Pure curcumin decreases the expression of WT1 by upregulation of miR-15a and miR-16-1 in leukemic cells

Shen-Meng Gao,Jun-Jie Chen,Lu-Yao Wang,Chong-Yun Xing,Li-Ping Ye,Jian-Bo Wu,Jun-Jun Yang,Kang Yu,Chi-Qi Chen

doi:10.1186/1756-9966-31-27

Abstract

BackgroundPure curcumin has been reported to down-regulate the expression of WT1 in leukemic cells. However, the molecular mechanism underlying the down-regulation of WT1 by curcumin is not completely delineated. The purpose of this present study is to identify a new miRNA-mediated mechanism which plays an important role in the anti-proliferation effects of curcumin in leukemic cells.MethodsK562 and HL-60 cells were treated with different concentrations of curcumin for 24 and 48 hours, the level of miR-15a/16-1 and WT1 were detected by qRT-PCR and Western blotting. WT1 expression and cell proliferation were detected by Western blotting and CCK-8, after curcumin treated-K562 and HL-60 cells were transfected with anti-miR-15a/16-1 oligonucleotides.ResultsWe found that pure curcumin upregulated the expression of miR-15a/16-1 and downregulated the expression of WT1 in leukemic cells and primary acute myeloid leukemia (AML) cells. Overexpression of miR-15a/16-1 deduced the protein level of WT1 in leukemic cells, but downregulation of WT1 by siRNA-WT1 could not increase the expression of miR-15a/16-1 in leukemic cells. These results reveal that curcumin induced-upregulation of miR-15a/16-1 is an early event upstream to downregulation of WT1. Furthermore, anti-miR-15a/16-1 oligonucleotides (AMO) partly reversed the downregulation of WT1 induced by pure curcumin in leukemic cells and AMO promoted the growth of curcumin treated-K562 and HL-60 cells.ConclusionThus, these data suggest for the first time that pure curcumin downregulated the expression of WT1 partly by upregulating the expression of miR-15a/16-1 in leukemic cells. miR-15a/16-1 mediated WT1 downregulation plays an important role in the anti-proliferation effect of curcumin in leukemic cells.

Highlights

The Wilms’ tumor 1 (WT1) gene, which is located at the short arm of chromosome 11 and contains 10 exons, encodes a DNA-binding transcription factor essential for embryonal development [1]
Pure curcumin downregulated the expression of WT1 and effectively inhibited cell proliferation in leukemic cells As reported previously [17], low concentration of pure curcumin could inhibit the growth of leukemic cells and downregulate the expression of WT1
The mRNA and protein levels of WT1 were detected by qRT-PCR and Western blotting respectively after K562 and HL-60 cells were treated with non-cytotoxic doses of pure curcumin (5, 10, 20 uM for K562 and 2.5, 5, 10 uM for HL-60) [17]

Summary

Introduction

The Wilms’ tumor 1 (WT1) gene, which is located at the short arm of chromosome 11 and contains 10 exons, encodes a DNA-binding transcription factor essential for embryonal development [1]. The molecular targets of curcumin include modulation of NF-kappaB, Jak/STAT, WT1, extracellular signal regulated kinase and other key molecules involved in tumorigenesis [6,7,8]. Bharti et al showed curcumin decreased NF-kappaB in human multiple myeloid cells, leading to the suppression of proliferation and induction of apoptosis [7]. Pure curcumin has been reported to down-regulate the expression of WT1 in leukemic cells. The molecular mechanism underlying the down-regulation of WT1 by curcumin is not completely delineated. The purpose of this present study is to identify a new miRNA-mediated mechanism which plays an important role in the anti-proliferation effects of curcumin in leukemic cells

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