EXPRESSION OF MULTIDRUG-RESISTANCE GENE (MDR-1) MESSENGER-RNA IN GASTRIC AND COLORECTAL CANCERS

Fresh surgical specimens of 52 gastric cancers and 25 colorectal cance rs were analyzed for the expression of multidrug resistance (mdr-1) ge ne mRNA with non-isotopic in situ hybridization (ISH) using a biotin-l abeled oligonucleotide probe. The mdr-l mRNA was expressed in 15.4% in cancerous portions and 1.9% in non-cancerous portions of gastric canc ers (p<0.02). In colorectal cancers, the mdr-l mRNA was positive in 36 % in cancerous pol?ions and 28% in non-cancerous portions. In gastric cancers, the well-differentiated type showed a significantly higher po sitive rate than the poorly differentiated type (p<0.01). These result s suggest that the mdr-1 mRNA expression in gastric and colorectal can cels is related to the degree of cellular differentiation.