[Fundamental studies on tumor angiogenesis factors with a choriocarcinoma model].

We have studied biologically active substances, tumor angiogenesis factors (TAF), which are supposed to be associated with the proliferation and metastases of choriocarcinoma cells. Eight human choriocarcinoma cell lines were used in the present study. TAF activity was assayed by bioassays using BALB/c mice subcutaneous tissue, chicken chorioallantoic membrane (CAM) and rabbit cornea in vivo and by proliferation of endothelial cells in vitro. 1. We found a positive correlation between the size of tumors developed in xenotransplantation and the number of blood vessels in the tumor tissues. A correlation between the number of blood vessels and TAF activity was also found. 2. With a gel-filtration method, TAF activity was observed in the common fractions in every cell line. The molecular weight of TAF was more than 10,000 daltons. 3. There was a heterogeneity of TAF activity among the cell lines. From these results, it appears that TAF initiates the choriocarcinoma cell-proliferation.