alpha 1-Proteinase inhibitor production by human adenocarcinomas xenotransplanted into nude mice

Human colon adenocarcinomas xenotransplanted into BALB/c nude mice were examined for the ectopic synthesis of alpha 1-proteinase inhibitor(s) (alpha 1Pi). Tumor extracts were prepared by homogenization followed by molecular sieve chromatography on Sepharose 4B. Fractions with immunoreactive alpha 1Pi were concentrated and adsorbed onto a concanavalin A-Sepharose 4B affinity column, then eluted, concentrated, and analyzed. All 4 colon tumors examined produced alpha 1Pi with full antigenic identity to normal human plasma alpha 1Pi. Electrophoretic mobilities of 3 of the tumor-derived alpha 1Pi were different from the electrophoretic mobility of the normal human plasma alpha 1Pi. Activities of the inhibitors were determined by the reaction of each tumor extract with pancreatic elastase (PE) followed by immunoelectrophoresis of the reaction mixture against both anti-human alpha 1Pi and anti-PE antisera. Two of the tumor-derived alpha 1Pi examined were active in inhibiting PE.