title: Increased expression of the coxsackie and adenovirus receptor downregulates αvβ3 and αvβ5 integrin expression and reduces cell adhesion and migration.
abstract: OBJECTIVE
  Coxsackie and adenovirus receptor (CAR) is a tumor suppressor and a primary receptor for adenovirus type 5 (Ad5). Our study aims to examine the influence of forced expression of CAR in rhabdomyosarcoma cells (RD) on expression levels of integrins implicated in Ad5 entry, and the effect of CAR on cell-extracellular matrix adhesion and migration.
  
  
  METHODS
  CAR expressing clones were established from RD cells by stable transfection. Flow cytometry was used to evaluate the expression of CAR and integrins. Adhesion was measured in plates previously coated with vitronectin or fibronectin. Boyden chambers were used to investigate migration. Transfection of cells with siRNA was used to achieve integrin silencing. Ad5-mediated transgene expression was measured by β-gal staining.
  
  
  RESULTS
  Increased expression of CAR in RD cells reduces the expression of αvβ3 and αvβ5 integrins. Cells overexpressing CAR exhibit significantly reduced adhesion to vitronectin and fibronectin, and reduced cell migration. Specifically silencing αvβ3 integrin in RD cells reduced cell migration indicating that reduced migration could be the consequence of αvβ3 integrin downregulation. This study also demonstrates the negative effect of reduced levels of αvβ3 and αvβ5 integrins on Ad5-mediated transgene expression with Ad5 retargeted to αv integrins.
  
  
  CONCLUSIONS
  The pharmacological upregulation of CAR aimed to increase Ad5-mediated transgene expression may actually downregulate αvβ3 and αvβ5 integrins and thus alter Ad5-mediated gene transfer. The mechanism of decreased cell migration, a prerequisite for metastasis and invasion, due to increased CAR expression may be explained by reduced αvβ3 integrin expression.
authors.affiliation: Laboratory for Genotoxic Agents, Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia.
authors.forename: Dragomira
authors.initials: D
authors.lastname: Majhen
authors.forename: Nikolina
authors.initials: N
authors.lastname: Stojanović
authors.forename: Tea
authors.initials: T
authors.lastname: Špeljko
authors.forename: Anamaria
authors.initials: A
authors.lastname: Brozovic
authors.forename: Tihana
authors.initials: T
authors.lastname: De Zan
authors.forename: Maja
authors.initials: M
authors.lastname: Osmak
authors.forename: Andreja
authors.initials: A
authors.lastname: Ambriović-Ristov
mesh_terms: D002448:Cell Adhesion / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D015536:Down-Regulation; D015967:Gene Expression Regulation, Viral; D006801:Humans; D039302:Integrin alphaVbeta3 / Q000235:genetics* / Q000378:metabolism; D011991:Receptors, Virus / Q000235:genetics* / Q000378:metabolism; D019030:Receptors, Vitronectin / Q000235:genetics* / Q000378:metabolism; D012208:Rhabdomyosarcoma; D014162:Transfection; D015854:Up-Regulation
chemical_list: C568771:CLMP protein, human; D062727:Coxsackie and Adenovirus Receptor-Like Membrane Protein; D039302:Integrin alphaVbeta3; D011991:Receptors, Virus; D019030:Receptors, Vitronectin; C064660:integrin alphaVbeta5