title: Magnolin inhibits cell migration and invasion by targeting the ERKs/RSK2 signaling pathway.
abstract: BACKGROUND
  Magnolin is a natural compound abundantly found in Magnolia flos, which has been traditionally used in oriental medicine to treat headaches, nasal congestion and anti-inflammatory reactions. Our recent results have demonstrated that magnolin targets the active pockets of ERK1 and ERK2, which are important signaling molecules in cancer cell metastasis. The aim of this study is to evaluate the effects of magnolin on cell migration and to further explore the molecular mechanisms involved.
  
  
  METHODS
  Magnolin-mediated signaling inhibition was confirmed by Western blotting using RSK2(+/+) and RSK2(-/-) MEFs, A549 and NCI-H1975 lung cancer cells, and by NF-κB and Cox-2 promoter luciferase reporter assays. Inhibition of cell migration by magnolin was examined by wound healing and/or Boyden Chamber assays using JB6 Cl41 and A549 human lung cancer cells. The molecular mechanisms involved in cell migration and epithelial-to-mesenchymal transition were determined by zymography, Western blotting, real-time PCR and immunocytofluorescence.
  
  
  RESULTS
  Magnolin inhibited NF-κB transactivation activity by suppressing the ERKs/RSK2 signaling pathway. Moreover, magnolin abrogated the increase in EGF-induced COX-2 protein levels and wound healing. In human lung cancer cells such as A549 and NCI-H1975, which harbor constitutive active Ras and EGFR mutants, respectively, magnolin suppressed wound healing and cell invasion as seen by a Boyden chamber assay. In addition, it was observed that magnolin inhibited MMP-2 and -9 gene expression and activity. The knockdown or knockout of RSK2 in A549 lung cancer cells or MEFs revealed that magnolin targeting ERKs/RSK2 signaling suppressed epithelial-to-mesenchymal transition by modulating EMT marker proteins such as N-cadherin, E-cadherin, Snail, Vimentin and MMPs.
  
  
  CONCLUSIONS
  These results demonstrate that magnolin inhibits cell migration and invasion by targeting the ERKs/RSK2 signaling pathway.
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. veritas0613@naver.com.
authors.forename: Cheol-Jung
authors.initials: CJ
authors.lastname: Lee
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. mhyun_lee@catholic.ac.kr.
authors.forename: Mee-Hyun
authors.initials: MH
authors.lastname: Lee
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. apple_ma@naver.com.
authors.forename: Sun-Mi
authors.initials: SM
authors.lastname: Yoo
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. luna239@naver.com.
authors.forename: Kyung-Il
authors.initials: KI
authors.lastname: Choi
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. xlzlzl1103@gmail.com.
authors.forename: Ji-Hong
authors.initials: JH
authors.lastname: Song
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. jhjang1717@gmail.com.|College of Pharmacy, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea. jhjang1717@gmail.com.
authors.forename: Jeong-Hoon
authors.initials: JH
authors.lastname: Jang
authors.affiliation: Natural Medicine Research Center, Korea Research Institute of Bioscience & Biotechnology, 30 Yeongudanji-ro, Ochang-eup, Cheongwon-gun, ChungBuk, 363-883, Republic of Korea. seiryang@kribb.re.kr.
authors.forename: Sei-Ryang
authors.initials: SR
authors.lastname: Oh
authors.affiliation: Natural Medicine Research Center, Korea Research Institute of Bioscience & Biotechnology, 30 Yeongudanji-ro, Ochang-eup, Cheongwon-gun, ChungBuk, 363-883, Republic of Korea. ryuhw@kribb.re.kr.
authors.forename: Hyung-Won
authors.initials: HW
authors.lastname: Ryu
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. sianalee@catholic.ac.kr.
authors.forename: Hye-Suk
authors.initials: HS
authors.lastname: Lee
authors.affiliation: College of Pharmacy, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 151-742, Republic of Korea. surh@plaza.snu.ac.kr.
authors.forename: Young-Joon
authors.initials: YJ
authors.lastname: Surh
authors.affiliation: College of Pharmacy, The Catholic University of Korea, 43, Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do, 420-743, Republic of Korea. yongyeon@catholic.ac.kr.
authors.forename: Yong-Yeon
authors.initials: YY
authors.lastname: Cho
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D006801:Humans; D017705:Lignans / Q000494:pharmacology*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects
chemical_list: D017705:Lignans; D016328:NF-kappa B; C094148:magnolin; D004815:Epidermal Growth Factor; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C069330:ribosomal protein S6 kinase, 90kDa, polypeptide 3; D048049:Extracellular Signal-Regulated MAP Kinases