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

It was reported that xanthine derivatives (caffeine and 1-methyl-3-propyl-7-butylxanthine) enhanced the antitumor activity of doxorubicin (DOX) with increasing DOX concentrations in tumors in vivo in our previous papers. In addition, these actions were found to be related to the inhibitory activity toward DOX efflux from tumor cells in vitro. In this study, we searched for novel biochemical modulators of DOX among 3-n-propylxanthines with functional groups at the 1- or 7-position by using an assay system for their inhibitory effect on DOX efflux from P388 leukemia and DOX resistant P388 leukemia (P388/DOX) cells. 1-Substituted xanthines facilitated the DOX efflux from P388 cells. In contrast, among 7-substituted xanthines, XT-141 and XT-139 significantly inhibited the DOX efflux from P388 cells. In addition, XT-141 inhibited the DOX efflux from P388/DOX cells, and P-glycoprotein (P-gp) inhibitor facilitated DOX influx and inhibited DOX efflux from P388/DOX cells in a dose-dependent manner. These results indicated that the resistance of P388/DOX might depend on the over-expression of P-gp, and that XT-141 inhibited DOX efflux through its interaction with P-gp. We suspect that XT-141 is a useful biochemical modulator of DOX in DOX-resistant tumors with over-expression of P-gp in addition in DOX-sensitive tumors.
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PMID:Effects of xanthine derivatives on the influx and efflux of doxorubicin in P388 and DOX-resistant P388 leukemia cells. 1224 72

Interactions between the protein kinase inhibitor UCN-01 and the PKC activator phorbol ester (PMA) have been examined in relation to differentiation and apoptosis in human myelomonocytic leukemia cells (U937). Coadministratation of 100 nM UCN-01 with a low concentration of PMA e.g., 2 nM, inhibited rather than promoted differentiation, reflected by reduced surface expression of the monocytic maturation marker CD11b and diminished cell adherence. Instead, administration of UCN-01 with PMA led to a marked increase in mitochondrial injury (e.g, cytochrome c release), activation of caspases-3 and -8, Bid cleavage, PARP degradation, and apoptosis, accompanied by a substantial reduction in viability and clonogenic survival. These phenomena were associated with multiple perturbations in cell cycle regulatory events, including abrogation of p21(CIP1) induction, p27(KIP1) cleavage, down-regulation of cyclin D1, dephosphorylation (activation) of p34cdc2, and degradation of underphosphorylated pRb. Potentiation of PMA-mediated apoptosis was partially mimicked by caffeine suggesting the involvement of Chk1 in the potentiation of apoptosis. Induction of cell death by UCN-01 and PMA was increased in cells stably expressing a p21(CIP1) mRNA antisense construct, suggesting that p21(CIP1) expression may protect cells from the lethal effects of this drug combination. Finally, ectopic expression of a Bcl-2 but not dominant-negative caspase-8 protected cells from UCN-01/PMA-mediated apoptosis, suggesting the lethal effects of this combination primarily involves the mitochondrial rather than the TNF-related extrinsic apoptotic pathway. Taken together, these findings suggest that UCN-01 disrupts a variety of cell cycle events in leukemic cells exposed to the maturation-inducing agent PMA, causing cells to engage an apoptotic rather than a differentiation-related program.
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PMID:UCN-01 (7-hydroxystauorsporine) blocks PMA-induced maturation and reciprocally promotes apoptosis in human myelomonocytic leukemia cells (U937). 1242 43

Idarubicin (IDA) is a member of an important class of anticancer agents, the anthracycline antibiotics. Although the clinical efficacy of anthracyclines is limited by a high incidence of severe cardiac toxicity, our understanding of IDA transport into the heart is still limited. In a previous study, we demonstrated that IDA is transported into the heart by a saturable mechanism. Based on in vitro data suggesting an enhancement by methylxanthines of IDA influx in leukemia cells, this study was designed to test the hypothesis that a commonly used methylxanthine, caffeine, might influence the myocardial uptake of IDA. In the Langendorff rat heart, after infusion of 0.5 mg IDA during 10 min, the presence of caffeine (1 microM) in perfusate enhanced the residual amount of IDA in the heart by 30% due to a 2.7-fold increase in the maximal uptake rate V(max). Theophylline (3 micro M), in contrast, did not influence the uptake process but caused a slight decrease of fractional myocardial sequestration rate (19% reduction). Caffeine reversed the cardiodepressive action of IDA (49% decrease in left ventricular developed pressure at the end of infusion) to a positive inotropic effect (18% increase of basal level). Theophylline significantly attenuated the negative inotropic effect of IDA (only 21% decrease) and led to positive inotropism in the washout phase (21% increase at the end of experiment). We speculate that co-administration of caffeine may enhance the chronic cardiotoxicity of IDA by increasing its accumulation in the heart.
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PMID:Caffeine enhances myocardial uptake of idarubicin but reverses its negative inotropic effect. 1259 56

