phenanthrenes and Leukemia--Myeloid

To explore whether triptolide (TPL) can enhance drug sensitivity of resistant myeloid leukemia cell lines through downregulation of HIF-1α and Nrf2.. HL60/A and K562/G cells were subjected to different treatments and thereafter an methyl thiazole tetrazolium bromide assay, flow cytometry, western blot and real-time PCR were used to determine IC₅₀, apoptotic status and expression of Nrf2, HIF-1α and their target genes.. Doxorubicin- or imatinib-induced apoptosis was enhanced when anticancer agents were used in combination with TPL. When combined with TPL, both doxorubicin and imatinib downregulate Nrf2 and HIF-1α expression at protein and mRNA levels. Genes downstream of Nrf2, for example, NQO1, GSR and HO-1, as well as target genes of HIF-1α, for example, BNIP3, VEGF and CAIX are also downregulated at the mRNA level.. TPL is able to enhance drug sensitivity of resistant myeloid leukemia cell lines through downregulation of HIF-1α and Nrf2.

Topics: Cell Line, Tumor; Diterpenes; Down-Regulation; Drug Resistance, Neoplasm; Drugs, Chinese Herbal; Epoxy Compounds; Gene Expression Regulation, Neoplastic; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Leukemia, Myeloid; NF-E2-Related Factor 2; Phenanthrenes

Tanshinone I (Tan I), a diterpene quinone extracted from herbal medicine Salvia miltiorrhiza Bunge, has recently been reported to have antitumor effects. As the mechanism of its proapoptotic effects on human myeloid leukemia cells has not been extensively studied, we performed an in-depth evaluation of the effects of Tan I on apoptosis in human K562 and HL-60 cells. The results revealed that Tan I could inhibit the growth of leukemia cells and cause apoptosis in a time- and dose-dependent manner. Apoptosis was observed clearly by flow cytometry and Hoechst 33258 staining, as well as DNA fragmentation analysis. After treatment by Tan I for 48 h, the percentage of disruption of mitochondrial membrane potential (Δψm) was increased in a dose-dependent manner. Western blotting analysis demonstrated the cleavage of caspase-3 zymogen protein and a dose-dependent cleavage of poly-(ADP-ribose) polymerase. Tan I-induced apoptosis was accompanied by a significant decrease in survivin and an increase in Bax. Moreover, Tan I treatment remarkably downregulated the phosphorylation of both P85/PI3K and Akt in a time-dependent manner, and the PI3K/AKT-specific inhibitor (LY294002) mimicked the apoptosis-inducing effects of Tan I. We therefore conclude that the induction of apoptosis by Tan I in these leukemia cells is mainly related to the disruption of Δψm, the upregulation of Bax expression, and the activation of caspase-3. This process is highly correlated with the inactivation of PI3K/Akt/survivin signaling pathways. The results indicate that Tan I may serve as an effective adjunctive reagent in the treatment of leukemia.

Topics: Abietanes; Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; DNA Fragmentation; Drugs, Chinese Herbal; Enzyme Activation; HL-60 Cells; Humans; K562 Cells; Leukemia, Myeloid; Membrane Potential, Mitochondrial; Molecular Structure; Phenanthrenes; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction

Background Aberrant or impaired repair of double-strand DNA breaks is a common feature of de novo acute myeloid leukemia and myelodysplastic syndromes. Since poly (ADP-ribose) polymerase (PARP) inhibitors have been recently shown to selectively target cells with defects in double-strand DNA repair, the aim of this study was to explore the possibility of exploiting defects in DNA repair in leukemic cells using PARP inhibitors.. Leukemic cell lines were exposed to various PARP inhibitors alone and in combination with non-cytotoxic concentrations of DNA methyltransferase inhibitor, 5' aza-2'-deoxycytidine and/or the histone deacetylase inhibitor, MS275, to test for potentiation of apoptosis with these agents.. PARP inhibitors, KU-0058948 and PJ34, induced cell cycle arrest and apoptosis of primary myeloid leukemic cells and myeloid leukemic cell lines in vitro. Immunofluorescence analysis also revealed that PARP inhibitor sensitivity in these leukemic cells was due to a defect in homologous recombination DNA repair. Addition of 5' aza-2'-deoxycytidine failed to increase the cytotoxicity of PARP inhibitors. In contrast, MS275 potentiated the cytotoxic effect of KU-0058948 and PJ34 in all PARP inhibitor-sensitive leukemic cells. Immunofluorescence analysis supported the idea that histone deacetylase inhibitors potentiate cytotoxicity by inhibiting DNA repair processes. Conclusions On the basis of the data presented here, we suggest that PARP inhibitors can potentially exploit defects in double-strand DNA break repair in leukemic cells, paving the way for testing the therapeutic potential of these agents in myelodysplastic syndromes and acute myeloid leukemia.

