benzofurans and Leukemia

P53 dysfunction has been associated with various malignant tumors, including acute leukemia. The overexpression of mouse double minute 2 (MDM2) causes the inactivation of p53 in acute leukemia. MDM2 inhibitors that activate p53 and induce apoptosis are currently being developed for potential treatment of acute leukemia. However, MDM2 inhibitors alone have limited efficacy in acute leukemia therapeutics. Combining other drugs to enhance the efficacy of MDM2 inhibitors is the thus considered as a potential treatment scheme. Here, we report that the combination of Nutlin-3 and Tanshinone IIA synergistically induces cytotoxicity, cell cycle arrest, apoptosis, and autophagic cell death, thereby imparting anti-leukemia effect in an acute leukemia cell line with wild-type p53 by effectively activating p53, inhibiting the AKT/mTOR pathway, and activating the RAF/MEK pathway. Using primary samples from acute leukemia patients, we show that the combination of Nutlin-3 plus Tanshinone IIA synergistically induces cytotoxicity by activating p53 and inhibiting the AKT/mTOR pathway. This specific combination of Nutlin-3 and Tanshinone IIA is also effective in preventing the recurrence of refractory leukemia, such as Ph+ ALL with the ABL kinase T315I mutation and AML with the FLT3-ITD mutation. Taken together, the results of this study demonstrate that the Nutlin-3 plus Tanshinone IIA combination exerts synergistic anti-leukemia effects by regulating the p53 and AKT/mTOR pathways, although further investigation is warranted. Small-molecule MDM2 antagonists plus Tanshinone IIA may thus be a promising strategy for the treatment of acute leukemia.

Topics: Acute Disease; Adolescent; Adult; Aged, 80 and over; Benzofurans; Cytotoxins; Drug Synergism; Female; Gene Expression Regulation, Leukemic; HL-60 Cells; Humans; Imidazoles; Leukemia; Male; Middle Aged; Piperazines; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins c-mdm2; TOR Serine-Threonine Kinases; Tumor Suppressor Protein p53

Protein methyltransferases (PMTs) are involved in numerous biological processes and have been studied as a promising target class in the field of oncology and other diseases. Disruptor of telomeric silencing 1-like (DOT1L), a histone H3 lysine 79 (H3K79) methyltransferase, plays an important role in the progressions of mixed-lineage leukemia (MLL)-rearranged leukemias and has been validated as a potential therapeutic target. Here we report the discovery and characterization of a novel DOT1L inhibitor, massonianoside B (MA), by pharmacophore-based in silico screening and biological studies. MA is a structurally unique natural product inhibitor of DOT1L with an IC

Topics: Apoptosis; Benzofurans; Cell Line, Tumor; Cell Proliferation; Computer-Aided Design; DNA Methylation; Down-Regulation; Drug Discovery; Gene Expression Regulation, Neoplastic; Histone-Lysine N-Methyltransferase; Humans; Leukemia; Mannose; Recombinant Proteins

Topics: Adaptor Proteins, Signal Transducing; Antineoplastic Agents; Apoptosis; Benzofurans; Binding Sites; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Drug Evaluation, Preclinical; Gene Expression Regulation, Neoplastic; Humans; Leukemia; Molecular Docking Simulation; Phosphorylation; Protein Kinase Inhibitors; Protein Structure, Tertiary; Proto-Oncogene Proteins c-pim-1; Signal Transduction; Stereoisomerism

Erypoegin K is an isoflavone isolated from the stem bark of Erythrina poeppigiana. It contains a furan group at the A-ring of the core isoflavone structure and can inhibit the activity of glyoxalase I, an enzyme that catalyzes the detoxification of methylglyoxal (MG), a by-product of glycolysis. In the present study, we found that erypoegin K has a potent cytotoxic effect on human leukemia HL-60 cells. Its cytotoxic effect was much stronger than that of a known glyoxalase I inhibitor S-p-bromobenzylglutathione cyclopentyl diester. Conversely, erypoegin K demonstrated weak cytotoxicity toward normal human peripheral lymphocytes. The treatment of HL-60 cells with erypoegin K significantly induced caspase-3 activity, whereas the pretreatment of the cells with caspase-3 inhibitor suppressed erypoegin K-induced cell death. Furthermore, nuclear condensation and apoptotic genome DNA fragmentation were observed in erypoegin K-treated HL-60 cells. These results indicated that the observed cell death was mediated by apoptosis. In addition, the toxic compound MG was highly accumulated in the culture medium of erypoegin K-treated HL-60 cells, suggesting that cell apoptosis was triggered by extracellular MG. The present study showed that erypoegin K has a potent apoptosis-inducing effect on cancerous cell lines, such as HL-60.

