AMRI-59 functions as a radiosensitizer via peroxiredoxin I-targeted ROS accumulation and apoptotic cell death induction

// Wan Gi Hong 1 , Ju Yeon Kim 1 , Jeong Hyun Cho 1 , Sang-Gu Hwang 1 , Jie-Young Song 1 , EunAh Lee 2 , Tong-Shin Chang 3 , Hong-Duck Um 1 and Jong Kuk Park 1 1 Division of Applied Radiation Bioscience, Korea Institute of Radiological and Medical Sciences, Seoul, Korea 2 Impedance Imaging Research Center, Kyung Hee University, Seoul, Korea 3 College of Pharmacy, Ewha Womans University, Seoul, Korea Correspondence to: Jong Kuk Park, email: jkpark@kirams.re.kr Keywords: peroxiredoxin; radiosensitizer; AMRI-59; ROS; non-small cell lung cancer Received: July 13, 2017     Accepted: November 26, 2017     Published: December 09, 2017 ABSTRACT Previously, we identified AMRI-59 as a specific pharmaceutical inhibitor of peroxiredoxin (PRX) I enzyme activity. In this study, we examined whether AMRI-59 acts as a radiosensitizer in non-small cell lung cancer cells using clonogenic assays. The intracellular mechanisms underlying the radiosensitization effect of AMRI-59 were determined via immunoblotting in addition to measurement of ROS generation, mitochondrial potential and cell death. AMRI-59 activity in vivo was examined by co-treating nude mice with the compound and γ-ionizing radiation (IR), followed by measurement of tumor volumes and apoptosis. The dose enhancement ratios of 30 μM AMRI-59 in NCI-H460 and NCI-H1299 were 1.51 and 2.12, respectively. Combination of AMRI-59 with IR augmented ROS production and mitochondrial potential disruption via enhancement of PRX I oxidation, leading to increased expression of γH2AX, a DNA damage marker, and suppression of ERK phosphorylation, and finally, activation of caspase-3. Notably, inhibition of ROS production prevented ERK suppression, and blockage of ERK in combination with AMRI-59 and IR led to enhanced caspase-3 activation and apoptosis. In a xenograft assay using NCI-H460 and NCI-H1299, combined treatment with AMRI-59 and IR delayed tumor growth by 26.98 and 14.88 days, compared with controls, yielding enhancement factors of 1.73 and 1.37, respectively. Taken together, the results indicate that AMRI-59 functions as a PRX I-targeted radiosensitizer by inducing apoptosis through activation of the ROS/γH2AX/caspase pathway and suppression of ERK.