benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and Neoplasms

The use of caspase inhibitors has revealed the existence of alternative backup cell death programs for apoptosis. The broad-spectrum caspase inhibitor zVAD-fmk modulates the three major types of cell death. Addition of zVAD-fmk blocks apoptotic cell death, sensitizes cells to necrotic cell death, and induces autophagic cell death. Several studies have shown a crucial role for the kinase RIP1 and the adenosine nucleotide translocator (ANT)-cyclophilin D (CypD) complex in necrotic cell death. The underlying mechanism of zVAD-fmk-mediated sensitization to necrotic cell death involves the inhibition of caspase-8-mediated proteolysis of RIP1 and disturbance of the ANT-CypD interaction. RIP1 is also involved in autophagic cell death. Caspase inhibitors and knockdown studies have revealed negative roles for catalase and caspase-8 in autophagic cell death. The positive role of RIP1 and the negative role of caspase-8 in both necrotic and autophagic cell death suggest that the pathways of these two types of cell death are interconnected. Necrotic cell death represents a rapid cellular response involving mitochondrial reactive oxygen species (ROS) production, decreased adenosine triphosphate concentration, and other cellular insults, whereas autophagic cell death first starts as a survival attempt by cleaning up ROS-damaged mitochondria. However, when this process occurs in excess, autophagy itself becomes cytotoxic and eventually leads to autophagic cell death. A better understanding of the molecular mechanisms of these alternative cell death pathways may provide therapeutic tools to combat cell death associated with neurodegenerative diseases, ischemia-reperfusion pathologies, and infectious diseases, and may also facilitate the development of alternative cytotoxic strategies in cancer treatment.

Topics: Adenine Nucleotide Translocator 1; Amino Acid Chloromethyl Ketones; Apoptosis; Autophagy; Binding, Competitive; Caspase Inhibitors; Cell Death; Cyclophilins; Cysteine Proteinase Inhibitors; Humans; Necrosis; Neoplasms; Nuclear Pore Complex Proteins; Peptidyl-Prolyl Isomerase F; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Receptors, Tumor Necrosis Factor; RNA-Binding Proteins; Signal Transduction; Tumor Necrosis Factor-alpha

A deficiency or an excess of programmed cell death (apoptosis) is an integral component of autoimmune disorders, organ and bone marrow transplant rejection, and cancer. A technique to image programmed cell death would be useful in the development of drugs to treat these and others diseases, and to monitor the effectiveness of therapy. The most widely studied agent for the in vivo study of apoptosis is radiolabeled annexin V, an endogenous protein labeled with technectium-99m, now undergoing clinical trials in both Europe and the United States. While annexin V has been studied extensively in humans the precise mechanism(s) of uptake of this agent in vivo is unclear and needs further study. Other agents are also underdevelopment including radiolabeled forms of Z-VAD.fmk, a potent inhibitor of the enzymatic cascade intimately associated with apoptosis. MR imaging techniques and tracers also hold promise as methods to monitor apoptotic cell death. In this article we will review these and other imaging technologies for the non-invasive imaging of cell death. The mechanism(s) and latest data on the conditions in which cellular stress and early apoptosis occur will also be discussed in detail including potential new strategies for the targeting and novel therapeutic interventions of tissues and organs undergoing stress or apoptosis when cell salvage is still possible.

Topics: Amino Acid Chloromethyl Ketones; Animals; Annexin A5; Apoptosis; Graft Rejection; Humans; Magnetic Resonance Spectroscopy; Microspectrophotometry; Neoplasms; Radioactive Tracers

Epstein-Barr virus (EBV)-encoded BARF1 (BamH1-A Rightward Frame-1) is expressed in EBV-positive malignancies such as nasopharyngeal carcinoma, EBV-associated gastric cancer, B-cell lymphoma and nasal NK/T-cell lymphoma, and has been shown to have an important role in oncogenesis. However, the mechanism by which BARF1 elicits its biological effects is unclear. We investigated the effects of BARF1 silencing on cell proliferation and apoptosis in EBV-positive malignant cells. We observed that BARF1 silencing significantly inhibits cell proliferation and induces apoptosis-mediated cell death by collapsing the mitochondrial membrane potential in AG876 and Hone-Akata cells. BARF1 knockdown up-regulates the expression of pro-apoptotic proteins and downregulates the expression of anti-apoptotic proteins. In BARF1-down-regulated cells, the Bcl-2/BAX ratio is decreased. The caspase inhibitor z-VAD-fmk was found to rescue siBARF1-induced apoptosis in these cells. Immunoblot analysis showed significant increased levels of cleaved caspase 3 and caspase 9. We observed a significant increase in cytochrome c level as well as the formation of apoptosome complex in BARF1-silenced cells. In conclusion, siRNA-mediated BARF1 down-regulation induces caspase-dependent apoptosis via the mitochondrial pathway through modulation of Bcl-2/BAX ratio in AG876 and Hone-Akata cells. Targeting BARF1 using siRNA has the potential to be developed as a novel therapeutic strategy in the treatment of EBV-associated malignancies.