Topics: Apoptosis; Benzofurans; Erythrina; HL-60 Cells; Humans; Isoflavones; Leukemia

E26 transformation-specific (ETS) gene family contains a common DNA-binding domain, the ETS domain, responsible for sequence-specific DNA recognition on target promoters. The Fli-1 oncogene, a member of ETS gene family, plays a critical role in hematopoiesis and is overexpressed in diverse hematological malignancies. This ETS transcription factor regulates genes controlling several hallmarks of cancer and thus represents an excellent target for cancer therapy. By screening compounds isolated from the medicinal plant Dysoxylum binectariferum in China, we identified two chemically related flavagline-like compounds including 4'-demethoxy-3',4'-methylenedioxyrocaglaol and rocaglaol that strongly inhibited Fli-1 transactivation ability. These compounds altered expression of Fli-1 target genes including GATA1, EKLF, SHIP1, and BCL2. Consequently, the flavagline-like compounds suppressed proliferation, induced apoptosis, and promoted erythroid differentiation of leukemic cells in culture. These compounds also suppressed erythroleukemogenesis in vivo in a Fli-1-driven mouse model. Mechanistically, the compounds blocked c-Raf-MEK-MAPK/ERK signaling, reduced phosphorylation of eukaryotic translation initiation factor 4E (eIF4E), and inhibited Fli-1 protein synthesis. Consistent with its high expression in myelomas, B-cell lymphoma, and B chronic lymphocytic leukemia (B-CLL), pharmacological inhibition of Fli-1 by the flavagline-like compounds or genetic knock-down via shRNA significantly hindered proliferation of corresponding cell lines and patients' samples. These results uncover a critical role of Fli-1 in growth and survival of various hematological malignancies and point to flavagline-like agents as lead compounds for the development of anti-Fli-1 drugs to treat leukemias/lymphomas overexpressing Fli-1.

Topics: Animals; Antineoplastic Agents, Phytogenic; Apoptosis; Benzofurans; Cell Cycle; Cell Proliferation; High-Throughput Screening Assays; Humans; Leukemia; Mice; Plant Extracts; Plants, Medicinal; Proto-Oncogene Protein c-fli-1; Signal Transduction; Tumor Cells, Cultured

Targeting the cancer cell cycle machinery is an important strategy for cancer treatment. Cdc25A is an essential regulator of cycle progression and checkpoint response. Over-expression of Cdc25A occurs often in human cancers. In this study, we show that Rocaglamide-A (Roc-A), a natural anticancer compound isolated from the medicinal plant Aglaia, induces a rapid phosphorylation of Cdc25A and its subsequent degradation and, thereby, blocks cell cycle progression of tumor cells at the G1-S phase. Roc-A has previously been shown to inhibit tumor proliferation by blocking protein synthesis. In this study, we demonstrate that besides the translation inhibition Roc-A can induce a rapid degradation of Cdc25A by activation of the ATM/ATR-Chk1/Chk2 checkpoint pathway. However, Roc-A has no influence on cell cycle progression in proliferating normal T lymphocytes. Investigation of the molecular basis of tumor selectivity of Roc-A by a time-resolved microarray analysis of leukemic vs. proliferating normal T lymphocytes revealed that Roc-A activates different sets of genes in tumor cells compared with normal cells. In particular, Roc-A selectively stimulates a set of genes responsive to DNA replication stress in leukemic but not in normal T lymphocytes. These findings further support the development of Rocaglamide for antitumor therapy.

