Antitumour effect of interferon combined with hyperthermia against experimental brain tumour.

Antiproliferative activity of recombinant murine interferon-beta (Rec-MuIFN-beta) combined with hyperthermia against Rous sarcoma virus-induced mouse malignant glioma (RSV glioma) was investigated both in vitro and in vivo. In vitro, the antiproliferative activity of Rec-MuIFN-beta was enhanced by incubation at elevated temperatures (40 degrees and 43 degrees C). In vivo, combined therapy of Rec-MuIFN-beta treatment and local tumour hyperthermia (43 degrees C) exerted a greater antitumour effect against transplanted RSV glioma in C3H/He mice than either treatment alone, especially when Rec-MuIFN-beta was administered intratumourally. Subsequently, in order to probe the mechanism of enhanced antiproliferative activity, the production of prostaglandin E2 (PGE2) and 2', 5'-oligoadenylate synthetase (2-5A synthetase) in the culture medium of RSV glioma cells was measured. Rec-MuIFN-beta treatment resulted in a significantly greater PGE2 and 2-5A synthetase production at 43 degrees C than at 37 degrees C.