P-glycoprotein in human sarcoma: evidence for multidrug resistance.
Overexpression of an immunologically conserved, cell-surface glycoprotein (P-glycoprotein) is consistently associated with multidrug resistance in cell lines in vitro. A preliminary survey of specimens from 12 solid tumor types in our laboratories indicates significant overexpression of P-glycoprotein in some sarcomas. When tested by immunoblotting with monoclonal antibodies directed against P-glycoprotein; tumors from six of 25 sarcoma patients displayed elevated levels of P-glycoprotein. Three of the sarcoma patients exhibiting P-glycoprotein had not previously been exposed to chemotherapy, implying that overexpression of this marker and possible concomitant multidrug resistance may not depend only on selection during prior drug treatments. The P-glycoprotein overexpression in the sarcoma specimens is evidence for the presence of multidrug resistant cells in these tumors; thus, our data suggest that this mode of resistance may have clinical significance in sarcoma patients.
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004351:Drug Resistance; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D066298:In Vitro Techniques; D009363:Neoplasm Proteins / Q000032:analysis*; D012509:Sarcoma / Q000032:analysis*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D006023:Glycoproteins; D009363:Neoplasm Proteins