dactolisib and Lymphoma--Large-B-Cell--Diffuse

Activated B cell-like subtype of diffuse large B cell lymphoma (ABC-DLBCL) presents aggressive clinical courses and poor prognosis. Targeting key pathways may raise the possibility of improving clinical outcomes.. The synergetic effects were assessed by CCK-8 assay and measured by isobologram analysis. The NVP-Bez235 and lenalidomide cytotoxicity were measured by flow cytometry, Western Blot and si-RNA transfection. The combined treatment inducing tumor regression in vivo was performed in nude mice of OCI-Ly10 xenograft mouse model.. Low dose of two agents represented significant inhibition of proliferation with CI value < 1. NVP-Bez235 combined with lenalidomide remarkably increased apoptosis through intrinsic pathway by upregulating Bim, Bax and downregulating Bcl-xL. Akt, especially NF-κB, played an important role in the synergetic effects. Cotreatment also induced the cell cycle to be arrested in G0/G1 phase, and decreased S phase by increasing p21 expression, downregulating cyclinA and diminishing CDK2 phosphorylation in Su-DHL2 and OCI-Ly3 but not in OCI-Ly10. Mice treated with NVP-Bez235/lenalidomide represented obvious tumor growth regression and prolonged overall survival.. Our findings demonstrated the synergistic effect of low dose of NVP-Bez235 and lenalidomide in ABC-DLBCL, the underlying mechanism may be multifunctional, involving apoptosis, Akt and NF-κB inactivation and cell cycle arrest. Cotreatment was also effective in vivo. These data pave the way for potential treatment of ABC-DLBCL with combination of NVP-Bez235 and lenalidomide.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Synergism; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Lenalidomide; Lymphoma, Large B-Cell, Diffuse; Mice; Mice, Nude; Phosphatidylinositol 3-Kinases; Quinolines; Thalidomide; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

We demonstrate the synergistic antitumor effect of oridonin and the PI3K/mTOR inhibitor NVP-BEZ235 on the non-germinal center B cell-like subtype of diffuse large B cell lymphoma (non-GCB DLBCL) both in vitro and in vivo. The underlying mechanism may be multifunctional, involving apoptosis, AKT/mTOR and NF-kB inactivation, and ROS-mediated DNA damage response. Our findings pave the way for a new potential treatment option for non-GCB DLBCL with the combination of oridonin and NVP-BEZ235.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; B-Lymphocytes; Cell Line, Tumor; Diterpenes, Kaurane; Drug Synergism; Heterografts; Humans; Imidazoles; Lymphoma, Large B-Cell, Diffuse; Mice; Phosphatidylinositol 3-Kinases; Protein Kinase Inhibitors; Quinolines; TOR Serine-Threonine Kinases

The PI3K/AKT/mTOR axis promotes survival and is a frequently mutated pathway in cancer. Yet, inhibitors targeting this pathway are insufficient to induce cancer cell death as single agents in some contexts, including diffuse large B cell lymphoma (DLBCL). In these situations, combinations with inhibitors targeting BCL-2 survival proteins (ABT-199 and ABT-263) may hold potential. Indeed, studies have demonstrated marked synergy in contexts where PI3K/mTOR inhibitors suppress expression of the pro-survival protein, MCL-1. In this study, we use BH3 profiling to confirm that BCL-2 and BCL-XL support survival following PI3K pathway inhibition, and that the dual PI3K/mTOR inhibitor BEZ235 strongly synergizes with BCL-2 antagonists in DLBCL. However, we identify an alternative mechanism of synergy between PI3K/mTOR and BCL-2 inhibitors, independent of MCL-1 down-regulation. Instead, we show that suppression of AKT activation by BEZ235 can induce the mitochondrial accumulation of pro-apoptotic BAD and BIM, and that expression of a constitutively active form of AKT prevents sensitization to BCL-2 antagonism. Thus, our work identifies an additional mechanism of synergy between PI3K pathway inhibitors and BCL-2 antagonists that strengthens the rationale for testing this combination in DLBCL.

