title: Irradiation-induced angiogenesis is associated with an MMP-9-miR-494-syndecan-1 regulatory loop in medulloblastoma cells.
abstract: Matrix metalloproteinase-9 (MMP-9) represents one of the most prominent proteins associated with tumorigenesis and is a modulator of the tumor microenvironment during angiogenesis. Recently, syndecan-1 (SDC1), a transmembrane heparan sulfate-bearing proteoglycan, was also speculated to have a critical role in contributing to angiogenesis when associated with MMP-9. However, the mechanism behind their synergistic regulation is not fully understood. In the current study, we report for the first time that ionizing radiation (IR)-induced MMP-9 enhances SDC1 shedding, corroborating to tube-inducing ability of medulloblastoma (MB) cells. Furthermore, we observed that the tumor angiogenesis is associated with higher MMP-9-SDC1 interactions on both the cell surface and extracellular medium. Our results also revealed the existence of a novel regulatory mechanism where MMP-9 drives the suppression of miR-494, resulting in enhanced SDC1 shedding and angiogenesis. From the in situ hybridization analysis, we found that MMP-9-specific shRNA (shMMP-9) treatment of mouse intracranial tumors resulted in elevated expression of miR-494. This negative correlation between MMP-9 and miR-494 levels was observed to be dependent on the methylation status of a miR-494 promoter-associated CpG island region (-186 to -20), which was confirmed by bisulfite-sequencing and methylation-specific PCR (MSP) analysis. Further, validation of MMP-9 and SDC1 3'-untranslated region (3'-UTR) targets with luciferase reporter assay provided a more favorable result for miR-494-mediated regulation of SDC1 but not of MMP-9, suggesting that the 3'-UTR of SDC1 mRNA is a direct target of miR-494. Overall, our results indicate that angiogenesis induced by radiotherapy is associated with an MMP-9-miR-494-SDC1 regulatory loop and that MMP-9-SDC1 activity creates a negative feedback loop by regulating the expression of miR-494.
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA.
authors.forename: S
authors.initials: S
authors.lastname: Asuthkar
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Velpula
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Nalla
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA.
authors.forename: V R
authors.initials: VR
authors.lastname: Gogineni
authors.affiliation: Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Gondi
authors.affiliation: 1] Department of Cancer Biology and Pharmacology, University of Illinois College of Medicine at Peoria, Peoria, IL, USA [2] Department of Neurosurgery, University of Illinois College of Medicine at Peoria, Peoria, IL, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Rao
mesh_terms: D000293:Adolescent; D000818:Animals; D045744:Cell Line, Tumor; D002528:Cerebellar Neoplasms / Q000235:genetics / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D025461:Feedback, Physiological / Q000502:physiology / Q000528:radiation effects; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology; D064593:Heterografts; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008527:Medulloblastoma / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D035683:MicroRNAs / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D011839:Radiation, Ionizing; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053668:Syndecan-1 / Q000378:metabolism*
chemical_list: C547168:MIRN494 microRNA, human; D035683:MicroRNAs; D034741:RNA, Small Interfering; C508241:SDC1 protein, human; D053668:Syndecan-1; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9