benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Leukemia-Lymphoma--Adult-T-Cell

We have shown that genistein inhibits the growth of adult T-cell leukemia (ATL) cells in vitro and in vivo, and this leads to pronounced G2/M arrest. This report shows that genistein induces apoptotic death in ATL cells. Although the pan-caspase inhibitor, Z-VAD-fmk, did not inhibit genistein-induced apoptosis, release of apoptosis-inducing factor (AIF) into the cytosol occurred. Poly-ADP ribose polymerase inhibition also abrogated genistein-induced apoptosis. Genistein decreased nuclear p65 translocation and IκBα phosphorylation, and downregulated the anti-apoptotic proteins, XIAP, cIAP and survivin, NF-κB-responsive gene products. Thus, genistein is a promising agent for ATL that induces caspase-independent apoptosis through inhibition of the NF-κB pathway.

Topics: Adult; Amino Acid Chloromethyl Ketones; Anticarcinogenic Agents; Apoptosis; Apoptosis Inducing Factor; Caspase Inhibitors; Cell Line, Tumor; G2 Phase Cell Cycle Checkpoints; Genistein; Humans; I-kappa B Proteins; Inhibitor of Apoptosis Proteins; Leukemia-Lymphoma, Adult T-Cell; M Phase Cell Cycle Checkpoints; NF-kappa B; NF-KappaB Inhibitor alpha; Phosphorylation; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Signal Transduction; Survivin; Transcription Factor RelA; X-Linked Inhibitor of Apoptosis Protein

Adult T-cell leukemia (ATL) is caused by infection with human T-lymphotropic virus type 1 (HTLV-1). A novel tetramethylnaphthalene derivative, TMNAA, selectively inhibited the proliferation of various HTLV-1-infected cells, including ATL cell lines and peripheral blood mononuclear cells (PBMCs) from ATL patients. In contrast, the proliferation of uninfected cell lines and PBMCs from healthy donors was hardly affected by the compound. Cell-cycle analysis revealed that TMNAA increased the population of the G0/G1 phase and reduced that of the S phase in HTLV-1-infected cells. TMNAA was found to suppress the phosphorylation of retinoblastoma protein and the expression of cyclin-dependent kinase 4 in HTLV-1-infected cells. Furthermore, the inhibition of cell proliferation was partially annihilated by removing the compound. These results indicate that TMNAA exerts selective inhibition of HTLV-1-infected cells through a novel mechanism, presumably modulating cell cycle regulatory proteins associated with the G0/G1 phase.

Topics: Amino Acid Chloromethyl Ketones; Caspase Inhibitors; Caspases; Cell Cycle; Cell Growth Processes; Cyclin-Dependent Kinase 4; Enzyme Activation; Human T-lymphotropic virus 1; Humans; Leukemia-Lymphoma, Adult T-Cell; Naphthalenes; Phosphorylation; Retinoblastoma Protein

Histone deacetylase inhibitors (HDACIs) are a new class of chemotherapeutic drugs able to induce tumor cell apoptosis and/or cell cycle arrest; however, the molecular mechanisms underpinning their anticancer effects are poorly understood. Herein, we assessed the apoptotic pathways activated by three HDACIs, suberoylanilide hydroxamic acid, oxamflatin, and depsipeptide. We determined that all three drugs induced the accumulation of cells with a 4n DNA content and apoptosis mediated by the intrinsic apoptotic pathway. HDACI-induced mitochondrial membrane damage and apoptosis were inhibited by overexpression of Bcl-2, but not by the polycaspase inhibitor N-tert-butoxy-carbonyl-Val-Ala-Asp-fluoromethylketone (zVAD-fmk). Moreover, induction of a G(1)-S checkpoint through overexpression of p16(INK4A) or suppression of de novo protein synthesis also inhibited HDACI-induced cell death. Proteolytic cleavage of caspase-2, which is poorly inhibited by zVAD-fmk, was concomitant with HDACI-induced death; however, full processing of caspase-2 to the p19 active form was blocked by Bcl-2. Whereas all three drugs induce the activation of the proapoptotic Bcl-2 protein Bid upstream of mitochondrial membrane disruption, Bid cleavage in response to depsipeptide was significantly attenuated by zVAD-fmk. Suberoylanilide hydroxamic acid and oxamflatin could kill both P-glycoprotein (P-gp)(+) MDR cells and their P-gp(-) counterparts, whereas depsipeptide was shown to be a substrate for P-gp and was less effective in killing P-gp(+) cells. These data provide insight into the functional profile of three HDACIs and are important for the development of more rational approaches to chemotherapy, where information regarding the genetic profile of the tumor is matched with the functional profile of a given chemotherapeutic drug to promote favorable clinical responses.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; ATP Binding Cassette Transporter, Subfamily B, Member 1; Caspase Inhibitors; Cell Cycle; Cyclin D1; Cytochrome c Group; Depsipeptides; Enzyme Inhibitors; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Intracellular Membranes; Leukemia-Lymphoma, Adult T-Cell; Mitochondria; Peptides, Cyclic; Tumor Cells, Cultured; Vorinostat

