Growth inhibition of experimental glioma by human interferon-beta superinduced by cationic liposomes entrapping polyinosilic:polycytidilic acid.

Intracellular production of human interferon-beta (HuIFN-beta) was enhanced in three glioma cell lines (U251-MG, U251-SP, and U251-NN) using modified superinduction with cationic liposomes containing polyinosilic:polycytidilic acid (polyI:polyC), initially given with cycloheximide, to decrease the toxicity due to polyI:polyC. Modified superinduction had a significantly (p < 0.02-0.0001) greater inhibitory effect on all three glioma cell lines, and less toxicity than superinduction. A pilot trial in experimental gliomas implanted into nude mice was also performed. Superinduction including intratumoral injection of cationic liposomes containing polyI:polyC resulted in growth inhibition of U251-NN tumors and eradication of U251-SP tumors. Weight gain in mice was not inhibited by modified superinduction. Cationic liposomes decreased drug toxicity, and may help to target tumor cells in the modified superinduction of endogenous HuIFN-beta production.