white cell count (fig 2). MiR-146a expression level was negative correlated with Th/Ts ratio among these patients (fig 3).

MiR-146a/Smad4 signal pathway is expressed in acute promyelocytic leukemia. The proliferation and apoptosis of the cells are modified by the Smad4 protein expression regulated by miR-146a expression. MiR-146a expression is somewhat associated with acknowledged clinical prognosis factors. It has potential possibility to take miR-146a as prognosis factor.