Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthetic oleanane triterpenoid 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and its chemical derivatives induce differentiation and apoptosis of human leukemia cells. The precise mechanisms responsible for the effects of CDDO, however, remain unclear. In the present study, we examined the effects of CDDO and its C-28 imidazolide ester (CDDO-Im) on apoptosis of multiple myeloma (MM) cells. The results show that both CDDO and CDDO-Im are potent inducers of MM cell apoptosis and that CDDO-Im is more active than CDDO. CDDO-Im treatment was associated with (a) depletion of glutathione, (b) increases in reactive oxygen species, (c) a reduction of the Fas-associated death domain (FADD)-like interleukin-1-converting enzyme (FLICE) inhibitory protein, (d) activation of caspase-8, and (e) a decrease of the mitochondrial transmembrane potential. The reducing agents, N-acetyl-L-cysteine, DTT, and catalase inhibited each of these CDDO-Im-induced proapoptotic signals. Inhibition of caspase-8 with z-IETD-fmk also abrogated CDDO-Im-induced decreases of the mitochondrial transmembrane potential and inhibited apoptosis. These results demonstrate that CDDO-Im disrupts intracellular redox balance and thereby activates the extrinsic caspase-8-dependent apoptotic pathway. We further show that CDDO-Im induces apoptosis of primary MM cells at submicromolar concentrations and that MM cells are more sensitive to this agent than normal bone marrow mononuclear cells. These results suggest that CDDO compounds have potential as new agents for the treatment of MM.
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PMID:Induction of redox imbalance and apoptosis in multiple myeloma cells by the novel triterpenoid 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid. 1474 74

Capsaicin (N-vanillyl-8-methyl-1-nonenamide) is a homovanillic acid derivative found in pungent fruits. Several investigators have reported the ability of capsaicin to inhibit events associated with the promotion of cancer. However, the effects of capsaicin on human leukemic cells have never been investigated. We investigated the effects of capsaicin on leukemic cells in vitro and in vivo and further examined the molecular mechanisms of capsaicin-induced apoptosis in myeloid leukemic cells. Capsaicin suppressed the growth of leukemic cells, but not normal bone marrow mononuclear cells, via induction of G(0)-G(1) phase cell cycle arrest and apoptosis. Capsaicin-induced apoptosis was in association with the elevation of intracellular reactive oxygen species production. Interestingly, capsaicin-sensitive leukemic cells were possessed of wild-type p53, resulting in the phosphorylation of p53 at the Ser-15 residue by the treatment of capsaicin. Abrogation of p53 expression by the antisense oligonucleotides significantly attenuated capsaicin-induced cell cycle arrest and apoptosis. Pretreatment with the antioxidant N-acetyl-L-cystein and catalase, but not superoxide dismutase, completely inhibited capsaicin-induced apoptosis by inhibiting phosphorylation of Ser-15 residue of p53. Moreover, capsaicin effectively inhibited tumor growth and induced apoptosis in vivo using NOD/SCID mice with no toxic effects. We conclude that capsaicin has potential as a novel therapeutic agent for the treatment of leukemia.
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PMID:Induction of apoptosis in leukemic cells by homovanillic acid derivative, capsaicin, through oxidative stress: implication of phosphorylation of p53 at Ser-15 residue by reactive oxygen species. 1487 40

