Expression of P-glycoprotein in breast cancer tissue and in vitro resistance to doxorubicin and vincristine.
Expression of P-glycoprotein was evaluated by C219 monoclonal antibody immunoblots in 34 previously untreated and 14 pretreated breast cancers and in benign breast lesions or histologically normal breast glands. P-glycoprotein was not detectable in the few cases of normal or benign tissue. P-glycoprotein was expressed in the 170 kD areas of 29% (10/34) of untreated and 64% (9/14) of previously treated tumours (P = 0.02). In treated tumours, high intensity expression was observed more frequently than in untreated breast cancer (40% vs. 9%). Moreover, there was a significant association between P-glycoprotein expression and in vitro resistance to doxorubicin and vincristine. Simultaneous resistance was observed in all of the P-glycoprotein positive and in only 56% of the P-glycoprotein negative tissues (P less than 0.01). Some aspects of the typical multidrug resistant phenotype, such as P-glycoprotein expression and simultaneous resistance to doxorubicin and vincristine, could be detected in small subsets of breast cancer patients. No relation between P-glycoprotein expression and the type of previous clinical treatment was observed.
Sanfilippo
O
O
Oncologia Sperimentale C, Milano, Italy.
Ronchi
E
E
De Marco
C
C
Di Fronzo
G
G
Silvestrini
R
R
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D001940:Breast / Q000737:chemistry; D001943:Breast Neoplasms / Q000737:chemistry*; D002460:Cell Line; D004317:Doxorubicin / Q000494:pharmacology*; D004351:Drug Resistance / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008562:Membrane Glycoproteins / Q000032:analysis*; D009363:Neoplasm Proteins / Q000032:analysis*; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000187:drug effects; D014750:Vincristine / Q000494:pharmacology*
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D014750:Vincristine; D004317:Doxorubicin