Syoichi Shirotake

Effect of methotrexate on the growth and human chorionic gonadotropin secretion of human choriocarcinoma cell lines in vitro

The effect of methotrexate (MTX) on the growth and human chorionic gonadotropin (hCG) secretion of five gestational and two nongestational human choriocarcinoma cell lines was studied in vitro. A striking heterogeneity in hCG secretion was noted among the cell lines. The growth of cells which secreted large quantities of hCG, such as HCCM-5, BeWo, and IMa, was inhibited by continuous exposure to 2 X 10(-8)M MTX. In contrast, cells which secreted little hCG, such as SCH, ENAMI-1, and GCH-1, showed no response to the growth inhibitory action of 2 X 10(-8)M MTX and the 3H-thymidine uptake was not reduced by treatment with MTX at doses of up to 10(-4)M for 48 hours. The common morphologic alterations observed in the cells which responded to MTX were an increase in the number of multinucleated giant cells, the appearance of vacuoles and granules in the cytoplasm, and enlargement of the nuclei. Increased hCG secretion was observed in accordance with the appearance of such morphologically altered cells. Part of the mechanisms of resistance to MTX appeared to involve both impairment of MTX uptake by the cells and an increase in the level of intracellular dihydrofolate reductase.

A newly established human gestational choriocarcinoma cell line and its characterization

The cell biological characteristics of a newly established human gestational choriocarcinoma cell line, HM, were examined and compared with four other gestational and two nongestational choriocarcinoma cell lines. Striking heterogeneity in the production and secretion of hCG and its subunits was observed among the cell lines. The HM cell line consisted mainly of cytotrophoblast-like cells, and the hCG and its subunit values in both the cells and culture fluid were extremely low. The syncytiotrophoblast-like multinucleated giant cells which were occasionally seen in other cell lines were scarce in the HM cell line in vitro. On the other hand, deviation of the LDH isozyme pattern to the heart-type (LDH1) was characteristic of the HM cells in contrast to the other cell lines in which LDH3 was dominant. The HM cell line represents useful material for investigating the cell biological heterogeneity of human choriocarcinomas.

Establishment and properties of a human choriocarcinoma cell line of ovarian origin

SummaryA human nongestational choriocarcinoma cell line of ovarian origin (IMa) was established in vitro. This cell line had been subcultured serially more than 22 times over 18 months. Small polygonal cells with a prominent nucleus were dominant and a sparsity of cytoplasmic organelles was an ultrastructural characteristic of the IMa cells. The production and secretion of human chorionic gonadotropin and its subunits were identified by radioimmunoassay. The IMa cells were transplantable in the hamster cheek pouch and the histological diagnosis was choriocarcinoma. A newly established ovarian choriocarcinoma cell line can be considered useful for clarifying the biological differences between nongestational and gestational choriocarcinoma cells.

Effect of cytochalasin B on growth, multinucleation and human chorionic gonadotropin secretion in a human choriocarcinoma cell line

Treatment of human choriocarcinoma cells with cytochalasin B at the doses of inhibiting cell division but not inhibiting nuclear division led to in vitro formation of the multinucleated syncytiotrophoblast-like ( STL ) cells. A concomitant increase in human chorionic gonadotropin (hCG) secretion per cell was noted. Immunocytochemical staining demonstrated the predominant localization of hCG in the STL cells. These results indicate that multinucleation stimulates hCG synthesis and secretion in the choriocarcinoma cells.