title: Downregulation of Axl in non-MYCN amplified neuroblastoma cell lines reduces migration.
abstract: Neuroblastomas (NBL) are common pediatric solid tumors with a variable clinical course. At diagnosis half of all neuroblastoma patients presents with metastatic disease. The mechanisms of metastasis are largely unknown. Gene expression profiles (HU133plus2.0 arrays, Affymetrix) of 17 NBL and 5 peripheral neuro-ectodermal cell lines were used to identify a subgroup of non-MYCN amplified (non-NMA) NBL cell lines with a distinct gene expression profile and characterized by high expression of AXL. Axl is a tyrosine kinase receptor which plays a role in the metastatic process of several types of cancer. We hypothesized that Axl contributes to the metastasizing potential of non-NMA NBL and tested if AXL silencing diminishes malignant properties of high Axl expressing cell lines. AXL was silenced in two non-NMA NBL cell lines by using a lentiviral shRNA construct that was able to transduce these cell lines with more than 90% infection efficiency. Axl mRNA and protein level were efficiently knocked-down resulting in a decrease of migration of Axl positive cell lines GI-M-EN and SH-EP-2, and decreased invasion of GI-M-EN. Morphologically, Axl knockdown induced more rounded cells with a loss of contact. Intracellularly, we observed induction of stress fibers (immunofluorescence F-actin). These changes in cytoskeleton were associated with decreased migration, but were not accompanied by changes in genes involved in epithelial to mesenchymal transition such as CDH2, VIM or MMP9. No effects were observed for cell proliferation, apoptosis or downstream pathways. In conclusion, AXL is identified as a possible mediator of NBL metastasis.
authors.affiliation: Department of Pediatric Oncology-Hematology, Erasmus MC-Sophia Children's Hospital, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands.
authors.forename: Floor A M
authors.initials: FA
authors.lastname: Duijkers
authors.forename: Jules P P
authors.initials: JP
authors.lastname: Meijerink
authors.forename: Rob
authors.initials: R
authors.lastname: Pieters
authors.forename: Max M
authors.initials: MM
authors.lastname: van Noesel
mesh_terms: D015703:Antigens, CD / Q000235:genetics; D017209:Apoptosis / Q000235:genetics; D015820:Cadherins / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D048430:Cell Shape; D003599:Cytoskeleton / Q000235:genetics; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000235:genetics; D000071447:N-Myc Proto-Oncogene Protein; D009447:Neuroblastoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D009687:Nuclear Proteins / Q000235:genetics; D015513:Oncogene Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism; D000094963:Axl Receptor Tyrosine Kinase
chemical_list: D015703:Antigens, CD; C050361:CDH2 protein, human; D015820:Cadherins; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D020794:Receptor Protein-Tyrosine Kinases; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9; D000094963:Axl Receptor Tyrosine Kinase; C000722289:AXL protein, human