The anthracycline antibiotic idarubicin (IDA) induces double-stranded DNA breaks, the generation of reactive oxygen species (ROS) and apoptosis in human leukaemic cells. It is unclear whether the generation of ROS is associated with the apoptotic process. Using the T-lymphoblastic leukaemic CEM cell line, we found that IDA-induced DNA breaks were correlated with final cell death. The reduction in mitochondrial membrane potential (Deltapsim) and the generation of ROS occurred simultaneously with IDA-induced activation of caspase-9 and caspase-3. Inhibition of caspases by a pan-caspase inhibitor, benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-fmk) completely blocked IDA-induced reduction of Deltapsim, apoptosis and final cell death. Interestingly, ROS generation was significantly enhanced by Z-VAD-fmk. ROS generation was neither caspase dependent nor part of the apoptotic process. IDA-mediated reduction in Deltapsim is caspase dependent and is not a consequence of the generation of ROS. These results indicate that IDA-induced generation of ROS and apoptosis are separate events. Inhibition of caspases facilitates IDA-mediated generation of ROS.

Topics: Amino Acid Chloromethyl Ketones; Antibiotics, Antineoplastic; Apoptosis; Caspase 3; Caspase 9; Caspase Inhibitors; Caspases; Cell Death; Cell Line; DNA Damage; Enzyme Activation; Enzyme Inhibitors; Humans; Idarubicin; Leukemia-Lymphoma, Adult T-Cell; Membrane Potentials; Mitochondria; Reactive Oxygen Species

A novel therapeutic potential for acute promyelocytic leukemia using arsenic trioxide (As(2) O(3) ) has been reported. Recent in vitro studies demonstrated that As(2) O(3) effectively inhibits the growth of some cell lines derived from patients with malignant lymphoma, chronic lymphocytic leukemia and multiple myeloma. Adult T-cell leukemia (ATL) is an aggressive neoplasm of mature T-cell origin caused by human T-cell leukemia virus type-I (HTLV-I) the prognosis of which still remains very poor. A possible role of As(2) O(3) for the treatment of ATL is demonstrated from evidence that As(2) O(3) significantly inhibits the growth of HTLV-I infected T-cell lines and induces apoptosis in fresh ATL cells at clinically achievable concentration of the agent. The growth inhibition of As(2) O(3) treated HTLV-I infected T-cell lines was induced by both apoptosis and G(1) phase accumulation. Cleaved bcl-2 protein and an enhanced expression of bak protein in the cells were coincidentally observed during As(2) O(3) treatment. A broad spectrum caspase inhibitor, z-Val-Ala-DL-Asp-fluoromethylketone inhibited the apoptosis induced by As(2) O(3). Increased expression of p53, Cip1/p21 and Kip1/p27, and dephosphorylation of retinoblastoma protein (pRb) were detected in the As(2) O(3) treated cells. In conclusion, As(2) O(3) might become a new therapeutic tool in the treatment of ATL as As(2) O(3) induces apoptosis by destruction of the bcl-2 protein and enhancement of the bak protein production proceeding to activate caspases, and also induces G(1) phase accumulation by enhancement of p53, Cip1/p21, Kip1/p27 and dephosphorylation of pRb to HTLV-I infected T-cell lines.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Arsenic Trioxide; Arsenicals; bcl-2 Homologous Antagonist-Killer Protein; Cell Cycle Proteins; Cell Line; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Cyclins; Cysteine Proteinase Inhibitors; Drug Screening Assays, Antitumor; G1 Phase; Gene Expression Regulation, Leukemic; Genes, bcl-2; Genes, p53; Human T-lymphotropic virus 1; Humans; Leukemia-Lymphoma, Adult T-Cell; Membrane Proteins; Neoplasm Proteins; Oxides; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-bcl-2; Retinoblastoma Protein; T-Lymphocytes; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Tumor Suppressor Proteins

