title: IL-24 inhibits lung cancer cell migration and invasion by disrupting the SDF-1/CXCR4 signaling axis.
abstract: BACKGROUND
  The stromal cell derived factor (SDF)-1/chemokine receptor (CXCR)-4 signaling pathway plays a key role in lung cancer metastasis and is molecular target for therapy. In the present study we investigated whether interleukin (IL)-24 can inhibit the SDF-1/CXCR4 axis and suppress lung cancer cell migration and invasion in vitro. Further, the efficacy of IL-24 in combination with CXCR4 antagonists was investigated.
  
  
  METHODS
  Human H1299, A549, H460 and HCC827 lung cancer cell lines were used in the present study. The H1299 lung cancer cell line was stably transfected with doxycycline-inducible plasmid expression vector carrying the human IL-24 cDNA and used in the present study to determine the inhibitory effects of IL-24 on SDF-1/CXCR4 axis. H1299 and A549 cell lines were used in transient transfection studies. The inhibitory effects of IL-24 on SDF1/CXCR4 and its downstream targets were analyzed by quantitative RT-PCR, western blot, luciferase reporter assay, flow cytometry and immunocytochemistry. Functional studies included cell migration and invasion assays.
  
  
  RESULTS
  Endogenous CXCR4 protein expression levels varied among the four human lung cancer cell lines. Doxycycline-induced IL-24 expression in the H1299-IL24 cell line resulted in reduced CXCR4 mRNA and protein expression. IL-24 post-transcriptionally regulated CXCR4 mRNA expression by decreasing the half-life of CXCR4 mRNA (>40%). Functional studies showed IL-24 inhibited tumor cell migration and invasion concomitant with reduction in CXCR4 and its downstream targets (pAKTS473, pmTORS2448, pPRAS40T246 and HIF-1α). Additionally, IL-24 inhibited tumor cell migration both in the presence and absence of the CXCR4 agonist, SDF-1. Finally, IL-24 when combined with CXCR4 inhibitors (AMD3100, SJA5) or with CXCR4 siRNA demonstrated enhanced inhibitory activity on tumor cell migration.
  
  
  CONCLUSIONS
  IL-24 disrupts the SDF-1/CXCR4 signaling pathway and inhibits lung tumor cell migration and invasion. Additionally, IL-24, when combined with CXCR4 inhibitors exhibited enhanced anti-metastatic activity and is an attractive therapeutic strategy for lung metastasis.
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
authors.forename: Janani
authors.initials: J
authors.lastname: Panneerselvam
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
authors.forename: Jiankang
authors.initials: J
authors.lastname: Jin
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
authors.forename: Manish
authors.initials: M
authors.lastname: Shanker
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
authors.forename: Jason
authors.initials: J
authors.lastname: Lauderdale
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bates
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Department of Biostatistics and Epidemiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
authors.forename: Yan D
authors.initials: YD
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, The University of Hull, Hull, United Kingdom.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Archibald
authors.affiliation: Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Department of Chemistry, Southwestern Oklahoma State University, Weatherford, Oklahoma, United States of America.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Hubin
authors.affiliation: Department of Pathology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America; Graduate Program in Biomedical Sciences, Oklahoma City, Oklahoma, United States of America.
authors.forename: Rajagopal
authors.initials: R
authors.lastname: Ramesh
mesh_terms: D001596:Benzylamines; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects* / Q000235:genetics; D054377:Chemokine CXCL12 / Q000378:metabolism*; D000080027:Cyclams; D004357:Drug Synergism; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006571:Heterocyclic Compounds / Q000494:pharmacology; D006801:Humans; D007378:Interleukins / Q000235:genetics / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D000099180:Interleukin-24
chemical_list: D001596:Benzylamines; D054377:Chemokine CXCL12; D000080027:Cyclams; D006571:Heterocyclic Compounds; D007378:Interleukins; D051057:Proto-Oncogene Proteins c-akt; D034741:RNA, Small Interfering; D019718:Receptors, CXCR4; D058570:TOR Serine-Threonine Kinases; D000099180:Interleukin-24; C088327:plerixafor