Glutaminase (GA) in mammalian tissues occurs in three
isoforms: LGA (liver-type), KGA (kidney-type) and GAC (a KGA variant). Our previous study showed that human
malignant gliomas (WHO grades III and IV) lack expression of LGA
mRNA but are enriched in GAC
mRNA relative to KGA
mRNA. Here we analyzed the expression of mRNAs coding for the three
isoforms in the biopsy material derived from other
central nervous system tumors of WHO grades I-III. Non-neoplastic resective epileptic surgery samples served as control, as did cultured rat astrocytes and neurons. The GAC
mRNA/KGA
mRNA expression ratio was as a rule higher in the neoplastic than in control tissues, irrespective of the cell type dominating in the
tumor or
tumor malignancy. LGA
mRNA expression was relatively very low in cultured astrocytes, and very low to absent in
astrocytoma pilocyticum,
ependymoma and
subependymal giant cell astrocytoma (SEGA),
tumors of astrocytic origin. LGA
mRNA expression was almost as high as that of KGA and GAC
mRNA in cultured neurons and epileptic surgery samples which were enriched in neurons. LGA
mRNA was also relatively high in
ganglioglioma which contains a discernable proportion of neuronal cells, and in
oligodendroglioma. The results show that low expression of LGA
mRNA is a feature common to normal astrocytes and astroglia-derived
tumor cells or
ependymomas and can be considered as a cell-type, rather than a
malignancy marker.