Intracellular expression of the anti-erbB-2 sFv N29 fails to accomplish efficient target modulation.
The use of intracellular single chain antibodies has recently emerged as a highly efficient method of down-regulating or ablating protein expression. In this regard, we have demonstrated that a single chain antibody directed against the extracellular domain of the erbB-2 molecule causes a specific toxicity in erbB-2 positive tumor types. To further investigate the mechanism of this effect, we developed a second anti-erbB-2 sFv predicted to recognize an alternate extracellular epitope of the erbB-2 molecule. When produced as a secreted protein from the erbB-2 negative COS-1 cell line, this sFv binds specifically to erbB-2 positive cells, indicating that cellular machinery is able to produce a properly folded and functional sFv protein. However, by several assays, this sFv was shown to be unable to retain the erbB-2 protein within the ER. These negative results have implications for the evaluation and utilization of sFv knockout strategies in experimental contexts.
Grim
J E
JE
Gene Therapy Program, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA.
Siegal
G P
GP
Alvarez
R D
RD
Curiel
D T
DT
D000818:Animals; D000906:Antibodies / Q000276:immunology* / Q000494:pharmacology; D019556:COS Cells; D003602:Cytotoxicity, Immunologic; D015536:Down-Regulation; D007141:Immunoglobulin Fc Fragments / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000276:immunology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000276:immunology*
D000906:Antibodies; D007141:Immunoglobulin Fc Fragments; D007135:Immunoglobulin Variable Region; D018719:Erb-b2 Receptor Tyrosine Kinases