Progression of regressor tumor cells by host reactive cells to such foreign bodies as plastic plate and hemostatic spongel

I examined the effects of host cells reactive to foreign bodies such as plastic plate or hemostatic spongel on the progression of tumor cells. QR tumor cells spontaneously regressed in normal C57BL/6 mice apparently associated with a reduction in production of PGE2 by the tumor cells. I have observed that such regressor tumor cells are able to grow lethally when implanted in mice after having been attached to plastic plate. The clones which were derived from these plastic plate-derived tumors in normal mice maintained their growth potential when they were injected into other normal mice. Furthermore the arising tumors produce much higher levels of PGE2 than the original QR tumor cells. Interestingly, I could not observe acquisition of tumorigenicity or a higher level of PGE2-production in the clones obtained from the arising tumors which were grown in 10Gy-irradiated mice. Moreover, QR tumor cells are able to grow in mice when they are injected at the site where plastic plate had been implanted about 30 days previously. These results indicate that the restoration of tumorigenicity of QR tumor cells is not only due to attachment to plastic plate, but also mediated by radiation-sensitive host cells reactive to plastic plate which enhance the progression of tumor cells. Similar results are also obtained by coinoculation of QR tumor cells with host reactive cells which had been induced by implantation of hemostatic spongels into the peritoneal cavity of mice. Greater amounts of PGE2-production by QR tumor cells were observed when the tumor cells were cocultured with spongel reactive cells. This PGE2-production was markedly inhibited by the presence of radical scavengers (Catalase, Mannitol, SOD + Catalase) in the coculture medium(ABSTRACT TRUNCATED AT 250 WORDS)