Apoptosis and cell growth inhibition as antitumor effector functions of interferons

Since their introduction to the clinic some 30 yr ago, interferons (IFNs) h ave become standard therapy for a range of disorders, including malignant a nd benign tumors as well as various viral diseases. Although IFNs will indu ce remissions in some patients with cancer, they are of no benefit or, at b est, lead only to minor improvements in the great majority of patients with malignant disease. One of the great challenges of IFN research is to under stand the multiple ways by which IFNs influence the behavior of tumor cells and to identify the factors that underlie the resistance of some tumors to IFNs. This review is written with a focus on two anticellular effects of I FN, inhibition of proliferation and induction of apoptosis, possible mechan isms underlying the antitumor action of IFN. In addition, possible reasons for IFN tumor cell resistance are also discussed.