title: Regulation of anoikis resistance by NADPH oxidase 4 and epidermal growth factor receptor.
abstract: Normal cells are sensitive to anoikis, which is a cell detachment-induced apoptosis. However, cancer cells acquire anoikis resistance that is essential for successful metastasis. This study aimed to demonstrate the function and potential mechanism of NADPH oxidase 4 (NOX4) and EGFR activation in regulating anoikis resistance in lung cancer.
  
  
  
  Cells were cultured either in the attached or suspended condition. Cell viability was measured by cell counting and live and dead cell staining. Expression levels of NOX4 and EGFR were measured by PCR and immunoblotting. Reactive oxygen species (ROS) levels were measured by flow cytometry. Effects of NOX4 overexpression or NOX4 knockdown by si-NOX4 on anoikis sensitivity were explored. Levels of NOX4 and EGFR in lung cancer tissues were evaluated by IHC staining.
  
  
  
  NOX4 was upregulated but EGFR decreased in suspended cells compared with attached cells. Accordingly, ROS levels were increased in suspended cells, resulting in the activation of Src and EGFR. NOX4 knockdown decreased activation of Src and EGFR, and thus sensitised cells to anoikis. NOX4 overexpression increased EGFR levels and attenuated anoikis. NOX4 expression is upregulated and is positively correlated with EGFR levels in the lung cancer patient tissues.
  
  
  
  NOX4 upregulation confers anoikis resistance by ROS-mediated activation of EGFR and Src, and by maintaining EGFR levels, which is critical for cell survival.
authors.affiliation: Comparative Biomedicine Research Branch, Division of Cancer Biology, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Hyeryeong
authors.initials: H
authors.lastname: Kim
authors.affiliation: Pediatric Oncology Branch, Division of Translational and Clinical Research II, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Jee Young
authors.initials: JY
authors.lastname: Sung
authors.affiliation: Comparative Biomedicine Research Branch, Division of Cancer Biology, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Park
authors.affiliation: Comparative Biomedicine Research Branch, Division of Cancer Biology, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Seongho
authors.initials: S
authors.lastname: Kho
authors.affiliation: Comparative Biomedicine Research Branch, Division of Cancer Biology, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Kyung Hee
authors.initials: KH
authors.lastname: Koo
authors.affiliation: Department of Pathology, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Seog-Yun
authors.initials: SY
authors.lastname: Park
authors.affiliation: Cancer Genomics Branch, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Sung-Ho
authors.initials: SH
authors.lastname: Goh
authors.affiliation: Department of Pathology, Seoul National University College of Medicine, 28 Daehak-ro, Jongno-gu, Seoul 110-779, Korea.
authors.forename: Yoon Kyung
authors.initials: YK
authors.lastname: Jeon
authors.affiliation: Department of Neurology and Neurological Sciences, School of Biological Science/Bio-Max Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Sekyung
authors.initials: S
authors.lastname: Oh
authors.affiliation: Pediatric Oncology Branch, Division of Translational and Clinical Research II, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Byung-Kiu
authors.initials: BK
authors.lastname: Park
authors.affiliation: School of Biological Science, Seoul National University, Gwanak-gu, Seoul 151-747, Korea.
authors.forename: Yong-Keun
authors.initials: YK
authors.lastname: Jung
authors.affiliation: Comparative Biomedicine Research Branch, Division of Cancer Biology, National Cancer Center, 323 Ilsan-ro, Ilsandong-gu, Goyang-si 410-769, Korea.
authors.forename: Yong-Nyun
authors.initials: YN
authors.lastname: Kim
mesh_terms: D000072283:A549 Cells; D023102:Anoikis / Q000187:drug effects / Q000235:genetics*; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology*; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000502:physiology*; D009362:Neoplasm Metastasis; D034741:RNA, Small Interfering / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D034741:RNA, Small Interfering; D000074663:NADPH Oxidase 4; D019255:NADPH Oxidases; C498910:NOX4 protein, human; C512478:EGFR protein, human; D066246:ErbB Receptors