This work led to the discovery of <b>1</b>, a potent Mcl-1 inhibitor (IC<sub>50</sub> = 19 nM in an OPM-2 cell viability assay) with good pharmacokinetic properties and excellent in vivo efficacy in an OPM-2 multiple myeloma xenograft model.
Co-culture experiments resulted in MDSC-induced AMPK phosphorylation in MM cells, which was associated with an increase in the anti-apoptotic factors MCL-1 and BCL-2, and the autophagy-marker LC3II.
In myeloma, in vitro sensitivity to venetoclax is mainly observed in plasma cells harboring the t(11;14) translocation, a molecular subgroup associated with high Bcl-2 and low Mcl-1/Bcl-XL expression.
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.
Our studies demonstrate that AZD5991 binds directly to Mcl-1 and induces rapid apoptosis in cancer cells, most notably myeloma and acute myeloid leukemia, by activating the Bak-dependent mitochondrial apoptotic pathway.
Members of MCL1-M captured both MM cell-intrinsically acting signals and the signals regulating the interaction between MM cells with bone marrow microenvironment.
In conclusion, the NEAT1/miR-193a/MCL1 pathway is closely associated with the development of DEX resistance in myeloma cells, and knockdown of NEAT1 can significantly improve DEX sensitivity in MM.
We used the Bcl-2/Bcl-x<sub>L</sub> inhibitor ABT-737 to study the factors regulating whether myeloma is Mcl-1 dependent, and thus resistant to ABT-737-induced apoptosis, or Bcl-2/Bcl-x<sub>L</sub> codependent, and thus sensitive to ABT-737.
Mcl-1 was up-regulated in all MM lines tested, including bortezomib-resistant lines, human MM xenograft mouse models, and primary CD138<sup>+</sup> MM cells.
Venetoclax is a selective, orally bioavailable BCL-2 inhibitor that induces cell death in multiple myeloma (MM) cells, particularly in those harboring t(11;14), which express high levels of BCL-2 relative to BCL-X<sub>L</sub> and MCL-1.
We show that our lead compound (compound 20) decreases glucose uptake and cell proliferation as well as inhibits the expression of pro-survival MCL-1 in MM similar to the effect observed via knockdown of GLUT4 expression.
IHC of multiple myeloma patient bone marrow biopsies and aspirates (n = 95) revealed high levels of BCL-2 and BCL-XL in 62% and 43% of evaluable samples, respectively, while 34% were characterized as BCL-2(High)/BCL-XL (Low) In addition to MCL-1, our data suggest that BCL-XL may also be a potential resistance factor to venetoclax monotherapy and in combination with bortezomib.
In conclusion, our data demonstrate that soluble factors from MM cells are able to generate MDSC through Mcl-1 upregulation and this cell population can be considered as a possible target in MM disease.
Ritonavir and metformin effectively suppressed AKT and mTORC1 phosphorylation and prosurvival BCL-2 family member MCL-1 expression in multiple myeloma cell lines in vitro and in vivo.
Furthermore, previous studies demonstrated that proteasome inhibitors induce Mcl-1 accumulation that, in turn, slows down their pro-apoptotic effects, and the cell survival in multiple myeloma is highly dependent on Mcl-1.