Cyclopentenyl cytosine inhibits cytidine triphosphate synthetase in paediatric acute non-lymphocytic leukaemia: a promising target for chemotherapy

• Published in: European journal of cancer (1990) Vol. 36; no. 5; pp. 627 - 635
• Main Authors: Verschuur, A.C., Van Gennip, A.H., Leen, R., Muller, E.J., Elzinga, L., Voûte, P.A., Van Kuilenburg, A.B.P.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2000; Elsevier
• Subjects: Acute non-lymphocytic leukaemia; Adolescent; Antineoplastic agents; Antineoplastic Agents - therapeutic use; Biological and medical sciences; Carbon-Nitrogen Ligases - antagonists & inhibitors; Chemotherapy; Child; Child, Preschool; CTP; Cyclopentenyl cytosine; Cytidine - analogs & derivatives; Cytidine - therapeutic use; Cytidine triphosphate synthetase; Female; Humans; Leukemia, Myeloid, Acute - drug therapy; Leukemia, Myeloid, Acute - enzymology; Male; Medical sciences; Neoplasm Proteins - antagonists & inhibitors; Pharmacology. Drug treatments; Ribonucleotides; Tumor Cells, Cultured; UTP; Cytidine triphosphate synthetase; UTP; Ribonucleotides; Acute non-lymphocytic leukaemia; Cyclopentenyl cytosine; CTP; Human; Antineoplastic agent; Cell culture; Enzyme; Acute; Leukemia; Malignant hemopathy; Triphosphates; Synthase; In vitro; Cytidine; Chemotherapy; Cytosine; Child; Ribonucleotide; Cyclopentane derivatives
• ISSN: 0959-8049; 1879-0852
• DOI: 10.1016/S0959-8049(00)00021-6

Cytidine triphosphate (CTP) synthetase is a key enzyme in the anabolic pathways of cytosine and uracil ribonucleotide metabolism. The enzyme catalyses the conversion of uridine triphosphate (UTP) into CTP, and has a high activity in various malignancies, which has led to the development of inhibitors of CTP synthetase for therapeutic purposes. We studied both CTP synthetase activity and ribonucleotide concentrations in leukaemic cells of 12 children suffering from acute non-lymphocytic leukaemia (ANLL), and performed incubation experiments with cyclopentenyl cytosine (CPEC), a nucleoside analogue that is capable of inhibiting CTP synthetase.The CTP synthetase activity in ANLL cells (5.1±2.3 nmol CTP/mg/h) was significantly higher compared with granulocytes of healthy controls (0.6±0.4 nmol CTP/mg/h, P=0.0002), but was not different from the CTP synthetase activity in non-malignant CD34+ bone marrow cells (5.6±2.4 nmol CTP/mg/h). Major shifts were observed in the various ribonucleotide concentrations in ANLL cells compared with granulocytes: the absolute amount of ribonucleotides was increased with a substantial rise of the CTP (2.4 versus 0.4 pmol/μg protein, P=0.0007) and UTP (8.7 versus 1.6 pmol/μg protein, P=0.0007) concentrations in ANLL cells compared with granulocytes. Treatment of ANLL cells in vitro with CPEC induced a major depletion (77% with 2.5 μM of CPEC) in the concentration of CTP, whilst the concentrations of the other ribonucleotides remained unchanged. Therefore, the high activity of CTP synthetase in acute non-lymphocytic leukaemic cells can be inhibited by CPEC, which provides a key to a new approach for the treatment of ANLL.