benzyloxycarbonylleucyl-leucyl-leucine-aldehyde and Leukemia

Topics: Animals; Antineoplastic Agents; Chromones; Hematopoietic Stem Cell Transplantation; Humans; Leukemia; Leupeptins; Morpholines; Neoplastic Stem Cells; NF-kappa B; Phosphoinositide-3 Kinase Inhibitors

Proteolysis Targeting Chimeras (PROTACs) based on multi-target inhibitors have been reported several times recently. The advantages of PROTACs technology and the synergistic mechanism of multi-target drugs endow this class of protein degraders with special research significance. Herein, twelve new PROTACs based on Sunitinib and VHL-ligand were synthesized and evaluated for their in vitro anticancer activities. Among them, PROTACs 5 (IC

Topics: HL-60 Cells; Humans; Leukemia; Proteasome Endopeptidase Complex; Proteolysis; Sunitinib

Heat shock protein 90 (HSP90) is a molecular chaperone that supports the stability of client proteins. The proteasome is one of the targets for cancer therapy, and studies are underway to use proteasome inhibitors as anti-cancer drugs. In this study, we found that HSP90 was cleaved to a 55kDa protein after treatment with proteasome inhibitors including MG132 in leukemia cells but was not cleaved in other tissue-derived cells. HSP90 has two major isoforms (HSP90α and HSP90β), and both were cleaved by MG132 treatment. MG132 treatment also induced a decrease in HSP90 client proteins. MG132 treatment generated ROS, and the cleavage of HSP90 was blocked by a ROS scavenger, N-acetylcysteine (NAC). MG132 activated several caspases, and the activation was reduced by pretreatment with NAC. Based on an inhibitor study, the cleavage of HSP90 induced by MG132 was dependent on caspase 10 activation. Furthermore, active recombinant caspase 10 induced HSP90 cleavage in vitro. MG132 upregulated VDUP-1 expression and reduced the GSH levels implying that the regulation of redox-related proteins is involved. Taken all together, our results suggest that the cleavage of HSP90 by MG132 treatment is mediated by ROS generation and caspase 10 activation. HSP90 cleavage may provide an additional mechanism involved in the anti-cancer effects of proteasome inhibitors.

Topics: Acetylcysteine; Carrier Proteins; Caspase 10; Free Radical Scavengers; Glutathione; HCT116 Cells; HSP90 Heat-Shock Proteins; HT29 Cells; Humans; Leukemia; Leupeptins; MCF-7 Cells; Protease Inhibitors; Proteolysis; Reactive Oxygen Species

The ability to modulate balance between cell survival and death is recognized for its great therapeutic potential. Therefore, research continues to focus on elucidation of cell machinery and signaling pathways that control cell proliferation and apoptosis. Conventional chemotherapeutic agents often have a cytostatic effect over tumor cells. New natural or synthetic chemotherapeutic agents have a wider spectrum of interesting antitumor activities that merit in-depth studies. In the present work, we aimed at characterizing the molecular mechanism leading to induction of cell death upon treatment of the lymphoblastoid cell line PL104 with caffeic acid phenylethyl ester (CAPE), MG132 and two conventional chemotherapeutic agents, doxorubicine (DOX) and vincristine (VCR). Our results showed several apoptotic hallmarks such as phosphatidylserine (PS) exposure on the outer leaflet of the cell membrane, nuclear fragmentation, and increase sub-G1 DNA content after all treatments. In addition, all four drugs downregulated survivin expression. CAPE and both chemotherapeutic agents reduced Bcl-2, while only CAPE and MG132 significantly increased Bax level. CAPE and VCR treatment induced the collapse of mitochondrial membrane potential (∆ψm). All compounds induced cytochrome c release from mitochondrial compartment to cytosol. However, only MG132 caused the translocation of Smac/DIABLO. Except for VCR treatment, all other drugs increased reactive oxygen species (ROS) production level. All treatments induced activation of caspases 3/7, but only CAPE and MG132 led to the activation of caspase 9. In conclusion, our results indicate that CAPE and MG132 treatment of PL104 cells induced apoptosis through the mitochondrial intrinsic pathway, whereas the apoptotic mechanism induced by DOX and VCR may proceed through the extrinsic pathway.

