Toxicity of ribosome-inactivating proteins-containing immunotoxins to a human bladder carcinoma cell line.
Immunotoxins were prepared by linking the type 1 ribosome-inactivating proteins (RIP) momordin I, pokeweed antiviral protein from seeds (PAP-S) and saporin-S6 to the 48-127 monoclonal antibody (MAb) recognising a glycoprotein (gp54) expressed on all human bladder tumours tested and on human bladder carcinoma cell lines, in particular on the T24 cell line. T24 cells required a 2 hr contact with immunotoxins to ensure binding and endocytosis. A time course of exposure, followed by further incubation without the immunotoxins, showed that maximum inhibition of protein synthesis by T24 cells was reached after 2 hr of contact followed by 3 days without the immunotoxins. Under optimal conditions, 48-127/RIP immunotoxins at nanomolar concentrations inhibited by 50% protein synthesis of target T24 cells. No toxicity was observed if (i) target cells were treated with non-conjugated RIP, (ii) target cells were treated with momordin I- or PAP-S-containing immunotoxins made with an irrelevant antibody and (iii) a non-target cell line was treated with the same 2 RIP conjugated to 48-127 antibody. The in vitro selective toxicity of these immunotoxins encourages further studies in view of a possible use in clinical trials for the local therapy of human bladder carcinomas.
Battelli
M G
MG
Department of Experimental Pathology, University of Bologna, Italy.
Polito
L
L
Bolognesi
A
A
Lafleur
L
L
Fradet
Y
Y
Stirpe
F
F
D006801:Humans; D000922:Immunotoxins / Q000494:pharmacology*; D009699:N-Glycosyl Hydrolases; D010940:Plant Proteins / Q000494:pharmacology*; D014176:Protein Biosynthesis; D054789:Ribosome Inactivating Proteins, Type 1; D054790:Ribosome Inactivating Proteins, Type 2; D012270:Ribosomes / Q000187:drug effects*; D000076985:Saporins; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy*
D000922:Immunotoxins; D010940:Plant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D054790:Ribosome Inactivating Proteins, Type 2; C470296:momordin I (protein); D009699:N-Glycosyl Hydrolases; D000076985:Saporins; C024275:pokeweed antiviral protein