Multi-organ metastatic capability of Chinese hamster ovary cells revealed by green fluorescent protein (GFP) expression

Stable high-level green fluorescent protein (GFP)-expressing Chinese hamste r ovary cells (CHO) were used to visualize the degree of metastatic behavio r of this cell line in nude and SCID mice. A stable GFP high-expression CHO clone, selected in 1.5 mu M methotrexate, was injected subcutaneously in n ude and severe combined immunodeficient (SCID) mice and implanted orthotopi cally in the ovary of nude mice. CHO proved to be highly metastatic from bo th the subcutaneous and orthotopic sites as brightly visualized by GFP fluo rescence. High-level GFP-expression allowed the visualization of metastatic tumor in fresh live host tissue in great detail. Metastases were visualize d by GFP expression in the lung, pleural membrane, spleen, kidney, ovary, a drenal gland, and peritoneum after orthotopic implantation in nude mice. Me tastases were visualized by GFP expression mainly in the lung, pleural memb rane after subcutaneous implantation in nude mice. Metastases were visualiz ed in the lung and pleural membrane, liver, kidney, and ovary after subcuta neous implantation in SCID mice. The construction of highly fluorescent sta ble GFP transfectants of CHO has revealed the multi-organ metastatic capabi lity of CHO cells. CHO has such a high degree of malignancy that it is meta static from both the orthotopic and subcutaneous transplant sites. This hig hly malignant GFP-expressing cell-line with multi-organ metastatic affinity should serve as a powerful tool to study tumor-host interaction.