The enhancement of tumor growth after partial hepatectomy and the effect of sera obtained from hepatectomized rats on tumor cell growth.

In the process of liver regeneration, the participation of various types of growth stimulators and changes in immune responses have been reported. Here, we examined the growth of subcutaneously transplanted AH130 cells and Walker 256 cells after partial hepatectomy. In the case of tumor cells being transplanted on the same day as partial hepatectomy, the increase in tumor size in hepatectomized rats was significantly greater compared with that in non-treated rats or in those having undergone a simple laparotomy. When the transplantation of tumor cells was done on the 7th day after partial hepatectomy, however, the increase was less marked. We also examined the effect of serum obtained from rats after partial hepatectomy on the in vitro growth of these tumor cells. Growth enhancement was observed with medium containing serum drawn from rats 1 to 4 days after partial hepatectomy. These results suggest that the growth of tumor cells was stimulated during liver regeneration and that some humoral factors participated in the process. Furthermore, as the conditions of the in vitro method appear to mimic those of the in vivo method, the in vitro approach should be very useful for analysis of the factors responsible.