Topics: Amino Acid Chloromethyl Ketones; Apoptosis; Apoptosis Regulatory Proteins; Apoptosomes; bcl-2-Associated X Protein; Caspase 3; Caspase 9; Caspase Inhibitors; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; Cytochromes c; Down-Regulation; Herpesvirus 4, Human; Humans; Membrane Potential, Mitochondrial; Mitochondria; Neoplasms; Proto-Oncogene Proteins c-bcl-2; RNA Interference; RNA, Small Interfering; Viral Proteins

Natural compounds isolated from medicinal plants are invaluable resources for drug discovery. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent unique by its cancer cell-specific proapoptotic action, but its potential is heavily curbed by acquired resistance. We herein reported for the first time the identification of cytotoxic and TRAIL-sensitizing components of Salvia miltiorrhiza (Danshen), a traditional medicinal plant effective for treating cardiovascular disorders. Specifically, we found that the ethanol extract and its group 5 fraction of S. miltiorrhiza showed evident cytotoxicity against the human lung adenocarcinoma cell line A549 and ovarian adenocarcinoma cell line TOV-21G in a concentration-dependent manner. Likewise, a dose-dependent cytotoxicity was exerted by the standard solutions of cryptotanshinone, tanshinone I and tanshinone IIA, the major components of the group 5 fraction, where tanshinone IIA were most potent and displayed an IC₅₀ of 2.00 ± 0.36 μM and 2.75 ± 0.23 μM for A549 and TOV-21G, respectively. Induction of apoptosis represents an essential mechanism underlying tanshinone IIA-mediated cytotoxic action, as evidenced by the proteolytic processing of PARP upon tanshinone IIA stimulation and, importantly, a marked rescue of the viability of tanshinone IIA-treated cells when co-treatment with the pan-caspase inhibitor z-VAD-fmk. Noteworthy, stimulation with cryptotanshinone, tanshinone I or tanshinone IIA all effectively potentiated TRAIL to reduce viability and inhibit the colony formation capacity of TRAIL-resistant TOV-21G and SKOV3. Collectively, we revealed the proapoptotic and TRAIL-sensitizing components of S. miltiorrhiza and further implicated the potential of developing these active compounds as monotherapeutic agent or TRAIL-based therapy for cancer chemoprevention or chemotherapy.

Topics: Abietanes; Amino Acid Chloromethyl Ketones; Apoptosis; Caspase Inhibitors; Cell Division; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drugs, Chinese Herbal; Female; Humans; Inhibitory Concentration 50; Neoplasms; Phenanthrenes; Phenanthrolines; Plant Extracts; Poly(ADP-ribose) Polymerases; Salvia miltiorrhiza; TNF-Related Apoptosis-Inducing Ligand

Numerous studies have demonstrated that autophagy plays a vital role in maintaining cellular homeostasis. Interestingly, several anticancer agents were found to exert their anticancer effects by triggering autophagy. Emerging data suggest that autophagy represents a novel mechanism that can be exploited for therapeutic benefit. Pharmacologically active natural compounds such as those from marine, terrestrial plants and animals represent a promising resource for novel anticancer drugs. There are several prominent examples from the past proving the success of natural products and derivatives exhibiting anticancer activity. Helenalin, a sesquiterpene lactone has been demonstrated to have potent anti-inflammatory and antitumor activity. Albeit previous studies demonstrating helenalin's multi modal action on cellular proliferative and apoptosis, the mechanisms underlying its action are largely unexplained.. To deduce the mechanistic action of helenalin, cancer cells were treated with the drug at various concentrations and time intervals. Using western blot, FACS analysis, overexpression and knockdown studies, cellular signaling pathways were interrogated focusing on apoptosis and autophagy markers.. We show here that helenalin induces sub-G1 arrest, apoptosis, caspase cleavage and increases the levels of the autophagic markers. Suppression of caspase cleavage by the pan caspase inhibitor, Z-VAD-fmk, suppressed induction of LC3-B and Atg12 and reduced autophagic cell death, indicating caspase activity was essential for autophagic cell death induced by helenalin. Additionally, helenalin suppressed NF-κB p65 expression in a dose and time dependent manner. Exogenous overexpression of p65 was accompanied by reduced levels of cell death whereas siRNA mediated suppression led to augmented levels of caspase cleavage, autophagic cell death markers and increased cell death.. Taken together, these results show that helenalin mediated autophagic cell death entails inhibition of NF-κB p65, thus providing a promising approach for the treatment of cancers with aberrant activation of the NF-κB pathway.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents, Phytogenic; Apoptosis; Arnica; Autophagy; Autophagy-Related Protein 12; Caspases; Cell Line, Tumor; Dose-Response Relationship, Drug; G1 Phase; Humans; Microtubule-Associated Proteins; Neoplasms; Phytotherapy; Plant Extracts; Receptors, NK Cell Lectin-Like; RNA, Small Interfering; Sesquiterpenes; Sesquiterpenes, Guaiane; Small Ubiquitin-Related Modifier Proteins

