nitrophenols and Lymphoma--B-Cell

B-cell lymphoma 2 (Bcl-2) is a regulator protein involved in apoptosis. In the past few decades, this protein has been demonstrated to have high efficacy in cancer therapy, and several approaches targeting Bcl-2 have been tested clinically (e.g., oblimersen, ABT-737, ABT-263, obatoclax mesylate, and AT-101). This review reports potential Bcl-2 inhibitors according to current information on their underlying mechanism and the results of clinical trials. In addition, the function and mechanisms of other potentially valuable Bcl-2 inhibitors that did not show efficacy in clinical studies are also discussed. This summary of the development of Bcl-2 inhibitors provides worthwhile viewpoints on the use of biomedical approaches in future cancer therapy.

Topics: Aniline Compounds; Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Cell Line, Tumor; Gossypol; Humans; Lymphoma, B-Cell; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Thionucleotides

Caloric restriction (CR) is proposed to decrease tumorigenesis through a variety of mechanisms including effects on glycolysis. However, the understanding of how CR affects the response to cancer therapy is still rudimentary. Here, using the Eµ-Myc transgenic mouse model of B-cell lymphoma, we report that by reducing protein translation, CR can reduce expression of the prosurvival Bcl-2 family member Mcl-1 and sensitize lymphomas to ABT-737-induced death in vivo. By using Eµ-Myc lymphoma cells lacking p53, we showed that CR mimetics such as 2-deoxyglucose led to a decrease in Mcl-1 expression and sensitized lymphoma cells to ABT-737-induced death independently of p53. In keeping with this, Eµ-Myc lymphoma cells lacking the BH3-only proapoptotic members Noxa, Puma, or Bim were also sensitized by CR mimetics to ABT-737-induced death. Remarkably, neither the loss of both Puma and Noxa, the loss of both Puma and Bim, nor the loss of all three BH3-only proteins prevented sensitization to ABT-737 induced by CR mimetics. Thus, CR can influence Mcl-1 expression and sensitize cells to BH3 mimetic-induced apoptosis, independently of the main BH3-only proteins and of p53. Exploiting this may improve the efficiency of, or prevent resistance to, cancer therapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; BH3 Interacting Domain Death Agonist Protein; Biphenyl Compounds; Caloric Restriction; Disease Models, Animal; Drug Resistance, Neoplasm; Lymphoma, B-Cell; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Myeloid Cell Leukemia Sequence 1 Protein; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Sulfonamides

As many oncogenic changes, such as Myc overexpression, promote apoptosis, the survival of emerging neoplastic clones may often initially depend upon endogenous levels of particular pro-survival members of the Bcl-2 protein family. Pertinently, we recently showed that in lymphoma-prone Eμ-myc transgenic mice, which overexpress Myc in all B-lymphoid cells, endogenous Bcl-x(L) is critical for the survival, as well as the expansion of preneoplastic B-lymphoid cells and the development of malignant disease. This discovery raised the possibility that pharmacological blockade of Bcl-x(L) might impede Myc-driven lymphoma development. Indeed, we report here that treatment of preleukaemic Eμ-myc transgenic mice with the Bcl-2 homology (BH)3 mimetic drug ABT-737, which inhibits Bcl-x(L), as well as Bcl-2 and Bcl-w, augmented apoptosis of preneoplastic B-lymphoid cells, reduced their numbers and greatly prolonged lymphoma-free survival. These findings reveal that BH3 mimetic drugs may provide a prophylactic strategy to prevent the development of certain tumours, particularly those driven by deregulated Myc expression. Moreover, such treatment may help in the management of patients with hereditary cancer syndromes and perhaps also in the prevention of tumour relapses.

