In vitro malignant transformation of in vivo ENU-induced rat ovarian Sertoli cell tumor (adenoma).

An N-ethyl-N-nitrosourea-induced rat ovarian Sertoli cell tumor was grown in tissue culture in Dulbecco's modified Eagle's medium (DMEM) supplemented with 25% horse serum (HS) and a hormone combination of 20 ng/ml each of hydrocortisone, insulin, and prolactin. This tissue culture derived from a nonsteroid hormone-producing tumor. Cytofluorometry and karyotyping of the nonhormone-producing tumor cell line (SCTL-1) revealed a diploid pattern for the early passage (P1), which became hyperdiploid (P10), and then aneuploid (P20). These cells had an epitheloid pattern, grew in a monolayer at early passages. After P10 the cells were transplanted into newborn rats and nude mice and resulted in high incidences of tumors (up to 100%). The cell line (SCTL-1) continued to grow in DMEM, 10% HS, and no hormone supplementation after P10. This study revealed that a benign rat ovarian Sertoli cell tumor after multiple passages in vitro underwent sequential genotypic and phenotypic changes and became highly malignant.