β-Apopicropodophyllin functions as a radiosensitizer targeting ER stress in non-small cell lung cancer

• Published in: Biomedicine & pharmacotherapy Vol. 113; p. 108769
• Main Authors: Kim, Ju Yeon, Cho, Jeong Hyun, Kim, Eun Mi, Shin, Hyun-Jin, Hwang, Sang-Gu, Song, Jie-Young, Um, Hong-Duck, Park, Jong Kuk
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.05.2019; Elsevier
• Subjects: Animals; Apoptosis; Apoptosis - drug effects; Apoptosis - radiation effects; Carcinoma, Non-Small-Cell Lung - pathology; Carcinoma, Non-Small-Cell Lung - radiotherapy; Cell Line, Tumor; Endoplasmic Reticulum Stress - drug effects; Endoplasmic Reticulum Stress - radiation effects; ER stress; Humans; Hydrogen Peroxide - metabolism; Lung Neoplasms - pathology; Lung Neoplasms - radiotherapy; Membrane Potential, Mitochondrial; Mice; Mice, Inbred BALB C; Mice, Nude; Mitochondria - metabolism; Non-small cell lung cancer; Podophyllin - administration & dosage; Podophyllin - pharmacology; Radiation-Sensitizing Agents - administration & dosage; Radiation-Sensitizing Agents - pharmacology; Radiosensitizer; Reactive Oxygen Species - metabolism; ROS; Xenograft Model Antitumor Assays; β-Apopicropodophylli; TFs; APP; MKK4; JNK; ROS/RNS; BiP; Radiosensitizer; SD; Gy; TUNEL; PO1; PDI; PPT; UPR; eIF2; NSCLC; ASK1; ER stress; IR; MAPK; ER; SAPK; DER; β-Apopicropodophylli; ROS; Non-small cell lung cancer; PI; ATF4; ERK; Apoptosis
• ISSN: 0753-3322; 1950-6007
• DOI: 10.1016/j.biopha.2019.108769

•β-Apopicropodophyllin is a candidate drug for treatment of non-small cell lung cancer.•Novel function of β-Apopicropodophyllin as a radiosensitizer was confirmed in vitro and in vivo.•Radiosensiting effect of β-Apopicropodophyllin is exerted by ER stress-mediated apoptosis via JNK activation. In this study, we examined whether β-apopicropodophyllin (APP) could act as a radiosensitizer in non-small cell lung cancer (NSCLC) cells. The in vitro radiosensitizing activity of APP was demonstrated with clonogenic assay, immunoblotting, Annexin V-Propidium iodide (PI) assay, BrdU incorporation, detection of mitochondrial ROS/intracellular of H2O2, mitochondrial membrane potential detection, and performing of isolation of mitochondrial and cytosolic fractions. The in vivo radiosensitizing activity of APP was determined in xenografted mice with co-treatment of APP and IR based on measurement of tumor volumes and apoptotic cell death. The results of a clonogenic assay indicated that a combination of APP and γ-ionizing radiation (IR) inhibits cell growth and increases cell death in NSCLC cells. Several signal transduction pathways were examined for their potential involvement in the apparent radiosensitization effect of APP, as assessed by immunoblotting analyses and mitochondrial potential determination in vitro. Treatment of NCI-H460 cells with 15 nM APP and NCI-H1299 cells with 10 nM APP yielded dose-enhancement ratios of 1.44 and 1.24, respectively. Enhanced ER stress, disrupted mitochondrial membrane potential, and increased reactive oxygen species (ROS) were observed in cells co-treated with APP and IR, and this was followed by the cytosolic release of cytochrome c and consequent activation of caspase-3 and -9. Notably, inhibition of JNK, which prevents caspase activation, blocked the APP/IR-induced activations of ER stress and apoptotic cell death. In NCI-H460 or NCI-H1299 cell-xenografted mice, APP/IR treatment delayed the time it took tumors to reach a threshold size by 22.38 and 16.83 days, respectively, compared with controls, to yield enhancement factors of 1.53 and 1.38, respectively. APP has a radiosensitizing function derived from its ability to induce apoptotic cell death via activation of ER stress, disruption of mitochondrial membrane potential, and induction of the caspase pathway.