Tumor grade, microvessel density, and activities of malate dehydrogenase, lactate dehydrogenase, and hexokinase in squamous cell carcinoma

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.