Growth Inhibition of Human Glioma Cells by Superinduced Human Interferon-β

Abstract

Superinduction of human interferon-β(HuIFN-β) from human glioma cells has greater cytotoxicity than purified HuIFN-β derived from fibroblasts. However, superinduction requires several reagents like polyI:polyC, cycloheximide, and actinomycin D, which may contaminate the conditioned medium and obscure the effect of superinduced HuIFN-β. The present study used minimum doses of polyI:polyC and cycloheximide without actinomycin D to superinduce HuIFN-β. The superinduced HuIFN-β was purified by passing the medium through molecular sieve column chromatography. Fractionation of the eluate provided semipurified superinduced HuIFN-β which demonstrated a growth inhibitory effect against both the U251-MG autologous human glioma cell line and the SK-MG-1 homologous glioma cell line. This effect was neutralized by addition of anti-HuIFN-β monoclonal antibody (YSB-1). In a separate experiment, combinations of superinduction reagents were found not to have growth inhibitory effects because all inhibition in superinduced medium was completely neutralized by YSB-1. Superinduced HuIFN-β has a pure growth inhibitory effect on both autologous and homologous glioma cells, so may affect autocrine secretion of cytokines.