Topics: Adolescent; Adult; Antineoplastic Agents; Apoptosis; Caffeic Acids; Child; Child, Preschool; Drugs, Investigational; Female; Humans; Leukemia; Leupeptins; Male; Middle Aged; Mitochondria; Phenylethyl Alcohol; Tumor Cells, Cultured; Young Adult

Proteasomes are highly expressed in rapidly growing neoplastic cells and essential for controlling the cell cycle process and mitochondrial homeostasis. Pharmacological inhibition of the proteasome shows a significant anticancer effect on hematopoietic malignancies that is usually associated with the generation of reactive oxygen species. In this study, we comprehensively investigated the role of endogenous oxidants in various cellular events of K562 leukemic cells in response to treatment with MG132, a proteasome inhibitor. MG132 at 1.4 µM potently triggered G2/M arrest, mitochondrial depolarization, and apoptosis. By such treatment, the protein level of inducible nitric oxide synthase (iNOS) was doubled and cellular oxidants, including nitric oxide, superoxide, and their derivatives, were increasingly produced. In MG132-treated cells, the increase in iNOS-derived oxidants was responsible for mitochondrial depolarization and caspase-dependent apoptosis, but was insignificant in G2/M arrest. The amount of iNOS was negatively correlated with that of manganese superoxide dismutase (MnSOD). Whereas iNOS activity was inhibited by aminoguanidine, cellular MnSOD levels as well as mitochondrial membrane potentials were upregulated, and consequentially G2/M arrest and apoptosis were thoroughly reversed. It is suggested that cells rich in functional mitochondria possess improved proteasome activity, which antagonizes the cytotoxic and cytostatic effects of MG132. In contrast to iNOS, endothelial NOS-driven cGMP-dependent signaling promoted mitochondrial function and survival of MG132-stressed cells. In conclusion, the functional interplay of proteasomes and mitochondria is crucial for leukemic cell growth, wherein iNOS plays a key role.

Topics: Apoptosis; Caspases; Cyclic GMP; Cysteine Proteinase Inhibitors; G2 Phase Cell Cycle Checkpoints; Humans; K562 Cells; Leukemia; Leupeptins; Membrane Potential, Mitochondrial; Mitochondria; Nitric Oxide; Nitric Oxide Synthase Type II; Proteasome Endopeptidase Complex; Signal Transduction; Superoxide Dismutase

In Oncology, the resistance of the cancerous cells to chemotherapy continues to be the principal limitation. The nuclear factor-kappa B (NF-κB) transcription factor plays an important role in tumor escape and resistance to chemotherapy and this factor regulates several pathways that promote tumor survival including some antiapoptotic proteins such as Bcl-2 and Bcl-XL. In this study, we investigated, in U937 human leukemia cells, the effects of PTX and the MG132 proteasome inhibitor, drugs that can disrupt the NF-κB pathway. For this, we evaluated viability, apoptosis, cell cycle, caspases-3, -8, -9, cytochrome c release, mitochondrial membrane potential loss, p65 phosphorylation, and the modification in the expression of pro- and antiapoptotic genes, and the Bcl-2 and Bcl-XL antiapoptotic proteins.. The two drugs affect the viability of the leukemia cells in a time-dependent manner. The greatest percentage of apoptosis was obtained with a combination of the drugs; likewise, PTX and MG132 induce G1 phase cell cycle arrest and cleavage of caspases -3,-8, -9 and cytochrome c release and mitochondrial membrane potential loss in U937 human leukemia cells. In these cells, PTX and the MG132 proteasome inhibitor decrease p65 (NF-κB subunit) phosphorylation and the antiapoptotic proteins Bcl-2 and Bcl-XL. We also observed, with a combination of these drugs overexpression of a group of the proapoptotic genes BAX, DIABLO, and FAS while the genes BCL-XL, MCL-1, survivin, IκB, and P65 were downregulated.. The two drugs used induce apoptosis per se, this cytotoxicity was greater with combination of both drugs. These observations are related with the caspases -9, -3 cleavage and G1 phase cell cycle arrest, and a decrease in p65 phosphorylation and Bcl-2 and Bcl-XL proteins. As well as this combination of drugs promotes the upregulation of the proapoptotic genes and downregulation of antiapoptotic genes. These observations strongly confirm antileukemic potential.

