Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An overview was presented of our approach of inhibition of de novo and salvage pathways in pyrimidine and purine metabolism. 1. Combination of acivicin, an inhibitor of de novo biosynthesis, and dipyridamole, a transport inhibitor, provided synergistic cytotoxicity in hepatoma and colon carcinoma cells. 2. AZT, a competitive inhibitor of the salvage enzyme, thymidine kinase, and 5-FU or MTX provided synergistic cytotoxicity in hepatoma 3924A. In human colon carcinoma HT-29 cells AZT and methotrexate yielded synergistic cytotoxicity and thymidine and hypoxanthine together provided protection from the action of these drugs. 3. These observations are significant because in rat hepatoma 3924A and in human cell lines HT-29, HL-60 and K562 thymidine kinase activity was 16- to 67-fold higher than that of dTMP synthase. Therefore, inhibition of dTMP synthase activity alone may provide poor responses because the salvage pathways can circumvent this block. 4. In leukemic patients treated with tiazofurin, an inhibitor of IMP dehydrogenase, the rate-limiting enzyme of GTP biosynthesis, and with allopurinol, which inhibits GPRT activity through raising plasma hypoxanthine levels, synergistic therapeutic results were obtained. The responses in sensitive patients entailed a decrease in IMP dehydrogenase activity and GTP concentration in leukemic cells and down-regulation of the ras and myc oncogenes. The down-regulation of the ras oncogene by tiazofurin through the decrease of GTP concentration has now been shown in K562, HL-60 and hepatoma cells and in patients with chronic granulocytic leukemia in blast crisis. Tiazofurin may be useful in studies on selective depression of the expression of the ras oncogene. 5. In 27 consecutive patients 50% responded positively to tiazofurin treatment. From this group, 10 out of 12 patients (83%) with chronic granulocytic leukemia in blast crisis responded to tiazofurin treatment.
 ...
PMID:Regulation of de novo and salvage pathways in chemotherapy. 187 99

3'-Azido-3'-deoxythymidine (AZT) is currently used in the treatment of patients with the acquired immunodeficiency syndrome (AIDS); this often, however, results in hematological toxicity. Although the mechanism of toxicity is not clear, it is thought to result in part from incorporation of AZT into DNA, which causes chain termination. In order to investigate the mechanism of AZT toxicity, the relationship between the presence of AZT in DNA of K562 cells, a chronic myelogenous leukemia cell line, and growth inhibition was examined. No growth inhibition was evident at less than 50 microM AZT, although incorporation of AZT into DNA was detected at 10 and 20 microM. This suggested that the presence of AZT in DNA was not sufficient to inhibit cell growth. Removal of AZT from the medium resulted in the removal of AZT from DNA of the cells, indicative of a cellular repair mechanism. Cellular DNA polymerases alpha, beta, gamma, and delta from human leukemic cells were inhibited by AZT trisphosphate to different degrees, polymerase alpha being the least potently inhibited. Furthermore, an enzyme with exonucleolytic activity, capable of removing AZT and dideoxycytidine from the correspondingly terminated DNA (in vitro), was obtained from these cells. In summary, AZT was incorporated into DNA at levels that were not toxic, and it could be removed by an exonuclease, which might play a key role in the susceptibility of cells to AZT.
 ...
PMID:Incorporation of 3'-azido-3'-deoxythymidine into cellular DNA and its removal in a human leukemic cell line. 236 51

Autologous bone marrow transplantation (ABMT) for chronic myelogenous leukemia (CML) is limited because of the difficulty in purging Ph chromosome positive cells from bone marrow cells (or peripheral blood stem cells). Combining hyperthermia with certain drugs that affect Ph+ cell growth in vivo and in vitro may enhance the killing (apoptosis) of CML cells in vitro. In this study, we chose such drugs (i.e., azidothymidine [AZT], interferon-alpha [IFN-alpha], tumor necrosis factor [TNF], and quercetin) and tested this hypothesis using two CML-derived cell lines in vitro, K562 and KU812, to enhance the killing of CML cells with heat. Our results indicate that the optimal hyperthermic purging effect is achieved by heating at 42 degrees C for 1 hour with IFN-alpha (100 U/mL) and AZT (0.5 microM/L) or with quercetin (50 microM) [corrected], depending on the sensitivity of the CML cells eliminated in vitro. K562 cells were significantly eradicated by a combination of IFN-alpha and AZT, while KU812 cells were significantly inhibited by quercetin at the temperature and drug concentrations above. This combined effect may enhance apoptosis of CML cells in vitro.
 ...
PMID:Enhanced elimination of Ph+ chromosome cells in vitro by combined hyperthermia and other drugs (AZT, IFN-alpha, TNF, and quercetin): its application to autologous bone marrow transplantation for CML. 772 Aug 16

