Résumé

CO-26

MiR-483-5p and miR-139-5p promote invasion of adrenocortical carcinoma by targeting N-Myc Downstream-Regulated Gene family members

Dr C. AGOSTAa, Dr JJ. FEIGEb, Pr J. BERTHERATc, Pr O. CHABREa, Dr N. CHERRADIb

a INSERM U1036; Hôpital Universitaire Albert Michallon, Service d’Endocrinologie; CEA, iRTSV, Biologie du Cancer et de l'Infection; Université Grenoble Alpes, Laboratoire BCI, Grenoble ; b INSERM U1036; CEA, iRTSV, Biologie du Cancer et de l’Infection; Université Grenoble Alpes, Laboratoire BCI, Grenoble ; c Université Paris Descartes; INSERM U1016, Institut Cochin, CNRS UMR8104; Assistance Publique Hôpitaux de Paris, Hôpital Cochin, Département d'Endocrinologie, Centre des maladies rares de la surrénale, Paris

MicroRNAs have emerged as key biomarkers for diagnosis and prognosis of adrenocortical tumors. We have previously shown that miR-483-5p and miR-139-5p were up-regulated in adrenocortical carcinomas (ACC) (Chabre et al, 2013). However, the role of these microRNAs in the pathogenesis of ACC is still unknown. Our aim was to identify target genes of miR-483-5p and miR-139-5p in ACC and to investigate their contribution to adrenocortical tumorigenesis. Target prediction was performed using miRWalk database combined with the previously published transcriptome of adrenocortical tumors (de Reyniès et al, 2009). Tumor miR-483-5p and miR-139-5p levels were measured by RT-qPCR in 30 patients from COMETE Network and correlated with the expression of their putative targets. The 3’-untranslated regions of target genes were cloned into pMiR-Luciferase vectors to evaluate miRNA-mRNA interactions. The role of miR-483-5p or miR-139-5p in the malignant phenotype of NCI-H295R cells was investigated using miRNA inhibitors. We identified NDRG2 (N-Myc Downstream-Regulated Gene 2) and NDRG4 as targets of miR-483-5p and miR-139-5p, respectively. In ACC, expression of NDRG2 and NDRG4 was inversely correlated with miR-483-5p and miR-139-5p levels. Downregulation of miR-483-5p or miR-139-5p in NCI-H295R cells induced an increase of NDRG2 or NDRG4 mRNAs. Moreover, NDRG2 and NDRG4 transcripts were negatively regulated via specific miRNA target sites. Finally, silencing miR-483-5p or miR-139-5p did not affect proliferation or apoptosis of NCI-H295R cells but inhibited their anchorage-independent growth and invasion. Our data indicate for the first time that targeting of NDRG2 and NDRG4 tumor suppressor genes by miR-483-5p and miR-139-5p might contribute to ACC aggressiveness.