5azadC treatment upregulates miR-375 level and represses HPV16 E6 expression.
Fiche publication
Date publication
mai 2017
Journal
Oncotarget
Auteurs
Membres identifiés du Cancéropôle Est :
Dr BAGUET Aurélie, Pr PRETET Jean-Luc, Dr GUENAT David
Tous les auteurs :
Morel A, Baguet A, Perrard J, Demeret C, Jacquin E, Guenat D, Mougin C, Prétet JL
Lien Pubmed
Résumé
High risk human papillomaviruses are the etiological agents of cervical cancer and HPV16 is the most oncogenic genotype. Immortalization and transformation of infected cells requires the overexpression of the two viral oncoproteins E6 and E7 following HPV DNA integration into the host cell genome. Integration often leads to the loss of the E2 open reading frame and the corresponding protein can no longer act as a transcriptional repressor on p97 promoter. Recently, it has been proposed that long control region methylation also contributes to the regulation of E6/E7 expression. To determine which epigenetic mechanism is involved in HPV16 early gene regulation, 5-aza-2'-deoxycytidine was used to demethylate Ca Ski and SiHa cell DNA. Decreased expression of E6 mRNA and protein levels was observed in both cell lines in an E2-independent manner. E6 repression was accompanied by neither a modification of the main cellular transcription factor expression involved in long control region regulation, nor by a modification of the E6 mRNA splicing pattern. In contrast, a pronounced upregulation of miR-375, known to destabilize HPV16 early viral mRNA, was observed. Finally, the use of miR-375 inhibitor definitively proved the involvement of miR-375 in E6 repression. These results highlight that cellular DNA methylation modulates HPV16 early gene expression and support a role for epigenetic events in high-risk HPV associated-carcinogenesis.
Mots clés
5azadC, DNA methylation, E6, HPV, miRNA
Référence
Oncotarget. 2017 May;: