Purpose: To investigate the roles of BCL2, MCL1, and BCL-XL in the survival of diffuse large B-cell lymphoma (DLBCL).Experimental designs: Immunohistochemical analysis of 105 primary DLBCL samples, and Western blot analysis of 18 DLBCL cell lines for the expression of BCL2, MCL1, and BCL-XL. Pharmacologic targeting of BCL2, MCL1, and BCL-XL with ABT-199, homoharringtonine (HHT), and ABT-737. Analysis of DLBCL clones with manipulated expressions of BCL2, MCL1, and BCL-XL. Immunoprecipitation of MCL1 complexes in selected DLBCL cell lines. Experimental therapy aimed at inhibition of BCL2 and MCL1 using ABT-199 and HHT, single agent, or in combination, in vitro and in vivo on primary cell-based murine xenograft models of DLBCL.Results: By the pharmacologic targeting of BCL2, MCL1, and BCL-XL, we demonstrated that DLBCL can be divided into BCL2-dependent and MCL1-dependent subgroups with a less pronounced role left for BCL-XL. Derived DLBCL clones with manipulated expressions of BCL2, MCL1, and BCL-XL, as well as the immunoprecipitation experiments, which analyzed MCL1 protein complexes, confirmed these findings at the molecular level. We demonstrated that concurrent inhibition of BCL2 and MCL1 with ABT-199 and HHT induced significant synthetic lethality in most BCL2-expressing DLBCL cell lines. The marked cytotoxic synergy between ABT-199 and HHT was also confirmed in vivo using primary cell-based murine xenograft models of DLBCL.Conclusions: As homoharringtonine is a clinically approved antileukemia drug, and ABT-199 is in advanced phases of diverse clinical trials, our data might have direct implications for novel concepts of early clinical trials in patients with aggressive DLBCL.
Purpose: Mantle cell lymphoma (MCL) is an aggressive subtype of B-cell non-Hodgkin lymphomas characterized by (over)expression of BCL2. A BCL2-targeting drug, venetoclax, has promising anticancer activity in MCL. We analyzed molecular mechanisms of venetoclax resistance in MCL cells and tested strategies to overcome it. Experimental Design: We confirmed key roles of proapoptotic proteins BIM and NOXA in mediating venetoclaxinduced cell death in MCL. Both BIM and NOXA are, however, differentially expressed in cell lines compared with primary cells. First, NOXA protein is significantly overexpressed in most MCL cell lines. Second, deletions of BIM gene harbored by three commonly used MCL cell lines (JEKO-1, MINO, and Z138) were not found by array comparative genomic hybridization using a validation set of 24 primary MCL samples. Results: We demonstrated that MCL1 andNOXA playimportant roles in mediating resistance to venetoclax. Consequently, we tested an experimental treatment strategy based on cotargeting BCL2 with venetoclax and MCL1 with a highly specific small-molecule MCL1 inhibitor S63845. The combination of venetoclax and S63845 demonstrated synthetic lethality in vivo on a panel of five patient-derived xenografts established from patients with relapsed MCL with adverse cytogenetics. Conclusions: Our data strongly support investigation of venetoclax in combination with S63845 as an innovative treatment strategy for chemoresistant MCL patients with adverse cytogenetics in the clinical grounds.
Tumor immunotherapy based on the use of chimeric antigen receptor modified T cells (CAR T cells) is a promising approach for the treatment of refractory hematological malignancies. However, a robust response mediated by CAR T cells is observed only in a minority of patients and the expansion and persistence of CAR T cells in vivo is mostly unpredictable.Lenalidomide (LEN) is an immunomodulatory drug currently approved for the treatment of multiple myeloma (MM) and mantle cell lymphoma, while it is clinically tested in the therapy of diffuse large B-cell lymphoma of activated B cell immunophenotype. LEN was shown to increase antitumor immune responses at least partially by modulating the activity of E3 ubiquitin ligase Cereblon, which leads to increased ubiquitinylation of Ikaros and Aiolos transcription factors, which in turn results in changed expression of various receptors on the surface of tumor cells. In order to enhance the effectiveness of CAR-based immunotherapy, we assessed the anti-lymphoma efficacy of LEN in combination with CAR19 T cells or CAR20 T cells in vitro and in vivo using various murine models of aggressive B-cell non-Hodgkin lymphomas (B-NHL).Immunodeficient NSG mice were transplanted with various human B-NHL cells followed by treatment with CAR19 or CAR20 T cells with or without LEN. Next, CAR19 T cells were subjected to series of tests in vitro to evaluate their response and signaling capacity following recognition of B cell in the presence or absence of LEN.Our data shows that LEN significantly enhances antitumor functions of CAR19 and CAR20 T cells in vivo. Additionally, it enhances production of interferon gamma by CAR19 T cells and augments cell signaling via CAR19 protein in T cells in vitro. Our data further suggests that LEN works through direct effects on T cells but not on B-NHL cells. The biochemical events underlying this costimulatory effect of LEN are currently being investigated. In summary, our data supports the use of LEN for augmentation of CAR-based immunotherapy in the clinical grounds.
Gene deregulation is a frequent cause of malignant transformation. Alteration of the gene structure and/or expression leading to cellular transformation and tumor growth can be experimentally achieved by insertion of the retroviral genome into the host DNA. Retrovirus-containing host loci found repeatedly in clonal tumors are called common viral integration sites (cVIS). cVIS are located in genes or chromosomal regions whose alterations participate in cellular transformation. Here, we present the chicken model for the identification of oncogenes and tumor suppressor genes in solid tumors by mapping the cVIS. Using the combination of inverse PCR and long terminal repeat-rapid amplification of cDNA ends technique, we have analyzed 93 myeloblastosisassociated virus type 2-induced clonal nephroblastoma tumors in detail, and mapped >500 independent retroviral integration sites. Eighteen genomic loci were hit repeatedly and thus classified as cVIS, five of these genomic loci have previously been shown to be involved in malignant transformation of different human cell types. The expression levels of selected genes and their human orthologues have been assayed in chicken and selected human renal tumor samples, and their possible correlation with tumor development, has been suggested. We have found that genes associated with cVIS are frequently, but not in all cases, deregulated at the mRNA level as a result of proviral integration. Furthermore, the deregulation of their human orthologues has been observed in the samples of human pediatric renal tumors. Thus, the avian nephroblastoma is a valid source of cancerassociated genes. Moreover, the results bring deeper insight into the molecular background of tumorigenesis in distant species. (Cancer Res 2006; 66(1): 78-86)
Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma (NHL) associated with poor prognosis. Animal models of MCL are scarce. We established and characterized various in vivo models of metastatic human MCL by tail vein injection of either primary cells isolated from patients with MCL or established MCL cell lines (Jeko-1, Mino, Rec-1, Hbl-2, and Granta-519) into immunodeficient NOD.Cg-Prkdc scid Il2rg tm1Wjl /SzJ mice. MCL infiltration was assessed with immunohistochemistry (tissues) and flow cytometry (peripheral blood). Engraftment of primary MCL cells was observed in 7 out of 12 patient samples. The pattern of engraftment of primary MCL cells varied from isolated involvement of the spleen to multiorgan infiltration. On the other hand, tumor engraftment was achieved in all five MCL cell lines used and lymphoma involvement of murine bone marrow, spleen, liver, and brain was observed. Overall survival of xenografted mice ranged from 22±1 to 54±3 days depending on the cell line used. Subsequently, we compared the gene expression profile (GEP) and phenotype of the engrafted MCL cells compared with the original in vitro growing cell lines (controls). We demonstrated that engrafted MCL cells displayed complex changes of GEP, protein expression, and sensitivity to cytotoxic agents when compared with controls. We further demonstrated that our MCL mouse models could be used to test the therapeutic activity of systemic chemotherapy, monoclonal antibodies, or angiogenesis inhibitors. The characterization of MCL murine models is likely to aid in improving our knowledge in the disease biology and to assist scientists in the preclinical and clinical development of novel agents in relapsed/refractory MCL patients. Mantle cell lymphoma (MCL) is an aggressive type of B-cell non-Hodgkin lymphoma (NHL) characterized by the chromosomal translocation t(11;14)(q13;q32) leading to overexpression of cyclin D1. 1 Apart from this canonical aberration, MCL may harbor a large number of recurrent cytogenetic changes that further deregulate cell cycle machinery (for example, deletion of 9p21 (CDKN2A) and amplification of 12q13 (CDK4)) or interfere with cellular response to DNA damage (for example, alterations of 11q22-q23 (ATM), 17p13 (TP53) and overexpression of MDM2). 2-5 MCL is associated with poor prognosis. 6,7 In order to improve the outcome of MCL patients, the rational development and preclinical/clinical testing of new agents are necessary. Reliable and reproducible in vivo models of MCL are thus urgently needed. In vivo models have several advantages over in vitro approaches. For example, they enable the study of MCL biology in its microenvironment, including engraftment, growth rate, spread patterns, or tumor associated neovascularization.
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