nitrophenols and Cell-Transformation--Neoplastic

Numerous data indicate that defects in apoptotic signaling pathways contribute to the development of cancer and to therapy resistance in many types of malignant tumors. Defective apoptotic cell death is not only a significant cause of cancer, but also increases tumor resistance to chemo- and radiotherapy. Therefore, there is an urgent need to elucidate the molecular basis of apoptosis resistance and to develop novel strategies to overcome this resistance. One important task is the identification of those anti-apoptotic proteins that render tumor cells resistant to therapy and to investigate how these resistance mechanisms can be regulated on a cellular and molecular level. Based on these findings, novel strategies to sensitize cancer cells to cell death induction can be developed. Moreover, the expression profiles of several apoptosis-regulating proteins can be used as prognostic factors in patients with diverse types of cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Cell Line, Tumor; Cell Survival; Cell Transformation, Neoplastic; Drug Resistance, Neoplasm; Humans; Neoplasms; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Receptors, Death Domain; Signal Transduction; Sulfonamides; TNF-Related Apoptosis-Inducing Ligand

Over the past 10 years evidence has been accumulating that antitumour agents induce apoptosis in cancer cells and that abnormalities in apoptosis signaling pathways often occur in cancer cells and are associated with drug resistance. The implication is that factors regulating the apoptotic process play a critical role in tumour sensitivity to chemotherapy, and hence may be rational molecular targets for novel antitumour agents. Significantly, oncogenic signals make cancer cells intrinsically more susceptible to apoptosis; defects in the pathway occur subsequent to cancer development. Important emerging questions are the pattern of alterations in the apoptotic pathway in a particular tumour (cell) and the best strategy to exploit them and induce selective tumour cell death. Here, we review recent progress in this field.

Topics: Animals; Antineoplastic Agents; Apoptosis; Biphenyl Compounds; Caspase 3; Cell Transformation, Neoplastic; Enzyme Activators; Humans; Inhibitor of Apoptosis Proteins; Neoplasms; Nitrophenols; Oligonucleotides, Antisense; Piperazines; Proto-Oncogene Proteins c-bcl-2; Pyridines; Sulfonamides; Triazenes

Senescent cells may promote tumour progression through the activation of a senescence-associated secretory phenotype (SASP), whether these cells are capable of initiating tumourigenesis in vivo is not known. Expression of oncogenic β-catenin in Sox2+ young adult pituitary stem cells leads to formation of clusters of stem cells and induction of tumours resembling human adamantinomatous craniopharyngioma (ACP), derived from Sox2- cells in a paracrine manner. Here, we uncover the mechanisms underlying this paracrine tumourigenesis. We show that expression of oncogenic β-catenin in Hesx1+ embryonic precursors also results in stem cell clusters and paracrine tumours. We reveal that human and mouse clusters are analogous and share a common signature of senescence and SASP. Finally, we show that mice with reduced senescence and SASP responses exhibit decreased tumour-inducing potential. Together, we provide evidence that senescence and a stem cell-associated SASP drive cell transformation and tumour initiation in vivo in an age-dependent fashion.

Topics: Aniline Compounds; Animals; beta Catenin; Biphenyl Compounds; Cell Transformation, Neoplastic; Cellular Senescence; Child; Craniopharyngioma; Disease Models, Animal; Exome Sequencing; Homeodomain Proteins; Humans; Mice; Neoplastic Stem Cells; Nitrophenols; Oncogenes; Piperazines; Pituitary Gland; Pituitary Neoplasms; Repressor Proteins; SOXB1 Transcription Factors; Sulfonamides; Young Adult

Drug resistance and metastasis remain major challenges in the treatment of high-risk hepatoblastoma (HB) and require the development of alternative therapeutic strategies. Modulation of apoptosis in HB cells enhances the sensitivity of these cells towards various drugs and has been discussed to enforce treatment. We investigated the impact of apoptosis sensitisers, BH3-mimetics, on the interaction between the host and HB to reduce tumour growth and dissemination while enhancing immunity. BH3-mimetics, such as obatoclax and ABT-737, enhanced the apoptosis-inducing effect of TRAIL and TNF-α resistant HB cells (HepT1 and HUH6). Tumour cell migration was inhibited by ABT-737 and more markedly by obatoclax. In an orthotopic model of HB, tumour uptake was reduced when the cells were pretreated with low concentrations of obatoclax. Only 1 of 7 mice developed HB in the liver, compared with an incidence of 0.8 in the control group. In summary, our study showed that apoptosis sensitisers had broader effects on HB cells than expected including migration and susceptibility to cytokines in addition to the known effects on drug sensitization. Sensitising HB to apoptosis may also allow resistant HB to be targeted by immune cells and prevent tumour cell dissemination.