The impact of disruption of the PI3K (phosphatidylinositol 3-kinase) pathway on the response of human leukemia cells to pharmacological cyclin-dependent kinase (CDK) inhibitors has been examined. Exposure of U937 monocytic leukemia cells to minimally toxic concentrations of flavopiridol (FP), roscovitine, or CGP74514A for 3 h in conjunction with the PI3K inhibitor LY294002 (abbreviated LY in the article) resulted in a marked decrease in Akt phosphorylation. Coexposure of cells to LY and CDK inhibitors also resulted in an early (i.e., within 3 h) and striking increase in mitochondrial damage [e.g., cytochrome c, second mitochondria-derived activator of caspases/direct inhibitor of apoptosis (IAP)-binding protein with low isoelectric point (Smac/DIABLO), and apoptosis-initiating factor (AIF) release], caspase activation, and apoptosis. Similar interactions were observed in a variety of other leukemia cell types (e.g., HL-60, Jurkat, Raji, and NB4). Apoptosis, induced by FP/LY, was substantially blocked by ectopic expression of Bcl-2, but to a considerably lesser extent by dominant-negative caspase-8. FP-induced apoptosis was not enhanced by agents that inhibited protein kinase (PK) A (H89), PKC (GFX), mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase (MEK1/2; U0126), p38 MAP kinase (MAPK; SB202190), m-target of rapamycin (TOR; rapamycin), or ataxia-telangiectasia mutation (ATM; caffeine), whereas the PI3K inhibitor wortmannin exerted effects similar to those of LY. The dramatic potentiation of CDK inhibitor-induced apoptosis by LY was accompanied by diminished Bad phosphorylation, induction of Bcl-2 cleavage, and down-regulation of X-linked IAP (XIAP) and Mcl-1. Cells exposed to CDK inhibitors + LY also exhibited reduced phosphorylation of glycogen synthase kinase (GSK)-3, forkhead transcription factor (FKHR), p70(S6K), and ERK, but increased activation of p34(cdc2) and p38 MAPK. LY/CDK inhibitor-treated cells also displayed diminished pRb dephosphorylation on CDK2- and CDK4-specific sites, retinoblastoma protein cleavage, and down-regulation of cyclin D(1). Inducible expression of constitutively active (myristolated) Akt significantly, albeit partially, attenuated apoptosis in Jurkat leukemia cells treated with either FP alone or the combination of FP and LY. Finally, cotreatment with LY and FP resulted in a dramatic increase in apoptosis in primary leukemic blasts obtained from a patient with acute myeloblastic leukemia. Together, these findings suggest that the PI3K/Akt pathway plays a major role in regulating the apoptotic response of human leukemia cells to pharmacological CDK inhibitors and raise the possibility that combined interruption of CDK- and PI3K-related pathways may represent a novel therapeutic strategy in hematological malignancies.
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PMID:The lethal effects of pharmacological cyclin-dependent kinase inhibitors in human leukemia cells proceed through a phosphatidylinositol 3-kinase/Akt-dependent process. 1270 69

