Background: The levels of mRNA-expression of multidrug resistance (MDR1) and glutathione-S-transferase pi (GST-pi) were measured and correlated with the immunohistochemical expressions of tumour markers.
Materials and methods: Analysis of total mRNA was performed by Northern and slot blots. The expression of carcinoembryonic antigen (CEA) and other tumour markers was assessed by immunohistochemistry. The tumour panel comprised tumours of different histologies.
Results: CEA-positive tumours showed a significantly higher ex-pression of MDR1 and GST-pi than CEA-negative tumours. Wilcoxon-Test: mean rank of the MDR1 expression (14.3 vs. 7.8; p < 0.05) and GST-pi expression (15.3 vs. 5.9; p < 0.001). No other correlation could be found.
Conclusions: The relationship of MDR1 and GST-pi with the tumour marker CEA implies that evaluation of CEA can help in discriminating between tumours with high or low expression of drug resistance. Furthermore, correlation between MDR1, GST-pi and CEA indicates that there might be a common mechanism, regulating drug resistance and expression of CEA.