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DNA damage response has been clearly described as an anti-cancer barrier in early human tumorigenesis. Moreover, interestingly, testicular germ cell tumors (TGCTs) have been reported to lack the DNA Damage Response (DDR) pathway activation. CCDC6 is a pro-apoptotic phosphoprotein substrate of the kinase ataxia telangectasia mutated (ATM) able to sustain DNA damage checkpoint in response to genotoxic stress and is commonly rearranged in malignancies upon fusion with different partners. In our study we sought to determine whether CCDC6 could have a role in the patho-genesis of testicular germ cell tumors. To achieve this aim, analysis for CCDC6 expression has been evaluated on serial sections of the mouse testis by immunohistochemistry and on separate populations of murine testicular cells by western blot. Next, the resistance to DNA damage-induced apoptosis and the production of reactive oxygen species has been investigated in GC1 cells, derived from immortalized type B murine germ cells, following CCDC6 silencing. Finally, the CCDC6 expression in normal human testicular cells, in Intratubular Germ Cell Neoplasia Unclassified (IGCNU), in a large series of male germ cell tumours and in the unique human seminoma TCam2 cell line has been evaluated by immunohistochemistry and by Western Blot analyses. The analysis of the CCDC6 expression revealed its presence in Sertoli cells and in spermatogonial cells. CCDC6 loss was the most consistent feature among the primary tumours and TCam2 cells. Interestingly, following treatment with low doses of H2O2, the silencing of CCDC6 in GC1 cells caused a decrease in the oxidized form of cytochrome c and low detection of Bad, PARP-1 and Caspase 3 proteins. Moreover, in the silenced cells, upon oxidative damage, the cell viability was protected, the γH2AX activation was impaired and the Reactive Oxygen Species (ROS) release was decreased. Therefore, our results suggest that the loss of CCDC6 could aid the spermatogonial cells to be part of a pro-survival pathway that helps to evade the toxic effects of endogenous oxidants and contributes to testicular neoplastic growth.

Chromobox protein homologue 7 (CBX7) is a chromobox family protein encoding a novel polycomb protein, the expression of which shows a progressive reduction, well related with the malignant grade of the thyroid neoplasias. Indeed, CBX7 protein levels decreased in an increasing percentage of cases going from benign adenomas to papillary, follicular, and anaplastic thyroid carcinomas. To elucidate the function of CBX7 in carcinogenesis, we searched for CBX7 interacting proteins by a proteomic analysis. By this approach, we identified several proteins. Among these proteins, we selected histone deacetylase 2 (HDAC2), which is well known to play a key role in neoplastic cell transformation and down-regulation of E-cadherin expression, the loss of which is a critical event in the epithelial-to-mesenchymal transition. We confirmed by coimmunoprecipitation that CBX7 physically interacts with the HDAC2 protein and is able to inhibit its activity. Then, we showed that both these proteins bind the E-cadherin promoter and that CBX7 up-regulates E-cadherin expression. Consistent with these data, we found a positive statistical correlation between CBX7 and E-cadherin expression in human thyroid carcinomas. Finally, we showed that the expression of CBX7 increases the acetylation status of the histones H3 and H4 on the E-cadherin promoter. Therefore, the ability of CBX7 to positively regulate E-cadherin expression by interacting with HDAC2 and inhibiting its activity on the E-cadherin promoter would account for the correlation between the loss of CBX7 expression and a highly malignant phenotype. [Cancer Res 2009;69(17):7079–87]

// Vincenza Leone 1 , Concetta Langella 1 , Francesco Esposito 1 , Claudio Arra 2 , Giuseppe Palma 2 , Domenica Rea 2 , Orlando Paciello 3 , Francesco Merolla 1 , Davide De Biase 3 , Serenella Papparella 3 , Angela Celetti 1 , Alfredo Fusco 1, 4 1 Istituto per l’Endocrinologia ed Oncologia Sperimentale del CNR e/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Universita degli Studi di Napoli “Federico II”, Naples, Italy 2 Istituto Nazionale per lo Studio e la Cura dei Tumori “Fondazione Giovanni Pascale”, IRCCS, Naples, Italy 3 Department of Pathology and Animal Health, University of Naples “Federico II”, Naples, Italy 4 Instituto Nacional de Câncer - INCA, Rua Andre Cavalcanti, Rio de Janeiro, CEP RJ, Brazil Correspondence to: Alfredo Fusco, e-mail: alfusco@unina.it Keywords: Ccdc6, thyroid, CREB1, knock-in mice Received: February 3, 2015 Accepted: April 14, 2015 Published: April 27, 2015 ABSTRACT CCDC6 was originally identified upon rearrangement with RET in human thyroid papillary carcinomas generating the RET/PTC1 oncogene. We have previously reported that CCDC6 interacts with CREB1 and represses its transcriptional activity. Since the function of at least one allele of CCDC6 is lost following RET/PTC1 rearrangements, we aimed at the generation of mice, carrying a CCDC6 mutant gene. Previous studies suggested that the coiled-coil domain of CCDC6, mainly encoded by human exon 2, is required for the protein function. Therefore, we engineered a murine Ccdc6 construct, carrying a deletion of the exon 2, that was able to exert only a mild repression on CREB1 transcriptional activity, with respect to the wild type Ccdc6. Subsequently, we generated Ccdc6 -ex2 knock-in mice. These mice developed thyroid hyperplasia associated with an enhanced CREB1 activity and an increased expression of the CREB-1 regulated genes. These results strongly support a CCDC6 promoting role, ascribed to its functional impairment, in the development of thyroid papillary carcinomas harboring the RET/PTC1 oncogene.

