Targeting multidrug resistant tumor cells with a recombinant single-chain FV fragment directed to P-glycoprotein.
The MDR1 gene product P-glycoprotein (Pgp) plays a key role in multidrug resistance of cancer cells. Pgp is an ATP-driven efflux pump that extrudes a variety of dissimilar hydrophobic cytotoxic compounds. P-glycoprotein overexpression results in multidrug resistance (MDR) of tumor cell lines in vitro as well as in cancer patients. To selectively target and eliminate MDR tumor cells, we have isolated a monoclonal antibody that specifically reacts with the first extracellular loop of the human Pgp. We have cloned the variable domain genes of this antibody and assembled a functional single-chain Fv fragment capable of specifically targeting various Pgp-expressing MDR carcinoma cells lines. Targeting and specific elimination of Pgp-dependent MDR human cancer cells was achieved by constructing a single-chain immunotoxin in which the scFv fragment was fused to a truncated form of Pseudomonas exotoxin (PE38). We conclude that recombinant Fv-immunotoxins or other Fv-based molecules armed with potent cytotoxins represent an effective tool in targeted cancer therapy aimed at specific elimination of MDR tumor cell sub-populations. Recombinant antibody fragments targeting MDR proteins such as Pgp may be also used for intracellular expression and consequent phenotypic knockout of MDR.
Niv
R
R
Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
Assaraf
Y G
YG
Segal
D
D
Pirak
E
E
Reiter
Y
Y
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors*; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D001483:Base Sequence; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D007128:Immunoglobulin Fragments / Q000494:pharmacology*; D000922:Immunotoxins / Q000494:pharmacology*; D051379:Mice; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000494:pharmacology
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D007128:Immunoglobulin Fragments; D000922:Immunotoxins; D011994:Recombinant Proteins; C055966:immunoglobulin Fv