A pulmonary metastatic model of human non-small cell lung carcinoma cells in SCID mice

We found that EBC-1, a human non-small cell lung cancer (NSCLC) cell line, formed multiple metastases in the lung after subcutaneous inoculation into severe combined immunodeficiency (SCID) mice. SCID mice were injected in the flank with 10 6 EBC-1 cells. Metastases in the lung were counted in histologic sections and stained immunohistochemically for neutrophil elastase (NE). Solid tumors were palpable in the flank at 3 weeks and grew steadily until 10 weeks. EBC-1 cells formed multiple metastases in the lung at 7 weeks; their numbers increased steadily until 12 weeks in all mice. Immunoreactivity for NE was intense in the metastatic tumor cells. As a marker for circulating tumor cells, human β-actin mRNA was detected in blood by reverse transcriptase–polymerase chain reaction (RT-PCR). Blood samples obtained at 3 weeks after tumor inoculation contained human β-actin mRNA. Our NSCLC EBC-1 pulmonary metastasis model is reliable, technically simple, and predictably results in pulmonary metastasis from early hematogenous spread. This model may be useful for screening potential new drugs, including specific NE inhibitors, for effectiveness against pulmonary metastasis of NSCLC.