This Is a Title in Title Case: A Combination of Low-Dose Decitabine and Chidamide Resulted in Synergistic Effects on the Proliferation and Apoptosis of Human Myeloid Leukemia Cell Lines

Abstract

Introduction: Myeloid leukemia is a malignant disease caused by both genetic and epigenetic changes. Aberrant DNA methylation and histone modifications are prevalent in cancers including leukemia and the process of epigenetic modifications is reversible, which makes them potential treatment targets using specific inhibitors. In this study, we sought to determine the antileukemic effects of low-dose decitabine (one of the most widely used DNA methyltransferase inhibitor) combined with chidamide (a novel orally active histone deacetylase inhibitor) on myeloid leukemia cells by detecting cell proliferation, cell cycle distribution and cell apoptosis to provide a promising regimen for clinical application. Methods: We conducted CCK-8 assay to determine the effect of low-dose decitabine combinated with chidamide on cell viability, cell cycle distribution analysis by use of flow cytometry accompanied with RT-qPCR and western blotting analysis to reveal its inhibitory mechanism of cell growth, and cell apoptotic analysis also by use of flow cytometry accompanied with RT-qPCR, western blotting analysis, intracellular ROS production and mitochondrial transmembrane potential assay to determine the apoptotic mechanism of combination of low-dose decitabine and chidamide in K562 and THP-1 cells. Result: Low-dose decitabine and chidamide alone played an inhibitory role in the proliferation of K562 and THP-1 cells in a dose- and time-dependent manner, and the combination of the two enhanced this effect, accompanied by induction of p21 expression and cell cycle arrest at G0/G1 phase. Chidamide instead of decitabine had pronounced effects on the histone H3 acetylation levels of leukemia cells. Meanwhile, combination of the two significantly induced cell apoptosis via mitochondrial transmembrane potential loss, resulting in upregulation of the cell apoptosis-related gene Bax and the protein cleaved PARP-1 and downregulation of antiapoptosis gene Bcl-2, and proteins, including pro-caspase 9, pro-caspase 3 and PARP-1. Conclusion: Our results provided evidence for the antileukemia effects of low-dose DNA methyltransferase inhibitor decitabine combinated with histone deacetylase inhibitor chidamide in preclinical myeloid leukemia models and suggested that combination of the two showed therapeutic potential for myeloid leukemia treatment. Disclosures No relevant conflicts of interest to declare.

Chidamide Combined With Doxorubicin Induced p53-Driven Cell Cycle Arrest and Cell Apoptosis Reverse Multidrug Resistance of Breast Cancer

“…CHI significantly increased the histone H3 acylation level of drug-resistant cells and reduced the expression of HDAC1 regardless of the addition of DOX. This was consistent with recent findings that CHI treatment increased the expression of Lys18 of H3 acetylation in myeloid leukemia K562 and ThP-1 cells, and the expression of Lys9 and Lys18 of H3 acetylation in human myeloma RPMI-8226 and ARP-1 cells ( 23 , 35 ). Drug-resistant cloning experiments and EDU experiments showed that single-drug CHI had a certain effect on CALDOX and MCF-7/A02 cell proliferation.…”

<p>The Synergistic Antitumor Activity of Chidamide in Combination with Bortezomib on Gastric Cancer</p>

“…23 In another study, combined treatment with bortezomib and MPT0G413 (a novel HDAC6selective inhibitor) leads to synergistic antiproliferative and proapoptotic effects in multiple myeloma cell lines through disturbing the bone marrow microenvironment and inducing caspase-dependent apoptosis. 25 In our study, the low-dose of bortezomib can significantly enhance the promotion of H3 and H4 acetylation when combined with chidamide in the MGC-803 and BGC-823 cells, suggesting the enhanced HDAC-mediated histone acetylation in the combined therapy. More importantly, phosphorylated PI3K and phosphorylated AKT were found significantly decreased while the expression of total PI3K and AKT remained unchanged in combination with bortezomib and chidamide, indicating the involvement of PI3K/Akt signaling pathway in synergistic antitumor effect.…”

“…**P<0.01, compared with the negative control, chidamide-, or bortezomib-alone groups).and C, the low-dose of bortezomib can significantly enhance the promotion of H3 and H4 acetylation by chidamide in the MGC-803 and BGC-823 cells. Previous studies have shown that chidamide can exert antitumor effects by activating the PI3K/Akt signaling pathway 24,25. Therefore, in order to clarify whether bortezomib regulates the antitumor effect of chidamide through PI3K/Akt, we examined the expression of total and phosphorylated PI3K and AKT.…”

Inhibition of EZH2 by chidamide exerts antileukemia activity and increases chemosensitivity through Smo/Gli-1 pathway in acute myeloid leukemia

“…Combined inhibition of EZH2 and DNA methylation produces a synergistic antileukemia effects through epigenetic regulation of multiple genes expression [ 54 ]. HDAC inhibitors decrease the expression of EZH2 and DNMT1 and increase hypomethylating agent-mediated apoptosis in human leukemia cells [ 55 – 57 ]. Knockdown of EZH2 expression inhibits histone methyltransferase activity, reduces H3K27me2/3 levels and increases the inhibition of clonogenic survival mediated by HDAC inhibitor in AML cells [ 58 ].…”