Superior antiproliferative effects mediated by interferon-alpha entrapped in liposomes against a newly established human lung cancer cell line.

The purpose of this study was to characterize the antiproliferative activity of a recombinant interferon-alpha (IFN-alpha) against a newly established human adenocarcinoma cell line (DMS-4C) and to determine whether IFN-alpha entrapped in multilamellar liposomes had superior antitumor effects compared with free IFN-alpha. Treatment of DMS-4C cells with 100 U/ml of free IFN-alpha resulted in 34% cytostasis. IFN-alpha encapsulated in phosphatidylcholine/phosphatidylserine multilamellar vesicles produced growth inhibition of 67%, which was significantly greater than that produced by free IFN-alpha or by control liposomes containing only medium combined with free IFN-alpha. Moreover, kinetic analysis revealed that to produce significant cytolysis, free IFN-alpha had to be incubated with target cells for at least 24 h, whereas IFN-alpha encapsulated into liposomes required only 30 min of exposure.