WIDESPREAD SKELETAL METASTATIC POTENTIAL OF HUMAN LUNG-CANCER REVEALED BY GREEN FLUORESCENT PROTEIN EXPRESSION

To understand the skeletal metastatic pattern of non-small cell lung c ancer, we developed a stable high-expression green fluorescent protein (GFP) transductant of human lung cancer cell line H460 (H460-GFP), Th e GFP-expressing lung cancer was visualized to metastasize widely thro ughout the skeleton when implanted orthotopically in nude mice. H460 w as transduced with the pLEIN retroviral expression vector containing t he enhanced GFP and the neomycin (G418) resistance gene, A stable high GFP-expressing clone was selected in vitro using 800 mu g/ml G418, St able high-level expression of GFP was maintained in s.c-growing tumors formed after injecting H460-GFP cells in nude mice. To use H460-GFP f or visualization of metastasis, fragments of s.c-growing H460-GFP tumo rs were implanted by surgical orthotopic implantation in the left lung of nude mice, Subsequent micrometastases were visualized by GFP fluor escence in the contralateral lung, plural membrane, and widely through out the skeletal system including the skull, vertebra, femur, tibia, p elvis, and bone marrow of the femur and tibia, The use of GFP-expressi ng H460 cells transplanted by surgical orthotopic implantation reveale d the extensive metastatic potential of lung cancer in particular to w idely disseminated sites throughout the skeleton. This new metastatic model can play a critical role in the study of the mechanism of skelet al and other metastasis in lung cancer and in screening of therapeutic s that prevent or reverse this process.