1. Academic Validation
  2. BCL2 inhibitor ABT-199 and BCL2L1 inhibitor WEHI-539 coordinately promote NOXA-mediated degradation of MCL1 in human leukemia cells

BCL2 inhibitor ABT-199 and BCL2L1 inhibitor WEHI-539 coordinately promote NOXA-mediated degradation of MCL1 in human leukemia cells

  • Chem Biol Interact. 2022 Jul 1;361:109978. doi: 10.1016/j.cbi.2022.109978.
Jing-Ting Chiou 1 Yuan-Chin Lee 1 Liang-Jun Wang 1 Long-Sen Chang 2
Affiliations

Affiliations

  • 1 Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan.
  • 2 Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, 804, Taiwan; Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807, Taiwan. Electronic address: lschang@mail.nsysu.edu.tw.
Abstract

Human leukemia U937 cells that were continuously treated with hydroquinone (HQ) were transformed into U937/HQ cells with increased MCL1 and BCL2L1 expression. Compared with their parental cells, U937/HQ cells were less sensitive to ABT-263 (BCL2/BCL2L1 inhibitor)/ABT-199 (BCL2 inhibitor) cytotoxicity. The combination of WEHI-539 (BCL2L1 inhibitor) with either ABT-199 or ABT-263 showed synergistic cytotoxicity to U937 and U937/HQ cells. Therefore, we further investigated the cytotoxic mechanism induced by the combination of WEHI-539 and ABT-199. The combined treatment of WEHI-539 and ABT-199 induced NOX4/ROS/p38 MAPK axis-mediated Autophagy, which in turn accelerated β-TrCP mRNA turnover. Downregulation of β-TrCP increased Sp1 expression, thereby promoting Sp1-mediated NOXA transcription, which in turn induced NOXA-dependent MCL1 degradation. Enforced expression of MCL1 alleviated the cytotoxicity of WEHI-539 plus ABT-199 to induce the loss of mitochondrial membrane potential and cell viability. WEHI-539 alone induced Sp1/NOXA axis-mediated MCL1 downregulation, while ABT-199 significantly decreased the dose of WEHI-539 by approximately 350- and 50-fold to induce MCL1 suppression in parental and HQ-selected cells, respectively. Furthermore, WEHI-539 sensitized ABT-199-resistant U937 cells to ABT-199 cytotoxicity by inducing NOXA-mediated degradation of MCL1. Collectively, the data in this study indicate that ABT-199 and WEHI-539 cooperatively induce NOXA-dependent MCL1 degradation, and the inhibition of MCL1 mainly explains their combined cytotoxicity in parental, HQ-selected, and ABT-199-resistant U937 cells.

Keywords

Autophagic degradation of β-TrCP mRNA; BCL2/BCL2L1 inhibitors; Leukemia; NOXA-dependent MCL1 degradation; p38 MAPK-mediated autophagy.

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