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 restoration 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 susceptibility 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 aggressive 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.

Paula Mussnich, Daniela D’Angelo, Vincenza Leone, Carlo Maria Croce, Alfredo Fusco* Istituto di Endocrinologia ed Oncologia Sperimentale del CNR, c/o Dipartimento di Biologia e Patologia Cellulare e Molecolare, Facolt a di Medicina e Chirurgia di Napoli, Universit a degli Studi di Napoli “Federico II”, via Pansini 5, 80131 Naples, Italy CAPES Foundation, Ministry of Education of Brazil, Bras ilia DF 70040-020, Brazil Department of Molecular Virology, Immunology, and Medical Genetics, Comprehensive Cancer Center, Ohio State University, 460 West 12th Avenue, Columbus, OH 43210, USA

Background DNA damage response has been clearly described as an anti-cancer barrier in early human tumorigenesis. Moreover, interestingly, testicular germ cell tumors (TGCTs) have been reported to lack the DNA Damage Response (DDR) pathway activation. CCDC6 is a pro-apoptotic phosphoprotein substrate of the kinase ataxia telangectasia mutated (ATM) able to sustain DNA damage checkpoint in response to genotoxic stress and is commonly rearranged in malignancies upon fusion with different partners. In our study we sought to determine whether CCDC6 could have a role in the patho-genesis of testicular germ cell tumors. Methods To achieve this aim, analysis for CCDC6 expression has been evaluated on serial sections of the mouse testis by immunohistochemistry and on separate populations of murine testicular cells by western blot. Next, the resistance to DNA damage-induced apoptosis and the production of reactive oxygen species has been investigated in GC1 cells, derived from immortalized type B murine germ cells, following CCDC6 silencing. Finally, the CCDC6 expression in normal human testicular cells, in Intratubular Germ Cell Neoplasia Unclassified (IGCNU), in a large series of male germ cell tumours and in the unique human seminoma TCam2 cell line has been evaluated by immunohistochemistry and by Western Blot analyses. Results The analysis of the CCDC6 expression revealed its presence in Sertoli cells and in spermatogonial cells. CCDC6 loss was the most consistent feature among the primary tumours and TCam2 cells. Interestingly, following treatment with low doses of H2O2, the silencing of CCDC6 in GC1 cells caused a decrease in the oxidized form of cytochrome c and low detection of Bad, PARP-1 and Caspase 3 proteins. Moreover, in the silenced cells, upon oxidative damage, the cell viability was protected, the γH2AX activation was impaired and the Reactive Oxygen Species (ROS) release was decreased. Conclusions Therefore, our results suggest that the loss of CCDC6 could aid the spermatogonial cells to be part of a pro-survival pathway that helps to evade the toxic effects of endogenous oxidants and contributes to testicular neoplastic growth.

The overexpression of the HMGA1 proteins is a feature of human malignant neoplasias and has a causal role in cell transformation. The aim of our study has been to investigate the microRNAs (miRNAs or miRs) regulated by the HMGA1 proteins in the process of cell transformation analyzing the miRNA expression profile of v‐ras‐Ki oncogene‐transformed thyroid cells expressing or not HMGA1 proteins. We demonstrate that, among the miRNAs regulated by cell transformation, there are miR‐10b, miR‐21, miR‐125b, miR‐221 and miR‐222 that are positively and miR‐34a and miR‐603 that are negatively regulated by HMGA1 expression. Then, we focused our attention on the miR‐10b and miR‐603 whose expression was dependent on the presence of HMGA1 also in other cell systems. We found that miR‐10b is able to target the PTEN gene, whereas miR‐603 targets the CCND1 and CCND2 genes coding for the cyclin D1 and cyclin D2 proteins, respectively. Moreover, functional studies showed that miR‐10b and miR‐603 regulate positively and negatively, respectively, cell proliferation and migration suggesting a role of their dysregulation in thyroid cell transformation.