Dichloromethane is widely used in industrial processes, food preparation, and agriculture. In industry, dichloromethane is used as a solvent in paint removers, degreasing agents, aerosol propellants, and triacetate solutions; as a blowing agent in flexible urethane foams; and as a process solvent in the manufacture of steroids, antibiotics, vitamins, and tablet coatings. The use of dichloromethane as an extraction solvent for spice oleoresins, hops, and caffeine from coffee has been approved by the U.S. Food and Drug Administration. Dichloromethane has been used as an inhalation anesthetic and as a fumigant for grain and strawberries. Toxicology and carcinogenesis studies of dichloromethane (99% pure) were conducted by inhalation exposure of groups of 50 male and 50 female F344/N rats and B6C3F1 mice 6 hours per day, 5 days per week, for 102 weeks. The exposure concentrations used (0, 1,000, 2,000, or 4,000 ppm for rats and 0, 2,000, or 4,000 ppm for mice) were selected on the basis of results from 13-week inhalation studies in which groups of 10 rats and 10 mice of each sex were exposed to dichloromethane at concentrations of 525-8,400 ppm 6 hours per day, 5 days per week. During the 2-year studies in rats, body weight gains for exposed males and females were comparable to those of the chamber controls. The survival of exposed male rats was comparable to that of the chamber controls; however, the survival of all groups of males at the termination of the study was low (control, 16/50; low dose, 16/50; mid dose, 17/50; high dose, 9/50). Most of the early deaths among male rats occurred during the final weeks of the study; the survival of male rats through week 86 of the study was 36/50, 39/50, 37/50, and 33/50. This decreased survival is believed to be related to the high incidence of leukemia (34/50; 26/50; 32/50; 35/50). Survival of female rats exposed at 4,000 ppm was reduced relative to that of the chamber controls (30/50; 22/50; 22/50; 15/50); leukemia occurred frequently in all female rat groups. Final mean body weights of high dose male mice and low and high dose female mice were 10%-17% lower than those of the chamber controls; these reductions occurred during the last 16 weeks of the study. The survival of dosed male mice and high dose female mice was reduced relative to that of the chamber controls (male: control, 39/50; low dose, 24/50; high dose, 11/50; female: 25/50; 25/50; 8/50). This reduced survival may have been due to the chemically induced development of liver and lung neoplasia in male and female mice. Increased incidences of benign mammary gland lesions (adenomas and fibroadenomas) occurred in male and female rats exposed to dichloromethane (male: 0/50; 0/50; 2/50; 5/50; female: 5/50; 11/50; 13/50; 23/50). The incidence of malignant mammary gland neoplasms was not increased in female rats (2/50; 2/50; 2/50; 0/50); none was observed in male rats. In addition, integumentary system tumors in the area of the mammary chain occurred with a positive trend in male rats (subcutaneous tissue fibroma or sarcoma: 1/50; 1/50; 2/50; 5/50); the combined incidence of all tumors in the mammary area in male rats was 1/50, 1/50, 4/50, and 9/50. Exposure to dichloromethane was associated with increased incidences of hepatic hemosiderosis, cytomegaly, cytoplasmic vacuolization, necrosis, granulomatous inflammation, and bile duct fibrosis in both male and female rats. There was a positive but marginal trend in the incidence of hepatocellular neoplastic nodules or hepatocellular carcinomas (combined) in female rats (2/50; 1/50; 4/50; 5/50). The incidence of squamous metaplasia of the nasal cavity was increased in female rats exposed at 4,000 ppm (1/50; 2/50; 3/50; 9/50) but not in males (4/50; 5/50; 3/50; 3/50). No nasal cavity tumors were observed in rats. The increased incidences of mononuclear cell leukemia in mid dose and high dose female rats (17/50; 17/50; 23/50; 23/50) were statistically significant by age-adjusted analyses. In male rats, mesotheliomas (arising primarily from the tunica vaginalis) occurred at increas) occurred at increased incidences (0/50; 2/50; 5/50; 4/50). Lung tumors occurred at increased incidences in male and female mice exposed to dichloromethane (alveolar/bronchiolar adenomas: male - 3/50; 19/50; 24/50; female - 2/50; 23/48; 28/48; alveolar/bronchiolar carcinomas: male - 2/50; 10/50; 28/50; female - 1/50; 13/48; 29/48). Cytologic degeneration of the liver was observed at increased incidences in high dose male and dosed female mice (male: 0/50; 0/49; 22/49; female: 0/50; 23/48; 21/48). Incidences of hepatocellular adenomas or hepatocellular carcinomas (combined) were increased in high dose male and dosed female mice (male: 22/50; 24/49; 33/49; female: 3/50; 16/48; 40/48). There were also dose-related increases in the numbers of mice bearing multiple lung or liver neoplasms. Dose-related increases were observed in the incidences of testicular atrophy in male mice and uterine and ovarian atrophy in female mice; these effects are considered to be secondary responses to neoplasia. An audit of the experimental data was conducted for the 2-year studies of dichloromethane. No data discrepancies were found that influenced the final interpretations. Under the conditions of these inhalation studies, there was some evidence of carcinogenicity of dichloromethane for male F344/N rats as shown by an increased incidence of benign neoplasms of the mammary gland. There was clear evidence of carcinogenicity of dichloromethane for female F344/N rats as shown by increased incidences of benign neoplasms of the mammary gland. There was clear evidence of carcinogenicity of dichloromethane for male and female B6C3F1 mice, as shown by increased incidences of alveolar/bronchiolar neoplasms and of hepatocellular neoplasms. Synonyms: DCM; methylene chloride
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PMID:NTP Toxicology and Carcinogenesis Studies of Dichloromethane (Methylene Chloride) (CAS No. 75-09-2) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). 1274 23

