Deciphering the molecular basis of invasiveness in Sdhb-deficient cells

// Céline Loriot 1, 2 , Mélanie Domingues 2, 3 , Adeline Berger 4, 5 , Mélanie Menara 1, 2 , Maëva Ruel 1, 2 , Aurélie Morin 1, 2 , Luis-Jaime Castro-Vega 1, 2 , Éric Letouzé 6 , Cosimo Martinelli 1, 2 , Alexis-Pierre Bemelmans 7, 8 , Lionel Larue 3 , Anne-Paule Gimenez-Roqueplo 1, 2, 9, 10 , Judith Favier 1, 2 1 INSERM, UMR970, Paris Cardiovascular Research Centre, F-75015 Paris, France 2 Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine, F-75006 Paris, France 3 INSERM, U1021, CNRS UMR3347, Institut Curie, F-91405 Orsay, France 4 INSERM, U968, Institut de la vision, F-75012 Paris, France 5 Université Pierre et Marie Curie Paris 06, F-75005 Paris, France 6 Programme Cartes d’Identité des Tumeurs, Ligue Nationale Contre Le Cancer, F-75013 Paris, France 7 CEA, DSV, I 2 BM, Molecular Imaging Research Center (MIRCen), F-92265 Fontenay-aux-Roses, France 8 CNRS, CEA URA 2210, F-92265 Fontenay-aux-Roses, France 9 Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Service de Génétique, F-75015 Paris, France 10 Rare Adrenal Cancer Network-Cortico Médullosurrénale Tumeurs Endocrines, Institut National du Cancer, F-75014 Paris, France Correspondence to: Judith Favier, e-mail: judith.favier@inserm.fr Keywords: paraganglioma, SDHB, metastasis, EMT, keratin 19 Received: May 11, 2015      Accepted: September 25, 2015      Published: October 08, 2015 ABSTRACT Metastatic pheochromocytomas and paragangliomas (PPGL) are malignant neuroendocrine tumors frequently associated with germline mutations in the SDHB gene. SDHB -mutated PPGL display a hypermethylator phenotype associated with hallmarks of epithelial-to-mesenchymal transition (EMT). In the present study, we report the characterization of a unique model of Sdhb knockout in mouse chromaffin cells. Sdhb deficient cells exhibit a metastatic phenotype as highlighted by increased individual cell migration (characterized by faster motility and increased persistence) as well as high invasive and adhesion abilities. This phenotype is associated with the modulation of Twist1, Twist2, Tcf3, Snai1, N-cadherin or Krt19 expression, reflecting an EMT-like reprogramming of cells. Krt19 is epigenetically silenced in Sdhb -deficient cells and re-expressed after treatment by the demethylating agent decitabine . Krt19 rescue by lentiviral transduction in Sdhb -deficient cells and Krt19 inhibition by RNA interference in wild-type cells were performed. Both studies revealed the involvement of KRT19 in the invasive phenotype by modulating collective and individual migration and cell/extra-cellular matrix adhesion properties. These findings underline the role of hypermethylation and EMT in the in vitro acquisition of metastatic properties, following SDHB loss of function.