Pregnane glycosides are potent cytotoxic agents which may represent new leads in the development of anti-tumour drugs, particularly in the treatment of breast cancer, because of the structural similarity to estrogenic agonists. Caralluma species are natural sources of a wide variety of pregnane glycosides. The aim of the study was to isolate, using an activity-guided fractionation approach, novel pregnane glycosides for testing on breast cancer and other tumour lines.. The effect of crude extracts, specific organic fractions and isolated compounds from Caralluma tuberculata was tested on the growth and viability of MCF-7 estrogen-dependent, and MDA-MB-468 estrogen-independent breast cancer cells, Caco-2 human colonic cells, HUVECs and U937 cells. Neutral red uptake and MTT assays were used. Apoptosis was detected by Western blot of poly-(ADP ribose) polymerase (PARP) as were other markers of nuclear fragmentation (DNA ladder assay, staining of cells with nuclear dye DAPI). The involvement of caspases was investigated using the pan-caspase inhibitor Z-VAD-FMK.. The ethyl acetate fraction of Caralluma tuberculata was found to be the most potent anti-proliferative fraction against all three cancer cell lines. Two novel steroidal glycosides were isolated from the active fraction after a series of chromatographic experiments. The structure of the isolated compounds was elucidated solely based on 2D-NMR (HMBC, HETCOR, DQF-COSY) and MS spectral analysis as compound 1: 12-O-benzoyl-20-O-acetyl-3β,12β,14β,20β-tetrahydroxy-pregnan-3-ylO-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1 → 4)-3-methoxy-β-D-ribopyranoside, and as compound 2: 7-O-acetyl-12-O-benzoyl-3β,7β,12β,14β-tetrahydroxy-17β-(3-methylbutyl-O-acetyl-1-yl)-androstan-3-ylO-β-D-glucopyranosyl-(1 → 4)-6-deoxy-β-D-allopyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1 → 4)-β-D-cymapyranosyl-(1→ 4)-β-D-cymaropyranoside. Compound 1 (pregnane glycoside) and compound 2 (androstan glycoside) induced apoptosis at <25 μM after 48 h as assessed by cell shrinkage, PARP cleavage, DNA fragmentation, and reversal with the caspase inhibitor.. Two novel steroid glycosides isolated from Caralluma tuberculata possess moderate, micromolar cytotoxic activity on breast cancer and other cells in vitro, which may indicate a source of activity in vivo of interest to future drug design.

Topics: Acylation; Amino Acid Chloromethyl Ketones; Androstanols; Antineoplastic Agents, Phytogenic; Apocynaceae; Apoptosis; Blotting, Western; Caco-2 Cells; Caspase Inhibitors; Caspases; Cell Proliferation; Cell Survival; Chemical Fractionation; Chromatography; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Glycosides; Human Umbilical Vein Endothelial Cells; Humans; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Structure; Neoplasms; Plants, Medicinal; Poly(ADP-ribose) Polymerases; Pregnanes; Structure-Activity Relationship; U937 Cells

We hypothesized that the basal apoptotic rate (BAR) of a cancer would predict sensitivity to subsequent proapoptotic stimuli. To explore this, preclinical and clinical BAR assays were developed measuring cumulative apoptotic events through ELISAs for soluble caspase-cleaved cytokeratin 18 (M30) normalized to either cell number increase or total tumor volume, respectively.. The BARs of A549, HCC44, and SW1573 non-small cell lung carcinoma cell lines were measured following different pro/antiapoptotic manipulations. In isogenic wild-type and stable knockdown (KD) series, pretreatment BARs were correlated with response to proapoptotic stimuli and compared with established apoptosis assays. Pretreatment and posttreatment serum was available from stereotactic body radiation therapy patients.. Caspase inhibition and p53 KDs reduced the BAR, whereas serum deprivation, XIAP, or Bcl2 KDs increased the BAR. The nontreated BAR rank ordering of the XIAP series recapitulated that with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and caspase-3/7 activity assays, and predicted each line's sensitivity to TRAIL or irradiation. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, however, underestimated basal apoptosis during increased apoptotic stress, and caspase-3/7 activity detected minimal death in the media. P53 KDs with lower nontreated BARs were less sensitive to TRAIL and cisplatinum than wild-type. Stereotactic body radiation therapy increased serum M30 values, and the pretreatment clinical BAR strongly correlated with fold change in M30 on treatment (r = 0.93).. M30-based BAR assays reflect apoptosis accurately and are more amenable to clinical application than existing apoptosis assays. The pretreatment BAR correlates with cell and/or tumor sensitivity to extrinsic and intrinsic apoptotic pathway stimulation. Prospective clinical exploration is warranted.

Topics: Adult; Aged; Aged, 80 and over; Amino Acid Chloromethyl Ketones; Apoptosis; Blotting, Western; Caspase 3; Caspase Inhibitors; Cell Line, Tumor; Cell Proliferation; Cysteine Proteinase Inhibitors; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoblotting; In Situ Nick-End Labeling; Keratin-18; Male; Middle Aged; Neoplasms; Prognosis; Proto-Oncogene Proteins c-bcl-2; RNA Interference; Signal Transduction; Tumor Suppressor Protein p53; X-Linked Inhibitor of Apoptosis Protein

