The origin of a human chorionic gonadotropin beta-subunit-core fragment excreted in the urine of patients with cancer.

Immunoreactive human Chorionic Gonadotropin (hCG), its subunits and hCG beta-core fragment were analyzed, using Sephadex G-100 chromatography, in urine and tumour extracts from four patients with cancer. These patients were selected for investigation because they were excreting proportionally large amounts of the hCG beta-core fragment in their urine. Although 30-85% of the total immunoreactive urinary hCG was hCG beta fragment, traces of the fragment (2% of total hCG) were found in only two of the tumours and none in the other two. The predominant molecular form of hCG in the tumours was intact free beta-subunit of hCG. The conclusion is that the hCG beta-core fragment found in the urine of some patients with cancer is not a secretion product of the tumours. This fragment is very likely a peripheral degradation product of the free beta-subunit of hCG which is secreted by the tumours.