Cd. Ross et al., Tumor grade, microvessel density, and activities of malate dehydrogenase, lactate dehydrogenase, and hexokinase in squamous cell carcinoma, OTO H N SUR, 122(2), 2000, pp. 195-200
Squamous cell carcinomas were evaluated with respect to tumor differentiati
on (through use of hematoxylin and eosin stain), microvessel density (throu
gh use of CD-34 immunocytochemical stain), and magnitudes of malate dehydro
genase (MDH), hexokinase, and lactate dehydrogenase (LDH) enzyme activities
. Direct correlations were found between tumor grade, MDH activity, and mic
rovessel density. Direct correlations were also found between hexokinase ac
tivity and MDH activity and microvessel density. Inverse correlations were
found between LDH activity and both tumor grade and MDH activity. These res
ults suggest that the high rate of glucose utilization (indicated by hexoki
nase activity) found in more poorly differentiated tumors has a higher comp
onent of aerobic oxidative metabolism (indicated by MDH activity) and a rel
atively lower contribution from anaerobic metabolism (indicated by LDH acti
vity) than do the rates found in more differentiated tumors. It is also sug
gested that as the glycolytic rate increases, more pyruvate goes into the K
rebs cycle than into lactate. The availability of glucose-derived pyruvate
for oxidative metabolism would mean less of a dependency on glutamine as a
carbon source in squamous cell carcinoma.