A Novel Anti-human DR5 Monoclonal Antibody with Tumoricidal Activity Induces Caspase-dependent and Caspase-independent Cell Death

Yabin Guo,Caifeng Chen,Yong Zheng,Jinchun Zhang,Xiaohui Tao,Shilian Liu,Dexian Zheng,Yanxin Liu

doi:10.1074/jbc.m503621200

Abstract

Like anti-Fas monoclonal antibodies, some monoclonal antibodies against tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptors have tumoricidal activity too. In this article we report a novel mouse anti-human DR5 monoclonal antibody, AD5-10, that induces apoptosis of various tumor cell lines in the absence of second cross-linking in vitro and showed strong tumoricidal activity in vivo. AD5-10 does not compete with TRAIL for binding to DR5 and synergizes with TRAIL to induce apoptosis of tumor cells. AD5-10 induces both caspase-dependent and caspase-independent cell death in Jurkat cells, whereas TRAIL induces only caspase-dependent cell death. We show for the first time that DR5 can mediate caspase-independent cell death, and DR5 can mediate distinct cell signals when interacting with different extracellular proteins. Studies on AD5-10 help us to understand more on the functions of DR5 and may provide new ideas for cancer immunotherapy.

Highlights

Tumor necrosis factor (TNF)2-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily with the ability to induce apoptosis in a wide variety of transformed cell lines of diverse origin [1]
AD5–10 Binds to DR5 and Does Not Compete with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)—Human DR5 has two isoforms, designated as DR5a and DR5b, which is a result of pre-mRNA alternative splicing
We showed that the bacterially expressed DR4 and DR5 extracellular regions bound to their natural ligand, TRAIL, (Fig. 1A), indicating that they are suitable for immunizing animals

Summary

Introduction

Tumor necrosis factor (TNF)2-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily with the ability to induce apoptosis in a wide variety of transformed cell lines of diverse origin [1]. Increasing experimental evidence on TRAIL-inducing apoptosis of normal cells (especially hepatocytes) were reported in recent studies [16, 17], arguing against the potential usefulness and safety of soluble TRAIL in cancer therapy. AD5–10 induces apoptosis in various tumor cell lines in the absence of second cross-linking in vitro and exhibits a strong tumoricidal activity in vivo. Downstream cell signals induced by AD5–10 and TRAIL were compared Both TRAIL and AD5–10 activate caspase cascade and induce a classical apoptosis in Jurkat cells. Both TRAIL and AD5–10 are capable of activating of NF-␬B, but there are differences between the regulation of NF-␬B activity by TRAIL and that by AD5–10 in certain cell lines These findings show that DR5 can mediate distinct cell signals when interacting with different extracellular proteins. Illustration of the mechanisms may lead to the development of new strategies for cancer immunotherapy

Methods

Results

Conclusion