Establishment of clonal human placental cells synthesizing human choriogonadotropin.

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Abstract
Seven clonal human placental cell lines were established by transformation of human 1st-trimester placental cells with SV 40. These transformed cells synthesized native human choriogonadotropin (chorionic gonadotropin) (hcG) as well as the free .alpha. and .beta. subunits of hCG. The amount of native hCG synthesized by these cells was, however, lower than the amount of free .beta. subunit. (Both hCG and the .beta. subunit are detected by the radioimmunoassay for .beta. subunit, but only hCG is detected by the radioreceptor assay). The .alpha. and .beta. subunits produced by these transformed placental cells were heterogeneous in size; the sizes of the predominant .alpha. and .beta. species, however, corresponded to those of urinary .alpha. and .beta. subunits, respectively. The 7 cell lines transformed by SV 40 had chromosome numbers from the near diploid to the near tetraploid range. Fluorescent staining demonstrated the Y chromosome in all the transformants. Furthermore, B-type glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP+ 1-oxidoreductase, EC 1.1.1.49) was present in all 7 lines. These characteristics ruled out possible HeLa [human cervical cancer] contamination of the transformed lines. Regulation of the synthesis of .alpha. and .beta. subunits plus hCG in these transformed human placental cells differed from the regulation in choriocarcinoma cells.