Growth enhancement of implanted human colorectal cancer cells by the addition of fibroblasts in vivo

Abstract

The effect of fibroblasts on the growth of HT29 human colorectal cancer cells was used to study stromal modulation of tumour growth dynamics. Fibroblasts were isolated from rat livers 1, 2.5 and 4 days after two‐thirds partial hepatectomy and from normal livers. Cells harvested 2.5 and 4 days after hepatectomy (‘fast’ fibroblasts) had a significantly faster growth rate in vitro than those harvested on day 1 or those from normal livers (P<0.02). The fibroblasts were inoculated with HT29 colorectal cancer cells into nude mice: Controls received cancer cells with or without a fibroblast cell line (C3H10T 1/2). At 3 weeks both tumour take and growth (size) were significantly greater in the group inoculated with cancer cells and ‘fast’ fibroblasts than in the other groups (tumour take 100 versus 42–75 per cent, P<0.03; median tumour size 3.5 versus 0.3–0.4 g, P<0.02). In conclusion, tumour growth is enhanced by fibroblasts, especially by those derived from actively regenerating liver. It is suggested that the stimulation is not only mechanical but may also involve a humoral mechanism.