Comparative In Vitro Study of 11 C-Methionine and 11 C-Deuterodeprenyl Uptake in Three Human Glioma Cell Lines.

AIM: To compare the uptake of 11 C-deuterodeprenyl (11 C-DED) and 11 C-methionine (11 C-MET) in three human glioma cell lines and study the relationship with glial fibrillary acid protein (GFAP) and monoamine oxidase B (MAO B) expression. 11 C-DED is used in positron emission tomography imaging as a marker of astrocytosis in various central nervous system pathologies. It binds irreversibly to MAO B, a glial dimeric enzyme with increased activity in some neurological pathologies.

MATERIALS AND METHODS: Binding and internalization studies of 11 C-MET and 11 C-DED were performed in astrocytoma grade III, glioblastoma grade IV, and radio-resistant glioblastoma grade IV cells. Immunofluorescence was used.

RESULTS: 11 C-MET specific activity bound to membrane was 9.0%-11.1% and that internalized was 88.9%-91.0%. 11 C-DED specific activity bound to membrane was 34.8%-58.0% and that internalized was 38.7%-65.2%. Immunocytochemistry revealed GFAP and MAO B expression.

CONCLUSIONS: The expression of MAO B measured by 11 C-DED uptake or immunocytochemistry was not significantly different in grade III or IV cells. The GFAP signal was higher for grade IV compared to grade III. 11 C-MET uptake was high in all the tumor cells. 11 C-DED is a dopamine analogue and the transport across cell membranes is expected to be mediated by DAT receptors present in astrocytes. Reactive astrocytes surround tumor lesions; so the authors suggest that the 11 C-DED uptake might be caused by the reactive astrocytosis and not by MAO B expression in tumor cells.