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)

Cladribine, a purine nucleoside analogue, is a safe and effective treatment for patients with hairy-cell leukaemia. It is administered at a dose of 0.09 mg/kg daily as a continuous intravenous infusion over 7 days. This chapter discusses the history, rationale, chemical structure and mechanism of action of cladribine. The indications for therapy and guidelines for clinical usage are reviewed. The response of hairy-cell leukaemia to cladribine, the acute and chronic complications and the risk for second malignancies are summarized. The chapter concludes with a section on salvage therapy.
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PMID:Cladribine in the treatment of hairy-cell leukaemia. 1267 Apr 69

2-Chloro-2'-deoxyadenosine (CldAdo, cladribine) is a clinically important nucleoside analog for adult and pediatric leukemias. We previously described an activity in HeLa cell nuclear extracts that specifically recognized CldAMP-substituted oligomers. The factor was present in extracts prepared from repair-deficient xeroderma pigmentosum (XP) complementation group A cells, but not from group E--which are defective in damaged DNA-binding (DDB) protein--suggesting a possible repair process for incorporated analogs. Here we examined XP lymphoblast survival after CldAdo treatment using a cell proliferation assay. Control CEM leukemia cells and immortalized normal human lymphoblasts exhibited similar cytotoxicity profiles at each concentration tested. However, a 2.1-fold increase in sensitivity to CldAdo was detected in XP-E (5) cells lacking a functional DDB subunit. XP-A, XP-D and XP-G cell lines also had increased sensitivity to CldAdo, ranging from 1.61- to 1.91-fold greater compared to normal lymphoblasts. Our findings suggest that the clinical efficacy of CldAdo may be attenuated by repair mechanisms that target and remove such altered nucleic acids from cellular DNA.
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PMID:Nucleotide excision repair-deficient human cells in culture exhibit decreased survival after 2-chlorodeoxyadenosine treatment. 1292 46

2-Chloro-2'-deoxyadenosine (CldAdo, cladribine) is used therapeutically for hairy cell and other leukemias. The nucleoside is converted in leukemia cells to the 2-Cl-analog of dATP and incorporated into DNA, where it may alter binding of transcription factors to gene regulatory AT-rich sequences. Here we model the effects of CldATP incorporation into the adenovirus major late promoter TATA element recognized by TATA binding protein (TBP). The modeling results are consistent with experimental studies of DNA:TBP binding and indicate which positions in the canonical TATA sequence are most severely affected by CldATP incorporation.FIGURE Structure of the DNA:TBP complex. The protein is shown as a ribbon structure, and the DNA as a stick model
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PMID:2-Chloro-2'-deoxyadenosine: alteration of DNA:TATA element binding protein (TBP) interactions. 1461 Jun 62

Deoxycytidine kinase (dCK) is a key enzyme in the deoxynucleoside salvage pathway and in the activation of numerous nucleoside analogues used in cancer and antiviral chemotherapy. Recent studies indicate that dCK activity might be regulated through reversible phosphorylation. Here, we report the effects of a large panel of protein kinase inhibitors on dCK activity in the B-leukemia cell line EHEB, both in basal conditions and in the presence of the nucleoside analogue 2-chloro-2'-deoxyadenosine (CdA) which induces activation of dCK. Except staurosporine and H-7 that significantly reduced the activation of dCK by CdA, no specific protein kinase inhibitor diminished basal dCK activity or its activation by CdA. In contrast, genistein, a general protein tyrosine kinase inhibitor, and AG-490, an inhibitor of JAK2 and JAK3, increased basal dCK activity more than two-fold. Two specific inhibitors of the MAPK/ERK pathway, PD-98059 and U-0126, also enhanced dCK activity. These data suggest that the JAK/MAPK pathway could be involved in the regulation of dCK. Moreover, we show that the activity of dCK, raised by CdA, can return to its initial level by treatment with protein phosphatase-2A (PP2A). Accordingly, dCK activity in intact cells increased upon incubation with okadaic acid (OA) at concentrations that should inhibit PP2A, but not protein phosphatase-1. Activation of dCK by protein kinase inhibitors and OA was also observed in CCRF-CEM cells and in chronic lymphocytic leukemia B-lymphocytes, suggesting a general mechanism of post-translational regulation of dCK, which could be exploited to enhance the activation of antileukemic nucleoside analogues.
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PMID:Activation of deoxycytidine kinase by protein kinase inhibitors and okadaic acid in leukemic cells. 1518 21

