[Molecular weight and fragmentation of human chorionic gonadotropin in urine in patients with trophoblastic diseases]

Molecular weights (MW) of urinary human chorionic gonadotropin (hCG) from trophoblastic diseases were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), followed by Western blotting using specific antibodies. Although the MW of hCG beta from hydatidiform mole and invasive mole were identical to that of standard hCG beta, those from choriocarcinoma were individually different. These results indicate that the structural changes of carbohydrates, which may be induced by malignant transformation of trophoblast, can be reflected as differences in MW. In SDS-PAGE under nonreducing conditions. Western blotting using anti-hCG beta-carboxy-terminal peptides (CTP) revealed a single band corresponding to hCG beta. Under reducing conditions with dithiothreitol (DTT), however, a second low MW material (CTP') could be observed with anti-hCG beta-CTP. All hCG samples from invasive mole and choriocarcinoma were much more susceptible than standard hCG to release of CTP' by DTT. Estimation of MW and susceptibility to DTT reducing of urinary hCG by Western blotting are useful in the diagnosis of invasive mole and choriocarcinoma.