Selection of malignant melanoma variant cell lines for ovary colonization

Abstract

Murine melanoma line B16‐F1, which shows some specificity for metastatic organ colonization of lung but rarely metastasizes to ovary, was used to select variant cell lines with increased preference for experimental ovary metastasis. Ovary‐colonizing melanoma cell lines were sequentially selected in syngeneic C57BL/6 mice by repeated intravenous administration and surgical recovery of ovarian melanoma tumors for tissue culture. After ten selections for experimental ovary metastasis, line B16‐010 was established which formed experimental metastatic ovary tumors in almost every test animal. In tissue culture B16–010 cells grew in circular in circular colonies with rounded, smooth cell peripheries compared to B16‐F1 cells which were flatter, grew in irregular patterns, and exhibited long cellular projections. Ovary‐selected B16 lines contained less melainin pigment (B16‐010 < B16‐05 < B16‐01 ≅ B16‐F1) compared to the parental melanoma line. Together with previous cloning and selection data, these results are consistent with the preexistence of highly malignant cells in the parental tumor population that possess the ability to metastasize to specific organs.