Maintenance of ectopic chorionic gonadotropin and alpha subunit secretion by a human lung cancer cell line (ChaGo) transplanted into nude mice.

ChaGo cells, derived from a human primary carcinoma of the lung, were successfully transplanted into nude mice without any change in morphologic characteristics over four generations and with continued ectopic secretion of human chorionic gonadotropin (HCG) and HCG alpha subunit (HCG-alpha). The concentration of free HCG-alpha was 1,100-fold higher than that of complete HCG in the original ChaGo culture medium but only 35-fold higher in nude mouse plasma, possibly due to slower metabolic clearance of complete HCG. Tumor weights correlated with plasma HCG-alpha but not with HCG. Tumor-bearing mice had significantly heavier uteri than did control mice.