Combinatorial Ixazomib and Belinostat Therapy Induce Nuclear Factor Erythroid 2-Related Factor 2 (NRF2)-Dependent Apoptosis in Hodgkin and T-cell Lymphoma
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ABSTRACT: Ixazomib has documented pre-clinical activity in T cell (TCL) and Hodgkin (HL) lymphoma models with transcriptomic analyses predicting synergistic activity in combination with histone deacetylase (HDAC) inhibition. In the present study, we determined the mechanistic basis for synergism with ixazomib in combination with the HDAC inhibitor, belinostat, in HL and TCL cells lines (ixazomib-sensitive and -resistant clones) and primary tumor cells. In ixazomib-treated TCL and HL cells, we observed induction of proteasomal gene expression and NRF2 as a prominent upstream regulator. Ixazomib treatment in TCL and HL cells resulted in transient inhibition followed by full recovery of proteasomal activity within 72 hours. Furthermore, transcriptomic analysis following belinostat treatment resulted in downregulation of both NRF2 and proteasomal gene expression (validated by qPCR) without direct impact on proteasomal activity in Jurkat and L428. In addition, CRISPR/Cas9 mediated knockdown of NRF2 in Jurkat cells resulted in a significant decrease in cell viability with ixazomib compared with untreated control cells. Using transcriptomic and proteosomal activity evaluation of ixazomib, belinostat or ixazomib+belinostat treated cells, we observed that NRF-2, proteasome gene expression and functional recovery were abrogated by the combination. We also confirmed that ixazomib/belinostat resulted in synergistic activity in ixazomib-sensitive and -resistant cell lines and primary cells. Altogether, these results suggest that the synergistic activity of ixazomib and belinostat is mediated via inhibition NRF2-dependent proteasomal recovery and extended proteasomal inhibition culminating in increased cell death. Further investigation is warranted to determine the full biological role for NRF2 as a response modifier in proteasomal targeted therapies.
ORGANISM(S): Homo sapiens
PROVIDER: GSE126768 | GEO | 2019/04/01
REPOSITORIES: GEO
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