2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid, a glutathione reductase inhibitor, induces G 2 /M cell cycle arrest through generation of thiol oxidative stress in human esophageal cancer cells

// Xia Li 1, 2 , Zhiming Jiang 1, 3 , Jianguo Feng 1, 2 , Xiaoying Zhang 4 , Junzhou Wu 1, 2 and Wei Chen 1, 3 1 Zhejiang Cancer Research Institute, Zhejiang Cancer Hospital, Zhejiang Cancer Center, Hangzhou, Zhejiang 310022, China 2 Zhejiang Key Laboratory of Diagnosis and Treatment Technology on Thoracic Oncology (Lung and Esophagus), Zhejiang Cancer Hospital, Hangzhou, Zhejiang 310022, China 3 Zhejiang Key Laboratory of Radiation Oncology, Zhejiang Cancer Hospital, Hangzhou, Zhejiang 310022, China 4 ACEA Bio CO., Ltd., Hangzhou, Zhejiang 310030, China Correspondence to: Wei Chen, email: chenwei@zjcc.org.cn Keywords: glutathione reductase, oxidative stress, S -glutathionylation, cell cycle arrest, microtubule depolymerization Received: January 10, 2017     Accepted: May 22, 2017     Published: June 27, 2017 ABSTRACT Esophageal squamous cell carcinoma (ESCC) is a highly malignant cancer with poor response to both of chemotherapy and radiotherapy. 2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid (2-AAPA), an irreversible inhibitor of glutathione reductase (GR), is able to induce intracellular oxidative stress, and has shown anticancer activity in many cancer cell lines. In this study, we investigated the effects of 2-AAPA on the cell proliferation, cell cycle and apoptosis and aimed to explore its mechanism of action in human esophageal cancer TE-13 cells. It was found that 2-AAPA inhibited growth of ESCC cells in a dose-dependent manner and it did not deplete reduced glutathione (GSH), but significantly increased the oxidized form glutathione (GSSG), resulting in decreased GSH/GSSG ratio. In consequence, significant reactive oxygen species (ROS) production was observed. The flow cytometric analysis revealed that 2-AAPA inhibited growth of esophageal cancer cells through arresting cell cycle in G 2 /M phase, but apoptosis-independent mechanism. The G 2 /M arrest was partially contributed by down-regulation of protein expression of Cdc-25c and up-regulation of phosphorylated Cdc-2 (Tyr15), Cyclin B1 (Ser147) and p53. Meanwhile, 2-AAPA-induced thiol oxidative stress led to increased protein S -glutathionylation, which resulted in α-tubulin S -glutathionylation-dependent depolymerization of microtubule in the TE-13 cells. In conclusion, we identified that 2-AAPA as an effective thiol oxidative stress inducer and proliferation of TE-13 cells were suppressed by G 2 /M phase cell cycle arrest, mainly, through α-tubulin S -glutathionylation-mediated microtubule depolymerization. Our results may introduce new target and approach for esophageal cancer therapy through generation of GR-mediated thiol oxidative stress.