MT110 is an EpCAM/CD3-bispecific antibody construct in clinical development for the treatment of patients with adenocarcinoma expressing EpCAM (CD326). Like other members of this antibody class, MT110 can engage resting, polyclonal CD8(+) and CD4(+) T cells for highly potent redirected lysis of target cells. Here we further explored the mechanism of this action. Complete lysis of EpCAM(+) Kato III gastric cancer cells by previously unstimulated T cells was achieved within 48 h. During this period, a high percentage of CD4(+) and CD8(+) T cells became activated and increased expression of granzyme B. This apparently boosted the capacity for serial target cell lysis as studied at very low effector-to-target ratios. Elimination of cancer cells by MT110-redirected T cells involved membrane damage as was evident from nuclear uptake of propidium iodide and release of the cytosolic enzyme adenylate kinase. Redirected T cells also potently triggered programmed cell death in cancer cells as was evident by membrane blebbing, activation of procaspases 3 and 7, fragmentation of nuclear DNA and cleavage of the caspase substrate poly (ADP ribose) polymerase. Chelation of extracellular calcium fully protected cancer cells from lysis by MT110-redirected T cells, while the pan-caspase inhibitor Z-VAD-FMK blocked activation of procaspases, cleavage of poly (ADP ribose) polymerase and fragmentation of nuclear DNA in cancer cells, but could not prevent nuclear uptake of propidium iodide. Soluble factors did not significantly contribute to cancer cell death. Our study shows that MT110 can efficiently gear up the potential of CD8(+) and CD4(+) T cells for serial lysis, and mediate kill of cancer cells predominantly through poreforming and pro-apoptotic components of cytotoxic T cell granules.

Topics: Adenylyl Cyclases; Amino Acid Chloromethyl Ketones; Antibodies, Monoclonal; Antigens, Neoplasm; Apoptosis; Caspase Inhibitors; CD3 Complex; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Cell Adhesion Molecules; Cell Line, Tumor; Collagen Type XI; Cytotoxicity, Immunologic; DNA Fragmentation; Epithelial Cell Adhesion Molecule; Granzymes; Humans; Lymphocyte Activation; Neoplasms; Single-Chain Antibodies

Despite recent advances in the management of breast and lung cancer, novel treatment strategies are still needed to further improve patient outcome. The targeting of cell death pathways has therefore been proposed to enhance therapeutic ratio in cancer. In this study, we examined the in vitro and in vivo effects of Z-VAD, a broad-spectrum caspase inhibitor, on breast and lung cancer in association with radiation. Using clonogenic assays, we observed that Z-VAD markedly radiosensitized breast and lung cancer cells, with a radiation dose enhancement ratio of 1.31 (P < 0.003). For both models, the enhanced tumor cytotoxicity was associated with induction of autophagy. Furthermore, we found that administration of Z-VAD with radiation in both breast and lung cancer xenograft produced a significant tumor growth delay compared with radiation alone and was well tolerated. Interestingly, Z-VAD also had dramatic antiangiogenic effect when combined with radiation both in vitro and in vivo and thus represents an attractive anticancer therapeutic strategy. In conclusion, this preclinical study supports the therapeutic potential of Z-VAD as a radiosensitizer in breast and lung cancer. This study also suggests caspase inhibition as a promising strategy to enhance the therapeutic ratio of radiation therapy in solid tumors. Therefore, clinical trials are needed to determine the potential of this combination therapy in cancer patients.

Topics: Amino Acid Chloromethyl Ketones; Animals; Autophagy; Caspase Inhibitors; Cell Line, Tumor; Cell Proliferation; Combined Modality Therapy; Female; Humans; Mice; Mice, Nude; Necrosis; Neoplasms; Neovascularization, Pathologic; Radiation Tolerance; Radiation-Sensitizing Agents; Xenograft Model Antitumor Assays

Cytotoxic lymphocytes are key players in the orchestration of immune response and elimination of defective cells. We have previously reported that natural killer (NK) cells enter target tumor cells, leading to either target cell death or self-destruction within tumor cells. However, it has remained elusive as to the fate of NK cells after internalization and whether the heterotypic cell-in-cell process is different from that of the homotypic cell-in-cell event recently named entosis. Here, we show that NK cells undergo a cell-in-cell process with the ultimate fate of apoptosis within tumor cells and reveal that the internalization process requires the actin cytoskeletal regulator, ezrin. To visualize how NK cells enter into tumor cells, we carried out real-time dual color imaging analyses of NK cell internalization into tumor cells. Surprisingly, most NK cells commit to programmed cell death after their entry into tumor cells, which is distinctively different from entosis observed in the homotypic cell-in-cell process. The apoptotic cell death of the internalized NK cells was evident by activation of caspase 3 and DNA fragmentation. Furthermore, NK cell death after internalization is attenuated by the caspase inhibitor, Z-VAD-FMK, confirming apoptosis as the mode of NK cell death within tumor cells. To determine protein factors essential for the entry of NK cells into tumor cells, we carried out siRNA-based knockdown analysis and discovered a critical role of ezrin in NK cell internalization. Importantly, PKA-mediated phosphorylation of ezrin promotes the NK cell internalization process. Our findings suggest a novel regulatory mechanism by which ezrin governs NK cell internalization into tumor cells.