Topics: Animals; Apoptosis; Biphenyl Compounds; Female; Hematopoiesis; Lymphoma, B-Cell; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Sulfonamides

Targeting altered cancer cell metabolism with the glycolysis inhibitor, 2-deoxyglucose (2DG), is a viable therapeutic strategy, but the effects of 2DG on lymphoma cells and the mechanism of action are unknown. Five T-cell lymphoma lines and two B-cell lymphoma lines were shown to be highly sensitive to 2DG. Examination of the cell death pathway demonstrated pro-apoptotic protein Bax 'activation' and caspase cleavage in 2DG-treated cells. However, Q-VD-OPh, a potent inhibitor of caspase activity provided minimal protection from death. In contrast, overexpressing the anti-apoptotic protein Bcl-2 dramatically enhanced the survival of 2DG-treated cells that was negated by a Bcl-2 antagonist. BH3-only members, Bim and Bmf, were upregulated by 2DG, and shRNAs targeting Bim protected from 2DG toxicity demonstrating that Bim is a critical mediator of 2DG toxicity. 2DG also induced GADD153/CHOP expression, a marker of endoplasmic reticulum (ER) stress and a known activator of Bim. Mannose, a reagent known to alleviate ER stress, transiently protected from 2DG-induced cell death. Examination of the effects of 2DG on energy metabolism showed a drop in ATP levels by 30 min that was not affected by either Bcl-2 or mannose. These results demonstrate that ER stress appears to be rate limiting in 2DG-induced cell death in lymphoma cells, and this cell killing is regulated by the Bcl-2 family of proteins. Bcl-2 inhibition combined with 2DG may be an effective therapeutic strategy for lymphoma.

Topics: Animals; Antimetabolites; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; bcl-2-Associated X Protein; Bcl-2-Like Protein 11; Biphenyl Compounds; Blotting, Western; Caspases; Cell Proliferation; Cells, Cultured; Deoxyglucose; Flow Cytometry; Immunoprecipitation; Lymphoma, B-Cell; Lymphoma, T-Cell; Membrane Proteins; Mice; Mice, Inbred C57BL; Nitrophenols; Piperazines; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulfonamides; Thymocytes

Cells that exhibit an absolute dependence on the anti-apoptotic BCL-2 protein for survival are termed "primed for death" and are killed by the BCL-2 antagonist ABT-737. Many cancers exhibit a primed phenotype, including some that are resistant to conventional chemotherapy due to high BCL-2 expression. We show here that 1) stable BCL-2 overexpression alone can induce a primed for death state and 2) that an ABT-737-induced loss of functional cytochrome c from the electron transport chain causes a reduction in maximal respiration that is readily detectable by microplate-based respirometry. Stable BCL-2 overexpression sensitized non-tumorigenic MCF10A mammary epithelial cells to ABT-737-induced caspase-dependent apoptosis. Mitochondria within permeabilized BCL-2 overexpressing cells were selectively vulnerable to ABT-737-induced cytochrome c release compared to those from control-transfected cells, consistent with a primed state. ABT-737 treatment caused a dose-dependent impairment of maximal O(2) consumption in MCF10A BCL-2 overexpressing cells but not in control-transfected cells or in immortalized mouse embryonic fibroblasts lacking both BAX and BAK. This impairment was rescued by delivering exogenous cytochrome c to mitochondria via saponin-mediated plasma membrane permeabilization. An ABT-737-induced reduction in maximal O(2) consumption was also detectable in SP53, JeKo-1, and WEHI-231 B-cell lymphoma cell lines, with sensitivity correlating with BCL-2:MCL-1 ratio and with susceptibility (SP53 and JeKo-1) or resistance (WEHI-231) to ABT-737-induced apoptosis. Multiplexing respirometry assays to ELISA-based determination of cytochrome c redistribution confirmed that respiratory inhibition was associated with cytochrome c release. In summary, cell-based respiration assays were able to rapidly identify a primed for death state in cells with either artificially overexpressed or high endogenous BCL-2. Rapid detection of a primed for death state in individual cancers by "bioenergetics-based profiling" may eventually help identify the subset of patients with chemoresistant but primed tumors who can benefit from treatment that incorporates a BCL-2 antagonist.

