The BCL-2 selective inhibitor ABT-199 sensitizes soft tissue sarcomas to proteasome inhibition by a concerted mechanism requiring BAX and NOXA

Abstract

Soft tissue sarcomas (STS) are a heterogeneous group of malignancies predominantly affecting children and young adults. Despite improvements in multimodal therapies, 5-year survival rates are only 50% and new treatment options in STS are urgently needed. To develop a rational combination therapy for the treatment of STS we focused on ABT-199 (Venetoclax), a BCL-2 specific BH3-mimetic, in combination with the proteasome inhibitor bortezomib (BZB). Simultaneous inhibition of BCL-2 and the proteasome resulted in strongly synergistic apoptosis induction. Mechanistically, ABT-199 mainly affected the multidomain effector BAX by liberating it from BCL-2 inhibition. The combination with BZB additionally resulted in the accumulation of BOK, a BAX/BAK homologue, and of the BH3-only protein NOXA, which inhibits the anti-apoptotic protein MCL-1. Thus, the combination of ABT-199 and BZB sensitizes STS cells to apoptosis by simultaneously releasing several defined apoptotic restraints. This synergistic mechanism of action was verified by CRISPR/Cas9 knockout , showing that both BAX and NOXA are crucial for ABT-199/BZB-induced apoptosis. Noteworthy, efficient induction of apoptosis by ABT-199/BZB was not affected by the p53 status and invariably detected in cell lines and patient-derived tumor cells of several sarcoma types, including rhabdomyo-, leiomyo-, lipo-, chondro-, osteo-, or synovial sarcomas. Hence, we propose the combination of ABT-199 and BZB as a promising strategy for the treatment of STS, which should warrant further clinical investigation.

Sorafenib, rapamycin, and venetoclax attenuate doxorubicin-induced senescence and promote apoptosis in HCT116 cells

“…Again, this suggests that venetoclax has limited cytotoxicity when given alone against proliferating colon cancer cells, despite targeting the antiapoptotic protein BCL-2. This phenomenon has been observed in several cancer cell lines, including HCT116 ( Ko et al, 2014 , Muenchow et al, 2020 , Shi et al, 2021 , Zhou et al, 2018 ). An extrinsic factor, such as chemotherapy treatment, that stimulates apoptosis might be required.…”

The BCL-2 inhibitor ABT-199/venetoclax synergizes with proteasome inhibition via transactivation of the MCL-1 antagonist NOXA

“…To investigate whether the synergistic cell death induction by ABT-199 and bortezomib [ 26 ] is specific to BTZ or class specific, we combined ABT-199 with the clinically relevant PIs carfilzomib (CFZ) and ixazomib (IXZ) and analyzed cell death in SW982/WT, SW982/BAX KO and SW982/BAK KO soft tissue sarcoma cell lines [ 26 ]. Cells were incubated with 5 nM BTZ, CFZ and IXZ alone and in combination with ABT-199.…”

“…Reduced efficacy of IXZ may result from the lowest inhibitory activity for the chymotrypsin-like β 5 activity, but might also result from biological availability or stability. Regardless of PI efficacy, knock-down of PMAIP1 confirms that NOXA is a key mediator of synergistically induced apoptosis by ABT-199&PIs [ 26 ].…”

“…We recently found that BTZ synergizes with the BH3-mimetic ABT-199 to induce apoptosis in various soft tissue sarcoma cells and cell lines. The synergistic activity of ABT-199&BTZ depends on BAX and the MCL-1 antagonist NOXA [ 26 ]. In continuation of this work, we show here that ABT-199 transactivates PMAIP1/ NOXA proposedly via stress-induced ATF4 with concomitant induction of ATF3 and thereby synergizes with clinically relevant PIs to overcome resistance and induce cell death.…”

Progress on the Application of Bortezomib and Bortezomib-Based Nanoformulations

“…The UPS pathway is the key pathway through which proteasome inhibitors exert their pharmacological effects. Proteasome inhibitors work by blocking the UPS, which is closely related to the degradation of caspase, the blockage of the nuclear factor-kappa B (NF-κB) signal pathway, the regulation of B-cell lymphoma-2 (Bcl-2) protein, the promotion of the expression of tumor suppressor genes, etc., [ 28 , 29 , 30 , 31 , 32 , 33 ].…”