Topics: Apoptosis; Azacitidine; Benzamides; Butyrates; Cell Cycle; Cell Line; Cell Line, Tumor; Cell Survival; Decitabine; DNA Modification Methylases; DNA Repair; Drug Synergism; Flow Cytometry; Fluorescent Antibody Technique; Fluorobenzenes; Histone Acetyltransferases; HL-60 Cells; Humans; Hydroxamic Acids; Immunohistochemistry; K562 Cells; Leukemia, Myeloid; Myelodysplastic Syndromes; Phenanthrenes; Phthalazines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Pyridines; U937 Cells

To investigate the effects of triptolide, a diterpenoid triepoxide from Tripterygium wilfordii Hook F (TWHF), on the co-stimulatory molecule expression and interleukin-12 (IL-12) production from THP-1 cells.. THP-1 cells were differentiated into macrophage-like cells by Me2SO, and then cultured with IFN-gamma (500 kU/L) and lipopolysaccharide (LPS) (1 mg/L) with or without triptolide. The surface molecule expressions were analyzed on a FACScan flow cytometer. IL-12p40, IL-12p70 were assayed by ELISA.. Triptolide suppressed CD80 and CD86 expressions on IFN-gamma (500 kU/L) and LPS (1 mg/L) activated THP-1 cells at nontoxic dosages of 2.5-0.625 microg/L. Furthermore, the production of IL-12p40 and IL-12p70 were also significantly reduced in THP-1 cells exposed to triptolide.. Triptolide impairs the antigen-presenting function by inhibiting CD80 and CD86 expressions and decreased IL-12p40 and IL-12p70 (bioactive form) productions from the activated THP-1 cells.

Topics: Antigens, CD; B7-1 Antigen; B7-2 Antigen; Cell Line, Tumor; Diterpenes; Epoxy Compounds; Humans; Immunosuppressive Agents; Interleukin-12; Interleukin-12 Subunit p40; Leukemia, Myeloid; Membrane Glycoproteins; Monocytes; Phenanthrenes; Plants, Medicinal; Protein Subunits; Tripterygium

Apoptosis is a new therapeutic target of cancer research. Tanshinone IIA isolated from Salvia miltiorrhiza BUNGE, a traditional oriental medical herb, was observed to induce apoptosis in HL60 human premyelocytic leukemia cell line. Tanshinone IIA induced DNA fragmentation into the multiples of 180 bp and increased the percentage of hypodiploid cells in flow cytometry after propidium iodide (PI) staining. Tanshinone IIA-induced apoptosis is accompanied by the specific proteolytic cleavage of poly(ADP-ribose) polymerase (PARP) and the activation of caspase-3, a major component in apoptotic cell death mechanism.

Topics: Abietanes; Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 3; Caspases; Coloring Agents; DNA Fragmentation; Drugs, Chinese Herbal; Flow Cytometry; Humans; In Vitro Techniques; Leukemia, Myeloid; Phenanthrenes; Plant Extracts; Poly(ADP-ribose) Polymerases; Propidium; Time Factors; Tumor Cells, Cultured

Topics: Humans; Hydrocarbons; Leukemia; Leukemia, Myeloid; Organic Chemicals; Phenanthrenes; Polycyclic Aromatic Hydrocarbons; Splenomegaly

Topics: Animals; Carcinogens; Leukemia; Leukemia, Myeloid; Neoplasms, Experimental; Phenanthrenes; Rats