Original Articles The cl2/dro1/ccdc80 null mice develop thyroid and ovarian neoplasias Vincenza Leone a,1 , Angelo Ferraro a,1 , Filippo Schepis b,1 , Antonella Federico a , Romina Sepe a , Claudio Arra c , Concetta Langella a , Giuseppe Palma a,c , Carlo De Lorenzo b , Giancarlo Troncone d , Valeria Masciullo e , Giovanni Scambia e , Alfredo Fusco a , Pierlorenzo Pallante a, * a Istituto per l’Endocrinologia e l’Oncologia Sperimentale (IEOS) “G. Salvatore”, Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche (DMMBM), Università degli Studi di Napoli “Federico II”, Via S. Pansini 5, Naples 80131, Italy b Dipartimento di Medicina Sperimentale, Campus Universitario “Salvatore Venuta”, Università degli Studi di Catanzaro “Magna Graecia”, Viale Europa – Località Germaneto, Catanzaro 88100, Italy c Istituto Nazionale dei Tumori, Fondazione Pascale, Via M. Semmola, Naples 80131, Italy d Dipartimento di Sanità Pubblica, Università degli Studi di Napoli “Federico II”, Via S. Pansini 5, Naples 80131, Italy e Dipartimento di Ginecologia Oncologica, Università Cattolica del Sacro Cuore, Largo Agostino Gemelli 8, Rome 00168, Italy ARTICLE INFO Article history: Received 5 June 2014 Received in revised form 26 November 2014 Accepted 4 December 2014 Keywords: Knock-out mice cl2/dro1/ccdc80 Thyroid Ovary Carcinoma A B ST R AC T We have previously reported that the expression of the CL2/CCDC80 gene is downregulated in human papillary thyroid carcinomas, particularly in follicular variants. We have also reported that the restora- tion of CL2/CCDC80 expression reverted the malignant phenotype of thyroid carcinoma cell lines and that CL2/CCDC80 positively regulated E-cadherin expression, an ability that likely accounts for the role of the CL2/CCDC80 gene in thyroid cancer progression. In order to validate the tumour suppressor role of the CL2/CCDC80 gene in thyroid carcinogenesis we generated cl2/ccdc80 knock-out mice. We found that embryonic fibroblasts from cl2/ccdc80 -/- mice showed higher proliferation rate and lower suscep- tibility to apoptosis. Furthermore, cl2/ccdc80 -/- mice developed thyroid adenomas and ovarian carcinomas. Finally, ret/PTC1 transgenic mice crossed with the cl2/ccdc80 knock-out mice developed more aggres- sive thyroid carcinomas compared with those observed in the single ret/PTC1 transgenic mice. Together, these results indicate CL2/CCDC80 as a putative tumour suppressor gene in human thyroid carcinogenesis. © 2014 Elsevier Ireland Ltd. All rights reserved. Introduction Our group has identified a gene, named CL2/CCDC80, that is dras- tically downregulated in thyroid carcinomas, particularly in the follicular variant (FV) of papillary carcinomas (PTC) [1,2]. PTC, the most common thyroid tumour, represents an intermediate form among thyroid neoplasms [3] that, in general, range from benign and differentiated adenoma to completely undifferentiated and very aggressive anaplastic carcinoma (ATC) [3]. Of note, in the 20% of PTC the presence of the RET/PTC oncogene, a fusion protein generated by the recombination of the RET proto-oncogene tyrosine kinase with several partners, has been causally linked to the generation of this kind of carcinoma [4]. The restoration of CL2/CCDC80 ex- pression in two human ATC cell lines resulted in suppression of a malignant phenotype associated with a higher susceptibility to apop- tosis. We hypothesized that the ability of the CL2/CCDC80 gene to positively regulate E-cadherin expression plays an important role in cancer progression [1]. A tumour suppressor role of CL2/CCDC80 has been also pro- posed in other human neoplasias such as colorectal and pancreatic carcinomas [5]. Indeed, CL2/CCDC80 expression levels are drasti- cally reduced in colorectal and pancreatic cell lines as well as in tumour tissues with respect to normal tissues [5]. Moreover, res- toration of CL2/CCDC80 expression is able to suppress malignant- related cell properties, such as anchorage-independent growth, by inducing anoikis [5]. In addition, CL2/CCDC80 enforced exogenous expression is able to modulate apoptotic pathways [5–7]. It is also important to note that CL2/CCDC80 is involved in the process of adi- pogenesis [8–10] and its disruption leads to a bidirectional modulation of this pathway [8]. Here, in order to further validate the tumour suppressor role for the CL2/CCDC80 gene we generated and characterized cl2/ccdc80 null mice for the appearance of neoplastic lesions. Consistent with our previous published results, mouse embryonic fibroblasts (MEFs) de- riving from knock-out mice showed higher proliferation rate and lower susceptibility to apoptosis in comparison with those gath- ered from wild type (wt) mice. Cl2/ccdc80 null mice developed thyroid adenomas and ovarian carcinomas: interestingly, * Corresponding author. Tel.: +39 081 7463347; fax: +39 081 2296674. E-mail address: pallante@ieos.cnr.it (P. Pallante). 1 These authors equally contributed to this work. http://dx.doi.org/10.1016/j.canlet.2014.12.010 0304-3835/© 2014 Elsevier Ireland Ltd. All rights reserved. Cancer Letters 357 (2015) 535–541 Contents lists available at ScienceDirect Cancer Letters journal homepage: www.elsevier.com/locate/canlet