CCDC6 was originally identified in chimeric genes as caused by chromosomal translocation involving the RET protooncogene in some thyroid tumors. Recognised as a 65 kDa pro-apoptotic phosphoprotein, CCDC6 has been enrolled as an ATM substrate that contribute to protect genome integrity by modulating PP4c activity in response to genotoxic stress. Recently, CCDC6 has been identified as a repressor of CREB1-dependent transcription. Sumoylation has emerged as an important mechanism in transcriptional control. Here, we report the identification and characterization of three sites of sumoylation in CCDC6 (K74, K266 and K424) which are highly conserved in vertebrates. We demonstrate that the post-translational modifications by SUMO2 constrain most of the CCDC6 protein in the cytosol and affect its functional interaction with CREB1 with a decrease of CCDC6 repressive function on CREB1 transcriptional activity. Indeed, the impairment of functional outcome of sumoylated CCDC6 is obtained knocking down all three the sumoylation sites. Interestingly, in thyroid cells the SUMO2-mediated CCDC6 post-translational modifications are induced by Forskolin, a cAMP analog. Signal transduction via the cAMP pathway is known to be ubiquitous and represents a major line of communication between many organisms and their environment. We believe that CCDC6 could be an important player in the dynamics of cAMP signaling by fine regulating CREB1 transcriptional activity in normal and transformed thyroid cells.

Using gene expression profiling, we found that the CBX7 gene was drastically down-regulated in six thyroid carcinoma cell lines versus control cells. The aims of this study were to determine whether CBX7 is related to the thyroid cancer phenotype and to try to identify new tools for the diagnosis and prognosis of thyroid cancer. We thus evaluated CBX7 expression in various snap-frozen and paraffin-embedded thyroid carcinoma tissues of different degrees of malignancy by quantitative reverse transcription-PCR and immunohistochemistry, respectively. CBX7 expression progressively decreased with malignancy grade and neoplasia stage. Indeed, it decreased in an increasing percentage of cases going from benign adenomas to papillary (PTC), follicular, and anaplastic (ATC) thyroid carcinomas. This finding coincides with results obtained in rat and mouse models of thyroid carcinogenesis. CBX7 loss of heterozygosity occurred in 36.8% of PTC and in 68.7% of ATC. Restoration of CBX7 expression in thyroid cancer cells reduced growth rate, with a retention in the G1 phase of the cell cycle, suggesting that CBX7 can contribute to the proliferation of the transformed thyroid cells. In conclusion, loss of CBX7 expression correlates with a highly malignant phenotype in thyroid cancer patients. [Cancer Res 2008;68(16):6770–8]

We have recently reported that MicroRNAs (miR)-221 and miR-222 were up-regulated in human thyroid papillary carcinomas in comparison with the normal thyroid tissue. Bioinformatic analysis proposed the p27Kip1 protein, a key regulator of cell cycle, as a candidate target for the miR-221/222 cluster. Here, we report that the enforced expression of miR-221 and miR-222 was able to reduce p27Kip1 protein levels in thyroid carcinoma and HeLa cells in the absence of significant changes in specific p27Kip1 mRNA levels. This effect is direct as miR-221 and miR-222 negatively regulate the expression of the 3′-untranslated region-based reporter construct from the p27Kip1 gene, and is dependent on two target sites in this region. Consistent with these results, an enforced expression of the miR-221 and miR-222 induced the thyroid papillary carcinoma cell line (TPC-1) to progress to the S phase of the cell cycle. It is likely that the negative regulation of p27Kip1 by miR-221 and miR-222 might also have a role in vivo since we report an inverse correlation between miR-221 and miR-222 up-regulation and down-regulation of the p27Kip1 protein levels in human thyroid papillary carcinomas. Therefore, the data reported here demonstrate that miR-221 and miR-222 are endogenous regulators of p27Kip1 protein expression, and thereby, the cell cycle.

