Enhancement of sensitivity of human lung adenocarcinoma cells to growth-inhibitory activity of interferon alpha by differentiation-inducing agents.

A low concentration of differentiation inducers such as dimethylsulphoxide (DMSO), sodium butyrate, hexamethylene bisacetamide and sodium phenylacetate greatly enhanced the antiproliferative effect in vitro and in vivo of interferon alpha (IFN-alpha) to several human lung adenocarcinoma cells. The agents induced morphological changes in the adenocarcinoma cells and the agents together with IFN-alpha-induced alkaline phosphatase activity, which is a typical marker of type II pneumocyte maturation. To understand the mechanism of the DMSO-enhanced interferon sensitivity, we examined the effect of DMSO on high-affinity IFN-alpha receptor and interferon-stimulated promoter-binding factors. The lung adenocarcinoma cells were not impaired in IFN-alpha receptor and interferon-stimulated gene transactivation factor 3 (ISGF-3). Our data suggest that the enhancement of interferon sensitivity in the lung adenocarcinoma cells acts downstream of the activation of ISGF-3.