Topics: Antineoplastic Agents; Ataxia Telangiectasia Mutated Proteins; Benzofurans; cdc25 Phosphatases; Cell Line, Tumor; Cell Proliferation; Checkpoint Kinase 1; Checkpoint Kinase 2; DNA Damage; HCT116 Cells; Hep G2 Cells; HT29 Cells; Humans; Jurkat Cells; Leukemia; MCF-7 Cells; Phosphorylation; Plant Extracts; Protein Biosynthesis; Protein Kinases; RNA Interference; RNA, Small Interfering; S Phase Cell Cycle Checkpoints; T-Lymphocytes

Malaria and cancer cause the death of millions of people every year. To combat these two diseases, it is important that new pharmaceutically active compounds have the ability to overcome multidrug resistance in cancer and Plasmodium falciparum strains. In search of effective anti-cancer and anti-malaria hybrids that possess improved properties compared to their parent compounds, a series of novel 1,2,4-trioxane-based hybrids incorporating egonol and/or ferrocene fragments were synthesized and tested in vitro against P. falciparum strains, CCRF-CEM cells and the multidrug-resistant P-glycoprotein-over-expressing CEM/ADR5000 cells. The most active compounds against P. falciparum strains were artesunic acid homodimers 12 and 13 (IC50 of 0.32 and 0.30 nM, respectively), whereas novel hybrids 7 (1,2,4-trioxane-ferrocene-egonol), 9 (1,2,4-trioxane-ferrocene) and 11 (artesunic acid-egonol) showed a remarkable cytotoxicity toward CCRF-CEM cells (IC50 of 0.07, 0.25 and 0.18 μM, respectively). A cooperative and synergistic effect of the three moieties 1,2,4-trioxane, ferrocene and egonol in hybrid molecule 7 is significant and is obviously stronger than in hybrids 9 (1,2,4-trioxane-ferrocene) and 11 (artesunic acid-egonol), which comprises of only two of the three considered parent compounds. Interestingly, hybrid 9 containing a 1,2,4-trioxane and a ferrocene fragment has shown to be the most effective among the studied hybrids against the tested multidrug-resistant leukemia CEM/ADR5000 cells (IC50 of 0.57 μM) and possesses a degree of cross-resistance of 2.34.

Topics: Antimalarials; Antineoplastic Agents; Benzofurans; Cell Lineage; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Ferrous Compounds; Heterocyclic Compounds; Humans; Leukemia; Malaria, Falciparum; Metallocenes; Plasmodium falciparum

Identification of agents that target human leukemia stem cells is an important consideration for the development of new therapies. The present study demonstrates that rocaglamide and silvestrol, closely related natural products from the flavagline class of compounds, are able to preferentially kill functionally defined leukemia stem cells, while sparing normal stem and progenitor cells. In addition to efficacy as single agents, flavaglines sensitize leukemia cells to several anticancer compounds, including front-line chemotherapeutic drugs used to treat leukemia patients. Mechanistic studies indicate that flavaglines strongly inhibit protein synthesis, leading to the reduction of short-lived antiapoptotic proteins. Notably though, treatment with flavaglines, alone or in combination with other drugs, yields a much stronger cytotoxic activity toward leukemia cells than the translational inhibitor temsirolimus. These results indicate that the underlying cell death mechanism of flavaglines is more complex than simply inhibiting general protein translation. Global gene expression profiling and cell biological assays identified Myc inhibition and the disruption of mitochondrial integrity to be features of flavaglines, which we propose contribute to their efficacy in targeting leukemia cells. Taken together, these findings indicate that rocaglamide and silvestrol are distinct from clinically available translational inhibitors and represent promising candidates for the treatment of leukemia.

Topics: Animals; Antigens, CD34; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzofurans; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Leukemia; Leukocytes, Mononuclear; Mice; Mitochondria; Neoplastic Stem Cells; Phenotype; Reactive Oxygen Species; Sirolimus; Stem Cells; Triterpenes; Tumor Suppressor Protein p53; Xenograft Model Antitumor Assays

Serine/threonine kinase PIM1 is an emerging therapeutic target for hematopoietic and prostate cancer therapy. To develop a novel PIM1 inhibitor, we focused on 1, a metabolically labile, nonselective kinase inhibitor discovered in our previous screening study. We adopted a rational optimization strategy based mainly on structural information for the PIM1-1 complex to improve the potency and selectivity. This approach afforded the potent and metabolically stable PIM1-selective inhibitor 14, which shows only a marginal increase in molecular weight compared with 1 but has a significantly decreased cLogP. The validity of our design concept was confirmed by X-ray structure analysis. In a cellular study, 14 potently inhibited the growth of human leukemia cell line MV4-11 but had a negligible effect on the growth of WI-38 (surrogate for general toxicity). These results demonstrate the effectiveness of our design strategy for evolving the screening-hit compound 1 into a novel type of PIM1 inhibitor, 14.