Aspirin displays, at millimolar concentrations, several mechanisms independent from its ability to inhibit cyclooxygenases. Occasionally, the mechanisms displayed in vitro have been clearly related to an effect of clinical relevance in vivo. An expanding literature has been focusing on the cytoprotective effect of aspirin in neurodegenerative disorders and the activation of AKT pathway in neuroprotection and induction of resistance to anticancer drugs. In this work, we tested the ability of aspirin to activate the AKT survival pathway in methylcholanthrene-induced fibrosarcoma cells (Meth A) transplanted into BALB/c nude mice and the clinical effect of aspirin cotreatment during etoposide (VP-16)–based anticancer therapy. We found that cotreatment with aspirin reduced VP-16-induced apoptosis and activated AKT in vitro and in vivo. In Meth A–bearing mice, aspirin administration also activated glycogen synthase kinase-3 and reduced the activity and the efficacy of anticancer therapy in VP-16 cotreated animals. Our data suggest that the antiapoptotic effect of aspirin operates in vivo through the activation of AKT-glycogen synthase kinase pathway causing a decrease in the outcome of VP-16-based therapy. These findings could have clinical relevance in treatment of human malignancies. [Mol Cancer Ther 2006;5(5):1318–24]

MiR-1 downregulation plays a critical role in thyroid cell proliferation V. Leone, D. D'Angelo, PL. Pallante, A. Ferraro. Istituto di Endocrinologia ed Oncologia Sperimentale del CNR c/o Dipartimento di Biologia e Patologia Cellulare e Molecolare, Facoltà di Medicina e Chirurgia di Napoli, Università degli Studi di Napoli “Federico II”, Naples, Italy. MicroRNAs have emerged as an important class of short endogenous RNAs that act as post-transcriptional regulators of gene expression, and their expression is constantly deregulated in human cancer. MiR-1 has been found downregulated in lung, colon and prostate cancer. The aim of our work has been to investigate the possible role of miR-1 in thyroid carcinogenesis. Therefore, we have analysed miR-1 expression in a panel of thyroid neoplasias including benign and malignant lesions. Our results show that miR-1 expression is drastically downregulated in thyroid adenomas and carcinomas in comparison with normal thyroid tissue. Interestingly, miR-1 downregulation was also found in thyroid hyperproliferative non neoplastic lesions such as goiters. These results suggested a general role of miR-1 downregulation in the control of thyroid cell proliferation. This suggestion was then confirmed by the drastic decrease in miR-1 expression following exposure of rat thyroid cells to thyrotropin (TSH), the physiological thyroid stimulator. Searching for miR-1 targets, we identified CREB1 transcriptional factor, that is the main effector of the TSH-induced thyroid cell growth, as miR-1 target, suggesting the presence of a regulatory synergistic loop including TSH, CREB1 and the miR-1. Moreover, we have demonstrated that also the CXCR4 protein and its ligand SDF1α, that are involved in cell migration and are constantly overexpressed in human thyroid carcinoma, are targets of miR-1. Functional studies demonstrate that miR-1 is able to inhibit thyroid carcinoma cell proliferation and migration validating a critical role of miR-1 downregulation in thyroid carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 119. doi:10.1158/1538-7445.AM2011-119

CBX7, chromobox homolog 7, is a chromobox family protein encoding a novel Polycomb protein, component of the Polycomb repressive complex 1 (PRC1). The Polycomb group (PcG) proteins are epigenetic transcriptional repressors involved in the control of cellular proliferation and oncogenesis. CBX7 protein levels show a progressive reduction, well related with the malignant grade of the thyroid neoplasias. Indeed, its expression decreased in an increasing percentage of cases going from benign adenomas to papillary, follicular and anaplastic thyroid carcinomas. To elucidate the function of CBX7 in carcinogenesis, we searched for CBX7 interacting proteins by a proteomic analysis. By this approach, we identified several proteins among which we selected Histone Deacetylase 2 (HDAC2) that is well known to play a key role in neoplastic cell transformation and to downregulate E-cadherin expression, whose loss is a critical event in the Epithelial-Mesenchymal Transition, and therefore emerging as one of the caretakers of the epithelial phenotype. We confirmed by co-immunoprecipitation that CBX7 physically interacts with the HDAC2 and demostrated that is able to inhibit its activity. Then, we showed that both these proteins bind the E-cadherin promoter, and that CBX7 is able to upregulate E-cadherin expression. Consistent with these data we found a positive statistical correlation between CBX7 and E-cadherin expression in human thyroid carcinomas. Finally, we demonstrated that the expression of CBX7 increases the acetylation status of the histones H3 and H4 on the E-cadherin promoter. Therefore, the ability of CBX7 to positively regulate E-cadherin expression, by interacting with HDAC2 and inhibiting its activity on the E-cadherin promoter, would account for the correlation between the loss of CBX7 expression and a highly malignant phenotype in thyroid cancer patients. Thus, several important interacting proteins of CBX7 and the pathways in which they are involved strongly suggest that CBX7 can be considerated a very important regulator of thyroid malignant transformation.