RESUMEN
Using a synthetic substitute, Ultroser HY, for fetal bovine serum to supplement a classical RPMI 1640 culture medium produced changes in the properties of sensitive and of multidrug-resistant K 562 cells. Though no morphological changes were found, a statistically significant decrease in doubling-time was noted. Plasma membranes were more rigid, as reflected by an increase in the order parameter values. Adriamycin cytotoxicity was decreased, as shown by an increase in IC 50 values. The THP-adriamycin uptake, monitored by fluorimetry, was diminished even when the revertant agent verapamil was added. Moreover, the apparent number of Pgp 170 molecules per cell was lower for resistant cells grown with Ultroser HY. Thus Pgp 170 was not involved in the MDR increase induced by Ultroser HY. In conclusion, it must be kept in mind that environmental factors such as media chemical composition influence the MDR phenomenon and that environmental factors may also influence the MDR phenomenon in clinical situations.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Antibióticos Antineoplásicos/farmacocinética , Medios de Cultivo/farmacología , Doxorrubicina/análogos & derivados , Resistencia a Múltiples Medicamentos , Animales , Antibióticos Antineoplásicos/farmacología , Bovinos , División Celular/efectos de los fármacos , Línea Celular/efectos de los fármacos , Línea Celular/patología , Medios de Cultivo/química , Doxorrubicina/farmacocinética , Doxorrubicina/farmacología , Humanos , Fluidez de la Membrana/efectos de los fármacos , Verapamilo/farmacologíaRESUMEN
Pgp 170 is the main integral membrane protein involved in acquired or de novo multidrug resistance (MDR), frequently implicated in chemotherapeutic failure. Because there is at present no method for quantitating Pgp 170 levels, a new and convenient assay, using flow cytometry with a standard fluorescence curve and MRK 16, a mAb recognizing an external epitope of human Pgp 170, was developed. Assuming a 1:1 stoichiometry, we calculated for the first time the apparent number of Pgp 170 molecules per cell. The method was applied successfully to cells in suspension or grown as monolayers and their mixtures. All quality criteria were checked and proved the suitability of the method for quantifying Pgp 170.