Topics: Antineoplastic Agents; Apoptosis; Aza Compounds; Benzofurans; Cell Line, Tumor; Cell Proliferation; Crystallography, X-Ray; Databases, Factual; Drug Screening Assays, Antitumor; G1 Phase; Humans; Indoles; Leukemia; Models, Molecular; Molecular Structure; Proto-Oncogene Proteins c-pim-1; Stereoisomerism; Structure-Activity Relationship

Albanol A (1), isolated from the root bark extract of Morus alba (mulberry), was evaluated for the cytotoxic and apoptosis-inducing activities in human leukemia (HL60) cells, and for the inhibitory activity in human DNA topoisomerases (Topo) I and II. This compound showed potent cytotoxic activity (IC(50) 1.7 microM) on the cells, and potent inhibitory activity on topoisomerase II (IC(50) 22.8 microM). In addition, albanol A induced early apoptosis which was detected by observing the membrane phospholipid exposure in flow cytometry. Western blot analysis showed that albanol A markedly reduced the levels of procaspases-3, 8, and 9, while being increased the levels of cleaved caspases-3, 8, and 9. The Bax/Bcl-2 ratio was significantly increased by albanol A treatment. Furthermore, albanol A induced caspase-2 activation. These results suggested that albanol A induces apoptotic cell death in HL60 via both the cell death receptor pathway by stimulation of death receptor, and the mitochondrial pathway by Topo II inhibition through caspase-2 activation. Therefore, albanol A may be a promising lead compound for developing an effective drug for treatment of leukemia.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Benzofurans; Cell Line, Tumor; DNA Topoisomerases, Type I; DNA Topoisomerases, Type II; Humans; Leukemia; Morus; Plant Roots; Terpenes; Topoisomerase I Inhibitors; Topoisomerase II Inhibitors

Three new flavonoid glycosides (cissosides I, II, and III) and a new benzofuran-type stilbene (cissusin) were isolated from the methanolic extract of the aerial parts of Cissus sicyoides cultivated in Brazil. Their structures were elucidated on the basis of chemical and physicochemical evidence. The inhibitory effects of the isolated constituents on the release of beta-hexosaminidase as a marker of degranulation in rat basophilic leukemia (RBL-2H3) cells were examined. Cissusin, flavonols (kaempferol, quercetin), flavones (7,3',4'-trihydroxyflavone, lanceolatin B), pterocarpanes (homopterocarpin), chalcones (isoliquiritigenin, E-7-O-methylpongamol), and tryptanthrin markedly inhibited the release of beta-hexosaminidase.

Topics: Animals; Benzofurans; beta-N-Acetylhexosaminidases; Cell Degranulation; Cell Line, Tumor; Cissus; Flavonoids; Herbal Medicine; Leukemia; Molecular Conformation; Rats; Stilbenes

With an increasing cancer rate worldwide, there is an urgent quest for the improvement of anticancer drugs. One of the main problems of present chemotherapy in treatment of tumor patients is the toxicity of drugs. Most of the existent anticancer drugs, unfortunately, attack also proliferating normal cells. In recent years, traditional Chinese herbal remedies have gradually gained considerable attention as a new source of anticancer drugs. Although their healing mechanisms are still largely unknown, some of the drugs have been used to help cancer patients fight their disease at reduced side effects compared to other treatments. In our study, we show that Rocaglamide (Roc), derived from the traditional Chinese medicinal plants Aglaia, induces apoptosis through the intrinsic death pathway in various human leukemia cell lines and in acute lymphoblastic leukemia, chronic myeloid leukemia and acute myeloid leukemia cells freshly isolated from patients. Investigation of the molecular mechanisms by which Roc kills tumors revealed that it induces a consistent activation of the stress-response mitogen-activated protein kinase (MAPK) p38 accompanied with a long-term suppression of the survival MAPK extracellular signal-regulated kinase. These events affect proapoptotic Bcl-2 family proteins leading to depolarization of the mitochondrial membrane potential and trigger caspase-mediated apoptosis involving caspase-9, -8, -3 and -2. Importantly, Roc shows no effects on MAPKs in normal lymphocytes and therefore has no or very low toxicity on healthy cells. Up to now, more than 50 different Roc derivatives have been isolated from Aglaia. Our study suggests that Roc derivatives may be promising candidates for the development of new drugs against hematologic malignancies.

