[Expression of P-glycoprotein (multidrug-resistance gene product) in haematological tumors]

The fact that cancer cell acquires multidrug resistance to carcinostatics at cancer treatment is a very important subject clinically. The mode of multidrug-resistance is complicated, but the gene associated with multidrug resistance (MDR 1) has been isolated. It has become evident that MDR 1 gene carries membrane glycoprotein (P-glycoprotein) which occurs in the cell acquired drug-resistance. Assessment has been made this time regarding the occurrence of P-glycoprotein in the tumorous cells and tissues by the use of monoclonal antibody (C 219) to P-glycoprotein. Occurrence of P-glycoprotein in malignant lymphoma exhibited positivity in 9 cases out of 36 immunohistologically. 170 KD P-glycoprotein was detected in 4 cases out of 10 at Western blotting analysis of the protein isolated from the nuclear cell in the peripheral blood in the patients with leukemia. Further, P-glycoprotein positive cases were all progressive cases clinically and showed resistance to treatment. From these results, it has been clarified that occurrence of P-glycoprotein in haematological tumors is related to multidrug resistance.