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Title: Membrane vesicles from multidrug-resistant human carcinoma cells contain a specific 150,000-170,000 dalton protein detected by photoaffinity labeling

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:7025283

The authors have selected multidrug-resistant human KB carcinoma cells in high levels of colchicine (KB-C4) or vinblastine (KB-V1) which are cross-resistant to many other structurally unrelated chemotheraputic agents. To determine the mechanism of reduced drug accumulation, they measured /sup 3/H-vinblastine (/sup 3/H-VBL) association with membrane vesicles made from parental drug sensitive, drug-resistant and revertant cells. Membrane vesicles from highly multidrug resistant cells exhibited increased specific and saturable binding of vinblastine, (Kd = 1 ..mu..M) that was temperature dependent and trypsin sensitive. To identify the molecules which bind vinblastine, membrane vesicles were exposed to two photo-activatable analogs of vinblastine, (N-P-(azido-3,5,-(/sup 3/H)-benzoyl)-N'-..beta..-aminoethylvindisine (/sup 3/H-NAB) and N-P-(azido-3-(/sup 125/I)-solicyl)-N'-..beta..-aminoethylvindesine (/sup 125/I-NASV). The specific labeling of a 150,000-170,000 dalton protein in membrane vesicles from multidrug-resistant KB-C4 and KB-V1 cells was found. /sup 125/I-NASV labeling was inhibited by vinblastine, vincrinstine and verapamil but not by colchicine or dexamethasone. The 150,000-170,000 dalton protein may have an important role in the multidrug resistance phenotype.

Research Organization:
National Institute of Health, Bethesda, MD
OSTI ID:
7025283
Report Number(s):
CONF-8606151-
Journal Information:
Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
Country of Publication:
United States
Language:
English

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