Ionizing radiation and chemotherapeutic drugs induce apoptosis in lymphocytes in the absence of Fas or FADD/MORT1 signaling: Implications for cancer therapy

Abstract

Ionizing radiation and cytotoxic drugs used in the treatment of cancer induce apoptosis in many cell types, including tumor cells. It has been reported that tumor cells treated with anticancer drugs increase surface expression of Fas ligand (FasL) and are killed by autocrine or paracrine apoptosis signaling through Fas (Friesen, C., I. Herr, P.H. Krammer, and K.- M. Debatin. 1996. Nat. Med. 2:574-577). We show that lymphocytes that cannot be killed by FasL, such as those from Fas-deficient lpr mice or transgenic mice expressing a dominant negative mutant of Fas-associated death domain protein (FADD/MORT1), are as sensitive as normal lymphocytes to killing by gamma radiation or the cytotoxic ..