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Affiliation(s)
- W Plunkett
- University of Texas MD Anderson Cancer Center, Houston 77030, USA
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Begleiter A, Mowat M, Israels LG, Johnston JB. Chlorambucil in chronic lymphocytic leukemia: mechanism of action. Leuk Lymphoma 1996; 23:187-201. [PMID: 9031099 DOI: 10.3109/10428199609054821] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Chronic lymphocytic leukemia (CLL) is the most common leukemia in Western countries but the clinical presentation and rate of disease progression are highly variable. When treatment is required the most commonly used therapy is the nitrogen mustard alkylating agent, chlorambucil (CLB), with or without prednisone. Although CLB has been used in the treatment of CLL for forty years the exact mechanism of action of this agent in CLL is still unclear. Studies in proliferating model tumor systems have demonstrated that CLB can bind to a variety of cellular structures such as membranes, RNA, proteins and DNA; however, DNA crosslinking appears to be most important for antitumor activity in these systems. In addition, a number of different mechanisms can contribute to CLB resistance in these tumor models including increased drug metabolism, DNA repair and CLB detoxification resulting from elevated levels of glutathione (GSH) and glutathione S-transferase (GST) activity. However, unlike tumor models in vitro, CLL cells are generally not proliferating and studies in CLL cells have raised questions about the hypothesis that DNA crosslinking is the major mechanism of antitumor action for CLB in this disease. CLB induces apoptosis in CLL cells and this appears to correlate with the clinical effects of this agent. Thus, alkylation of cellular targets other than DNA, which can also induce apoptosis, may contribute to the activity of CLB. Alterations in genes such as p53, mdm-2, bcl-2 and bax which control entry into apoptosis may cause drug resistance. Loss of wild-type p53 by mutation or deletion occurs in 10 to 15% of CLL patients and appears to correlate strongly with poor clinical response to CLB. The induction of apoptosis by CLB is paralleled by an increase in P53 and Mdm-2 but this increase in not observed in patients with p53 mutations indicating that with high drug concentrations CLB can produce cell death through P53 independent pathways. The level of Mdm-2 mRNA in the CLL cells is not a useful predictor of drug sensitivity. In addition, although Bax and Bcl-2 are important regulators of apoptosis and the levels of these proteins are elevated in CLL cells compared with normal B cells, the levels of Bax and Bcl-2, or the Bax:Bcl-2 ratio, are not important determinants of drug sensitivity in this leukemia. Finally, whereas CLB and nucleoside analogs may produce cell death in CLL by a P53 dependent pathway other agents, such as dexamethasone or vincristine, may act through P53-independent pathways.
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Affiliation(s)
- A Begleiter
- Manitoba Institute of Cell Biology, Manitoba Cancer Treatment and Research Foundation, Winnipeg, Canada
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3
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Lipidic peptides. XIII: Synthesis, structure elucidation and in vitro toxicity assessment of chlorambucil conjugates with lipidic acids, lipidic amino acids and their oligomers. Int J Pharm 1992. [DOI: 10.1016/0378-5173(92)90237-v] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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4
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Sunters A, Springer CJ, Bagshawe KD, Souhami RL, Hartley JA. The cytotoxicity, DNA crosslinking ability and DNA sequence selectivity of the aniline mustards melphalan, chlorambucil and 4-[bis(2-chloroethyl)amino] benzoic acid. Biochem Pharmacol 1992; 44:59-64. [PMID: 1632839 DOI: 10.1016/0006-2952(92)90038-k] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Three aniline derivatives melphalan (L-PAM), chlorambucil (CHL) and 4-[bis(2-chloroethyl)amino] benzoic acid (BAM) have been compared on the basis of their in vitro cytotoxicities, DNA interstrand crosslinking ability and DNA sequence selectivity. Cytotoxicity was assessed in the human colonic adenocarcinoma LS174T and leukaemic K562 cell lines using the sulpho-rhodamine B and tetrazolium dye reduction assays. The order of cytotoxicities was L-PAM greater than CHL greater than BAM in both cell lines with K562 being less sensitive than LS174T. This was different from the order CHL greater than L-PAM greater than BAM which would be predicted from simple chemical reactivity or rate of hydrolysis, parameters which have been used previously as indicators of biological potency for aromatic nitrogen mustards. DNA interstrand crosslinking in cells as determined by alkaline elution showed a correlation with IC50 values. The ranking order of activity was further predicted by the ability of the agents to produce interstrand crosslinks in isolated DNA. The extent of guanine N-7 alkylation, assessed using a modified DNA sequencing technique, mirrored cytotoxicity and crosslinking ability, but at equivalent levels of alkylation there was no significant difference in DNA sequence selectivity. These data demonstrates that simple chemical reactivity or hydrolysis rate is not a good indicator of DNA reactivity or cytotoxicity for a number of aniline mustards, whereas DNA interstrand crosslinking ability either measured directly in cells or in isolated DNA, gives a good indication of biological activity.
