We report the immunohistochemical detection of the 170–180 kDa multi‐drug‐resistance‐related P‐glycoprotein in human tumor cells with a low level of resistance. A series of human squamous lung cancer cell lines with increasing levels of resistance to doxorubicin (DOX) was developed and stained for P‐glycoprotein, using the JSB‐lMAb. Subline SW1573/50A with a 4‐ to 6‐fold cross‐resistance to daunorubicin (DNR) and vincristine (VCR) showed rather uniform positive staining for P‐glycoprotein apparently at cytoplasmic sites. Only in cells with higher degrees of resistance (> 10‐fold) could plasmamembrane‐associated P‐glycoprotein be made visible. DNR efflux was increased in SW1573I50A as compared to the parent line SWl573 (52 and 70% DNR were retained during 3 min efflux respectively). Verapamil partially reversed DNR and VCR resistance in SWl573/50A. Cells obtained from a metastasized renal cell carcinoma and cultured in vitro stained in a similar way to SWl573/50A and showed some sensitivity to verapamil modulation of VCR cytotoxicity. Our results suggest that weakly resistant cancer cells obtained from patients can be routinely detected with JSB‐l on cytospins, and Implicate that in such weakly resistant cells P‐glycoprotein may be present, while plasma membrane expression is not yet readily detectable. Copyright © 1989 Wiley‐Liss, Inc., A Wiley Company
Immunohistochemical detection of P‐glycoprotein in human tumor cells with a low degree of drug resistance
DE LANGE, Pieter;
1989
Abstract
We report the immunohistochemical detection of the 170–180 kDa multi‐drug‐resistance‐related P‐glycoprotein in human tumor cells with a low level of resistance. A series of human squamous lung cancer cell lines with increasing levels of resistance to doxorubicin (DOX) was developed and stained for P‐glycoprotein, using the JSB‐lMAb. Subline SW1573/50A with a 4‐ to 6‐fold cross‐resistance to daunorubicin (DNR) and vincristine (VCR) showed rather uniform positive staining for P‐glycoprotein apparently at cytoplasmic sites. Only in cells with higher degrees of resistance (> 10‐fold) could plasmamembrane‐associated P‐glycoprotein be made visible. DNR efflux was increased in SW1573I50A as compared to the parent line SWl573 (52 and 70% DNR were retained during 3 min efflux respectively). Verapamil partially reversed DNR and VCR resistance in SWl573/50A. Cells obtained from a metastasized renal cell carcinoma and cultured in vitro stained in a similar way to SWl573/50A and showed some sensitivity to verapamil modulation of VCR cytotoxicity. Our results suggest that weakly resistant cancer cells obtained from patients can be routinely detected with JSB‐l on cytospins, and Implicate that in such weakly resistant cells P‐glycoprotein may be present, while plasma membrane expression is not yet readily detectable. Copyright © 1989 Wiley‐Liss, Inc., A Wiley CompanyI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
