[Immuno-ricin A chain specific for gastric cancer: internalization and its significance].
Biotinylated ricin A chain (RTA) was introduced to antigastric cancer monoclonal antibody MGb2 with chemical conjugating technique to form an immuno-ricin A chain conjugate (I-RTA) specific for gastric cancer. Its internalization in human gastric cancer cell line SGC-7901 was followed by double dynamic EM labelling procedure using streptavidin-gold and sheep anti-mouse IgG-gold probes. The effects of verapamil on I-RTA internalization routings were also observed. The results demonstrated that the main entry modality of I-RTA was non-coated microinvagination, followed by coated pits and interioration of microvilli. The internalized I-RTA was found to be quickly transported to multivesicular bodies and finally to lysosomes, where it was degraded, whilst in the non-membranous structures I-RTA was only occasionally encountered. Ultrastructurally, verapamil displayed its effects by making the internalized I-RTA stay longer in tubulovesicular structures and be delivered in a less amount and more slowly into lysosomes. Furthermore, I-RTA was increased in the non-membranous structures, and the in vitro killing effect was significantly enhanced. The present data revealed the basic cell biology process of I-RTA-cell interaction, which will provide not only an important clue to improving I-RTA targeting therapy efficiency, but also a new way for further screening targeting potentiators.
Wang
F
F
Laboratory of Gastroenterology, Xijing Hospital, Xi'an.
D000818:Animals; D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D004705:Endocytosis; D006801:Humans; D000922:Immunotoxins / Q000494:pharmacology*; D051379:Mice; D012276:Ricin; D013274:Stomach Neoplasms / Q000276:immunology / Q000473:pathology* / Q000648:ultrastructure; D014407:Tumor Cells, Cultured / Q000473:pathology / Q000648:ultrastructure; D014700:Verapamil / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000922:Immunotoxins; D012276:Ricin; D014700:Verapamil