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Affiliation(s)
- A Sunters
- Department of Medical Oncology, Charing Cross Hospital, London, U.K
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Begleiter A, Goldenberg GJ, Anhalt CD, Lee K, Mowat MR, Israels LG, Johnston JB. Mechanisms of resistance to chlorambucil in chronic lymphocytic leukemia. Leuk Res 1991; 15:1019-27. [PMID: 1961006 DOI: 10.1016/0145-2126(91)90107-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The postulated biochemical mechanisms responsible for clinical resistance to chlorambucil (CLB) in chronic lymphocytic leukemia (CLL) have been examined. The total sulfhydryl, non-protein-bound sulfhydryl, protein-bound sulfhydryl (PSH) and glutathione (GSH) levels, in addition to glutathione S-transferase (GST) activities, were measured in the leukemic cells of 18 CLL patients. In addition, the formation and repair of DNA cross-links were measured following incubation of the cells with 100 microM chlorambucil in vitro. These parameters were then correlated with the subsequent clinical responses of the patients, as measured by the percent fall in lymphocyte count 3 weeks following 0.9 mg/kg chlorambucil. No correlations were observed between any of the individual parameters and clinical response, although a slight positive correlation was observed between the PSH:GSH ratio and clinical response. These findings suggest that multiple mechanisms may contribute to CLB-resistance in CLL.
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Affiliation(s)
- A Begleiter
- Department of Internal Medicine, University of Manitoba, Canada
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Kruse E, Hartley-Asp B. A time study on the uptake of estramustine into prostatic tumour 1013L cells in vitro. Biochem Pharmacol 1989; 38:702-4. [PMID: 2917024 DOI: 10.1016/0006-2952(89)90221-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- E Kruse
- Department of Biochemistry, University of Lund, Sweden
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Silber R, Potmesil M, Bank BB. Studies on drug resistance in chronic lymphocytic leukemia. ADVANCES IN ENZYME REGULATION 1989; 29:267-76. [PMID: 2561248 DOI: 10.1016/0065-2571(89)90106-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Chronic lymphocytic leukemia is a neoplastic disease in which drug resistance invariably occurs. We have studied the uptake and interaction with molecular targets of two drugs, chlorambucil and adriamycin, in CLL lymphocytes and CHO cell lines. Resistance does not appear related to uptake for either drug. Exposure to CLB causes DNA cross-links in the sensitive but not in the resistant cell line. The GSH content of B-CLL lymphocytes is depleted after a 20-hr incubation. An inability to maintain its GSH content may contribute to this cell's vulnerability to CLB. The resistance of CLL lymphocytes to ADR may be related to the undetectable levels of its target enzyme DNA topoisomerase II. Future approaches may involve study of novel anthracyclines, DNA topoisomerase I inhibitors and the development of in vitro predictive tests.
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MESH Headings
- Animals
- Cell Line
- Chlorambucil/metabolism
- Chlorambucil/pharmacology
- DNA Topoisomerases, Type I/metabolism
- DNA Topoisomerases, Type II/metabolism
- DNA, Neoplasm/drug effects
- DNA, Neoplasm/metabolism
- Doxorubicin/pharmacology
- Drug Resistance
- Glutathione/metabolism
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/drug therapy
- Leukemia, Lymphocytic, Chronic, B-Cell/metabolism
- Tumor Cells, Cultured
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Affiliation(s)
- R Silber
- New York University School of Medicine, Department of Medicine, New York 10016
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Affiliation(s)
- P B Farmer
- MRC Toxicology Unit, Medical Research Council Laboratories, Carshalton, Surrey, U.K
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Mikkelsen RB, Asher C, Hicks T. Extracellular pH, transmembrane distribution and cytotoxicity of chlorambucil. Biochem Pharmacol 1985; 34:2531-4. [PMID: 4015693 DOI: 10.1016/0006-2952(85)90538-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The effects of extracellular pH (6.2 to 7.3) on uptake and cytotoxicity of the weak acid anti-tumor drug chlorambucil were investigated. Decreasing extracellular pH from 7.3 to 6.5 had a negligible effect on the intracellular pH of Chinese hamster V79 fibroblasts, thus resulting in the formation of a transmembrane pH gradient (intracellular alkaline). Addition of high concentrations of acetate or bicarbonate partially collapsed the pH gradient. Chlorambucil (pKa = 5.8) behaved as a weak acid with enhanced accumulation and cytotoxicity at extracellular pH less than 7.0. As predicted for a weak acid, partial collapse of the transmembrane pH gradient decreased both uptake and cell killing. Since the interstitial pH of micrometastases and solid tumors of many cancers is low relative to normal tissues, these results have potential implications for both in vitro drug testing and in vivo therapy.
