MicroRNA-375/SEC23A as biomarkers of the in vitro efficacy of vandetanib

// Sandra Lassalle 1, 2, 3, 4, 5, * , Joséphine Zangari 2, 3, 5, * , Alexandra Popa 3, 5, 6 , Marius Ilie 1, 2, 3, 4, 5 , Véronique Hofman 1, 2, 3, 4, 5 , Elodie Long 1, 2, 3, 4, 5 , Martine Patey 7 , Frédérique Tissier 8 , Geneviève Belléannée 9 , Hélène Trouette 9 , Bogdan Catargi 10 , Isabelle Peyrottes 5, 11 , Jean-Louis Sadoul 12 , Olivier Bordone 4, 5 , Christelle Bonnetaud 4, 5 , Catherine Butori 1, 5 , Alexandre Bozec 2, 3, 5, 13 , Nicolas Guevara 5, 13 , José Santini 5, 13 , Imène Sarah Hénaoui 3, 6 , Géraldine Lemaire 14 , Olivier Blanck 14 , Philippe Vielh 15 , Pascal Barbry 3, 5, 6 , Bernard Mari 3, 5, 6, * , Patrick Brest 2, 3, 5, * , Paul Hofman 1, 2, 3, 4, 5, *  1 Centre Hospitalier Universitaire de Nice, Laboratory of Clinical and Experimental Pathology, Nice, France  2 Institute of Research on Cancer and Ageing of Nice (IRCAN), INSERM U1081/CNRS UMR7284, Nice, France  3 University of Nice Sophia-Antipolis, Nice, France  4 Centre Hospitalier Universitaire de Nice, Hospital Integrated Biobank (BB 0033-00025), Nice, France  5 Fédération Hospitalo-Universitaire “OncoAge”, University of Nice Sophia Antipolis, Nice, France  6 Institut de Pharmacologie Moléculaire et Cellulaire IPMC, CNRS UMR7275, Sophia-Antipolis, France  7 Hôpital Universitaire de Reims - Hôpital Robert Debré, Department of Pathology, Institut Jean Godinot, Reims, France  8 Assistance Publique - Hôpitaux de Paris (AP-HP), Groupe Hospitalier Pitié-Salpêtrière, Laboratory of Pathology, Paris, France  9 Centre Hospitalier Universitaire de Bordeaux, Hôpital Universitaire de Pessac-Haut Lévêque, Laboratory of Pathology, Pessac, France 10 Centre Hospitalier Universitaire de Bordeaux, Department of Endocrinology, Pessac, France 11 Centre Antoine Lacassagne, Laboratory of Pathology, Nice, France 12 Centre Hospitalier Universitaire de Nice, Hôpital de l’Archet, Department of Endocrinology, Nice, France 13 Centre Antoine Lacassagne, Head and Neck Institute, Surgery and Otorhinolaryngology Department, Nice, France 14 Bayer CropScience SA, Research Center, Sophia Antipolis, Valbonne, France 15 Institut Gustave Roussy, Translational Research Laboratory, Department of Pathology, Villejuif, France * These authors have contributed equally to this work Correspondence to: Paul Hofman, email: hofman.p@chu-nice.fr Keywords: microRNA, medullary thyroid carcinoma, microRNA-375, treatment, vandetanib Received: November 25, 2015      Accepted: March 10, 2016      Published: March 29, 2016 ABSTRACT In this study, we performed microRNA (miRNA) expression profiling on a large series of sporadic and hereditary forms of medullary thyroid carcinomas (MTC). More than 60 miRNAs were significantly deregulated in tumor vs adjacent non-tumor tissues, partially overlapping with results of previous studies. We focused our attention on the strongest up-regulated miRNA in MTC samples, miR-375, the deregulation of which has been previously observed in a variety of human malignancies including MTC. We identified miR-375 targets by combining gene expression signatures from human MTC (TT) and normal follicular (Nthy-ori 3-1) cell lines transfected with an antagomiR-375 inhibitor or a miR-375 mimic, respectively, and from an in silico analysis of thyroid cell lines of Cancer Cell Line Encyclopedia datasets. This approach identified SEC23A as a bona fide miR-375 target, which we validated by immunoblotting and immunohistochemistry of non-tumor and pathological thyroid tissue. Furthermore, we observed that miR-375 overexpression was associated with decreased cell proliferation and synergistically increased sensitivity to vandetanib, the clinically relevant treatment of metastatic MTC. We found that miR-375 increased PARP cleavage and decreased AKT phosphorylation, affecting both cell proliferation and viability. We confirmed these results through SEC23A direct silencing in combination with vandetanib, highlighting the importance of SEC23A in the miR-375-associated increased sensitivity to vandetanib. Since the combination of increased expression of miR-375 and decreased expression of SEC23A point to sensitivity to vandetanib, we question if the expression levels of miR-375 and SEC23A should be evaluated as an indicator of eligibility for treatment of MTC patients with vandetanib.