Cleavage of GSDME by caspase-3 determines lobaplatin-induced pyroptosis in colon cancer cells

Junhui Yu,Zilu Chen,Jie Qi,Jianbao Zheng,Jing Guo,Shan Li,Xuejun Sun,Kai Wang,Yunhua Wu

doi:10.1038/s41419-019-1441-4

Abstract

Pyroptosis, a form of programmed cell death (PCD), has garnered increasing attention as it relates to innate immunity and diseases. However, the involvement of pyroptosis in the mechanism by which lobaplatin acts against colorectal cancer (CRC) is unclear. Our study revealed that treatment with lobaplatin reduced the viability of HT-29 and HCT116 cells in a dose-dependent manner. Morphologically, HT-29 and HCT116 cells treated with lobaplatin exhibited microscopic features of cell swelling and large bubbles emerging from the plasma membrane, and transmission electron microscopy (TEM) revealed multiple pores in the membrane. GSDME, rather than GSDMD, was cleaved in lobaplatin-induced pyroptosis in HT-29 and HCT116 cells due to caspase-3 activation. Knocking out GSDME switched lobaplatin-induced cell death from pyroptosis to apoptosis but did not affect lobaplatin-mediated inhibition of growth and tumour formation of HT-29 and HCT116 cells in vivo and in vitro. Further investigation indicates that lobaplatin induced reactive oxygen species (ROS) elevation and JNK phosphorylation. NAC, a ROS scavenger, completely reversed the pyroptosis of lobaplatin-treated HT-29 and HCT116 and JNK phosphorylation. Activated JNK recruited Bax to mitochondria, and thereby stimulated cytochrome c release to cytosol, followed by caspase-3/-9 cleavage and pyroptosis induction. Therefore, in colon cancer cells, GSDME mediates lobaplatin-induced pyroptosis downstream of the ROS/JNK/Bax-mitochondrial apoptotic pathway and caspase-3/-9 activation. Our study indicated that GSDME-dependent pyroptosis is an unrecognized mechanism by which lobaplatin eradicates neoplastic cells, which may have important implications for the clinical application of anticancer therapeutics.

Highlights

Colorectal cancer (CRC) is one of the most common malignancies, whose incidence rate ranks as the fourth leading cause of cancer death[1]
Lobaplatin inhibits cell viability and induces pyroptosis in colon cancer cells To determine the viability of colon cancer cells treated with lobaplatin, HT-29 and HCT116 cells were treated with different doses of lobaplatin for 8 h, and CCK8 assays were performed
Lobaplatin-treated HT-29 and HCT116 cells exhibited large bubbles emerging from the plasma membrane and cell swelling (Fig. 1b, c), which highly resembled the pyroptosis induced by the N-terminus of GSDMD8

Summary

Introduction

Colorectal cancer (CRC) is one of the most common malignancies, whose incidence rate ranks as the fourth leading cause of cancer death[1]. With the ageing of the population, the changes in the lifestyle and the deterioration of the environment, the incidence of CRC in China has increased year after year and has become one of patients are diagnosed at an advanced stage and cannot undergo surgery as a treatment[3]. Chemotherapy is an important part of the comprehensive treatment for advanced CRC4. The overall response rate of chemotherapy in CRC patients is unsatisfactory and concurrent with a high incidence of adverse effects[5,6]. The precise mechanism by which chemotherapy combats CRC requires further elucidation. The pyroptotic cells release interleukin-1β (IL-1β) and interleukin-18 (IL-18), which recruit inflammatory cells and expand the inflammatory response[8]

Objectives

Methods

Results

Conclusion