The cytotoxicity and apoptosis-inducing activity of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and 2-tert-butyl-4-methylphenol (BMP) and the mixture of BHA and BHT (BHA/BHT) (1:1, molar ratio) were investigated, using human promeylocytic leukemia cell lines (HL-60) and human squamous cell carcinoma cell lines (HSC-2). The 50% cytotoxic concentration (CC50) declined in the order of BHA, BHT (0.2-0.3 mM) > BHA/BHT (0.04-0.07 mM) > BMP (0.02-0.05 mM). The addition of antioxidants (N-acetyl-Lcysteine, sodium ascorbate, catalase) reduced the cytotoxicity of BHA/BHT or BMP against HSC-2 cells, but not that of BHA or BHT, whereas the addition of NADH, a quinone reductase to BMP, enhanced the cytotoxicity. These findings suggested that the cytotoxicity of BHA/BHT and BMP might be caused by reactive intermediates. BHA-induced cytotoxicity was enhanced by horseradish peroxidases, suggesting that BHA was oxidizable and produced cytotoxic BHA radicals. Internucleosomal DNA fragmentation of HL-60 cells was preferably induced by BHA/BHT and BMP, followed by BHA. The MnSOD mRNA expression in HL-60 cells assayed by reverse transcriptase-polymerase chain reaction was highly inhibited by BHA/BHT or BMP, accompanied by the change in the electrophoretic mobility of MnSOD on polyacryamide gel. These compounds activated caspase-3, 8 and 9 in HL-60 cells. Activations of caspases, particularly caspase-3, declined in the order of BHA/BHT > BHA > BMP > BHT. The most cytotoxic BMP activated caspase-3 activity to the least extent, possibly in part due to the occurrence of necrosis. The great cytotoxicity and apoptosis induction by BHA/BHT may be due to reactive intermediates derived from the interaction between BHA phenoxyl radical and BHT or BHT phenoxyl radical.
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PMID:Cytotoxicity and apoptosis induction by butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). 1498 15

Clinical application of anticancer agents has been often hampered by toxicity against normal cells, so the achievement of their cancer-specific action is still one of the major challenges to be addressed. Previously, we reported that arsenic trioxide (As2O3) could be a promising new drug against not only leukemia but also solid tumors. The cytotoxicity of As2O3 occurred through the generation of reactive oxygen species (ROS), thus inhibiting radical scavenging systems would enhance the therapeutic efficacy of As2O3 provided that normal cells were relatively resistant to such a measure. Here, we report that the combination therapy of As2O3 with L-buthionine-sulfoximine (BSO), which inhibits a critical step in glutathione synthesis, effectively enhanced in vitro growth inhibition effect of As2O3 on all 11 investigated cell lines arising from prostate, breast, lung, colon, cervix, bladder, and kidney cancers, compared with As2O3 treatment alone. Furthermore, this combination enhanced cytotoxicity to cell lines from prostate cancer with less toxicity to those from normal prostate. In vitro cytotoxic assay using ROS-related compounds demonstrated that hydrogen peroxide (H2O2) is a major cytotoxic mediator among ROS molecules. Biochemical analysis showed that combined use of As2O3 and BSO blocked H2O2-scavenging systems including glutathione, catalase, and glutathione peroxidase, and that the degree of this blockade was well correlated with intracellular ROS levels and sensitivity to this treatment. Finally, the effectiveness of the combination therapy of As2O3 with BSO was demonstrated with an orthotopic model of prostate cancer metastasis. We propose that the combination therapy of As2O3 with BSO is a valid means of blockade of H2O2-scavenging system, and that the combination of a ROS-generating agent with an inhibitor of major scavenging systems is effective in terms of both efficacy and selectivity. Furthermore, because the effective doses of both compounds are within clinically achievable range, this report will lead to immediate benefit for the development of a new cancer therapy.
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PMID:Effective treatment of advanced solid tumors by the combination of arsenic trioxide and L-buthionine-sulfoximine. 1500 36