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Begleiter A, Goldenberg GJ. Uptake and decomposition of chlorambucil by L5178Y lymphoblasts in vitro. Biochem Pharmacol 1983; 32:535-9. [PMID: 6847702 DOI: 10.1016/0006-2952(83)90535-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The uptake of [14C]chlorambucil by L5178Y lymphoblasts was studied using thin-layer chromatography to identify the various radioactive components that enter or leave cells. Theoretical calculations predicted that entry of chlorambucil into cells by simple diffusion would be rapid and essentially complete in 45 sec or less. Uptake of intact chlorambucil was rapid, reaching a cell/medium ratio of approximately 1.5 in less than 15 sec at both 37 degrees and 4 degrees, consistent with a simple diffusion mechanism. In cells treated with [14C]chlorambucil for 60 min, the intracellular level of intact drug decreased with time, and this decay was attributed to hydrolysis and alkylation. The level of intact drug in the medium decreased at a similar rate resulting in a nearly constant cell/medium distribution ratio. Intact chlorambucil in the cells was found to be entirely ethanol- and trichloroacetic acid-soluble. Efflux of intact chlorambucil was very rapid and temperature-insensitive. These findings suggest that chlorambucil efflux, as well as influx, is by a simple diffusion mechanism. A derivative of chlorambucil was found in ethanol solutions of the drug. This derivative, which may be the ethyl ester of the drug, is highly concentrated in cells and may interfere with pharmacological investigations of chlorambucil.
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13
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Abstract
1. The metabolic dispositionof chlorambucil, 4-p-(di-2-chloroethyl)aminophenylbutyric acid, was studied in the rat. 2. After oral administration of [14C]chlorambucil to rats, plasma, liver, and kidney showed the highest concentration of 14C. After intravenous administration, plasma and kidney were heavily labelled. Although plasma contained as much as 10% of the administered dose in the first few hours after administration, the level decreased to 1% by 24 h. Elimination of radioactivity was mainly through the kidney. 3. Ten metabolites were isolated and characterized by mass spectrometry. Most metabolites had undergone oxidation on the butyric acid side-chain to form phenylacetic acid and benzoic acid derivatives. Spontaneous degradation products of [14C]chlorambucil were analysed and compared with the metabolites.
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Godeneche D, Madelmont JC, Sauvezie B, Billaud A. [Absorption kinetics, distribution and elimination of (N,N-di-(2-chloroethyl)-p-amino-4-phenyl)butyric acid (chloraminophene) labeled with 14-C in the rat]. Biochem Pharmacol 1975; 24:1303. [PMID: 1148018 DOI: 10.1016/0006-2952(75)90342-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Hill BT. Differential effects of cytotoxic concentrations of chlorambucil on drug-resistant and drug-sensitive cell lines of the Yoshida ascites sarcoma in culture. Eur J Cancer 1975; 11:91-6. [PMID: 1169147 DOI: 10.1016/0014-2964(75)90031-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Stevenson AC. Letter: Effects of amylobarbitone on the frequency of chromosomal aberrations in human lymphocytes determined by chlorambucil and melphalan in vitro. Mutat Res 1974; 23:403-4. [PMID: 4407665 DOI: 10.1016/0027-5107(74)90117-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Harrap KR, Riches PG, Jackson RC, Smith CA. Some effects of chlorambucil on the uptake and utilization of sulphydryl-containing compounds by tumour cells. Biochem Pharmacol 1973; 22:2881-9. [PMID: 4761557 DOI: 10.1016/0006-2952(73)90155-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Stevenson AC, Roman CS, Patel CR. Effects of amylobarbitone on the frequency of chromosomal aberrations in human lymphocytes determined by chlorambucil and melphalan in vitro. Mutat Res 1973; 19:225-9. [PMID: 4748977 DOI: 10.1016/0027-5107(73)90080-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Hill BT, Douglas ID, Grover PL. Increased antitumour activity of chlorambucil following pretreatment with inducers of drug-metabolizing enzymes. Biochem Pharmacol 1973; 22:1083-9. [PMID: 4695667 DOI: 10.1016/0006-2952(73)90173-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Hill BT, Harrap KR. The uptake and utilization of chlorambucil by lymphocytes from patients with chronic lymphocytic leukaemia. Br J Cancer 1972; 26:439-43. [PMID: 4647395 PMCID: PMC2008659 DOI: 10.1038/bjc.1972.60] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
It has been shown that lymphocytes isolated from the peripheral blood of patients with chronic lymphocytic leukaemia do not modify the mustard group of chlorambucil, as has been demonstrated previously in Yoshida ascites cells. However, lymphocytes from patients with an unsatisfactory clinical course or poor response to treatment were able to modify the aromatic region of the drug molecule; little change occurred in the aromatic absorption of intracellular chlorambucil in patients who responded to treatment. This simple test may provide a rapid assessment of a patient's potential response to chemotherapy.
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Hill BT. Studies on the transport and cellular distribution of chlorambucil in the Yoshida ascites sarcoma. Biochem Pharmacol 1972; 21:495-502. [PMID: 5014507 DOI: 10.1016/0006-2952(72)90322-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Hill BT, Riches PG, Furness ME. Effects of chlorambucil treatment on the rates of respiration and glycolysis in drug-sensitive and -resistant strains of the Yoshida ascites sarcoma. Biochem Pharmacol 1970; 19:2973-8. [PMID: 5534949 DOI: 10.1016/0006-2952(70)90083-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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