Topics: Apoptosis; bcl-X Protein; Carrier Proteins; Gene Expression Regulation, Leukemic; Humans; Intracellular Signaling Peptides and Proteins; Leukemia; Leupeptins; Neoplasm Proteins; NF-kappa B; Pentoxifylline; Phosphorylation; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; U937 Cells

A growing body of evidence suggests the inhibition of NFkappaB as a strategy to induce cell death in tumor cells. In this work, we evaluated the effects of the pharmacological NFkappaB inhibitors BAY117082 and MG132 on leukemia cells apoptosis. BAY117082 and MG132 presented potent apoptotic effects compared to inhibitors of MAPKs, EGFR, PI3K/Akt, PKC and PKA signaling pathways. Non-tumor peripheral blood cells were insensitive to BAY117082 and MG132 apoptotic effects. BAY117082 and MG132-induced apoptosis was dependent on their ability to increase ROS as a prelude to mitochondria membrane potential (MMP) depolarization, permeability transition pore opening and cytochrome c release. Antioxidants blocked MG132 and BAY117082 effects on ROS, MMP and cell death. Although apoptotic markers as phosphatidylserine externalization, chromatin condensation and sub-G1 were detected in BAY117082-treated cells, caspases activation did not occur and apoptosis was insensitive to caspase inhibitors, suggesting a caspase-independent mechanism. In contrast, MG132 induced classical apoptosis through ROS-mitochondria and subsequent caspase-9/caspase-3 activation. At sub-apoptotic concentrations, BAY117082 and MG132 arrested cells in G2/M phase of the cell cycle and blocked doxorubicin-induced NFkappaB, which sensitized doxorubicin-resistant cells. Data suggest that the NFkappaB inhibitors MG132 and BAY117082 are potential anti-leukemia agents.

Topics: Antibiotics, Antineoplastic; Antineoplastic Agents; Apoptosis; Caspases; Cell Proliferation; Cytochromes c; Dose-Response Relationship, Drug; Doxorubicin; Drug Resistance, Neoplasm; Enzyme Activation; Humans; Jurkat Cells; K562 Cells; Leukemia; Leupeptins; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; NF-kappa B; Nitriles; Reactive Oxygen Species; Sulfones; Time Factors; U937 Cells

To investigate the role of proteasome inhibitors MG132 in the inducing the expression of the costimulatory molecules CD80 and CD86 in leukemia cells and its effect on allogeneic mixed lymphocyte reaction.. Acute myelocytic leukemia cells of the line HL-60 and chronic myelocytic leukemia cells of the line K562 were cultured. 7-AAD staining and flow cytometry (FC) were used to examine the viability of the cells. MG132, a proteasome inhibitor, of the concentrations of 2 or 3 micromol/L was added into the culture fluid of HL-60 cells for 24 h and 48 h respectively and then annexin V/7-AAD staining and FC were used to detect the apoptosis of the cells. HL-60 and K562 cells treated with 1 micromol/L MG132 for 24 h and 48 h respectively, anti-CD80 and anti-CD86 antibodies were added, then FC was used to detect the expression of CD80 and CD86. The mRNA expression of CD86 in the HL-60 cells treated with 1 micromol/L MG132 was examined by RT-PCR. HL-60 and K562 cells were treated by 1 micromol/L MG132 for 48 h and then underwent irradiation of 75 Gy Co-60 to kill the cells with their antigenicity preserved. Peripheral blood mononuclear cells (PBMNC) of healthy volunteers, as reactive cells, were isolated and inoculated into the Co-60 treated HL-60 and K532 cells of different concentrations, as stimulating cells, for 5 d, CCK-8, a new agent to detect the cell viability, was added for 4 h, and then the A value of absorbance was measured at the wave length of 450 nm of enzyme labeling instrument. Control groups were set up for all tests.. The cell viability rates of the HL-60 cell treated with 1 micromol/L MG132 for 24 h and 48 h were 92.95% and 85.87% respectively. The apoptotic rats of the HL-60 cells treated with MG132 were increased dose- and time-dependently. Before MG132 treatment K562 cells did not express CD86, and the CD86 expression of the HL-60 cells was up-regulated time-dependently (all P < 0.01). The mRNA expression of CD86 in the HL-60 treated with MG132 was up-regulated time-dependently (P < 0.01). CKK8 test showed that the proliferation level of PBMNC gradually increased along with the concentration of HL-60 cells treated with MG132 and reached its peak when the concentration of the HL-60 cells was 1 x 10(5) (P < 0.01). No remarkable proliferation of PBMNC was seen in the K562 groups no matter if the HL-60 cells had been treated with MG132.. MG132 induces the expression of costimulatory molecule CD86 in the HL-60 cells, thus improving the proliferation of PBMNC.