Previous studies demonstrated that hydroxyl groups play important roles in the antioxidative activities of flavonoids; however, the importance of structurally related hydroxylation in their apoptosis-inducing activities is still undefined. In the present study, flavanone with hydroxylation at C4' and C6 had a significant cytotoxic effect in human leukemia HL-60 cells accompanied by the occurrence of DNA ladders, apoptotic bodies, and hypodiploid cells, characteristics of apoptosis. The replacement of a hydroxyl group (OH) by a methoxyl (OCH3) group at C4' or C6 attenuated the apoptotic effect in cells, and there was no significant cytotocity of flavanone or flavanone with OH or OCH3 in C7-treated HL-60 cells. Induction of enzyme activity of caspase-3 and -9, but not caspase-1 and -8, accompanied by release of cytocrome C from mitochondria to cytosol and the appearance of cleaved of PARP (85 kDa), D4-GDI (23 kDa), and caspase-3 (p17/p15) fragments, was identified in 4'-OH- or 6-OH- flavanone-treated HL-60 cells. Caspase-3 and -9 inhibitors Ac-DEVD-FMK and Ac-LEHD-FMK, but not caspase-1 and -8 inhibitors Ac-YVAD-FMK and Ac-LETD-FMK, attenuated 4'-OH- or 6-OH-flavanone-induced cell death. And, inhibition of capsase-9 activity by Ac-LEHD-FMK suppresses caspase-3 protein procession induced by 4'-OH- and 6-OH-flavanone, indicative of caspase-9 activation locating upstream of caspase-3. A decrease in the antiapoptotic protein Mcl-1 and increases in the pro-apoptotic proteins Bax and Bad were found in 4'-OH- or 6-OH-flavanone-treated HL-60 cells. Induction of endogenous ROS production was detected in 4'-OH- or 6-OH-flavanone-treated HL-60 cells by the DCHF-DA assay. Antioxidants such as N-acetylcysteine (NAC), catalase (CAT), superoxide dismutase (SOD), and allopurinol (ALL), but not pyrrolidine dithiocarbamate (PDTC) or diphenylene iodonium (DPI), significantly inhibited 4'-OH- or 6-OH-flavanone-induced ROS production, with blocking of the apoptosis induced by 4'-OH- or 6-OH-flavanone. The apoptosis-inducing activity of 4'-OH- or 6-OH-flavanone was also observed in another leukemia cell line (Jurkat), but was not found in mature monocytic cells (THP-1) and normal human polymorphonuclear neutrophils (PMNs). This suggests that hydroxylation at C4' or C6 is important to the apoptosis-inducing activities of flavanone through ROS production, and that activation of the caspase-3 cascade, downstream of caspase-9 activation, is involved.
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PMID:Hydroxylation at C4' or C6 is essential for apoptosis-inducing activity of flavanone through activation of the caspase-3 cascade and production of reactive oxygen species. 1501 74

Propyl gallate (PG), widely used as an antioxidant in foods, is carcinogenic to mice and rats. PG increased the amount of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a characteristic oxidative DNA lesion, in human leukemia cell line HL-60, but not in HP100, which is hydrogen peroxide (H2O2)-resistant cell line derived from HL-60. Although PG induced no or little damage to 32P-5'-end-labeled DNA fragments obtained from genes that are relevant to human cancer, DNA damage was observed with treatment of esterase. HPLC analysis of the products generated from PG incubated with esterase revealed that PG converted into gallic acid (GA). GA induced DNA damage in a dose-dependent manner in the presence of Fe(III)EDTA or Cu(II). In the presence of Fe(III) complex such as Fe(III)EDTA or Fe(III)ADP, GA caused DNA damage at every nucleotide. Fe(III) complex-mediated DNA damage by GA was inhibited by free hydroxy radical (*OH) scavengers, catalase and an iron chelating agent. These results suggested that the Fe(III) complex-mediated DNA damage caused by GA is mainly due to *OH generated via the Fenton reaction. In the presence of Cu(II), DNA damage induced by GA occurred at thymine and cytosine. Although *OH scavengers did not prevent the DNA damage, methional inhibited the DNA damage. Cu(II)-mediated DNA damage was inhibited by catalase and a Cu(I) chelator. These results indicated that reactive oxygen species formed by the interaction of Cu(I) and H2O2 participates in the DNA damage. GA increased 8-oxodG content in calf thymus DNA in the presence of Cu(II), Fe(III)EDTA or Fe(III)ADP. This study suggested that metal-mediated DNA damage caused by GA plays an important role in the carcinogenicity of PG.
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PMID:Metal-mediated oxidative damage to cellular and isolated DNA by gallic acid, a metabolite of antioxidant propyl gallate. 1503 24

