Antitumor activity of interferon against murine osteogenic sarcoma cells in vitro.

Murine interferon inhibited the growth of a continuous line of osteogenic sarcoma (OGS) cells in tissue culture. Inhibition of tumor cell growth by interferon was demonstrated by: a) decreased colony formation in soft agar, b) suppression of clone formation in liquid medium, and c) reduction of tumor cell counts in monolayer cultures. This inhibition of cell growth was further documented by suppression of [3H]thymidine uptake by OGS cells exposed to interferon, which suggested inhibition of DNA synthesis of tumor cells. Exposure of tumor cells for 4 hours, 24 hours, and 2,3,4,6, and 8 days demonstrated greater activity with prolonged exposure to interferon. Inhibition of cell growth was significantly greater for OGS cells than for normal mouse embryo fibroblasts. Finally, the antitumor activity of the interferon preparation could be reversed by anti-interferon antibody.