Topics: Aniline Compounds; Animals; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Biphenyl Compounds; Cell Death; Cell Line; Cell Line, Tumor; Cell Respiration; Cytochromes c; Cytological Techniques; Energy Metabolism; Humans; Lymphoma, B-Cell; Mice; Mitochondria; Models, Biological; Nitrophenols; Oxygen Consumption; Phenotype; Piperazines; Proto-Oncogene Proteins c-bcl-2; Rats; Sulfonamides

We report the synthesis and in vitro evaluation of a multivalent homing device, a polymer which contains preordered pendant groups with dual specificity, a trisaccharide moiety, which is specific for the siglec CD22, and an antibody specific hapten, nitrophenol. The device efficiently attracts antihapten IgM to the surface of human lymphoma B cells as well as to CD22-conjugated magnetic beads by mediating the formation of a ternary complex on the surface of the target.

Topics: Antigen-Antibody Complex; Cell Membrane; Haptens; Humans; Immunoglobulin M; Ligands; Lymphoma, B-Cell; Macromolecular Substances; Magnetics; Microspheres; Nitrophenols; Sialic Acid Binding Ig-like Lectin 2; Surface Properties

The chimeric monoclonal antibody rituximab is the standard of care for patients with B-cell non-Hodgkin lymphoma (B-NHL). Rituximab mediates complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity of CD20-positive human B cells. In addition, rituximab sensitizes B-NHL cells to cytotoxic chemotherapy and has direct apoptotic and antiproliferative effects. Whereas expression of the CD20 antigen is a natural prerequisite for rituximab sensitivity, cell-autonomous factors determining the response of B-NHL to rituximab are less defined. To this end, we have studied rituximab-induced apoptosis in human B-NHL models. We find that rituximab directly triggers apoptosis via the mitochondrial pathway of caspase activation. Expression of antiapoptotic Bcl-xL confers resistance against rituximab-induced apoptosis in vitro and rituximab treatment of xenografted B-NHL in vivo. B-NHL cells insensitive to rituximab-induced apoptosis exhibit increased endogenous expression of multiple antiapoptotic Bcl-2 family proteins, or activation of phosphatidylinositol-3-kinase signaling resulting in up-regulation of Mcl-1. The former resistance pattern is overcome by treatment with the BH3-mimetic ABT-737, the latter by combining rituximab with pharmacologic phosphatidylinositol-3-kinase inhibitors. In conclusion, sensitivity of B-NHL cells to rituximab-induced apoptosis is determined at the level of mitochondria. Pharmacologic modulation of Bcl-2 family proteins or their upstream regulators is a promising strategy to overcome rituximab resistance.

Topics: Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Murine-Derived; Antigens, CD20; Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Humans; Lymphoma, B-Cell; Mice; Mice, SCID; Myeloid Cell Leukemia Sequence 1 Protein; Neoplasm Transplantation; Nitrophenols; Phosphatidylinositol 3-Kinases; Piperazines; Proto-Oncogene Proteins c-bcl-2; Rituximab; Signal Transduction; Sulfonamides

Cancer cells exhibit many abnormal phenotypes that induce apoptotic signaling via the intrinsic, or mitochondrial, pathway. That cancer cells nonetheless survive implies that they select for blocks in apoptosis. Identifying cancer-specific apoptotic blocks is necessary to rationally target them. Using a panel of 18 lymphoma cell lines, we show that a strategy we have developed, BH3 profiling, can identify apoptotic defects in cancer cells and separate them into three main classes based on position in the apoptotic pathway. BH3 profiling identifies cells that require BCL-2 for survival and predicts sensitivity to the BCL-2 antagonist ABT-737. BCL-2 dependence correlates with high levels of proapoptotic BIM sequestered by BCL-2. Strikingly, BH3 profiling can also predict sensitivity to conventional chemotherapeutic agents like etoposide, vincristine, and adriamycin.

Topics: Antibiotics, Antineoplastic; Antineoplastic Agents, Phytogenic; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; BH3 Interacting Domain Death Agonist Protein; Biphenyl Compounds; Blotting, Western; Doxorubicin; Etoposide; Humans; Immunoblotting; Immunoprecipitation; Lymphoma, B-Cell; Lymphoma, Large B-Cell, Diffuse; Membrane Proteins; Nitrophenols; Piperazines; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Sulfonamides; Tumor Cells, Cultured; Vincristine