Enhancement of antitumor properties of rhTRAIL by affinity increase toward its death receptors.

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent and selective inducer of apoptosis in various tumor types, raising enthusiasm for TRAIL as a potential anticancer agent. TRAIL-induced apoptosis is mediated by death receptors 4 (DR4) and DR5. The design of rhTRAIL variants either with improved affinity or selectivity toward one or both death-inducing receptors is thought to enhance the therapeutical potential of TRAIL. Here we demonstrate that a single amino acid mutation at the position of glycine 131 to lysine or arginine in wild-type rhTRAIL significantly improved the affinity of rhTRAIL toward its death receptors, with the highest affinity increase observed for the DR4 receptor. These variants were able to induce higher in vitro levels of apoptosis in cancer cells responsive to only DR4 or to both death receptors and could therefore increase the potential use of rhTRAIL as an anticancer therapeutic agent.