Topics: Apoptosis; B7-1 Antigen; B7-2 Antigen; Cell Proliferation; Cell Survival; Cells, Cultured; Coculture Techniques; Cysteine Proteinase Inhibitors; Flow Cytometry; Gene Expression Regulation, Leukemic; HL-60 Cells; Humans; K562 Cells; Leukemia; Leukocytes, Mononuclear; Leupeptins; Proteasome Inhibitors; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

Curcumin, the active chemical of the Asian spice turmeric, exhibits anticancer activity in several human cancer cell lines. We previously have proved that curcumin was a new member of the histone deacetylases (HDAC) inhibitors, while constitutive nuclear factor kappa B (NF-kappaB) is believed to be a crucial event for enhanced proliferation and survival of malignant cells. Here, we investigate the effect of curcumin on the activation of NF-kappaB signal molecule in Raji cells to explore its relationship with HDACs or p300/CREB binding protein (CBP). Curcumin presented striking proliferation inhibition potency on Raji cells in vitro, with the IC(50) value for 24 hr being 25 micromol/l. Significant decreases in the amounts of p300, HDAC1 and HDAC3 were detected after treatment with curcumin. These suppressing effects were more pronounced when the administered dose increased. The protection degradation of HDAC1 and p300 by MG-132 could be partially reversed by curcumin. Furthermore, curcumin could also prevent degradation of I kappaB alpha and inhibit nuclear translocation of the NF-kappaB/p65 subunit, as well as expression of Notch 1, induced by tumour necrosis factor-alpha. The results suggest that the depressive effect of curcumin on NF-kappaB signal transduction pathway may be mediated via the various components of the HDACs and p300/Notch 1 signal molecules, and may represent a new remedy for acute leukaemia.

Topics: Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; CREB-Binding Protein; Curcumin; Dose-Response Relationship, Drug; E1A-Associated p300 Protein; Gene Expression Regulation; Histone Deacetylase 1; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; I-kappa B Proteins; Inhibitory Concentration 50; Leukemia; Leupeptins; NF-kappa B; NF-KappaB Inhibitor alpha; Receptor, Notch1; Signal Transduction; Transcription Factor RelA; Tumor Necrosis Factor-alpha

The house dust mite (HDM) is considered to be the most common indoor allergen associated with bronchial asthma. In this study, we investigated whether crude extract of the HDM Dermatophagoides farinae could activate human eosinophilic leukemic cells (EoL-1) to induce upregulation of cell-surface adhesion molecules. When EoL-1 cells were incubated with D. farinae extract, expression of intercellular adhesion molecule-1 (ICAM-1) significantly increased on the cell surfaces compared to cells incubated with medium alone. In contrast, surface expression of CD11b and CD49d in EoL-1 cells was not affected by D. farinae extract. In addition, pretreatment of cells with NF-kappaB inhibitor (MG-132) or JNK inhibitor (SP600125) significantly inhibited ICAM-1 expression promoted by HDM extract. However, neither p38 MAP kinase inhibitor nor MEK inhibitor prevented HDM-induced ICAM-1 expression in EoL-1 cells. These results suggest that crude extract of D. farinae induces ICAM-1 expression in EoL-1 cells through signaling pathways involving both NF-kappaB and JNK.

