Thymoquinone Synergizes With Arsenic and Interferon Alpha to Target Human T-cell leukemia/lymphoma

Life Sci. 2020 Jun 15;251:117639. doi: 10.1016/j.lfs.2020.117639. Epub 2020 Apr 6.


Aims: To reduce the dose of arsenic used against human T-cell leukemia/lymphoma and to sensitize cells to drug treatment, we combined arsenic/interferon-alpha (As/IFN-α) with thymoquinone (TQ) in HTLV-I positive (HuT-102 and C91) and HTLV-1 negative (CEM and Jurkat) cell lines.

Main methods: Cells were treated with TQ, As/IFN-α and combinations. Trypan blue and flow cytometry were used to investigate viability and cell cycle effects. Annexin-V staining, rhodamine assay and western blotting were used to determine apoptosis induction and changes in protein expression. Efficacy of single drugs and combinations were tested in adult T-cell leukemia (HuT-102) mouse xenograft model.

Key findings: TQ/As/IFN-α led to a more pronounced and synergistic time-dependent inhibitory effect on HTLV-I positive cells in comparison to As/IFN-α. While As/IFN-α combination was not effective against CEM or Jurkat cells, the triple combination TQ/As/IFN-α sensitized these two cell lines and led to a pronounced time-dependent inhibition of cell viability. TQ/As/IFN-α significantly induced apoptosis in all four cell lines and disrupted the mitochondrial membrane potential. Apoptosis was confirmed by the cleavage of caspase 3 and poly (ADP-ribose) polymerase (PARP), downregulation of Bcl-2 and XIAP and upregulation of Bax. TQ alone or in combination activated p53 in HTLV-1 positive cell lines. Strikingly, TQ/As/IFN-α resulted in a pronounced significant decrease in tumor volume in HuT-102 xenograft mouse model, as compared to separate treatments or double combination therapy.

Significance: Our results suggest a strong potential for TQ to enhance the drug targeting effects of the standard clinical drugs As and IFN-α against CD4+ malignant T-cells.

Keywords: Combination therapy; Leukemia; Lymphoma; Targeted therapy; Xenograft.

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / administration & dosage
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Apoptosis / drug effects*
  • Arsenic / administration & dosage
  • Benzoquinones / administration & dosage
  • Benzoquinones / pharmacology*
  • Cell Line, Tumor
  • Cell Survival / drug effects*
  • Drug Synergism
  • Human T-lymphotropic virus 1 / isolation & purification
  • Humans
  • Interferon-alpha / administration & dosage
  • Jurkat Cells
  • Leukemia-Lymphoma, Adult T-Cell / drug therapy*
  • Leukemia-Lymphoma, Adult T-Cell / pathology
  • Membrane Potential, Mitochondrial / drug effects
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Time Factors
  • Xenograft Model Antitumor Assays


  • Benzoquinones
  • Interferon-alpha
  • Arsenic
  • thymoquinone