The nucleoside analog 2-chlorodeoxyadenosine (Cladribine, CdA) is used in the treatment of patients with several hematological malignancies. After administration of CdA, the major catabolite measured in plasma and urine is 2-chloroadenine (CAde). This study was performed to determine the pharmacokinetics after oral and intravenous (iv) infusion of CdA in patients treated for chronic lymphocytic leukemia and to evaluate the toxicity of CAde to leukemia cells in vitro. CdA and CAde were also determined in plasma from 31 patients and in urine from 16 patients with reversed-phase high-performance liquid chromatographic. The toxicity of CdA and CAde was also determined in leukemic cells from 7 patients by fluorometric microculture cyotoxicity assay. Five times more CAde was quantified after oral treatment compared with an iv infusion of CdA. After iv infusion, the half-life was the same for CdA and CAde, but after oral administration the half-life was doubled for CAde. Excreted amount of CAde in urine constituted about 1.1% after iv infusion and 4.7% after oral CdA treatment. In vitro exposure of leukemia cells to CAde showed that it was eight times less toxic as compared to CdA. We conclude that CAde has a lower cytotoxic effect than CdA but may contribute significantly to the cytotoxicity after oral administration.
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PMID:Cytotoxicity and pharmacokinetics of cladribine metabolite, 2-chloroadenine in patients with leukemia. 1518 32

Systemic mastocytosis (SM) are defined by an abnormal growth and accumulation of mast cells in bone marrow and/or other extracutaneous organs. There is currently no cure for this disease. Because of similarities and/or association of mastocytosis with myeloproliferative disorders, interferon alpha has been tested but with contradictory reported results. A first prospective multicenter phase II trial was then started in France. From 1994 to 1997, 20 adult patients with confirmed bone marrow involvement received interferon alpha-2b for at least 6 months, (from 1 million U per day up to 5 million U/m(2)/day). Thirteen patients who presented systemic and/or specific cutaneous manifestations, demonstrated objective responses: seven (35%) were partial, six (30%) minor but no complete response could be observed at the time of analysis. The bone marrow remained unchanged in 12/13. Thus, interferon should be offered to patients with severe systemic manifestations, who have not responded to symptomatic therapies, even in case of non-aggressive mastocytosis, with or without corticosteroids the first weeks. Long-term therapy should be offered to patients with initial positive response. To control more aggressive SM or mastocytosis associated with clonal hematologic non-mast cell lineage or leukaemia mast cell, other chemotherapeutic regimens should be proposed like Cladribine (2-chlorodeoxyadenosine, 2-CDA) or polychemotherapies including interferon as it is being tested in France in a new multicentric protocol, coordinated by the association AFIRMM, with interferon and oral cytarabine.
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PMID:Interest of interferon alpha in systemic mastocytosis. The French experience and review of the literature. 1521 17

