Thymoquinone and Difluoromethylornithine (DFMO) Synergistically Induce Apoptosis of Human Acute T Lymphoblastic Leukemia Jurkat Cells Through the Modulation of Epigenetic Pathways

Abstract

Thymoquinone (TQ), a natural anticancer agent exerts cytotoxic effects on several tumors by targeting multiple pathways, including apoptosis. Difluoromethylornithine (DFMO), an irreversible inhibitor of the ornithine decarboxylase (ODC) enzyme, has shown promising inhibitory activities in many cancers including leukemia by decreasing the biosynthesis of the intracellular polyamines. The present study aimed to investigate the combinatorial cytotoxic effects of TQ and DFMO on human acute T lymphoblastic leukemia Jurkat cells and to determine the underlying mechanisms. Here, we show that the combination of DFMO and TQ significantly reduced cell viability and resulted in significant synergistic effects on apoptosis when compared to either DFMO or TQ alone. RNA-sequencing showed that many key epigenetic players including Ubiquitin-like containing PHD and Ring finger 1 (UHRF1) and its 2 partners DNA methyltransferase 1 (DNMT1) and histone deacetylase 1 (HDAC1) were down-regulated in DFMO-treated Jurkat cells. The combination of DFMO and TQ dramatically decreased the expression of UHRF1, DNMT1 and HDAC1 genes compared to either DFMO or TQ alone. UHRF1 knockdown led to a decrease in Jurkat cell viability. In conclusion, these results suggest that the combination of DFMO and TQ could be a promising new strategy for the treatment of human acute T lymphoblastic leukemia by targeting the epigenetic code.

Thymoquinone Is a Multitarget Single Epidrug That Inhibits the UHRF1 Protein Complex

“…UHRF1 has been reported to be a target of several natural compounds or derivatives that exhibit anticancer properties by downregulating UHRF1. These compounds include TQ [ 11 , 12 , 23 , 60 , 61 , 62 , 63 ], curcumin [ 134 ], epigallocatechin-3-gallate [ 24 , 135 ], anisomycin [ 136 ], dihydroartemisinin [ 40 ], emodin [ 137 ], hinokitiol [ 33 ], shikonin [ 138 ], and luteolin [ 139 , 140 ], which can all upregulate many TSGs. Of these natural products, epigallocatechin-3-gallate and TQ have been shown to specifically target the SRA and RING domains of UHRF1, respectively.…”

“…Of particular interest to this review is that several studies have now shown that TQ can target the epigenetic reader UHRF1 as well as its partners, the epigenetic writers (DNMT1 and G9A) and erasers like HDAC1 [ 23 , 60 , 61 , 62 , 63 , 64 , 65 , 66 ] ( Table 1 ).…”

Targeting Post-Translational Modifications of the p73 Protein: A Promising Therapeutic Strategy for Tumors

“…We and others have shown that thymoquinone (TQ), the bioactive compound of black seed oil, has inhibitory effects on several cancers through the targeting of several signaling pathways [ 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 , 159 ], including the reactivation of the p73 protein in p53-mutated tumors [ 136 , 160 , 161 ]. Recently, TQ was proposed to increase the expression of the p73 protein in a p53-mutant acute lymphoblastic leukemia cell line (Jurkat cells) by targeting the expression of various E3 ubiquitin ligases for p73, including Itch, Mdm2, FBXO45, and TRIM32 [ 62 ].…”

The First Insight Into the Supramolecular System of D,L-α-Difluoromethylornithine: A New Antiviral Perspective

“…Firstly, it was approved by FDA in the treatment of human African trypanosomiasis (sleeping sickness) (ornidyl1, United States) ( Pepin et al, 1987 ), as a hair growth retardant in female facial hisrutism (Vaniqa; Allergan, Irvine, CA, United States) ( U.S. National Library of Medicine, 2021 ; Wolf et al, 2007 ). Notably, DFMO has a significant and promising inhibitory effect on diverse cancers, such as leukemia ( Bacchi et al, 1980 ; Xie et al, 2008 ; Casero and Woster, 2009 ; Alhosin et al, 2020 ), skin cancer ( Elmets and Athar, 2010 ), breast cancer ( Xu et al, 2008 ), prostate cancer ( Arisan et al, 2014 ) and pancreatic cancer ( Mohammed et al, 2014 ), cervical, small-cell lung cancer and melanoma ( Levin and Ellingson, 2018 ; Levin et al, 2018 ), gastric cancer ( Aziz et al, 2020 ), colorectal cancer ( Gutierrrez et al, 2019 ), neuroblastoma ( Lewis et al, 2020 ), glial tumors, such as malignant gliomas ( Levin et al, 2018 ), either as a single or in combination therapy ( Wallace and Fraser, 2004 ). DFMO has anabolic, wound-healing and immuno-enhancing actions.…”

“…The L -enantiomer of DFMO is 20-times more likely to form an enzyme–inhibitor complex than the D -form ( Qu et al, 2003 ), but the D -form is suggested as less toxic ( Levenson and Shaked, 2003 ). In order to overcome limitations, structural modifications and/or a combination therapy with other drugs is recommended to achieve optimal treatment outcomes ( Creaven et al, 1993 ; Alexiou et al, 2017 ; Li et al, 2019 ; Alhosin et al, 2020 ).…”