Melatonin, an indolic pineal hormone, is produced primarily at night in mammals and is important in controlling biological rhythms. Although melatonin is known to be effective as a free radical scavenger and has an anti-cancer effect, carcinogenic properties have also been reported. In relation to its carcinogenic potential, we have examined whether 6-hydroxymelatonin, a major melatonin metabolite, can induce DNA damage in the presence of metal ion using [32P]-5'-end-labeled DNA fragments obtained from genes relevant to human cancer. 6-Hydroxymelatonin induced site-specific DNA damage in the presence of Cu(II). Formamidopyrimidine-DNA glycosylase treatment induced cleavage sites mainly at G residues of the 5'-TG-3' sequence, whereas piperidine treatment induced cleavage sites at T mainly of 5'-TG-3'. Interestingly, 6-hydroxymelatonin strongly damaged G and C of the 5'-ACG-3' sequence complementary to codon 273 of the p53 gene. These results suggest that 6-hydroxymelatonin can cause double-base lesions. DNA damage was inhibited by both catalase and bathocuproine, Cu(I)-specific stabilizer, suggesting that reactive species derived from the reaction of H2O2 with Cu(I) participate in DNA damage. Cytochrome P450 reductase efficiently enhanced 6-hydroxymelatonin-induced oxidative DNA damage and oxygen consumption, suggesting the formation of redox cycle. It is noteworthy that 6-hydroxymelatonin can efficiently induce DNA damage via non-o-quinone type of redox cycle. Formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a characteristic oxidative DNA lesion, in calf thymus DNA was significantly increased by 6-hydroxymelatonin in the presence of Cu(II). Furthermore, 6-hydroxymelatonin significantly increased the formation of 8-oxodG in human leukemia cell line HL-60 but not in HP100, a hydrogen peroxide (H2O2)-resistant cell line derived from HL-60. The 6-hydroxymelatonin-induced 8-oxodG formation in HL-60 cells significantly decreased by the addition of bathocuproine or o-phenanthroline. Therefore, it is concluded that melatonin may exhibit carcinogenic potential through oxidative DNA damage by its metabolite.
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PMID:Oxidative DNA damage induced by a melatonin metabolite, 6-hydroxymelatonin, via a unique non-o-quinone type of redox cycle. 1545 Sep 52

Our previous study demonstrates that copper induces histone hypoacetylation by inhibiting histone acetyltransferase (HAT) activity. However, it lacks direct evidences whether copper-inhibited histone acetylation right contributes to the toxicity of copper. Exposure of human leukemia cells (HL-60) to Cu2+ resulted in cell proliferation arrest and a concentration- and time-dependent decrease of histone acetylation. At the same time, Cu2+-induced significant increase of H2O2 and O2.- generation via a concentration- and time-dependent manner too. The histone acetylation was efficiently suppressed by exogenous H2O2, and enhanced by superoxide dismutase (the scavenger of O2.-), catalase (the scavenger of H2O2) or the combination of both, indicating that Cu2+ at least partially inhibited histone acetylation through triggering oxidative stress. Further studies found that sodium butyrate, the inhibitor of histone deacetylase (HDAC), which had no obvious effect on oxidative stress but increased histone acetylation at the concentration of 50 microM, attenuated Cu2+-inhibited cell proliferation, indicating that histone acetylation inhibition is simultaneously involved in the cytotoxicity of Cu2+. Considering the important role of histone acetylation in gene transcription and regulation of cell fate, the present study may open a new door to further understand the mechanism of Cu2+-induced toxicity.
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PMID:Oxidative stress is involved in inhibition of copper on histone acetylation in cells. 1573 38