Topics: Acute Disease; Antineoplastic Agents; Apoptosis; Benzofurans; Cell Line, Tumor; Drugs, Chinese Herbal; Humans; JNK Mitogen-Activated Protein Kinases; Leukemia; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Leukemia, Myeloid; Mitogen-Activated Protein Kinases; p38 Mitogen-Activated Protein Kinases; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Tubulin

17-allylamino-17-demethoxygeldanamycin (17-AAG), an inhibitor of the molecular chaperone heat shock protein 90, results in cell type-specific inhibition of proliferation of leukemic cells. GTP14564 is a tyrosine kinase inhibitor actively against FLT3. The current study evaluated the single and combined effects of 17-AAG and GTP14564, and the role of FLT3 in their inhibitory effects. The importance of FLT3 mutations was demonstrated using small interfering RNA (siRNA) targeted to FLT3. Similar to FLT3 siRNA, GTP14564 inhibited FLT3 internal tandem duplication (ITD) cells (MV4;11) and FLT3 amplified wild-type cells (SEMK2-M1), but not wild-type FLT3 cells (RS4;11). However, when RS4;11 cells were stimulated with FLT3-ligand, phosphorylation of STAT5 and GTP14564 inhibition were observed. Responses to GTP14564 in all cell types were directly related to the level of STAT5 phosphorylation in the cells. We observed synergistic effects of combined 17-AAG and GTP14564 in cell lines with FLT3-ITD and amplified wild-type FLT3. Combined treatment with 17-AAG and GTP14564 reduced the levels of p-FLT3 and p-STAT5, enhanced G0/G1 arrest and apoptosis in FLT3-ITD and amplified wild-type FLT3. The combination of 17-AAG with FLT3 kinase inhibitors can enhance targeted therapy in leukemias with FLT3 mutations, such as MLL fusion gene leukemias.

Topics: Apoptosis; Benzofurans; Benzoquinones; Cell Line, Tumor; Cell Proliferation; DNA-Binding Proteins; Drug Synergism; Drug Therapy, Combination; Enzyme Inhibitors; fms-Like Tyrosine Kinase 3; Gene Expression Regulation, Leukemic; HSP90 Heat-Shock Proteins; Humans; Lactams, Macrocyclic; Leukemia; Ligands; Milk Proteins; Mutation; Phosphorylation; Proto-Oncogene Proteins; Pyrazoles; Receptor Protein-Tyrosine Kinases; Rifabutin; RNA, Small Interfering; Sensitivity and Specificity; Signal Transduction; STAT5 Transcription Factor; Trans-Activators

Thirteen naturally occurring 1H-cyclopenta[b]benzofuran lignans of the rocaglamide type as well as one naturally occurring aglain congener all of them isolated from three Aglaia species (Aglaia duperreana, A. oligophylla and A. spectabilis) collected in Vietnam were studied for their antiproliferative effects using the human monocytic leukemia cell lines MONO-MAC-1 and MONO-MAC-6. Only rocaglamide type compounds showed significant inhibition of [3H-]thymidine incorporation and the most active compound didesmethylrocaglamide inhibited cell growth in a similar concentration range as the well-known anticancer drug vinblastine sulfate. Detailed structure-activity analysis indicated that the OH-group at C-8b which is a common structural feature of most naturally occurring rocaglamide compounds is essential for the described antiproliferative activity since replacement of this group by methylation led to a complete loss of the inhibitory activity for the resulting derivative. Rocaglamide derivatives rapidly inhibited DNA as well as protein biosynthesis of MONO-MAC-6 cells at concentrations well below those of actinomycin D or cycloheximide which were used as positive controls in the respective experiments. Didesmethylrocaglamide was furthermore able to induce growth arrest of MONO-MAC-1 cells in the G2/M and probably G0/G1-phase of the cell cycle with no morphological indication of cellular damage. Our data suggests that 1H-cyclopenta[b]benzofuran lignans of the rocaglamide type act primarily by a cytostatic mechanism.

Topics: Antineoplastic Agents, Phytogenic; Benzofurans; Cell Cycle; Cell Division; Humans; Leukemia; Lignans; Plants; Tumor Cells, Cultured