Topics: Actins; Amino Acid Chloromethyl Ketones; Apoptosis; Caspase 3; Cell Line, Tumor; Cyclic AMP-Dependent Protein Kinases; Cytoskeletal Proteins; Cytoskeleton; DNA Fragmentation; Down-Regulation; Endocytosis; Enzyme Inhibitors; Gene Expression Regulation; Humans; Image Processing, Computer-Assisted; Killer Cells, Natural; Neoplasms; Phagocytosis; Phosphorylation; RNA, Small Interfering

Human telomerase reverse transcriptase (hTERT) is a catalytic enzyme that is required for telomerase activity (TA) and cancer progression. Telomerase inhibition or inactivation increases cellular sensitivity to UV irradiation, DNA-damaging agents, the tyrosine kinase inhibitor, imatinib, and pharmacological inhibitors, such as BIBR1532. hTERT is associated with apoptosis. Some patients show drug-resistance during anti-cancer drug treatment and the cancer cell acquire anti-apoptotic mechanism. Therefore, we attempted to study correlation between hTERT and drug-resistance.. To study the correlation between protein level and activity of hTERT and drug-resistance, Western blotting and telomerase repeat amplification protocol (TRAP) assays were performed. To investigate whether hTERT contributes to drug resistance in tumor cells, we transiently decreased hTERT levels using small interfering RNA (siRNA) in T24/R2 cells.. hTERT knockdown increased Bax translocation into the mitochondria and cytochrome C release into the cytosol. Caspase inhibitors, especially Z-VAD-FMK, rescued this phenomenon, suggesting that the stability or expression of hTERT might be regulated by caspase activity.. These data suggest that hTERT might be a target molecule for drug-resistant tumor therapy.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents; bcl-2-Associated X Protein; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cisplatin; Cysteine Proteinase Inhibitors; Cytochrome c Group; Drug Resistance, Neoplasm; Humans; Neoplasms; RNA, Small Interfering; Telomerase

The IgA Fc receptor (FcalphaRI) has dual proinflammatory and anti-inflammatory functions that are transmitted through the immunoreceptor tyrosine-based activation motifs (ITAMs) of the associated FcRgamma subunit. Whereas the involvement of FcalphaRI in inflammation is well documented, little is known of its anti-inflammatory mechanisms. Here we show that monomeric targeting of FcalphaRI by anti-FcalphaRI Fab or serum IgA triggers apoptosis in human monocytes, monocytic cell lines, and FcalphaRI+ transfectants. However, the physiologic ligand IgA induced apoptosis only when cells were cultured in low serum conditions, indicating differences with induction of anti-inflammatory signaling. Apoptosis signaling required the FcRgamma ITAM, as cells transfected with FcalphaRI or with a chimeric FcalphaRI-FcRgamma responded to death-activating signals, whereas cells expressing a mutated FcalphaRI(R209L) unable to associate with FcRgamma, or an ITAM-mutated chimeric FcalphaRI-FcRgamma, did not respond. FcalphaRI-mediated apoptosis signals were blocked by treatment with the pan-caspase inhibitor zVAD-fmk, involved proteolysis of procaspase-3, and correlated negatively with SHP-1 concentration. Anti-FcalphaRI Fab treatment of nude mice injected subcutaneously with FcalphaRI+ mast-cell transfectants prevented tumor development and halted the growth of established tumors. These findings demonstrate that, on monomeric targeting, FcalphaRI functions as an FcRgamma ITAM-dependent apoptotic module that may be fundamental for controlling inflammation and tumor growth.

Topics: Amino Acid Chloromethyl Ketones; Amino Acid Motifs; Animals; Antigens, CD; Apoptosis; Caspase 3; Cell Line, Tumor; Cells, Cultured; Culture Media, Serum-Free; Cysteine Proteinase Inhibitors; Enzyme Activation; Female; Humans; Immunoglobulin A; Immunoglobulin Fab Fragments; Inflammation; Leukemia, Basophilic, Acute; Mast Cells; Mice; Mice, Inbred C57BL; Mice, Nude; Mice, Transgenic; Neoplasms; Protein Tyrosine Phosphatase, Non-Receptor Type 6; Rats; Receptors, Fc; Receptors, IgG; Recombinant Fusion Proteins; RNA, Small Interfering; Skin Transplantation; Transfection

15-Deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), the terminal derivative of the PGJ series, is emerging as a potent antineoplastic agent among cyclopentenone prostaglandins derivatives and also known as the endogenous ligand of peroxisome proliferator-activated receptor gamma (PPARgamma). On the other hand, death receptor 5 (DR5) is a specific receptor for tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), which is one of the most promising candidates for new cancer therapeutics. Here, we report that 15d-PGJ(2) induces DR5 expression at both mRNA and protein levels, resulting in the synergistic sensitization of TRAIL-induced apoptosis in human neoplastic cells, such as Jurkat human leukemia cells or PC3 human prostate cancer cells. 15d-PGJ(2) significantly increased DR5 mRNA stability, whereas it did not activate DR5 promoter activity. Synthetic PPARgamma agonists, such as pioglitazone or rosiglitazone, did not mimic the DR5-inducing effects of 15d-PGJ(2), and a potent PPARgamma inhibitor GW9662 failed to block DR5 induction by 15d-PGJ(2), suggesting PPARgamma-independent mechanisms. Cotreatment with 15d-PGJ(2) and TRAIL enhanced the sequential activation of caspase-8, caspase-10, caspase-9, caspase-3, and Bid. DR5/Fc chimera protein, zVAD-fmk pancaspase inhibitor, and caspase-8 inhibitor efficiently blocked the activation of these apoptotic signal mediators and the induction of apoptotic cell death enhanced by cotreatment with 15d-PGJ(2) and TRAIL. Moreover, a double-stranded small interfering RNA targeting DR5 gene, which suppressed DR5 up-regulation by 15d-PGJ(2), significantly attenuated apoptosis induced by cotreatment with 15d-PGJ(2) and TRAIL. These results suggest that 15d-PGJ(2) is a potent sensitizer of TRAIL-mediated cancer therapeutics through DR5 up-regulation.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Apoptosis Regulatory Proteins; Caspases; Cell Line, Tumor; Drug Resistance, Neoplasm; Drug Synergism; Enzyme Activation; Gene Expression; Humans; Jurkat Cells; Membrane Glycoproteins; Neoplasms; Pioglitazone; PPAR gamma; Prostaglandin D2; Receptors, TNF-Related Apoptosis-Inducing Ligand; Receptors, Tumor Necrosis Factor; RNA Stability; RNA, Messenger; RNA, Small Interfering; Rosiglitazone; Thiazolidinediones; TNF-Related Apoptosis-Inducing Ligand; Tumor Necrosis Factor-alpha

