Quantitative evaluation of the murine B16 melanoma tumor model after gene marking with an EGFP/Neo expressing retroviral vector.

Reliable evaluation of tumor growth in animal models depends upon accurate identification of all malignant cells in affected organs. An ideal tumor cell label is non-toxic, labels the cells in a population uniformly and does not affect their biological behavior. A good candidate for such a cell label is enhanced green fluorescence protein (EGFP). However, the stability of EGFP expression and the characteristics of EGFP-marked tumors cells in vivo have not yet been elucidated in detail. We here report that a B16 murine melanoma subline stably transduced with an EGFP/Neo encoding retroviral vector display the same growth patterns in vitro and in vivo as the parental cell line. Furthermore, the transduced cells were found to maintain the level of EGFP expression in vivo for at least 15 days. Thus, B16 malignant melanoma cells stably transduced with the gene for EGFP seem well suited for studies on tumor growth in mouse models.