Topics: Animals; Biomimetic Materials; Biphenyl Compounds; Cell Transformation, Neoplastic; Cells, Cultured; Disease Models, Animal; Drug Evaluation, Preclinical; Hepatoblastoma; Humans; Indoles; Liver Neoplasms; Mice; Mice, Inbred C57BL; Mice, Inbred NOD; Mice, Nude; Mice, Transgenic; Nitrophenols; Peptide Fragments; Piperazines; Proto-Oncogene Proteins; Pyrroles; Sulfonamides

Myelodysplastic syndrome (MDS) transforms into an acute myelogenous leukemia (AML) with associated increased bone marrow (BM) blast infiltration. Using a transgenic mouse model, MRP8[NRASD12/hBCL-2], in which the NRAS:BCL-2 complex at the mitochondria induces MDS progressing to AML with dysplastic features, we studied the therapeutic potential of a BCL-2 homology domain 3 mimetic inhibitor, ABT-737. Treatment significantly extended lifespan, increased survival of lethally irradiated secondary recipients transplanted with cells from treated mice compared with cells from untreated mice, with a reduction of BM blasts, Lin-/Sca-1(+)/c-Kit(+), and progenitor populations by increased apoptosis of infiltrating blasts of diseased mice assessed in vivo by technicium-labeled annexin V single photon emission computed tomography and ex vivo by annexin V/7-amino actinomycin D flow cytometry, terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling, caspase 3 cleavage, and re-localization of the NRAS:BCL-2 complex from mitochondria to plasma membrane. Phosphoprotein analysis showed restoration of wild-type (WT) AKT or protein kinase B, extracellular signal-regulated kinase 1/2 and mitogen-activated protein kinase patterns in spleen cells after treatment, which showed reduced mitochondrial membrane potential. Exon specific gene expression profiling corroborates the reduction of leukemic cells, with an increase in expression of genes coding for stem cell development and maintenance, myeloid differentiation, and apoptosis. Myelodysplastic features persist underscoring targeting of BCL-2-mediated effects on MDS-AML transformation and survival of leukemic cells.

Topics: Animals; Antigens, Ly; Biphenyl Compounds; Cell Lineage; Cell Membrane; Cell Proliferation; Cell Transformation, Neoplastic; Cell Transplantation; Disease Models, Animal; Flow Cytometry; Gene Expression Regulation, Leukemic; Leukemia, Myeloid, Acute; MAP Kinase Signaling System; Membrane Proteins; Mice; Mice, Transgenic; Mitochondria; Nitrophenols; Piperazines; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogene Proteins c-kit; ras Proteins; Stem Cells; Sulfonamides

BIM represents a BH3-only proapoptotic member of the BCL-2 family of apoptotic regulatory proteins. Recent evidence suggests that in addition to its involvement in normal homeostasis, BIM plays a critical role in tumor cell biology, including the regulation of tumorigenesis through activities as a tumor suppressor, tumor metastasis, and tumor cell survival. Consequently, BIM has become the focus of intense interest as a potential target for cancer chemotherapy. The control of BIM expression is complex, and involves multiple factors, including epigenetic events (i.e., promoter acetylation or methylation, miRNA), transcription factors, posttranscriptional regulation, and posttranslational modifications, most notably phosphorylation. Significantly, the expression of BIM by tumor cells has been shown to play an important role in determining the response of transformed cells to not only conventional cytotoxic agents, but also to a broad array of targeted agents that interrupt cell signaling and survival pathways. Furthermore, modifications in BIM expression may be exploited to improve the therapeutic activity and potentially the selectivity of such agents. It is likely that evolving insights into the factors that regulate BIM expression will ultimately lead to novel BIM-based therapeutic strategies in the future.