Abrogation of mitochondrial permeability and induction of reactive oxygen species (ROS) production have been observed in chemical-induced apoptosis; however, the relationship between the mitochondria and intracellular ROS levels in apoptosis is still unclear. In the present study, myricetin (ME) but not its respective glycoside, myricitrin (MI; myricetin-3-O-rhamnose) reduced the viability of human leukemia HL-60 cells via apoptosis, characterized by the occurrence of DNA ladders and hypodiploid cells. Results of Western blotting and caspase activity assays showed that activation of caspases 3 and 9 but not caspases 1, 6 or 8 with cleavage of PARP and D4-GDI proteins is involved in ME-induced apoptosis. A reduction in mitochondrial functions characterized by a decrease in the Bcl-2/Bax protein ratio and translocation of cytochrome c (cyt c) from the mitochondria to the cytosol in accordance with a decrease in mitochondrial membrane potential were observed in ME-treated HL-60 cells. No significant induction of intracellular ROS levels by ME was observed by the DCHF-DA assay, DPPH assay or plasmid digestion assay, and antioxidants including N-acetyl-cysteine (NAC), catalase (CAT), superoxide dismutase (SOD), and tiron (TIR) showed no protective effects on ME-induced apoptosis. A PKC activator, 12-O-tetradecaoylphorbol-13-acetate (TPA) significantly attenuated ME-induced apoptosis via preventing cytochrome c release to the cytosol and maintaining the mitochondrial membrane potential by inhibiting the decrease in the Bcl-2/Bax protein ratio; these effects were blocked by protein kinase C (PKC) inhibitors including GF-109203X, H7, and staurosporin. Removing mitochondria by ethidium bromide (EtBr) treatment reduced the apoptotic effect of ME. Results of SAR studies showed that the presence of OH at C3', C4', and C5' is important for the apoptosis-inducing activities of ME, and that ME induces apoptosis in another leukemia cell line, Jurkat cells, but not in primary human polymorphonuclear (PMN) cells or in murine peritoneal macrophages (PMs). The results of the present study suggest that apoptosis induced by ME occurs through a novel mitochondrion-dependent, ROS-independent pathway; TPA protects cells from ME-induced apoptosis via PKC activation which prevents the occurrence of mitochondrial destruction during apoptosis.
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PMID:Mitochondrial-dependent, reactive oxygen species-independent apoptosis by myricetin: roles of protein kinase C, cytochrome c, and caspase cascade. 1574 3

The effects of 2-Methoxyestradiol (2ME)-induced apoptosis was examined in human leukemia cells (U937 and Jurkat) in relation to mitochondrial injury, oxidative damage, and perturbations in signaling pathways. 2ME induced apoptosis in these cells in a dose-dependent manner associated with release of mitochondrial proteins (cytochrome c, AIF), generation of reactive oxygen species (ROS), downregulation of Mcl-1 and XIAP, and inactivation (dephosphorylation) of Akt accompanied by activation of JNK. In these cells, enforced activation of Akt by a constitutively active myristolated Akt construct prevented 2ME-mediated mitochondrial injury, XIAP and Mcl-1 downregulation, JNK activation, and apoptosis, but not ROS generation. Conversely, 2ME lethality was potentiated by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002. Furthermore, in U937 cells, the hydrogen peroxide scavenger catalase and a superoxide dismutase (SOD) mimetic, TBAP, blocked these events, as well as Akt inactivation. Interruption of the JNK pathway by pharmacologic or genetic (e.g. siRNA) means attenuated 2ME-induced mitochondrial injury, XIAP and Mcl-1 downregulation, and apoptosis. Collectively, these findings suggest a hierarchical model of 2ME-related apoptosis induction in human leukemia cells in which 2ME-induced oxidative injury represents a primary event resulting in Akt inactivation, leading, in turn, to JNK activation, and culminating in XIAP and Mcl-1 downregulation, mitochondrial injury, and apoptosis. They also suggest that in human leukemia cells, the Akt pathway plays a critical role in mediating the response to oxidative stress induced by 2ME.
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PMID:2-Methoxyestradiol-induced apoptosis in human leukemia cells proceeds through a reactive oxygen species and Akt-dependent process. 1578 27


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