Arsenic trioxide (As(2)O(3)), an effective drug for the treatment of acute promyelocytic leukemia (APL), can induce apoptosis and partial differentiation in APL cells in vitro and in vivo. However, As(2)O(3) also induces apoptosis in cancer cells other than APL with complex mechanisms, which seem to be cell type dependent. In this study, we report that APL cells (NB4 cell line) are arrested at early mitotic phase before the collapse of mitochondrial transmembrane potential (Deltavarphi(m)) and apoptosis after treatment with pharmacological concentrations (1.0-2.0 micro M) of As(2)O(3). We have also made the following new discoveries: (1) 0.5 micro M As(2)O(3) that fails to induce apoptosis has no effects on cell cycle distribution. (2) With inhibition of As(2)O(3)-induced Deltavarphi(m) collapse and apoptosis, dithiothreitol also effectively inhibits As(2)O(3)-induced mitotic arrest, suggesting that both As(2)O(3)-induced apoptosis and mitotic arrest involve proteins with thiol groups. (3) 1.5 mM caffeine that relieves cells from G(2)/M arrest also inhibits As(2)O(3)-induced Deltavarphi(m) collapse and apoptosis, (4) 1.0 micro M As(2)O(3) increases the expression of both cyclin B(1) and hCDC20 whereas it inhibits Tyr15 phosphorylation of p34(cdc2). In conclusion, our results strongly support that there is a tight link between As(2)O(3)-induced apoptosis and mitotic arrest, the latter being one of common mechanisms for As(2)O(3)-induced apoptosis in cancer cells.
Leukemia 2003 Jul
PMID:Arsenic trioxide-induced mitotic arrest and apoptosis in acute promyelocytic leukemia cells. 1283 21

Most cell lines that lack functional p53 protein are arrested in the G(2) phase of the cell cycle due to DNA damage. It was previously found that the human promyelocyte leukemia cells HL-60 (TP53 negative) that had been exposed to ionizing radiation at doses up to 10 Gy were arrested in the G(2) phase for a period of 24 h. The radioresistance of HL-60 cells that were exposed to low dose-rate gamma irradiation of 3.9 mGy/min, which resulted in a pronounced accumulation of the cells in the G(2) phase during the exposure period, increased compared with the radioresistance of cells that were exposed to a high dose-rate gamma irradiation of 0.6 Gy/min. The D(0) value (i.e. the radiation dose leading to 37% cell survival) for low dose-rate radiation was 3.7 Gy and for high dose-rate radiation 2.2 Gy. In this study, prevention of G(2) phase arrest by caffeine (2 mM) and irradiation of cells with low dose-rate irradiation in all phases of the cell cycle proved to cause radiosensitization (D(0)=2.2 Gy). The irradiation in the presence of caffeine resulted in a second wave of apoptosis on days 5-7 post-irradiation. Caffeine-induced apoptosis occurring later than day 7 post-irradiation is postulated to be a result of unscheduled DNA replication and cell cycle progress.
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PMID:Caffeine induces a second wave of apoptosis after low dose-rate gamma radiation of HL-60 cells. 1456 3