The present study was undertaken to gain insights into the molecular mechanism of apoptosis induction by phenethyl isothiocyanate (PEITC) using prostate cancer cell lines derived from transgenic adenocarcinoma mouse prostate (TRAMP) mice (TRAMP-C1 and TRAMP-C2).. The viability of TRAMP-C1 and TRAMP-C2 cells was reduced significantly in the presence of PEITC in a concentration-dependent manner as determined by sulforhodamine B and trypan blue dye exclusion assays. Treatment of TRAMP-derived cells with PEITC revealed features characteristic of apoptosis induction, including appearance of subdiploid cells (determined by flow cytometry), cytoplasmic histone-associated DNA fragmentation (determined by an ELISA assay), and cleavage of caspase-3 (determined by immunoblotting). The PEITC-induced apoptosis in TRAMP-derived cells was associated with a marked increase in the level of proapoptotic protein Bak and/or a decrease in the levels of antiapoptotic protein Mcl-1 or Bcl-xL and disruption of mitochondrial membrane potential. The SV40 immortalized mouse embryonic fibroblasts derived from Bak and Bax double knockout mice were significantly more resistant to PEITC-induced DNA fragmentation compared with wild-type or Bak-/- mouse embryonic fibroblasts. The PEITC-induced apoptosis in both cell lines was significantly attenuated in the presence of caspase inhibitors zVAD-fmk, zLEHD-fmk, and zIETD-fmk. Oral administration of PEITC (9 or 12 micromol PEITC/d, Monday-Friday) significantly retarded growth of TRAMP-C1 xenografts in nude mice without causing weight loss or any other side effects.. The results of the present study indicate that caspase-dependent apoptosis by PEITC is mediated by Bak and Bax proteins.

Topics: Adenocarcinoma; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; bcl-2 Homologous Antagonist-Killer Protein; bcl-2-Associated X Protein; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cell Survival; Cysteine Proteinase Inhibitors; Dose-Response Relationship, Drug; Immunoblotting; Intracellular Membranes; Isothiocyanates; Male; Membrane Potentials; Membrane Proteins; Mice; Mice, Knockout; Mice, Transgenic; Mitochondria; Neoplasms; Plant Preparations; Prostatic Neoplasms; Proto-Oncogene Proteins c-bcl-2; Vegetables

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) might represent a future cytotoxic drug to treat cancer as it induces apoptosis in tumor cells without toxicity in animal trials. We recently described that in contrast to apoptosis, TRAIL mediates tumor cell survival and proliferation in certain tumor cells. Here we studied the effect of TRAIL on 18 cell lines and 53 primary leukemia cells and classified these tumor cells into four groups: TRAIL, anti-DR4 or anti-DR5 induced apoptosis in group A cells, whereas they had no effect on group 0 cells and mediated proliferation in group P cells. To our surprise, TRAIL induced simultaneous apoptosis and proliferation in group AP cells. More than 20% of all cells tested belonged to group P and showed TRAIL-mediated proliferation even in the presence of certain cytotoxic drugs but not inhibitors of nuclear factor-kappaB. Transfection with B-cell leukemia/lymphoma protein 2 transformed group A cells into group 0 cells, whereas transfection with Fas-associated polypeptide with death domain (FADD)-like interleukin-1-converting enzyme-inhibitory protein (FLIP) transformed them into group AP cells. Loss of caspase-8 or transfection of dominant-negative FADD transformed group A cells into group P cells. Taken together, our data suggest that proliferation is a frequent effect of TRAIL on tumor cells, which is related to receptor-proximal apoptosis defects at the level of the death-inducing signaling complex and should be prevented during antitumor therapy with TRAIL.

