A human embryonal-yolk sac carcinoma model system in athymic mice.

Two new human cell lines (1411H and 1411HRQmet) have been established from a patient with metastatic testicular cancer whose primary and metastatic histology included seminoma, teratoma, embryonal carcinoma (EC), and yolk sac tumor (YST). In vitro, the cells have been maintained for more than 70 passages, produce alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG), and have a human karyotype. When 2 X 10(7) cells of either line are inoculated into athymic mice, 87.5% of the animals (21/24) develop tumors. Initially 80% to 90% of the mass is EC, whereas the central portion is YST. After 90 to 390 days in vivo, the tumors achieve a large volume (2.13 +/- 0.97 cm3), become cystic, and undergo histologic change. The peripheral rim of the mass remains EC, but the central 80% to 90% becomes YST. The sera of tumor-bearing mice were positive for hCG and AFP in 11% and 38% of animals, respectively. Tumor cyst fluid was positive for hCG and AFP in 87% and 59% of animals, with mean values of 108 mIU/ml and 2,478 ng/ml, respectively. Tumor cyst fluid also contained placental alkaline phosphatase and human fibronectin. These two cell lines are useful for studies on the interrelationship of EC and YST and the differentiation of human germ cell cancer.