Selective killing of squamous carcinoma cells by an immunotoxin that recognizes the EGF receptor.
We have conjugated a murine monoclonal antibody (B4G7) against the human epidermal growth factor (EGF) receptor to gelonin, a 60S ribosome inactivating protein, via N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP) and 2-iminothiolane. The B4G7-gelonin conjugate bound to the cell surface in proportion to the number of EGF receptors and competed with B4G7 antibody for binding to EGF receptors. The conjugate killed EGF receptor-hyperproducing squamous carcinoma cells (A431, NA, Ca9-22, TE5), and to some extent, human fibroblasts (HFO). It did not kill EGF receptor-deficient small-cell lung cancer cells (H69) and mouse fibroblasts (Swiss/3T3). Free B4G7, gelonin or a mixture of B4G7 and gelonin did not kill A431 cells. The number of EGF receptors was correlated to cytotoxicity at 10(-8) M of the conjugate, and the data were fitted to the regression equation: y = -35.83 log x +233.4 (correlation coefficient = -0.9995). These results suggest that the B4G7-gelonin conjugate may be a useful weapon for targeting therapy to squamous-cell carcinomas.
Ozawa
S
S
Department of Surgery, Keio University School of Medicine, Tokyo, Japan.
Ueda
M
M
Ando
N
N
Abe
O
O
Minoshima
S
S
Shimizu
N
N
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D002460:Cell Line; D066246:ErbB Receptors / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D007116:Immunization, Passive; D000922:Immunotoxins / Q000494:pharmacology*; D051379:Mice; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1
D000922:Immunotoxins; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; C025674:GEL protein, Gelonium multiflorum; D066246:ErbB Receptors