Topics: Adaptor Proteins, Signal Transducing; Amino Acid Chloromethyl Ketones; Animals; Apoptosis; Apoptosis Regulatory Proteins; CASP8 and FADD-Like Apoptosis Regulating Protein; Caspase 8; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cell Proliferation; Fas-Associated Death Domain Protein; HT29 Cells; Humans; Intracellular Signaling Peptides and Proteins; Leukemia; Membrane Glycoproteins; Mice; Neoplasms; TNF-Related Apoptosis-Inducing Ligand; Tumor Necrosis Factor-alpha

Systemic anticancer chemotherapy is immunosuppressive and mostly induces nonimmunogenic tumor cell death. Here, we show that even in the absence of any adjuvant, tumor cells dying in response to anthracyclins can elicit an effective antitumor immune response that suppresses the growth of inoculated tumors or leads to the regression of established neoplasia. Although both antracyclins and mitomycin C induced apoptosis with caspase activation, only anthracyclin-induced immunogenic cell death was immunogenic. Caspase inhibition by Z-VAD-fmk or transfection with the baculovirus inhibitor p35 did not inhibit doxorubicin (DX)-induced cell death, yet suppressed the immunogenicity of dying tumor cells in several rodent models of neoplasia. Depletion of dendritic cells (DCs) or CD8+T cells abolished the immune response against DX-treated apoptotic tumor cells in vivo. Caspase inhibition suppressed the capacity of DX-killed cells to be phagocytosed by DCs, yet had no effect on their capacity to elicit DC maturation. Freshly excised tumors became immunogenic upon DX treatment in vitro, and intratumoral inoculation of DX could trigger the regression of established tumors in immunocompetent mice. These results delineate a procedure for the generation of cancer vaccines and the stimulation of anti-neoplastic immune responses in vivo.

Topics: Amino Acid Chloromethyl Ketones; Animals; Antibiotics, Antineoplastic; Apoptosis; Caspase Inhibitors; Caspases; CD8-Positive T-Lymphocytes; Cell Line, Tumor; Dendritic Cells; Doxorubicin; Immunoblotting; In Situ Nick-End Labeling; Mice; Mitomycin; Neoplasms; Rats; Vaccination; Viral Proteins

Interferon alpha (IFNalpha) has been used in the treatment of several types of cancer for almost 30 years, yet the mechanism(s) responsible for its anti-tumoral action remains unknown. A variety of cellular responses, including inhibition of cell growth and induction of apoptosis are induced by IFNs, and apoptotic induction by this cytokine has been proposed to be of importance for both its anti-tumoral in addition to its anti-viral responses. The aim of the present study was to delineate the pathways activated during IFNalpha-induced apoptosis in malignant cell lines. We found that apoptosis induced by IFNalpha was associated with activation of caspases-1, -2, -3, -8 and -9 and that this activation was a critical event. Caspase-3 activation was dependent on activity of caspases-8 and -9, moreover, activation of caspase-8 seems to be the upstream event in IFNalpha-induced caspase cascade. We also found loss of mitochondrial membrane potential as well as release of cytochrome c post IFN-treatment, clearly implicating the involvement of mitochondria in IFN-mediated apoptosis. Furthermore, IFNalpha-induced apoptosis was found to be independent on interactions between the Fas-receptor and its ligand. These studies form the basis for further investigations aiming to improve IFN therapy and the development of future strategies to overcome the IFN resistance observed in some malignancies.

Topics: Amino Acid Chloromethyl Ketones; Annexin A5; Apoptosis; Blotting, Western; Caspase Inhibitors; Caspases; Cell Cycle; Cytochrome c Group; Enzyme Activation; fas Receptor; Flow Cytometry; Humans; Interferon-alpha; Mitochondria; Neoplasm Metastasis; Neoplasms; Signal Transduction; Tumor Cells, Cultured

Phenethyl isothiocyanate and allyl isothiocyanate induce apoptosis of human leukaemia HL60 cells in vitro. Apoptosis was associated with cleavage of p22 BID protein to p15, p13 and p11 fragments and activation of JNK and tyrosine phosphorylation (18 kDa and 45 kDa proteins). All these effects and apoptosis were prevented by exogenous glutathione (15 mM). Protein tyrosine phosphatase activity was unchanged. The general caspase inhibitor Z-VAD-fmk prevented apoptosis but not JNK activation - excluding a role for caspases in JNK activation, whereas curcumin prevented JNK activation but only delayed apoptosis. This suggests that in isothiocyanate-induced apoptosis, the caspase pathway has an essential role, the JNK pathway a supporting role, and inhibition of protein tyrosine phosphatases is not involved.

Topics: Amino Acid Chloromethyl Ketones; Anticarcinogenic Agents; Apoptosis; BH3 Interacting Domain Death Agonist Protein; Carrier Proteins; Cysteine Proteinase Inhibitors; Enzyme Activation; Enzyme Inhibitors; HL-60 Cells; Humans; Isothiocyanates; JNK Mitogen-Activated Protein Kinases; Mitogen-Activated Protein Kinases; Neoplasms; Phosphorylation; Phosphotyrosine; Signal Transduction

In addition to myelosuppression, anticancer drugs cause rapid and persistent depletion of lymphocytes, possibly by direct apoptosis induction in mature T and B cells. Induction of apoptosis regulators was analyzed in peripheral blood lymphocytes from pediatric patients undergoing first-cycle chemotherapy for solid tumors. In vivo chemotherapy induced a significant increase in lymphocyte apoptosis ex vivo. The activation of initiator caspase-8 and effector caspase-3 and the cleavage of caspase substrates was detected 12 to 48 hours after the onset of therapy. Caspase inhibition by Z-VAD-fmk did not reduce ex vivo lymphocyte apoptosis in all patients, indicating the additional involvement of caspase-independent cell death. No evidence for the involvement of activation-induced cell death was found in the acute phase of lymphocyte depletion as analyzed by activation marker expression and sensitivity for CD95 signaling. Lymphocyte apoptosis in vivo appeared to be predominantly mediated by the mitochondrial pathway because a marked decrease of mitochondrial membrane potential (DeltaPsi(M)) was detected after 24 to 72 hours of treatment, preceded by the increased expression of Bax. Interestingly, despite the use of DNA-damaging agents, p53 remained completely undetectable throughout treatment. In contrast, in vitro treatment with cytarabine and etoposide induced p53 protein, CD95 receptor expression, CD95 sensitivity, and CD95 receptor-ligand interaction in stimulated cycling lymphocytes, but no such induction was seen in resting cells. These data suggest that chemotherapy-induced lymphocyte depletion involves distinct mechanisms of apoptosis induction, such as direct mitochondrial and caspase-dependent pathways in resting cells and p53-dependent pathways in cycling lymphocytes.