An asymptomatic HIV-positive patient with Philadelphia chromosome positive chronic myelogenous leukemia (CML) was treated by interferon-a (IFN-a) for four years. A sustained hematological response and major cytogenetic response were achieved. However, a complete cytogenetic remission (100% Ph-negative cells) was observed when zidovudine (AZT) was introduced as treatment for HIV-related immunodepression. Moreover, this complete cytogenetic remission was confirmed by quantitative PCR showing decreased BCR-ABL rearrangement at very low level. As, there are some in vitro reports demonstrating a synergistic antiproliferative effect of IFN-a and zidovudine, we discuss the possibility of synergistic effects between AZT and IFNa in the treatment of CML.
 ...
PMID:Improving the cytogenetic response to interferon alpha by zidovudine (AZT) in an HIV-positive chronic myelogenous leukemia patient. 925 Aug 8

A series of N-diisopropylphosphoryl (DIPP) L-amino acid ester prodrugs of zidovudine (AZT) (3a-3e) and stavudine (d4T) (4a-4e) has been prepared. The activity of these compounds against MCF-7 cells (human pleural effusion breast adenocarcinoma cell line) and K562 cells (human chronic myeloid leukemia (CML) cell line) was evaluated. In difference from that of AZT amino acid phosphoramidates, the alophatic amino acid esters of AZT were found to be more cytotoxic than the aromatic analogues toward MCF-7 cell. Two DIPP-L-amino acid esters of d4T 4b (CC50 = 83 microM) and 4c (CC50 = 182 microM) were found to be more cytotoxic than the parent drug toward K562 cells. MCF-7 and K562 cell cycle disturbance was investigated showing detectable blockade in the S phase when exposed to biologically active AZT, 3a, 3b, 3c, 4b and 4c, indicating that they inhibit cell growth by blocking cell cycle progression. Together with previous reports, present findings suggest that anti-breast cancer activity of AZT may be due to hamper DNA synthesis.
 ...
PMID:Synthesis, in vitro anticancer evaluation, and interference with cell cycle progression of N-phosphoamino acid esters of zidovudine and stavudine. 1559 79

This study deals with the combination of chloroquine (CQ, an anti-malaric drug) and 3'-azido-3'-deoxythymidine (AZT, anti-human immuno-deficiency virus (HIV) drug) with a chimeric toxin (TS) obtained by chemical linking of saporin (a ribosome inactivating protein from the plant Saponaria officinalis) and human transferrin, in the intoxication of the human chronic myeloid leukaemia cells (K562). Our data demonstrate that AZT, at concentrations comparable to those reached in the blood of HIV-infected patients under pharmacological treatment with this drug, can increase the toxicity of TS in cooperation with CQ inducing an increased effect on protein synthesis in K562 cells ( approximately 50% inhibition of protein synthesis for TS alone, and TS with AZT and approximately 70% with both AZT and CQ). Furthermore, pre-treatment of cells with AZT alone can induce an increase of apoptosis in K562 cells intoxicated with TS. By comparing data obtained with the model toxin ricin, we get indications that the two toxins partially differ in their intracellular routes, also suggesting that chimeric constructs containing ricin-like toxins (i.e. immunotoxins) could be coupled with the use of common and cheap drugs for the treatment of cancer in HIV-infected patients.
 ...
PMID:The effect of AZT and chloroquine on the activities of ricin and a saporin-transferrin chimeric toxin. 1598 41