The -549T>C PTGDR promoterpolymorphism influence the respond todexamethasone administration in theA549 lung cell line

Resumen

Background:Asthma is a multifactorialdisease influenced by environmental andgenetic factors. Glucocorticoids (GC) arethe mainstay treatment of asthma. GCdecrease symptoms regulating genesinvolved in the inflammatory process bybinding to specific GRE (GlucocorticoidResponse Elements). Polymorphismslocated in the promoter region of the Pros-taglandin D Receptor gene (PTGDR) havebeen related to asthma. We aimed to ana-lyze the effect of the -549T>C PTGDRpromoter polymorphism on the responseto corticosteroid administration.Method:MatInspector and Biobase soft-ware were used for an initialin silicoanalysis ofPTGDRpromoter region. TheA549 cell line was transfected with con-structs of the reporter vector pGL3Basicincluding a 700 bp insert ofPTGDRpro-moter with the mutated and non-mutatedgene variants of the -549T>C polymor-phism. Cells were treated with dexametha-sone (Dex) 10 6M and with the vehicle(ethanol) for 36 h. Luciferase assays wereperformed by Dual Luciferase ReporterAssay System, and data were normalisedusing Renilla. The assays were carried outin triplicate. Changes inCYP3A5expres-sion as GC metabolizer gene were analyzedusing qPCR.Results:There was an increased geneexpression of CYP3A5 (18.23 fold) in cul-tures treated with Dex, which validates theexperimental model. A549 cells transfectedwith the non-mutated variant did not expressed Luciferase, not even when trea-ted with Dex, while cells transfected withthe mutated variant of 549T>C SNPtreated with Dex showed a significant2.07 0.11 times increased signal(P<0.001). Thein silicoanalysis of thePTGDR promoter region indicated thepresence of GRE as well as multiplechanges in the binding sites of transcrip-tion factors between the gene variants.Conclusion:The presence of the mutatedvariant of the 549T>C PTGDR promoterSNP resulted in a modification of geneexpression in response to corticosteroidtreatment probably due to a change in thetranscription factor binding pattern.