Metastatic behavior of tumor cells isolated from primary and metastatic human colorectal carcinomas implanted into different sites in nude mice.

The purpose of these studies was to examine the growth characteristics and metastatic behavior of freshly isolated human colorectal carcinomas implanted into athymic nude mice. Four tumor lines were derived from primary colorectal carcinomas, three lines from hepatic metastases, and one line from a metastasis to a mesenteric lymph node. Subsequent to implantation into the subcutis or the muscularis, tumor lines derived from metastases grew faster in the nude mice than did cells isolated from the primary neoplasms. Regardless of the source of the cells, however, little or no visceral organ metastasis was found. Subsequent to i.v. injection, experimental lung colonies could be produced by some of the cells, but there was no correlation between lung tumor colony formation and the origin of the human colorectal cells. The intrasplenic injection of colorectal carcinoma cells provided a useful procedure to identify human colorectal carcinoma cells with metastatic potential to liver. Extensive tumor burdens in the liver were observed as early as 30 days after injection with two of the three liver metastasis-derived tumor lines. No liver metastases were found after the intrasplenic injection of cells isolated from the lymph node-derived tumor line. Ninety days after the intrasplenic injection of cells from the four primary colorectal carcinomas, limited liver metastases were observed. We conclude that metastasis of human colorectal carcinomas can be studied in nude mice, and its outcome depends upon both the intrinsic metastatic capacity of the human tumor cells and the organ environment of implantation.