[Ectopic production of HCG beta by bladder carcinoma in vitro and in vivo]

Ectopic production of immunoreactive hCG/hCG beta (IR-hCG beta) by bladder tansitional cell carcinoma cell lines was investigated in vitro and in vivo.

As an in vitro study, IR-hCG beta in culture media from 2 bladder transitional cell carcinoma cell lines (KoTCC-1 and HT-1197) was analyzed by three kinds of enzyme immunoassays (EIA) which were specific for intact hCG, free hCG beta and beta-core fragment (beta-CF). As an in vivo study, distribution of IR-hCG beta was analyzed in tumor tissues, sera, and urine of the nude mice and the nude rat transplanted with KoTCC-1 cell line.

Both of the cell lines were determined to secrete IR-hCG beta into the media, which consisted principally of free hCG beta. Intact hCG and beta-CF were scarecely detected in the media. Immunohistochemical study revealed the localization of IR-hCG beta in transitional cell carcinoma cells of the transplanted tumor. Although a large amount of IR-hCG beta could be detected in both of the serum and urine from the animals, there were quantitative and qualitative differences between serum and urinary IR-hCG beta. Quantitatively, the concentrations of IR-hCG beta in the urine were consistently much higher than those in the serum. Qualitatively, free hCG beta was exclusively detected in the serum whereas a large amount of beta-CF, in addition to free hCG beta, were found in the urine. Intact hCG could not be detected in both serum and urine. These distributions of IR-hCG beta in the animals bearing tumors were completely analogous to those in patients with bladder carcinoma.

The present results suggested that ectopic production of IR-hCG beta by bladder carcinoma is not rare phenomenon and it is clinically useful as a tumor marker when beta-CF is measured in the urine.