Topics: Acetylation; Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; Biphenyl Compounds; Cell Transformation, Neoplastic; DNA Methylation; Drug Synergism; Forkhead Box Protein O3; Forkhead Transcription Factors; Gene Expression Regulation, Neoplastic; Histone Deacetylase Inhibitors; Humans; MAP Kinase Signaling System; Membrane Proteins; Neoplasms; Nitrophenols; Phosphorylation; Piperazines; Promoter Regions, Genetic; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Proto-Oncogene Proteins; Sulfonamides; Transcription Factors; Transcription, Genetic

Cell killing is a critical pharmacological activity of imatinib to eradicate Bcr/Abl+ leukemias. We found that imatinib kills Bcr/Abl+ leukemic cells by triggering the Bcl-2-regulated apoptotic pathway. Imatinib activated several proapoptotic BH3-only proteins: bim and bmf transcription was increased, and both Bim and Bad were activated posttranslationally. Studies using RNAi and cells from gene-targeted mice revealed that Bim plays a major role in imatinib-induced apoptosis of Bcr/Abl+ leukemic cells and that the combined loss of Bim and Bad abrogates this killing. Loss of Bmf or Puma had no effect. Resistance to imatinib caused by Bcl-2 overexpression or loss of Bim (plus Bad) could be overcome by cotreatment with the BH3 mimetic ABT-737. These results demonstrate that Bim and Bad account for most, perhaps all, imatinib-induced killing of Bcr/Abl+ leukemic cells and suggest previously undescribed drug combination strategies for cancer therapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; bcl-Associated Death Protein; Benzamides; Biphenyl Compounds; Cell Line, Tumor; Cell Transformation, Neoplastic; Cytotoxicity, Immunologic; Drug Resistance, Neoplasm; Fetus; Fusion Proteins, bcr-abl; Humans; Imatinib Mesylate; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Liver; Membrane Proteins; Mice; Myeloid Progenitor Cells; Nitrophenols; Piperazines; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Pyrimidines; Sulfonamides

External ATP causes passive permeability change in several transformed cells, but not in untransformed cells. We studied the effect of external ATP on the passive permeability of CHO-K1 cells, a transformed clone of Chinese hamster ovary cells. Treatment of the cells with external ATP alone did not produce a permeability change, and this was observed only when a mitochondrial inhibitor, such as rotenone or oligomycin, was present together with ATP. These inhibitors reduced the concentration of intracellular ATP and a permeability change by external ATP was observed when intracellular ATP was decreased more than 70%. This requirement for permeability change of CHO-K1 cells was quite unique, since passive permeability change of other transformed cells so far tested was induced by ATP alone. Treatment of CHO-K1 cells with cyclic AMP analogues increased their sensitivity to external ATP about 2-fold. The roles of external and intracellular ATP in controlling passive permeability are discussed.

Topics: Adenosine Triphosphate; Alkaline Phosphatase; Animals; Cell Membrane Permeability; Cell Transformation, Neoplastic; Cell Transformation, Viral; Clone Cells; Cricetinae; Cricetulus; Female; Kinetics; Nitrophenols; Organophosphorus Compounds; Ovary; Rotenone

Topics: Amino Acids; Animals; Benzenesulfonates; Binding Sites; Carbon Radioisotopes; Cell Membrane; Cell Transformation, Neoplastic; Cells, Cultured; Chromatography, Affinity; Electrophoresis, Disc; Fibroblasts; Iodine Radioisotopes; Mice; Microscopy, Electron; Molecular Weight; Neoplasm Proteins; Nitro Compounds; Nitrophenols; Peroxidases; Protein Binding; Rabbits; Simian virus 40; Solubility; Spectrophotometry; Viral Proteins

Topics: Aflatoxins; Aminopyrine; Animals; Benzopyrenes; Carcinogens; Carcinoma, Hepatocellular; Cell Transformation, Neoplastic; Diet; Hyperplasia; Lipotropic Agents; Liver; Liver Neoplasms; Male; Mixed Function Oxygenases; Neoplasms, Experimental; Nitrophenols; Oxidoreductases; Precancerous Conditions; Rats; Thymidine; Transferases; Tritium