A Radiation‐induced Murine Ovarian Granulosa Cell Tumor Line: Introduction of v‐ras Gene Potentiates a High Metastatic Ability

A non‐metastatic epithelial tumor cell line, OV3121, was established from ovarian granulosa cell tumor in B6C3F1 mouse irradiated with (60)Co‐gamma rays. OV3121 cells showed an epithelial morphology and grew in monolayer with a population doubling time of 28–30 h. The production of estradiol and the expression of cytokeratin confirmed the epithelial origin of the line. No pulmonary metastasis was observed from solid tumors after subcutaneous (s.c.) injection or after intravenous (i.v.) injection of a clonal subline, OV3121–1 cells. We examined the experimental metastasis of individual clones of OV3121–1 cells, containing various introduced viral oncogenes: v‐Ha‐ras, v‐Ki‐ras, v‐fms, v‐mos, v‐raf, v‐src, v‐sis, v‐fos and v‐myc. Among them, only OV3121–1 cells with v‐Ha‐MuSV or v‐Ki‐MuSV produced lung colonies at high frequencies. In a more detailed analysis, the v‐Ha‐ras transfectants OV‐ras4 and OV‐ras7 were found to form colonies in various organs by metastasis from tumors after s.c. injection, as well as lung colonies after i.v. injection. Moderately metastatic OV‐ras7 cells showed high gelatinolytic activity at 72 kDa (MMP‐2) and 92 kDa (MMP‐9) as compared with the parental OV3121–1 and OV‐Neo control cells by zymographic analysis. However, more metastatic OV‐ras4 cells produced progressively weaker bands of 72 kDa gelatinolytic activity. No gross alterations in the expression of MMP‐1, MMP‐3, TIMP‐1 and TIMP‐2 transcripts were detected in these cell lines. These results suggest that this ovarian granulosa cell tumor line may provide a useful system for understanding the mechanisms by which oncogenes influence the occurrence of metastasis.