title: Dual roles of extracellular signal-regulated kinase (ERK) in quinoline compound BPIQ-induced apoptosis and anti-migration of human non-small cell lung cancer cells.
abstract: BACKGROUND
  2,9-Bis[2-(pyrrolidin-1-yl)ethoxy]-6-{4-[2-(pyrrolidin-1-yl)ethoxy] phenyl}-11H-indeno[1,2-c]quinoline-11-one (BPIQ), is a synthetic quinoline analog. A previous study showed the anti-cancer potential of BPIQ through modulating mitochondrial-mediated apoptosis. However, the effect of BPIQ on cell migration, an index of cancer metastasis, has not yet been examined. Furthermore, among signal pathways involved in stresses, the members of the mitogen-activated protein kinase (MAPK) family are crucial for regulating the survival and migration of cells. In this study, the aim was to explore further the role of MAPK members, including JNK, p38 and extracellular signal-regulated kinase (ERK) in BPIQ-induced apoptosis and anti-migration of human non-small cell lung cancer (NSCLC) cells.
  
  
  METHODS
  Western Blot assay was performed for detecting the activation of MAPK members in NSCLC H1299 cells following BPIQ administration. Cellular proliferation was determined using a trypan blue exclusion assay. Cellular apoptosis was detected using flow cytometer-based Annexin V/propidium iodide dual staining. Cellular migration was determined using wound-healing assay and Boyden's chamber assay. Zymography assay was performed for examining MMP-2 and -9 activities. The assessment of MAPK inhibition was performed for further validating the role of JNK, p38, and ERK in BPIQ-induced growth inhibition, apoptosis, and migration of NSCLC cells.
  
  
  RESULTS
  Western Blot assay showed that BPIQ treatment upregulates the phosphorylated levels of both MAPK proteins JNK and ERK. However, only ERK inhibitor rescues BPIQ-induced growth inhibition of NSCLC H1299 cells. The results of Annexin V assay further confirmed the pro-apoptotic role of ERK in BPIQ-induced cell death of H1299 cells. The results of wound healing and Boyden chamber assays showed that sub-IC50(sub-lethal) concentrations of BPIQ cause a significant inhibition of migration in H1299 cells accompanied with downregulating the activity of MMP-2 and -9, the motility index of cancer cells. Inhibition of ERK significantly enhances BPIQ-induced anti-migration of H1299 cells.
  
  
  CONCLUSIONS
  Our results suggest ERK may play dual roles in BPIQ-induced apoptosis and anti-migration, and it would be worthwhile further developing strategies for treating chemoresistant lung cancers through modulating ERK activity.
authors.affiliation: Department of Thoracic Surgery, Chi-Mei Medical Center, Tainan, 710 Taiwan.
authors.forename: Yao
authors.initials: Y
authors.lastname: Fong
authors.affiliation: Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804 Taiwan.|Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.
authors.forename: Chang-Yi
authors.initials: CY
authors.lastname: Wu
authors.affiliation: Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.
authors.forename: Kuo-Feng
authors.initials: KF
authors.lastname: Chang
authors.affiliation: Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.|The Institute of Biomedical Sciences, National Sun Yat-Sen University, Kaohsiung, 804 Taiwan.
authors.forename: Bing-Hung
authors.initials: BH
authors.lastname: Chen
authors.affiliation: Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.
authors.forename: Wan-Ju
authors.initials: WJ
authors.lastname: Chou
authors.affiliation: School of Pharmacy, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.
authors.forename: Chih-Hua
authors.initials: CH
authors.lastname: Tseng
authors.affiliation: Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.
authors.forename: Yen-Chun
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Graduate Institute of Biomedical Engineering, National Chung Hsing University, Taichung, 402 Taiwan.
authors.forename: Hui-Min David
authors.initials: HD
authors.lastname: Wang
authors.affiliation: Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.
authors.forename: Yeh-Long
authors.initials: YL
authors.lastname: Chen
authors.affiliation: Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung, 804 Taiwan.|Department of Biotechnology, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.|Translational Research Center, Cancer Center and Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, 807 Taiwan.|Research Center for Environment Medicine, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.|Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 807 Taiwan.
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Chiu
keywords: Apoptosis; BPIQ; Cellular migration; ERK; Indeno[1,2-c]quinoline; Lung cancer; MAPK; Quinoline