Interferons and cell growth control

Cytokines modulate cell growth, differentiation, and immune defenses in the vertebrates. Interferons (IFNs) are a unique class of cytokines that stimu late antiviral, antitumor and antigen presentation by inducing the expressi on of several cellular genes. Recent studies have identified a novel gene r egulatory pathway activated by IFNs, which serves as a paradigm for most cy tokine signal transduction pathways. A number of genes induced by IFNs part icipate in cell growth regulation and apoptosis. These include novel tumor suppressor genes. Although discovered as IFN-regulated factors, deletions o f these genes cause leukemias in experimental models and in human patients. Genetic approaches have identified several novel regulators of apoptosis. Studies on the mechanism of action of these growth regulatory molecules are not only useful in identifying novel targets for the development of therap eutics but also help understand the molecular basis for loss of cell growth control and resistance to IFNs. This review focuses on the functions and r oles of IFN regulated factors in cell growth control and mechanisms of disr uption of IFN action in cancer cells.