![]() |
6th ESACP Congress, Heidelberg, April 7-11, 1999 |
A019
G6PDH activity can be demonstrated histochemically by using a tetrazolium
salt as final electron acceptor which is reduced to coloured formazan that
precipitates where G6PDH activity is localized. When the reaction is
performed with a special tetrazolium salt, neotetrazolium, formazan
production is a proper reflection of G6PDH activity in all cell types when
the reaction is performed in the absence of oxygen. In the presence of oxygen,
however, formazan deposition is prevented in normal epithelium but not in
carcinomas of various organs. Oxygen insensitivity of cancer cells is
dependent on their high G6PDH activity, decreased superoxide dismutase levels
and decreased lipid peroxidation capacity as compared with their normal
counterparts. Diagnostic and prognostic values of this so-called oxygen
insensitivity test were determined quantitatively in colorectal carcinogenesis
using image analysis. Normal and hyperplastic epithelial cells showed oxygen
sensitivity. Oxygen insensitivity was observed in half of the adenomas tested
and in all carcinomas. The test proved to be a strong
prognosticator for survival of patients with a carcinoma, that is better
than Dukes' classification as single prognosticator. The quantitative
oxygen insensitivity test was also applied to diagnose differentially chronic
pancreatitis and pancreatic carcinoma. Pancreatic carcinomas were oxygen
insensitive whereas normal appearing and simple hyperplastic ducts in chronic
pancreatitis were, just as in normal pancreas, oxygen sensitive. Since the
test was also successful in the application to cytologic specimens, the test
is an excellent tool to be used for pre-operative differential diagnosis
between the two pancreatic diseases as well. It is concluded that oxygen
insensitivity of the histochemical assay of G6PDH activity is a valid
discriminator between malignant and normal epithelial cells in both colon and
pancreas. Moreover, it provides a strong prognostic prediction of survival
for individual colorectal cancer patients.
THE QUANTITATIVE HISTOCHEMICAL INSENSITIVITY ASSAY OF G6PDH ACTIVITY IN HUMAN
CANCER PATHOLOGY
Van Noorden CJF
Academic Medical Center, University of Amsterdam, Department of Cell Biology
and Histology, Amsterdam, the Netherlands
References:
Van Driel et al: J Pathol 1997; 182:398-403, Van Driel and
Van Noorden: J Histochem Cytochem 1999; 47:in press