Clinical significance of P-glycoprotein expression analyzed by immunohistochemical staining in cancer tissues.
P-glycoprotein is a transmembrane protein with increased drug efflux from resistant cells, which is encoded by the MDR1 gene. An overexpression of P-glycoprotein has been reported to correlate with the degree of resistance to anticancer agents, especially to adriamycin. In this study, the expression of P-glycoprotein was analyzed immunohistochemically by using a monoclonal antibody, MRK16 against P-glycoprotein in 18 fresh human tumors. The expression of P-glycoprotein was detected in eight (44 per cent) tumor specimens out of 18 patients. Although six (75.0 per cent) of the 8 P-glycoprotein positive tumors were resistant to adriamycin, the other two tumors showed clinical responses. Furthermore, five (50.0 per cent) of the 10 P-glycoprotein negative tumors exhibited positive clinical responses. These results suggest that P-glycoprotein expression may not be a useful marker to predict intrinsic resistance to adriamycin in fresh human tumors.
Department of Surgery, Hiroshima University, Japan.
R
R
Kim
N
N
Hirabayashi
M
M
Nishiyama
K
K
Aogi
T
T
Toge
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002460:Cell Line; D004317:Doxorubicin / Q000627:therapeutic use; D004351:Drug Resistance; D006801:Humans; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000032:analysis*; D009363:Neoplasm Proteins / Q000032:analysis; D009369:Neoplasms / Q000737:chemistry* / Q000188:drug therapy
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D004317:Doxorubicin