Herceptin conjugates linked by EDC boost direct tumor cell death via programmed tumor cell necrosis.

Jiemiao Hu,Joya Chandra,Francisco J Esteva,Bolin Liu,Shulin Li,Xinli Liu,Dennis Hughes,Mikhail V Blagosklonny

doi:10.1371/journal.pone.0023270

Abstract

Tumor-targeted antibody therapy is one of the safest biological therapeutics for cancer patients, but it is often ineffective at inducing direct tumor cell death and is ineffective against resistant tumor cells. Currently, the antitumor efficacy of antibody therapy is primarily achieved by inducing indirect tumor cell death, such as antibody-dependent cell cytotoxicity. Our study reveals that Herceptin conjugates, if generated via the crosslinker EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride), are capable of engendering human epidermal growth factor receptor 2 (Her2) positive tumor cells death. Using a high-performance liquid chromatography (HPLC) system, three peaks with estimated molecular weights of antibody monomer, dimer, and trimer were isolated. Both Herceptin trimer and dimer separated by HPLC induced significant levels of necrotic tumor cell death, although the trimer was more effective than the dimer. Notably, the Herceptin trimer also induced Herceptin-resistant tumor cell death. Surprisingly different from the known cell death mechanism that often results from antibody treatment, the Herceptin trimer elicited effective and direct tumor cell death via a novel mechanism: programmed cell necrosis. In Her2-positive cells, inhibition of necrosis pathways significantly reversed Herceptin trimer-induced cell death. In summary, the Herceptin trimer reported herein harbors great potential for overcoming tumor cell resistance to Herceptin treatment.

Highlights

Human epidermal growth factor receptor 2 (Her2) is overexpressed in many types of cancers. [1,2]
Generation of Herceptin conjugates The anti-Her2 antibody, Herceptin, has proven effective in blocking the Her2 downstream signaling pathway [9,10,11] and in sensitizing Her2-expressing tumor cells to other treatments [12,13]; there is no evidence that Herceptin alone induces potent tumor cell death
The hypothetical basis of this study tested whether the oligomerization of Herceptin immunoglobulin G (IgG) causes direct and effective tumor cell death

Summary

Introduction

Human epidermal growth factor receptor 2 (Her2) is overexpressed in many types of cancers. [1,2]. Antibody therapy provides excellent tumor specificity; the clinical response to Herceptin therapy has not been very strong, with only 12–34% tumor remission noted over 9 months in metastatic breast cancer patients in early clinical trials [3]. Both primary resistance and acquired resistance to Herceptin were observed, limiting broad application of this safe therapy [4]. We sought to test whether Herceptin conjugate promotes induction of direct tumor cell death and whether such effect may overcome tumor resistance to antibody treatment

Methods

Results

Conclusion