INTERFERON - DEMONSTRATION OF IN VITRO ANTITUMOR ACTIVITY AGAINST OSTEOGENIC SARCOMA CELLS

Abstract

Interferon (IF) is a substance which has primarily been recognized for its antiviral activity and its role in host resistance. More recently, however, IF has been observed to also have striking antitumor effect. A cell line obtained from a Pu239 induced murine osteogenic sarcoma(OGS) has been utilized as a model system to define the antitumor activity of IF. Serial dilutions of IF (30,000 - 3 units) strikingly inhibited OGS cell growth as evidenced 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. The incorporation of 3H-thymidine in OGS cells was inhibited by 60-80% in the presence of IF suggesting a suppression of DNA synthesis. In OGS cells antitumor activity of IF was 2-to 5-fold less than the antiviral effect in these same cells against vesicular stomatitis virus. Exposure of tumor cells for 4hr, 24hr, 2d, 3d and 4d demonstrated greater activity with prolonged exposure to IF, thus indicating that the continued presence of IF was important for inhibition of OGS cells inhibition of cell growth was significantly greater for OGS cells than heterologous lamb kidney cells or normal mouse embryo fibroblasts. Finally, anti-IF antibody was shown to reverse the antitumor activity of the IF preparation.These data: (1) confirm the antitumor activity of IF, (2) demonstrate efficacy in vitro against a murine OGS cell line, and (3) suggest that IF may have potential as an antitumor, as well as an antiviral chemotherapeutic agent.