title: A MT1-MMP/NF-kappaB signaling axis as a checkpoint controller of COX-2 expression in CD133+ U87 glioblastoma cells.
abstract: BACKGROUND
  The CD133(+) stem cell population in recurrent gliomas is associated with clinical features such as therapy resistance, blood-brain barrier disruption and, hence, tumor infiltration. Screening of a large panel of glioma samples increasing histological grade demonstrated frequencies of CD133(+) cells which correlated with high expression of cyclooxygenase (COX)-2 and of membrane type-1 matrix metalloproteinase (MT1-MMP).
  
  
  METHODS
  We used qRT-PCR and immunoblotting to examine the molecular interplay between MT1-MMP and COX-2 gene and protein expression in parental, CD133(+), and neurospheres U87 glioma cell cultures.
  
  
  RESULTS
  We found that CD133, COX-2 and MT1-MMP expression were enhanced when glioma cells were cultured in neurosphere conditions. A CD133(+)-enriched U87 glioma cell population, isolated from parental U87 cells with magnetic cell sorting technology, also grew as neurospheres and showed enhanced COX-2 expression. MT1-MMP gene silencing antagonized COX-2 expression in neurospheres, while overexpression of recombinant MT1-MMP directly triggered COX-2 expression in U87 cells independent from MT1-MMP's catalytic function. COX-2 induction by MT1-MMP was also validated in wild-type and in NF-kappaB p65-/- mutant mouse embryonic fibroblasts, but was abrogated in NF-kappaB 1 (p50-/-) mutant cells.
  
  
  CONCLUSIONS
  We provide evidence for enhanced COX-2 expression in CD133(+) glioma cells, and direct cell-based evidence of NF-kappaB-mediated COX-2 regulation by MT1-MMP. The biological significance of such checkpoint control may account for COX-2-dependent mechanisms of inflammatory balance responsible of therapy resistance phenotype of cancer stem cells.
authors.affiliation: Laboratoire d'Oncologie Moléculaire, Département de Chimie, Centre de Recherche BIOMED, Université du Québec à Montréal, Quebec, Canada. annabi.borhane@uqam.ca
authors.forename: Borhane
authors.initials: B
authors.lastname: Annabi
authors.forename: Carl
authors.initials: C
authors.lastname: Laflamme
authors.forename: Asmaa
authors.initials: A
authors.lastname: Sina
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Lachambre
authors.forename: Richard
authors.initials: R
authors.lastname: Béliveau
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D005347:Fibroblasts / Q000502:physiology; D005434:Flow Cytometry; D015870:Gene Expression; D005909:Glioblastoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D015151:Immunoblotting; D053511:Matrix Metalloproteinase 14 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051996:Transcription Factor RelA / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D051996:Transcription Factor RelA; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; C507086:MMP14 protein, human; D053511:Matrix Metalloproteinase 14