Immunophenotype of human HT29 colon cancer cell metastases in the lungs of scid mice: spontaneous versus artificial metastases.

The aim of this study was to compare the immunophenotype of the human colon cancer cell line HT29 tumour deposits in the lung which occurred spontaneously after subcutaneous implantation with those which arose after intravenous injection into severe combined immunodeficient (scid) mice. Irrespective of the route of implantation the colon cancer cells were readily observed in the lungs of the scid mice. Similar patterns of immunoreactivity for the proliferative markers (MiB-1, PCNA), and for the tumour suppressor gene (p53) were detected in both groups, and for carcinoembryonic antigen, with only minor quantitative differences in levels of marker expression. Whereas the marker CD44 variant 6 gave very little reaction after either route, cytokeratin expression varied amongst the different cytokeratins (CK 7, 18 or 20), and with the route of implantation. CA125 and E-cadherin were weakly expressed after intravenous injection, but generally not after subcutaneous implantation. Vimentin was not demonstrated in any of the specimens examined. In general, the expression of proliferative markers, and of oncogenes, appears to be independent of the implantation route, whilst expression of cell adhesion molecules can be dependent on the route of implantation.