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; Carbon-Nitrogen Ligases; Caspase Inhibitors; Cell Line; Cysteine Proteinase Inhibitors; Cytidine; Enzyme Inhibitors; Humans; Leukemia-Lymphoma, Adult T-Cell; Time Factors

Mistletoe lectin I (ML-I) is a major active component in plant extracts of Viscum album that is increasingly used in adjuvant cancer therapy. ML-I exerts potent immunomodulating and cytotoxic effects, although its mechanism of action is largely unknown. We show that treatment of leukemic T- and B-cell lines with ML-I induced apoptosis, which required the prior activation of proteases of the caspase family. The involvement of caspases is demonstrated because (a) a peptide caspase inhibitor almost completely prevented ML-I-induced cell death and (b) proteolytic activation of caspase-8, caspase-9, and caspase-3 was observed. Because caspase-8 has been implicated as a regulator of apoptosis mediated by death receptors, we further investigated a potential receptor involvement in ML-I-induced effects. Cell death triggered by ML-I was neither attenuated in cell clones resistant to CD95 nor in cells that were rendered refractory to other death receptors by overexpressing a dominant-negative FADD mutant. In contrast, ML-I triggered a receptor-independent mitochondria-controlled apoptotic pathway because it rapidly induced the release of cytochrome c into the cytosol. Because ML-I was also observed to enhance the cytotoxic effect of chemotherapeutic drugs, these data may provide a molecular basis for clinical trials using MLs in anticancer therapy.

Topics: Amino Acid Chloromethyl Ketones; Antibiotics, Antineoplastic; Antineoplastic Agents, Phytogenic; Apoptosis; Apoptotic Protease-Activating Factor 1; Arabidopsis Proteins; Brefeldin A; Caspase 3; Caspase 8; Caspase 9; Caspases; Cysteine Proteinase Inhibitors; Cytochrome c Group; Drug Synergism; Enzyme Activation; Enzyme Precursors; Etoposide; fas Receptor; Fatty Acid Desaturases; Humans; Jurkat Cells; Leukemia-Lymphoma, Adult T-Cell; Leukemia, B-Cell; Mitochondria; Mitomycin; Neoplasm Proteins; Plant Preparations; Plant Proteins; Proteins; Ribosome Inactivating Proteins, Type 2; Toxins, Biological; Tumor Cells, Cultured

The two apoptosis receptors of mammalian cells, i.e. the 55 kDa TNF receptor (TNF-R1) and CD95 (Fas/APO1) are activated independently of each other, however, their signaling involves a variety of ICE-related proteases [I]. We used a cell-permeable inhibitor of ICE-like protease activity to examine in vivo whether post-receptor signaling of TNF and CD95 are fully independent processes. Mice pretreated with the inhibitor, Z-VAD-fluoromethylketone (FMK) were dose-dependently protected from liver injury caused by CD95 activation as determined by plasma alanine aminotransferase and also from hepatocyte apoptosis assessed by DNA fragmentation (ID50 = 0.1 mg/kg). A dose of 10 mg/kg protected mice also from liver injury induced by TNF-alpha. Similar results were found when apoptosis was initiated via TNF-alpha or via CD95 in primary murine hepatocytes (IC50 = 1.5 nM) or in various human cell lines. In addition to prevention, an arrest of cell death by Z-VAD-FMK was demonstrated in vivo and in vitro after stimulation of apoptosis receptors. These findings show in vitro and in vivo in mammals that CD95 and the TNF-alpha receptor share a distal proteolytic apoptosis signal.

Topics: Alanine Transaminase; Amino Acid Chloromethyl Ketones; Animals; Antigens, CD; Apoptosis; Carcinoma, Hepatocellular; Caspase 1; Cells, Cultured; Chemical and Drug Induced Liver Injury; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; DNA Fragmentation; fas Receptor; HeLa Cells; Humans; Interleukin-1; Leukemia-Lymphoma, Adult T-Cell; Lipopolysaccharides; Liver; Liver Neoplasms; Male; Mice; Mice, Inbred BALB C; Receptors, Tumor Necrosis Factor; Receptors, Tumor Necrosis Factor, Type I; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha