J. Rasschaert et Wj. Malaisse, ACTIVITY OF CYTOSOLIC AND MITOCHONDRIAL-ENZYMES PARTICIPATING IN NUTRIENT CATABOLISM OF NORMAL AND TUMORAL ISLET CELLS, International journal of biochemistry & cell biology, 27(2), 1995, pp. 195-200
The aim of the present study is to compare normal and tumoral pancreat
ic islet cells in terms of both the activity of selected cytosolic and
mitochondrial enzymes participating to nutrient catabolism and the in
trinsic properties of FAD-glycerophosphate dehydrogenase. The activity
of the glycolytic enzymes hexokinase and lactate dehydrogenase was hi
gher in tumoral (RINm5F) than normal islet cells. The opposite was see
n for glutamate decarboxylase, glutamate-oxaloacetate transaminase, gl
utamate-pyruvate transaminase, glutamate dehydrogenase, 2-ketoglutarat
e dehydrogenase and FAD-glycerophosphate dehydrogenase (m-GDH). These
findings are consistent with the high rates of glycolysis and protein
synthesis seen in tumoral islet cells compared with normal islet cells
, which favour mitochondrial oxidative events associated with the cata
bolism of D-glucose and amino acids. The intrinsic catalytic propertie
s of m-GDH were comparable, albeit not identical, in normal and tumora
l islet cells. Since a deficiency of m-GDH in pancreatic islets may re
present a contributing factor in the pathogenesis of non-insulin-depen
dent diabetes, it is proposed that RINm5F cells may readily yield suff
icient islet m-GDH for purification and further gene cloning.