Specific detection of metastasized human tumor cells in embryonic chicks by the polymerase chain reaction

We have established a highly sensitive method for specific detection of metastasized human tumor cells in embryonic chicks using the polymerase chain reaction (PCR). The cells (HT-1080 or KMST-6) were inoculated into the chorioallantoic membrane vein of the chick embryo and DNA of each embryonic organ was extracted. Then, a human beta-globin-related sequence (576 bp) in the DNA from the embryonic liver and lung was specifically amplified and detected by gel electrophoresis and by a specific oligonucleotide probe. The amplified fragments from the liver DNA samples increased gradually from 2 h to 7 days after HT-1080 inoculation. On the other hand, with inoculation of non-tumorigenic human embryonal fibroblast KMST-6 cells, the DNA from the embryonic liver 7 days after inoculation did not show the PCR-amplified product. This detection technique can contribute significantly to the precise detection of microscopic metastasis.