Topics: Adolescent; Amino Acid Chloromethyl Ketones; Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Caspases; Cells, Cultured; Child; Child, Preschool; Cysteine Proteinase Inhibitors; DNA Damage; Enzyme Activation; fas Receptor; Gene Expression Regulation, Neoplastic; Humans; Infant; Intracellular Membranes; Lymphocyte Activation; Lymphocytes; Membrane Potentials; Mitochondria; Neoplasm Proteins; Neoplasms; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; T-Lymphocyte Subsets; Tumor Suppressor Protein p53

Inhibitors of proteases are currently emerging as a potential anti-cancer modality. Nonselective protease inhibitors are cytotoxic to leukemia and cancer cell lines and we found that this cytotoxicity is correlated with their potency as inhibitors of the proteasome but not as inhibitors of calpain and cathepsin. Highly selective inhibitors of the proteasome were more cytotoxic and fast-acting than less selective inhibitors (PS341>>ALLN>>ALLM). Induction of wt p53 correlated with inhibition of the proteasome and antiproliferative effect in MCF7, a breast cancer cell line, which was resistant to apoptosis caused by proteasome inhibitors. In contrast, inhibitors of the proteasome induced apoptosis in four leukemia cell lines lacking wt p53. The order of sensitivity of leukemia cells was: Jurkat>HL60> or =U937>>K562. The highly selective proteasome inhibitor PS-341 induced cell death with an IC50 as low as 5 nM in apoptosis-prone leukemia cells. Cell death was preceded by p21WAF1/CIP1 accumulation, an alternative marker of proteasome inhibition, and by cleavage of PARP and Rb proteins and nuclear fragmentation. Inhibition of caspases abrogated PARP cleavage and nuclear fragmentation and delayed, but did not completely prevent cell death caused by PS-341. Reintroduction of wt p53 into p53-null PC3 prostate carcinoma cells did not increase their sensitivity to proteasome inhibitors. Likewise, comparison of parental and p21-deficient cells demonstrated that p21WAF1/CIP1 was dispensable for proteasome inhibitor-induced cytotoxicity. We conclude that accumulation of wt p53 and induction of apoptosis are independent markers of proteasome inhibition.

Topics: Acetylcysteine; Acrylates; Amino Acid Chloromethyl Ketones; Apoptosis; Boronic Acids; Bortezomib; Calpain; Cathepsins; Cell Division; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Cysteine Endopeptidases; Drug Synergism; Genes, p53; Humans; Jurkat Cells; Leupeptins; Multienzyme Complexes; Neoplasm Proteins; Neoplasms; Oligopeptides; Protease Inhibitors; Proteasome Endopeptidase Complex; Pyrazines; Tumor Cells, Cultured; Tumor Suppressor Protein p53; U937 Cells

Apoptosis is a morphologically defined type of cell death associated with the activation of certain proteases belonging to the ICE/CED-3 family, known as caspases. Resistance to apoptosis has been implicated as one of the mechanisms that participates in oncogenesis. We found that the broad-spectrum peptide inhibitor of the caspases, zVAD-fmk, interferes in a dose-dependent way with all the morphological and biochemical changes associated with apoptosis induced by anti-CD95 mAb, staurosporine, VP-16 and Act-D. However, with the exception of anti-CD95-triggered apoptosis, the insulted cells lost their clonogenic potential, even when pre-treated with a high dose of zVAD-fmk. Under these circumstances, the dying cells displayed no signs of apoptosis, including activation of caspases, externalization of phosphatidylserine, nuclear condensation, or DNA fragmentation. Instead, this cell death was characterized by cytoplasmic and nuclear vacuolization followed by the loss of plasma membrane integrity. Thus, preventing the onset of apoptosis by blocking caspase activity did not rescue cells from dying in response to drugs such as staurosporine, VP-16 and Act-D. In comparison, ectopic expression of anti-apoptotic oncogenes such as bcl-2 and bcr-abl not only inhibited apoptosis but also preserved the clonogenic potential of the cells. Therefore, oncogenesis is promoted not by simply interfering with caspase-mediated apoptosis, but by preventing an upstream event which we define as the commitment point for cell death.

Topics: Amino Acid Chloromethyl Ketones; Antibodies, Monoclonal; Apoptosis; Caspase Inhibitors; Caspases; Cysteine Proteinase Inhibitors; Dactinomycin; Enzyme Activation; Etoposide; fas Receptor; HL-60 Cells; Humans; Jurkat Cells; Neoplasms; Oncogenes; Staurosporine