Glutaminase activity determines cytotoxicity of L-asparaginases on most leukemia cell lines.
L-Asparaginase (ASNase) is a front-line chemotherapy for acute lymphoblastic leukemia (ALL), which acts by deaminating asparagine and glutamine. To evaluate the importance of glutaminase activity, we exploited a recently developed mutant of Helicobacter pylori ASNase (dm HpA), with amino acid substitutions M121C/T169M. The mutant form has the same asparaginase activity as wild-type but lacks glutaminase activity. Wild-type and dm HpA were compared with the clinically used ASNases from Escherichia coli (l-ASP) and Erwinia chrysanthemi (ERWase). Asparaginase activity was similar for all isoforms, while glutaminase activity followed the rank order: ERWase>l-ASP>wild-type HpA>dm HpA. Cytotoxic efficacy of ASNases was tested on 11 human leukemia cell lines and two patient-derived ALL samples. Two cell lines which we had previously shown to be asparagine-dependent were equally sensitive to the asparaginase isoforms. The other nine lines and the two patient-derived samples were more sensitive to isoforms with higher glutaminase activities. ERWase was overall the most effective ASNase on all cell lines tested whereas dm HpA, having the lowest glutaminase activity, was the least effective. These data demonstrate that asparaginase activity alone may not be sufficient for ASNase cytotoxicity, and that glutaminase activity may be required for full anti-leukemic efficacy.
Center for Endocrinology, Diabetes & Metabolism, Children's Hospital Los Angeles, Los Angeles, CA, United States.
Jean Hugues
JH
Parmentier
Department of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Italy.
Maristella
M
Maggi
Department of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Italy.
Erika
E
Tarasco
Department of Molecular Medicine, Unit of Immunology and General Pathology, University of Pavia, Italy.
Claudia
C
Scotti
Center for Childhood Cancer and Blood Diseases, Children's Hospital Los Angeles, Los Angeles, CA, United States; Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.
Vassilios I
VI
Avramis
Center for Endocrinology, Diabetes & Metabolism, Children's Hospital Los Angeles, Los Angeles, CA, United States; Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States; Department of Physiology & Biophysics, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States. Electronic address: smittelman@chla.usc.edu.
Steven D
SD
Mittelman
D001215:Asparaginase / Q000378:metabolism*; D045744:Cell Line, Tumor; D005972:Glutaminase / Q000378:metabolism*; D016480:Helicobacter pylori / Q000201:enzymology; D006801:Humans; D007938:Leukemia / Q000473:pathology*
D001215:Asparaginase; D005972:Glutaminase
ALL; Asparaginase; Glutaminase; Leukemia