Characterization of tumorigenicity, mortality, metastasis, and splenomegaly of two cultured murine colon lines.

The murine colon tumors 26 and 36 have been adapted to culture in vitro from the parental, serially transplanted tumors. The biological activities of these cultured colon lines (C-C26 and C-C36) have been characterized in vivo by s.c. inoculation of serial doses of cells into syngeneic BALB/c mice. The C-C26 line is highly tumorigenic and has a low tendency (9.1%) for metastasis to the lungs. Moreover, mice inoculated with C-C26 exhibited high mortality and normal or atrophied spleens. In contrast, the C-C36 line is less tumorigenic and highly metastatic to the lungs (77.8%). Mortality was lower in animals inoculated with C-C36, and at autopsy, splenomegaly was frequently (72.2%) observed without any visible metastatic nodules in these spleens. Metastasis to the lungs was intimately associated with splenomegaly, and death followed closely. Our findings with the C-C26 and C-C36 lines agree with those reported for the parental tumors with respect to tumorigenicity, tumor growth, and mortality. However, they differ with respect to their metastatic potential, because previous reports showed this to be higher for the serially transplanted colon 26 than the colon 36 tumor cells. Furthermore, this work describes the remarkable splenomegaly observed in mice inoculated with C-C36 but not with C-C26. This finding may in turn provide us with the opportunity to compare the functional status of the spleen in these tumor-bearing animals.