Obatoclax Interacts Synergistically with the Irreversible Proteasome Inhibitor Carfilzomib in GC- and ABC-DLBCL Cells In Vitro and In Vivo

Abstract

Interactions between the the irreversible proteasome inhibitor carfilzomib (CFZ) and the pan-BH3 mimetic obatoclax (Obato) were examined in GC- and ABC-DLBCL cells. Co-treatment with minimally toxic concentrations of CFZ (i.e., 2–6 nM) and sub-toxic concentrations of obato (0.05–2.0μM) synergistically increased apoptosis in multiple DLBCL cell lines and increased lethality toward primary human DLBCL but not normal CD34+ cells. Synergistic interactions were associated with sharp increases in caspase-3 activation, PARP cleavage, phospho-JNK induction, up-regulation of Noxa, and AKT dephosphorylation. Combined treatment also diminished CFZ-mediated Mcl-1 up-regulation while immunoprecipitation analysis revealed reduced associations between Bak and Mcl-1/Bcl-xL, and Bim and Mcl-1. The CFZ/Obato regimen triggered translocation, conformational change and dimerization of Bax and activation of Bak. Genetic interruption of JNK and Noxa by shRNA knockdown, ectopic Mcl-1 expression, or enforced activation of AKT significantly attenuated CFZ/Obato-mediated apoptosis. Notably, co-administration of CFZ/Obato sharply increased apoptosis in multiple bortezomib-resistant DLBCL models. Finally, in vivo administration of CFZ and Obato to mice inoculated with SUDHL4 cells substantially suppressed tumor growth, activated JNK, inactivated AKT, and increased survival compared to the effects of single agent treatment. Together, these findings argue that a strategy combining CFZ and Obato warrants attention in DLBCL.

In Vitro and In Vivo Interactions between the HDAC6 Inhibitor Ricolinostat (ACY1215) and the Irreversible Proteasome Inhibitor Carfilzomib in Non-Hodgkin Lymphoma Cells

“…Parallel studies were performed in previously described bortezomib-resistant DLBCL and MCL cells (21, 29, 31). Whereas ricolinostat or CFZ were minimally toxic to SUDHL16-10BR, OCY-LY7-40BR (GC-DLBCL), or Granta-25BR (MCL) cells individually, combined treatment sharply increased cell death (Supplementary Fig 6A).…”

“…In vivo experiment was carried out as described (31) and detail methods are presented in supplementary methods…”

PI3KCA plays a major role in multiple myeloma and its inhibition with BYL719 decreases proliferation, synergizes with other therapies and overcomes stroma-induced resistance

“…Previous studies showed that some bortezomib-resistant cell lines (Kuhn et al, 2009) and patients (Vij et al, 2012) were responsive to carfilzomib. Carfilzomib induced apoptosis by activation of pJNK (Dasmahapatra et al, 2012); in this study we tested the effect of the combination of BYL719 with carfilzomib on the proliferation and apoptosis of MM cells, and found that the drugs synergize through activation of p-JNK and induction of more caspase and PARP cleavage in MM cells.…”

The BH3-mimetic obatoclax reduces HIF-1α levels and HIF-1 transcriptional activity and sensitizes hypoxic colon adenocarcinoma cells to 5-fluorouracil

“…One such agent is obatoclax (OBX), a synthetic indolylprodigiosin derivative that was shown to bind to Bcl-2, Bcl-xL, Bcl-w and Mcl-1 [19][20][21]. Preclinical studies have shown that OBX is effective as a single agent against a broad range of cancer cell lines and xenografts [22] and that it synergizes with a number of cytotoxic and targeted anticancer agents [23][24][25][26][27][28][29]. Clinical activity and tolerability have been assessed in a number of phase I and II trials (clinicaltrials.gov).…”