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.
Gene Therapy Program, University of Alabama at Birmingham, Birmingham, Alabama, 35294, USA.
J E
JE
Grim
G P
GP
Siegal
R D
RD
Alvarez
D T
DT
Curiel
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