Topics: Animals; Anthracenes; CD11b Antigen; Cell Line, Tumor; Cell Membrane; Eosinophils; Flow Cytometry; Gene Expression Regulation; Humans; Integrin alpha4; Intercellular Adhesion Molecule-1; Leukemia; Leupeptins; Mitogen-Activated Protein Kinase 8; NF-kappa B; p38 Mitogen-Activated Protein Kinases; Pyroglyphidae

SHP-1 has been proposed to be a tumor suppressor gene for several cancers. The expression of SHP-1 protein is diminished or abolished in most leukemia and lymphoma cell lines and tissues, and in some non-hematopoietic cancer cell lines, such as estrogen receptor (ER) negative breast cancer cell lines and some colorectal cancer cell lines. However, we do not know whether the reduced SHP-1 expression is the cause of cancer diseases or the secondary effect of cancer developments. Here, we first demonstrate that SHP-1 has general tumor suppressing function in SHP-1 transfected cell lines. Transfected SHP-1 inhibits the growth of three lymphoma/leukemia cell lines (Ramos, H9, Jurkat) and one breast cancer cell line (HTB26). We also demonstrate a possible molecular mechanism for the tumor suppressing function of SHP-1: SHP-1 inhibits cell growth partly by negative regulation of activated JAK kinase. In addition, we find, for the first time, that SHP-1 down-regulates the level of TYK2 kinase in H9 cells and of JAK1 kinase in HTB26 cells, by accelerating their degradation. The SHP-1 accelerated degradation of JAK1 kinase in HTB26 cells was blocked with the treatment of MG132, a specific inhibitor for proteasome-mediated proteolysis. Our data suggest a new function of SHP-1 in the regulation of proteasome-mediated degradation pathway.

Topics: Breast Neoplasms; Cell Division; Cysteine Proteinase Inhibitors; Down-Regulation; Female; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Intracellular Signaling Peptides and Proteins; Janus Kinase 1; Leukemia; Leupeptins; Lymphoma; Protein Tyrosine Phosphatase, Non-Receptor Type 6; Protein Tyrosine Phosphatases; Protein-Tyrosine Kinases; src Homology Domains; Transfection; Tumor Cells, Cultured; TYK2 Kinase

The 26S proteasome is a non-lysosomal multicatalytic protease complex for degrading intracellular proteins by ATP/ubiquitin-dependent proteolysis. Tightly ordered proteasomal degradation of proteins critical for cell cycle control implies a role of the proteasome in maintaining cell proliferation and cell survival. In this study, we demonstrate that cell-permeable proteasome inhibitors, lactacystin, benzyloxycarbonyl(Z)-leucyl-leucyl-leucinal (ZLLLal; MG-132) and 4-hydroxy-5-iodo-3-nitrophenylacetyl-leucyl-leucyl-leucine vinyl sulfone (NLVS), induce apoptosis abundantly in p53-defective leukemic cell lines CCRF-CEM, U937 and K562 as well as in myelogenic and lymphatic leukemic cells obtained from adult individuals with relapsed acute leukemias. Leukemic cell apoptosis induced by the proteasome inhibitors was dependent on activation of caspase-3 and related caspase family proteases, because caspase-3 inhibitor N-acetyl-L-aspartyl-L-glutamyl-L-valyl-L-aspartal (Ac-DEVD-cho) and, more effectively, the general caspase-inhibitor N-benzyloxycarbonyl-L-valyl-L-alanyl-L-aspartate fluoromethylketone (Z-VAD-fmk) were capable of blocking apoptosis induced by lactacystin, ZLLLal or NLVS. Induction of apoptosis by lactacystin or ZLLLal was accompanied by cell cycle arrest at G2/M phase and by accumulation and stabilization of cyclin-dependent kinase inhibitor p21WAF1/Cip and tumor suppressor protein p53. A role of p53 in mediating apoptosis or induction of p21WAF1/Cip1 was ruled out since CCRF-CEM and U937 cells express non-functional mutant p53, and K562 cells lack expression of p53. Viability and hematopoietic outgrowth of human CD34+ progenitor cells treated with lactacystin were slightly reduced, whereas treatment of CD34 + cells with ZLLLal or the cytostatic drugs doxorubicin and gemcitabine resulted in markedly reduced viability and hematopoietic outgrowth. These results demonstrate a basic role of the proteasome in maintaining survival of human leukemic cells, and may define cell-permeable proteasome inhibitors as potently anti-leukemic agents which exhibit a moderate hematopoietic toxicity in vitro.

Topics: Acetylcysteine; Acute Disease; Adult; Antigens, CD34; Apoptosis; Caspase 3; Caspases; Cell Culture Techniques; Cell Cycle; Cell Division; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Cysteine Proteinase Inhibitors; Enzyme Inhibitors; Flow Cytometry; G2 Phase; Hematopoietic Stem Cells; Humans; K562 Cells; Leukemia; Leupeptins; Mitosis; Multienzyme Complexes; Neoplasm Proteins; Tumor Cells, Cultured; Tumor Suppressor Protein p53; U937 Cells

The ubiquitin-proteasome pathway is the principal mechanism for the degradation of short-lived proteins in eukaryotic cells. Here we examine the possibility that ubiquitin-proteasome is involved in regulating the levels of Bcl-2, which is abundantly expressed in M-07e cells, a granulocyte/macrophage colony-stimulating factor (GM-CSF)-dependent human leukaemic cell line. Apoptosis in M-07e cells, induced by GM-CSF withdrawal, was associated with a gradual cleavage of Bcl-2 into a 22 kDa fragment. Treatment of M-07e cells with benzyloxycarbonyl-Leu-Leu-l-leucinal (Z-LLL-CHO; MG-132), a reversible ubiquitin-proteasome inhibitor, markedly accelerated the cleavage of Bcl-2 and promoted cell death through the apoptotic pathway. The cleavage of Bcl-2 was inhibited by a caspase-3 (CPP32)-specific inhibitor [acetyl-Asp-Glu-Val-Asp-CHO (DEVD-CHO)] but not caspase 1 inhibitor (acetyl-Tyr-Val-Ala-Asp-CHO), suggesting that Bcl-2 is a proteolytic substrate of a caspase-3-like protease activated during apoptosis. The simultaneous addition of recombinant human GM-CSF (rhGM-CSF) to M-07e cultures delayed the activation of caspase 3 and Bcl-2 cleavage triggered by Z-LLL-CHO, suggesting that the activation of the GM-CSF signalling pathway can partly overcome the apoptotic effect induced by Z-LLL-CHO. Apoptosis induced by inhibition of the proteasome pathway was verified in studies with lactacystin, a highly specific and irreversible proteasome inhibitor. Lactacystin-induced apoptosis in M-07e cells was remarkably similar to that induced by Z-LLL-CHO, which included caspase 3 activation, cleavage of Bcl-2 into a 22 kDa fragment and, ultimately, cell death. These results showed that inhibition of the ubiquitin-proteasome pathways can lead to the activation of a DEVD-CHO-sensitive caspase and induces Bcl-2 cleavage, which might have a role in mediating apoptosis in M-07e cells.

Topics: Acetylcysteine; Apoptosis; Caspase 3; Caspase Inhibitors; Caspases; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Enzyme Activation; Enzyme Precursors; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Leukemia; Leupeptins; Molecular Weight; Multienzyme Complexes; Oligopeptides; Proteasome Endopeptidase Complex; Proto-Oncogene Proteins c-bcl-2; Recombinant Proteins; Signal Transduction; Time Factors; Tumor Cells, Cultured; Ubiquitins