Bryostatin, a macrocyclic lactone and protein kinase C (PKC) modulator, has been shown to have differentiation and anti-tumor activity against several leukemia cell lines in vitro. In this study, we demonstrated Bryostatin-induced differentiation in B-cell chronic lymphocytic leukemia (B-CLL) cells, characterized by an increase in cell size and a marked up-regulation of CD11c expression. The specific inhibitors of the extracellular signal-regulated kinase (ERK) and protein kinase C pathways, PD98059 and GF 109203X respectively, each completely blocked Bryostatin-induced differentiation of B-CLL cells, suggesting that activation of the ERK pathway plays a direct role in this process in a PKC-dependent manner. Furthermore, Bryostatin reduced both spontaneous and drug-induced apoptosis with chlorambucil, fludarabine and 2-chloro-2'-deoxyadenosine (2-Cda) in B-CLL cells. This resistance was associated with an early up-regulation of the anti-apoptotic protein Mcl-1 and post-translational phosphorylation of Bcl-2 at serine 70. The anti-apoptotic effects of Bryostatin were abrogated by GF 109203X, and to a lesser extent by the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor, LY294002. Interestingly, the ERK inhibitor, PD98059 inhibited Mcl-1 expression but had little effect on Bryostatin-induced survival suggesting that the ERK pathway predominantly affects differentiation. Taken together these results present an explanation for Bryostatin-induced B-CLL cell survival in which modulation of the PKC pathway couples differentiation with an increase in antiapoptotic protein expression and calls into question the rationale for its use in the treatment of B-CLL.
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PMID:Bryostatin induces protein kinase C modulation, Mcl-1 up-regulation and phosphorylation of Bcl-2 resulting in cellular differentiation and resistance to drug-induced apoptosis in B-cell chronic lymphocytic leukemia cells. 1529 60

To explain why 2-chloro-2'-deoxyadenosine (CdA) is unable to block DNA synthesis and cell cycle progression, and paradoxically enhances progression from G1 into S phase in the CdA-resistant leukemia EHEB cell line, we studied its metabolism and effects on proteins regulating the transition from G1 to S phase. A low deoxycytidine kinase activity and CdATP accumulation, and a lack of p21 induction despite p53 phosphorylation and accumulation may account for the inability of CdA to block the cell cycle. An alternative pathway involving pRb phosphorylation seems implicated in the CdA-induced increase in G1 to S phase progression.
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PMID:Effects of 2-chloro-2'-deoxyadenosine on the cell cycle in the human leukemia EHEB cell line. 1557 Dec 71

In the 1990s, cladribine was developed as an adenosine deaminase-resistant nucleoside analog with selective lymphotoxic specificity in the hope that it might become useful in the treatment of some lymphoid neoplasms and autoimmune disorders. Several clinical trials demonstrated very significant effectiveness and safety of cladribine in the cure of hairy-cell leukemia, and the control of many other lymphoid malignancies. Cladribine was also extensively tested in selected autoimmune disorders, most notably in multiple sclerosis, with evidence of efficacy, tolerability and acceptable side effects/toxicity. The previous clinical studies and current status of cladribine for the treatment of multiple sclerosis are considered in this drug profile. In January 2005, Serono and IVAX announced plans to initiate a Phase III study of a specially formulated oral tablet of cladribine (Mylinax, Serono and IVAX) for the treatment of relapsing forms of multiple sclerosis. The proposed study will be the first large multicenter randomized controlled clinical trial of oral cladribine in multiple sclerosis.
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PMID:Cladribine for multiple sclerosis: review and current status. 1627 30

To clarify the role of lipid rafts in 2-chloro-2'-deoxyadenosine (2CdA; Cladribine)-induced apoptosis, the effects of disruption of lipid rafts by methyl-beta-cyclodextrin (MbetaCD) and filipin on 2CdA-induced apoptosis were investigated in four human acute lymphoblastic leukemia (ALL) cell lines comprised of T cells (MOLT-4, Jurkat) and B cells (NALM, BALL-1). The disruption of lipid rafts significantly inhibited 2CdA-induced apoptosis, indicating the crucial role of lipid rafts in the induction of apoptosis in leukemia cells. These reagents significantly inhibited 2CdA-induced elevation of the intracellular calcium concentration ([Ca(2+)](i)) in MOLT-4 cells, and 2CdA-induced apoptosis was partly inhibited by the Ca(2+) chelators BAPTA-AM and EGTA, and the L-type Ca(2+) channel blocker nifedipine. On the other hand, they had no effects on the cellular uptake of 2CdA. These results indicated that lipid rafts partly contributed to 2CdA-induced apoptosis by regulating Ca(2+) influx via the plasma membrane.
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PMID:Lipid raft disruption prevents apoptosis induced by 2-chloro-2'-deoxyadenosine (Cladribine) in leukemia cell lines. 1673 61


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