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BCL2 inhibitor ABT-199 and JNK inhibitor SP600125 exhibit synergistic cytotoxicity against imatinib-resistant Ph+ ALL cells.

ABSTRACT: Imatinib (IMT), a specific tyrosine kinase inhibitor (TKI), has drastically changed the treatment strategy for Ph+ ALL (Philadelphia chromosome-positive acute lymphoblastic leukemia). However, TKI resistance remains a serious problem for patient prognosis. Here, a Ph+ ALL cell line NphA2 and the IMT-resistant subline NphA2/STIR were analyzed to identify a potential novel treatment strategy. We also examined other Ph+ ALL cells, MR87 and its IMT-resistant subline, MR87/STIR. IMT induced apoptosis of NphA2 and MR87 but had no effect on resistant sublines. Increased phosphorylated ERK and BCL2, but not BCL-XL, were observed in NphA2/STIR compared with NphA2. NphA2/STIR but not NphA2 was moderately sensitive to U0126, an ERK inhibitor. Interestingly, SP600125, a JNK inhibitor, was potent in cell growth inhibition and apoptosis induction of both parental and IMT-resistant NphA2 and MR87 cells. Moreover, NphA2 and MR87 and their IMT-resistant sublines were sensitive to ABT-199, a specific BCL2 inhibitor. The combination of SP600125 and ABT-199 synergistically suppressed both parental and IMT-resistant cells, including one with T315I mutation, suggesting that Ph+ ALL exhibits high sensitivity to ABT-199 and SP600125 regardless of TKI resistance. This combination might be a possible therapeutic strategy for Ph+ ALL in the future.

SUBMITTER: Inoue C

PROVIDER: S-EPMC6068087 | biostudies-other | 2018 Sep

REPOSITORIES: biostudies-other

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BCL2 inhibitor ABT-199 and JNK inhibitor SP600125 exhibit synergistic cytotoxicity against imatinib-resistant Ph+ ALL cells.

Inoue Chisato C Sobue Sayaka S Aoyama Yuka Y Mizutani Naoki N Kawamoto Yoshiyuki Y Nishizawa Yuji Y Ichihara Masatoshi M Abe Akihiro A Hayakawa Fumihiko F Suzuki Motoshi M Nozawa Yoshinori Y Murate Takashi T

Biochemistry and biophysics reports 20180713

Imatinib (IMT), a specific tyrosine kinase inhibitor (TKI), has drastically changed the treatment strategy for Ph+ ALL (Philadelphia chromosome-positive acute lymphoblastic leukemia). However, TKI resistance remains a serious problem for patient prognosis. Here, a Ph+ ALL cell line NphA2 and the IMT-resistant subline NphA2/STIR were analyzed to identify a potential novel treatment strategy. We also examined other Ph+ ALL cells, MR87 and its IMT-resistant subline, MR87/STIR. IMT induced apoptosis ...[more]

PMID: 30073206

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Project description:Drug-tolerant “persister” tumor cells underlie the emergence of drug-resistant clones contribute to relapse and disease progression; thus, identifying actionable targets that disable persisters and mitigate relapse are a high priority need. Although the BCL2-targeting agent venetoclax (ABT-199) has shown promising responses in mantle cell and double hit B cell lymphomas, resistance often arises, yet mechanistically how this occurs is unclear. Here we report that ABT-199 resistance can evolve from persister clones that have selective deletions at 18q21 that involve the drug target BCL2 and the apoptotic regulators Noxa (PMAIP1) and TCF4. Notably, reprogramming of super enhancers (SE) in persisters contributes to resistance, where there is a selection for SE-directed overexpression of the apoptotic regulator BCL2A1 and oncogenic transcription factors IKZF1 and FOXC1. At the same time, the SE reprogramming confers an opportunity for overcoming ABT-199 resistance. An unbiased drug screen on a platform that recapitulates the lymphoma microenvironment revealed that persisters are vulnerable to inhibitors of transcription initiation and elongation, and especially so to inhibitors of cyclin-dependent kinase 7 (CDK7) that is essential for transcription initiation. Specifically, CDK7 loss or inhibition eliminated the persister phenotype by disabling SE-driven expression of BCL2A1, IKZF1 and FOXC1. Thus, the co-treatment of ABT-199 with CDK7 inhibitors blocked the evolution of drug resistance, and provoked tumor regression in models of mantle cell lymphoma (MCL) and double hit lymphomas (DHL) that overexpress both MYC and BCL2. Together, these findings establish loss of apoptotic regulators and an adaptive transcriptional response as drug resistance mechanisms in lymphoma, more importantly, establish a rationale for transcription inhibition-based combination strategies to prevent and overcome drug resistance in B cell malignancies toward BCL2 inhibitor.

Project description:Multiple myeloma (MM) remains an incurable disease in need of the development of novel therapeutic agents and drug combinations. ABT-199 is a specific Bcl-2 inhibitor in clinical trials for MM; however, its activity as a single agent was limited to myeloma patients with the t(11;14) translocation who acquire resistance due to co-expression of Mcl-1 and Bcl-xL. These limitations preclude its use in a broader patient population. We have recently found that a sphingosine kinase 2-specific inhibitor (ABC294640) induces apoptosis in primary human CD138+ cells and MM cell lines. ABC294640 is currently in phase I/II clinical trials for myeloma (clinicaltrials.gov: #NCT01410981). Interestingly, ABC294640 down-regulates c-Myc and Mcl-1, but does not have any effects on Bcl-2. We first evaluated the combinatorial anti-myeloma effect of ABC294640 and ABT-199 in vitro in 7 MM cell lines, all of which harbor no t(11;14) translocation. Combination index calculation demonstrated a synergistic anti-myeloma effect of the combination of ABC294640 and ABT-199. This synergistic anti-myeloma effect was maintained even in the presence of bone marrow (BM) stromal cells. The combination of ABC294640 and ABT-199 led to enhanced cleavage of PARP and caspase-3/9 and increased Annexin-V expression, consistent with the induction of apoptosis by the combination treatment. In addition, the combination of ABC294640 and ABT-199 resulted in the down-regulation of the anti-apoptotic proteins Mcl-1, Bcl-2, and Bcl-xL and the cleavage of Bax and Bid. The combination induced both the mitochondrial mediated- and caspase-mediated apoptosis pathways. Finally, the combination of ABC294640 and ABT-199 resulted in augmented anti-myeloma effect in vivo in a mouse xenograft model. These findings demonstrate that the co-administration of ABC294640 and ABT-199 exhibits synergistic anti-myeloma activity in vitro and in vivo, providing justification for a clinical study of this novel combination in patients with relapsed/refractory multiple myeloma.

Dataset Information

BCL2 inhibitor ABT-199 and JNK inhibitor SP600125 exhibit synergistic cytotoxicity against imatinib-resistant Ph+ ALL cells.

Publications

BCL2 inhibitor ABT-199 and JNK inhibitor SP600125 exhibit synergistic cytotoxicity against imatinib-resistant Ph+ ALL cells.

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