Biochemical changes and cytotoxicity associated with methionine depletion in paediatric central nervous system tumour cell lines.
BACKGROUND
The aim of this study was to investigate the importance of the extent and duration of methionine depletion as a cause of cytotoxicity for CNS tumour cell lines, and also to investigate the associated in vitro cellular biochemical responses.


METHODS
Cell growth inhibition was assayed by the SRB assay. Intracellular methionine levels were measured by GC/MS following dervatization with MTBSTFA. After methionine depletion, methionine synthase and MGMT activities were also determined. Glutathione levels were assayed by HPLC after derivatization with OPA.


RESULTS
Medulloblastoma (Daoy) and glioma (D54) cells were found to be methionine dependent and effects on proliferation, apoptosis and clonogenic survival were dependent on time and degree of methionine depletion. Methionine depletion also caused a demonstrable decrease in L-methionine levels and an increase in glutathione levels for both cell lines, with a decrease in MGMT activity for Daoy cells.


CONCLUSIONS
Daoy and D54 cells are methionine dependent; the degree and duration of methionine depletion is related to cell death. The associated biochemical changes in MGMT and glutathione may be expected to modulate chemosensitivity and this will be investigated in future studies.
Najim
N
N
Kidscan Children's Cancer Research Centre, Biomedical Sciences Research Institute, School of Environment and Life Sciences, University of Salford, Salford M54WT, UK.
Podmore
I D
ID
McGown
A
A
Estlin
E J
EJ
D017209:Apoptosis; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle; D049109:Cell Proliferation; D002528:Cerebellar Neoplasms / Q000378:metabolism / Q000473:pathology*; D002648:Child; D015254:DNA Modification Methylases / Q000378:metabolism; D045643:DNA Repair Enzymes / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D005910:Glioma / Q000378:metabolism / Q000473:pathology*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D008527:Medulloblastoma / Q000378:metabolism / Q000473:pathology*; D008715:Methionine / Q000172:deficiency*; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay; D025521:Tumor Suppressor Proteins / Q000378:metabolism
D025521:Tumor Suppressor Proteins; D008715:Methionine; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes; D005978:Glutathione