Multidrug-resistant tumor cells remain sensitive to a recombinant interleukin-4-Pseudomonas exotoxin, except when overexpressing the multidrug resistance protein MRP1.
Tumor cells may become resistant to conventional anticancer drugs through the occurrence of transmembrane transporter proteins such as P-glycoprotein (ABCB1), breast cancer resistance protein (ABCG2), or members of the multidrug resistance-associated protein family (MRP1-MRP5; ABCC1-ABCC5). In this report, we studied whether tumor cells that are cytostatic drug resistant because of overexpression of one of the above mentioned proteins are sensitive to a new anticancer agent, interleukin-4 toxin (IL-4 toxin). IL-4 toxin is a fusion protein composed of circularly permuted IL-4 and a truncated form of Pseudomonas exotoxin (PE) [IL-4(38-37)-PE38KDEL]. Ninety-six-h cytotoxicity assays and 10-day clonogenic assays showed that drug-selected multidrug resistant (MDR) tumor cells that overexpress P-glycoprotein or breast cancer resistance proteins are still sensitive to IL-4 toxin. Also, tumor cells transfected with cDNA for MRP2-5 showed no resistance, or marginal resistance, only to the toxin as compared with the parent cells. In contrast, MRP1-overexpressing cells, both drug selected and MRP1 transfected, are clearly resistant to IL-4 toxin with resistance factors of 4.3 to 8.4. MRP1-overexpressing cells were not resistant to PE itself. IL-4 toxin resistance in MRP1-overexpressing cells could be reversed by the MRP1 inhibitors probenecid or MK571 and were not affected by glutathione depletion by DL-buthionine-S,R-sulfoximine. In a transport assay using plasma membrane vesicles prepared from MRP1-overexpressing cells, IL-4 toxin and IL-4, but not PE, inhibited the translocation of the known MRP1 substrate 17beta-estradiol 17-(beta-D-glucuronide) (E(2)17betaG). These data suggest that MRP1-overexpressing cells are resistant to IL-4 toxin because of extrusion of this agent by MRP1. Still, the results of this study demonstrate that IL-4 toxin effectively kills most MDR tumor cells and, therefore, represents a promising anticancer drug.
de Jong
Mariska C
MC
Department of Pathology, VU University Medical Center, 1081 HV Amsterdam, The Netherlands.
Scheffer
George L
GL
Broxterman
Henk J
HJ
Hooijberg
Jan H
JH
Slootstra
Jerry W
JW
Meloen
Rob H
RH
Kreitman
Robert J
RJ
Husain
Syed R
SR
Joshi
Bharat H
BH
Puri
Raj K
RK
Scheper
Rik J
RJ
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D005098:Exotoxins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D015847:Interleukin-4 / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D020024:Leukotriene Antagonists / Q000494:pharmacology; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D011339:Probenecid / Q000494:pharmacology; D011422:Propionates / Q000494:pharmacology; D011804:Quinolines / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism*; D014162:Transfection; D014528:Uricosuric Agents / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D001427:Bacterial Toxins; D019328:Buthionine Sulfoximine; D018076:DNA, Complementary; D005098:Exotoxins; D015847:Interleukin-4; D020024:Leukotriene Antagonists; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D011339:Probenecid; D011422:Propionates; D011804:Quinolines; D011994:Recombinant Proteins; D014528:Uricosuric Agents; C479467:interleukin-4-Pseudomonas exotoxin; C059141:verlukast; C421109:multidrug resistance-associated protein 1