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

K562 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.We 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.Thus, 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.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]. High level of WT1, which is detected in most cases of acute human leukemia and chronic myelogeous leukemia (CML) in blast crisis, is associated with a worse long-time prognosis [2]. Downregulation of WT1 by special siRNA can inhibit cell proliferation and induce apoptosis in K562 and HL-60 cells [3]. WT1 acts as a potent transcriptional regulation factor involved in cell growth and development due to the presence of zinc fingers [4]. WT1 is fir