Effect of Hispidulin on Proliferation and Apoptosis of Leukemia K562 Cells by Up-Regulating IL-37

Abstract

To investigate the effect and underlying mechanism of hispidulin on the proliferation and apoptosis of leukemia K562 cells. K562 cells were cultured in vitro and treated with 0, 5, 25 or 100 μmol/L hispidulin for 24 h. Cell proliferation and apoptosis were detected by CCK-8 and flow cytometry, respectively. Western blot was used to assess the expression of Bax, Bcl-2 and interleukin (IL)-37 proteins. Bone marrow mononuclear cells were extracted from 17 chronic myeloid leukemia patients and 21 healthy individuals by Ficoll-Hypaque density gradient method, and the expression of IL-37 protein was measured by Western blot. K562 cells with IL-37 overexpression or knockdown were constructed, and then treated with 0 or 100 μmol/L hispidulin for 24 h. Cell proliferation, apoptosis and protein expression of Bax and Bcl-2 were determined in the same way as above. After K562 cells were treated with hispidulin, the cell inhibition rate, apoptosis rate, and the protein expression of Bax and IL-37 were significantly increased (P <0.05), but the cell proliferation and expression of Bcl-2 protein were decreased (P <0.05). The expression of IL-37 protein in bone marrow mononuclear cells of the leukemia patient was 0.24±0.03, which was significantly lower than 0.91±0.05 of healthy controls (P <0.05). Overexpression of IL-37 significantly promoted inhibition rate, apoptosis rate, and expression of Bax protein in K562 cells (P <0.05), but suppressed the expression of Bcl-2 protein (P <0.05). In addition, knockdown of IL-37 could reverse the effects of hispidulin on proliferation and apoptosis of K562 cells. Hispidulin inhibits the proliferation and induces apoptosis of leukemia K562 cells, which may be related to the up-regulation of IL-37 protein in cells.