Expression of cyclin E is believed to be a critical factor promoting cell entry into the S-phase and cell proliferation. Indeed, normal proliferating cells and most tumor cell lines are characterized by the existence of a minimal cyclin E threshold level in the G1-phase, and only those cells expressing cyclin E over this threshold enter into the S-phase of the cell cycle. However, through studying clinical tumor tissue specimens, we recently observed that some cancer cells can enter into the S-phase with minimal levels of cyclin E expression. In an effort to establish an in vitro cell model system for studying the mechanisms underlying this phenomenon, we treated MOLT-4 lymphocyte leukemia cells with 50 mM caffeine and found that the levels of cyclin E expression were decreased markedly in these cells following 2 to 4-h exposure to caffeine. Quite unexpectedly, we observed that the percentage of the cells progressing through the S-phase increased despite the reduced levels of cyclin E, as analyzed for the cellular DNA contents, expression of nuclear-bound PCNA, immunolabelling with Ki-67 antibody and incorporation of BrdU. In fact, these cells entered into the S-phase with a level of cyclin E well below the threshold level for untreated cells, thus suggesting that lower levels of cyclin E expression are associated with cell proliferation under certain circumstances. We speculate that caffeine may enhance MOLT-4 cell entrance into the S-phase through activation of Cdc25, which in turn activates cyclin-dependent protein kinases (CDKs) including CDK2 and drives the cell cycle progression; while degradation of cyclin E by the ubiquitin/proteasome pathway may account for the decreased levels of cyclin E in these cells. Our findings from both the MOLT-4 cell line and patients' cancer tissues may help decipher the mystery of the deregulation of cell cycle progression and carcinogenesis in some malignant tumors.
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PMID:Down-regulation of cyclin E expression by caffeine promotes cancer cell entry into the S-phase of the cell cycle. 1551 6

The ataxia-telangiectasia-mutated (ATM) kinase plays a central role in responses to various forms of DNA damage and has been suggested to facilitate human immunodeficiency virus type 1 (HIV-1) integration. Here, we describe a series of experiences that indicate that ATM can enhance HIV-1 replication by stimulating the action of the Rev viral posttranscriptional regulator. The Rev-dependent stimulation of viral late gene expression was observed with ATM-overexpressing cells, a result confirmed with a Rev-dependent reporter construct. Both parameters were also enhanced upon treatment of HeLa cells with caffeine, a xanthine that, in this cellular context, stimulates ATM activity. As well, decreased levels of virions with reduced infectivity were released by ATM knockdown cells. Notably, ATM overexpression did not stimulate the HIV-1 late gene expression within the context of Rev-independent constructs or the Rex-dependent production of capsid from human T-cell leukemia virus type 1 proviral constructs. Altogether, these results indicate that ATM can positively influence HIV-1 Rev function.
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PMID:Ataxia-telangiectasia-mutated (ATM) protein can enhance human immunodeficiency virus type 1 replication by stimulating Rev function. 1647 51

BCR/ABL-positive leukemia cells accumulated more replication-dependent DNA double-strand breaks (DSBs) than normal counterparts after treatment with cisplatin and mitomycin C (MMC, as assessed by pulse field gel electrophoresis (PFGE) and neutral comet assay. In addition, leukemia cells could repair these lesions more efficiently than normal cells and eventually survive genotoxic treatment. Elevated levels of drug-induced DSBs in leukemia cells were associated with higher activity of ATR kinase, and enhanced phosphorylation of histone H2AX on serine 139 (gamma-H2AX). gamma-H2AX eventually started to disappear in BCR/ABL cells, while continued to increase in parental cells. In addition, the expression and ATR-mediated phosphorylation of Chk1 kinase on serine 345 were often more abundant in BCR/ABL-positive leukemia cells than normal counterparts after genotoxic treatment. Inhibition of ATR kinase by caffeine but not Chk1 kinase by indolocarbazole inhibitor, SB218078 sensitized BCR/ABL leukemia cells to MMC in a short-term survival assay. Nevertheless, both caffeine and SB218078 enhanced the genotoxic effect of MMC in a long-term clonogenic assay. This effect was associated with the abrogation of transient accumulation of leukemia cells in S and G2/M cell cycle phases after drug treatment. In conclusion, ATR-Chk1 axis was strongly activated in BCR/ABL-positive cells and contributed to the resistance to DNA cross-linking agents causing numerous replication-dependent DSBs.
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PMID:ATR-Chk1 axis protects BCR/ABL leukemia cells from the lethal effect of DNA double-strand breaks. 1668 21


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