Ectopic Production of the Isolated Beta Subunit

of human chorionic gonadotropin (hCG-fi) was detected in serum (300 ng/ml) and tumor extract from a 75-yr-old man with pancreatic adenosquamous carcinoma. This material was indistinguishable from hCG-P in three different types of radioimmunoassay that dis-played widely varying reactions with glycoprotein trophic hormones and their subunits. In gel chromatography there appeared to be heterogeneity of the serum beta-like immunoactivity, including one component that co-eluted with standard hCG-P tracer and another immuno-logically indistinguishable component that displayed a slightly lower elution volume. Neither complete human chorionic gonadotropin (hCG) nor its alpha subunit was detected in radioimmunoassays of serum, before or after fractionation, or in tumor extract. The absence of complete hCG was confirmed in a gonadotropin bioassay sensitive to 15 ng of hCG, which showed no bioactivity in serum or tumor extract containing 450 and 90 ng of hCG-P, respectively. This case probably represents the first demonstration of isolated polypeptide subunit pro-duction of ectopic origin and suggests that-hCG-9, as well as other subunits, may prove useful as cancer markers