Topics: Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Drug Synergism; Genes, bcl-2; Humans; Imidazoles; Lymphoma, Large B-Cell, Diffuse; Myeloid Cell Leukemia Sequence 1 Protein; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Quinolines; Signal Transduction; TOR Serine-Threonine Kinases

The aim of this study is to explore the efficacy and define mechanisms of action of coadministration of the PI3K/mTOR inhibitor BEZ235 and pan-HDAC inhibitor panobinostat in diffuse large B-cell lymphoma (DLBCL) cells.. Various DLBCL cells were exposed to panobinostat and BEZ235 alone or together after which apoptosis and signaling/survival pathway perturbations were monitored by flow cytometry and Western blot analysis. Genetic strategies defined the functional significance of such changes, and xenograft mouse models were used to assess tumor growth and animal survival.. Panobinostat and BEZ235 interacted synergistically in ABC-, GC-, and double-hit DLBCL cells and MCL cells but not in normal CD34(+) cells. Synergism was associated with pronounced AKT dephosphorylation, GSK3 dephosphorylation/activation, Mcl-1 downregulation, Bim upregulation, increased Bcl-2/Bcl-xL binding, diminished Bax/Bak binding to Bcl-2/Bcl-xL/Mcl-1, increased γH2A.X phosphorylation and histone H3/H4 acetylation, and abrogation of p21(CIP1) induction. BEZ235/panobinostat lethality was not susceptible to stromal/microenvironmental forms of resistance. Genetic strategies confirmed significant functional roles for AKT inactivation, Mcl-1 downregulation, Bim upregulation, and Bax/Bak in synergism. Finally, coadministration of BEZ235 with panobinostat in immunocompromised mice bearing SU-DHL4-derived tumors significantly reduced tumor growth in association with similar signaling changes observed in vitro, and combined treatment increased animal survival compared with single agents.. BEZ235/panobinostat exhibits potent anti-DLBCL activity, including in poor-prognosis ABC- and double-hit subtypes, but not in normal CD34(+) cells. Synergism is most likely multifactorial, involving AKT inactivation/GSK3 activation, Bim upregulation, Mcl-1 downregulation, enhanced DNA damage, and is operative in vivo. Combined PI3K/mTOR and HDAC inhibition warrants further attention in DLBCL.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Cell Line, Tumor; Drug Synergism; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Imidazoles; Immunoblotting; Immunoprecipitation; In Vitro Techniques; Indoles; Lymphoma, Large B-Cell, Diffuse; Membrane Proteins; Mice; Mice, Nude; Myeloid Cell Leukemia Sequence 1 Protein; Panobinostat; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins; Quinolines; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays

Phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling is frequently dysregulated in diffuse large B cell lymphoma (DLBCL) including the favorable germinal centre B-cell (GCB) and the unfavorable activated B-cell (ABC) subtypes. mTOR promotes cap-dependent translation of proteins, like Mcl-1, through inhibitory phosphorylation of the eukaryotic translation initiation factor 4E binding protein 1 (4EBP1). Inhibition of mTOR by RAD001 reduces proliferation but fails to dephosphorylate 4EBP1 and to induce cell death in either DLBCL subtype. In contrast, concurrent inhibition of PI3K and mTOR with NVP-BEZ235 inhibits proliferation, dephosphorylates 4EBP1, and induces cells death, notably more pronounced in CGB cells. Small RNA interference identifies Mcl-1 as a crucial cell death mediator of both DLBCL subtypes. Inhibition of the PI3K/mTOR/4EBP1 by NVP-BEZ235 results in suppression of the cap-dependent translation initiation complex and concomitant downregulation of Mcl-1 in GCB cell lines. In ABC cell lines, this suppression is possibly compensated by NF-κB- or Pim kinase-mediated signaling.

Topics: Adaptor Proteins, Signal Transducing; Cell Cycle Checkpoints; Cell Cycle Proteins; Cell Death; Cell Line, Tumor; Everolimus; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Lymphoma, Large B-Cell, Diffuse; Myeloid Cell Leukemia Sequence 1 Protein; NF-kappa B; Phosphatidylinositol 3-Kinase; Phosphoinositide-3 Kinase Inhibitors; Phosphoproteins; Phosphorylation; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-pim-1; Quinolines; Ribosomal Protein S6 Kinases, 70-kDa; RNA Interference; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases