Genomic and transcriptomic analyses of thyroid cancers identify DICER1 somatic mutations in adult follicular-patterned RAS-like tumors.

Background: Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer (TC). Several genomic and transcriptomic studies explored the molecular landscape of follicular cell-derived TCs, and BRAFV600E, RAS mutations, and gene fusions are well-established drivers. DICER1 mutations were described in specific sets of TC patients but represent a rare event in adult TC patients. Methods: Here, we report the molecular characterization of 30 retrospective follicular cell-derived thyroid tumors, comprising PTCs (90%) and poorly differentiated TCs (10%), collected at our Institute. We performed DNA whole-exome sequencing using patient-matched control for somatic mutation calling, and targeted RNA-seq for gene fusion detection. Transcriptional profiles established in the same cohort by microarray were investigated using three signaling-related gene signatures derived from The Cancer Genome Atlas (TCGA). Results: The occurrence of BRAFV600E (44%), RAS mutations (13%), and gene fusions (13%) was confirmed in our cohort. In addition, in two patients lacking known drivers, mutations of the DICER1 gene (p.D1709N and p.D1810V) were identified. DICER1 mutations occur in two adult patients with follicular-pattern lesions, and in one of them a second concurrent DICER1 mutation (p.R459*) is also observed. Additional putative drivers include ROS1 gene (p.P2130A mutation), identified in a patient with a rare solid-trabecular subtype of PTC. Transcriptomics indicates that DICER1 tumors are RAS-like, whereas the ROS1-mutated tumor displays a borderline RAS-/BRAF-like subtype. We also provide an overview of DICER1 and ROS1 mutations in thyroid lesions by investigating the COSMIC database. Conclusion: Even though small, our series recapitulates the genetic background of PTC. Furthermore, we identified DICER1 mutations, one of which is previously unreported in thyroid lesions. For these less common alterations and for patients with unknown drivers, we provide signaling information applying TCGA-derived classification.

Chronic liver diseases: From development to novel pharmacological therapies: IUPHAR Review 37.

Chronic liver diseases comprise a broad spectrum of burdensome diseases that still lack effective pharmacological therapies. Our research group focuses on fibrosis, which is a major precursor of liver cirrhosis. Fibrosis consists in a progressive disturbance of liver sinusoidal architecture characterised by connective tissue deposition as a reparative response to tissue injury. Multifactorial events and several types of cells participate in fibrosis initiation and progression, and the process still needs to be completely understood. The development of experimental models of liver fibrosis alongside the identification of critical factors progressing fibrosis to cirrhosis will facilitate the development of more effective therapeutic approaches for such condition. This review provides an overlook of the main process leading to hepatic fibrosis and therapeutic approaches that have emerged from a deep knowledge of the molecular regulation of fibrogenesis in the liver. LINKED ARTICLES: This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

Traditional Knowledge Evolution over Half of a Century: Local Herbal Resources and Their Changes in the Upper Susa Valley of Northwest Italy.

Susa Valley, located in the Italian Western Alps, has served as a meeting point for cultural, spiritual, and commercial exchange for a long period of history. The valley's role as one of the main connecting routes between south and southwestern Europe resulted in its acquisition of a rich traditional ecological knowledge. However, like other Italian mountainous valleys, this valley has suffered from abandonment and depopulation in the past 50 years. Our study aims to investigate the current ethnobotanical medicinal knowledge in the valley and to compare our findings with a study conducted over 50 years ago in the same area. In 2018, we conducted 30 in-depth semi-structured interviews on medicinal plants and food-medicines used in the Susa Valley. We documented 36 species, of which 21 species were used for medical purposes and 15 species were used as food-medicine. The comparison with the previous study on medicinal herbs conducted in 1970 in the valley demonstrated a significant decrease in both the knowledge and use of medicinal plants, which could be attributed to socioeconomic, cultural, and possibly environmental changes that occurred in the past half-century. Our study highlights several promising species for future use as nutraceuticals, food, and medicinal products, such as Taraxacum officinale, Urtica dioica, and Artemisia genipi.

Medullary Thyroid Carcinoma Mutational Spectrum Update and Signaling-Type Inference by Transcriptional Profiles: Literature Meta-Analysis and Study of Tumor Samples.

Medullary thyroid carcinoma (MTC) is a rare but aggressive tumor. Although RET and RAS genes are recognized drivers in MTC, associated downstream signaling pathways are largely unknown. In this study, we report 17 sporadic MTCs, collected at our institution, comprising patient-matched primary and lymph node metastatic tumors investigated for mutational and transcriptional profiles. As we identified two uncommon RET deletions (D898_E901del and E632_L633del), we also performed a literature review and meta-analysis to assess the occurrence of unconventional alterations in MTC, focusing on next-generation sequencing studies. We found that new gene alterations are emerging, along with the known RET/RAS drivers, involving not only RET by multiple concurrent mutations or deletions but also other previously underestimated cancer-related genes, especially in sporadic MTCs. In our MTC gene profiles, we found transcriptome similarity between patient-matched tissues and expression of immune genes only by a few samples. Furthermore, we defined a gene signature able to stratify samples into two distinct signaling types, termed MEN2B-like and MEN2A-like. We provide an updated overview of the MTC mutational spectrum and describe how transcriptional profiles can be used to define distinct MTC signaling subtypes that appear to be shared by various gene drivers, including the unconventional ones.

Senescent Thyrocytes, Similarly to Thyroid Tumor Cells, Elicit M2-like Macrophage Polarization In Vivo.

Inflammation plays a critical role in thyroid cancer onset and progression. We previously characterized the in vitro interplay between macrophages and senescent human thyrocytes and thyroid tumor-derived cell lines, modeling the early and the late thyroid tumor phases, respectively. We reported that both models are able to induce pro-tumoral M2-like macrophage polarization, through the activation of the COX2-PGE2 axis. Here, we investigated the presence of macrophage infiltrating cells in mouse xenografts derived from the above described cells models. We showed that subcutaneous injection in immunodeficient mice of both senescent human thyrocytes and thyroid tumor-derived cell lines elicits macrophage recruitment. Furthermore, considering the type of macrophage infiltrate, we observed a stronger infiltration of Arginase I positive cells (M2-like). Overall, these results demonstrate the in vivo capability of senescent and tumor thyroid cells to recruit and polarize macrophages, suggesting that the promotion of a pro-tumoral microenvironment through tumor associated macrophages may occurs in late as well as in early thyroid tumor stages, favoring tumor onset and progression.

BRAF Inhibitors Induce Feedback Activation of RAS Pathway in Thyroid Cancer Cells.

BRAFV600E is the most frequent oncogenic mutation identified in papillary thyroid cancer (PTC). In PTC patients who do not respond to standard treatment, BRAF inhibitors are currently tested as alternative strategies. However, as observed for other targeted therapies, patients eventually develop drug resistance. The mechanisms of BRAF inhibitors response are still poorly understood in a thyroid cancer (TC) context. In this study, we investigated in BRAFV600E mutated TC cell lines the effects of Vemurafenib and Dabrafenib, two BRAF inhibitors currently used in a clinical setting. We assessed cell proliferation, and the expression and activity of the thyroid function related transporter NIS following the treatment with BRAF inhibitors. In addition, we investigated the global gene expression by microarray, the relevant modulated biological processes by gene set enrichment analysis (GSEA), and TC specific gene signatures related to MAPK pathway activation, thyroid differentiation, and transcriptional profile associated with BRAFV600E or RAS mutation. We found that both inhibitors induce antiproliferative and redifferentiative effects on TC cells, as well as a rewiring of the MAPK pathway related to RAS signaling. Our results suggest a possible mechanism of drug response to the BRAF inhibitors Vemurafenib or Dabrafenib, supporting very recent findings in TC patients treated with targeted therapies.

Loss of activating transcription factor 3 prevents KRAS-mediated pancreatic cancer.

The unfolded protein response (UPR) is activated in pancreatic pathologies and suggested as a target for therapeutic intervention. In this study, we examined activating transcription factor 3 (ATF3), a mediator of the UPR that promotes acinar-to-ductal metaplasia (ADM) in response to pancreatic injury. Since ADM is an initial step in the progression to pancreatic ductal adenocarcinoma (PDAC), we hypothesized that ATF3 is required for initiation and progression of PDAC. We generated mice carrying a germline mutation of Atf3 (Atf3-/-) combined with acinar-specific induction of oncogenic KRAS (Ptf1acreERT/+KrasG12D/+). Atf3-/- mice with (termed APK) and without KRASG12D were exposed to cerulein-induced pancreatitis. In response to recurrent pancreatitis, Atf3-/- mice showed decreased ADM and enhanced regeneration based on morphological and biochemical analysis. Similarly, an absence of ATF3 reduced spontaneous pancreatic intraepithelial neoplasia (PanIN) formation and PDAC in Ptf1acreERT/+KrasG12D/+ mice. In response to injury, KRASG12D bypassed the requirement for ATF3 with a dramatic loss in acinar tissue and PanIN formation observed regardless of ATF3 status. Compared to Ptf1acreERT/+KrasG12D/+ mice, APK mice exhibited a significant decrease in pancreatic and total body weight, did not progress through to PDAC, and showed altered pancreatic fibrosis and immune cell infiltration. These findings suggest a complex, multifaceted role for ATF3 in pancreatic cancer pathology.

Synthesis of Carboxamide-Containing Tranylcypromine Analogues as LSD1 (KDM1A) Inhibitors Targeting Acute Myeloid Leukemia.

Lysine-specific demethylase 1 (LSD1/KDM1A) oxidatively removes methyl groups from histone proteins, and its aberrant activity has been correlated with cancers including acute myeloid leukemia (AML). We report a novel series of tranylcypromine analogues with a carboxamide at the 4-position of the aryl ring. These compounds, such as 5 a and 5 b with benzyl and phenethylamide substituents, respectively, had potent sub-micromolar IC50 values for the inhibition of LSD1 as well as cell proliferation in a panel of AML cell lines. The dose-dependent increase in cellular expression levels of H3K4me2, CD86, CD11b and CD14 supported a mechanism involving LSD1 inhibition. The tert-butyl and ethyl carbamate derivatives of these tranylcypromines, although inactive in LSD1 inhibition, were of similar potency in cell-based assays with a more rapid onset of action. This suggests that carbamates can act as metabolically labile tranylcypromine prodrugs with superior pharmacokinetics.

NUPR1 protects liver from lipotoxic injury by improving the endoplasmic reticulum stress response.

Non-alcoholic fatty liver (NAFL) and related syndromes affect one-third of the adult population in industrialized and developing countries. Lifestyle and caloric oversupply are the main causes of such array of disorders, but the molecular mechanisms underlying their etiology remain elusive. Nuclear Protein 1 (NUPR1) expression increases upon cell injury in all organs including liver. Recently, we reported NUPR1 actively participates in the activation of the Unfolded Protein Response (UPR). The UPR typically maintains protein homeostasis, but downstream mediators of the pathway regulate metabolic functions including lipid metabolism. As increases in UPR and NUPR1 in obesity and liver disease have been well documented, the goal of this study was to investigate the roles of NUPR1 in this context. To establish whether NUPR1 is involved in these liver conditions we used patient-derived liver biopsies and in vitro and in vivo NUPR1 loss of functions models. First, we analyzed NUPR1 expression in a cohort of morbidly obese patients (MOPs), with simple fatty liver (NAFL) or more severe steatohepatitis (NASH). Next, we explored the metabolic roles of NUPR1 in wild-type (Nupr1+/+ ) or Nupr1 knockout mice (Nupr1-/- ) fed with a high-fat diet (HFD) for 15 weeks. Immunohistochemical and mRNA analysis revealed NUPR1 expression is inversely correlated to hepatic steatosis progression. Mechanistically, we found NUPR1 participates in the activation of PPAR-α signaling via UPR. As PPAR-α signaling is controlled by UPR, collectively, these findings suggest a novel function for NUPR1 in protecting liver from metabolic distress by controlling lipid homeostasis, possibly through the UPR.

NUPR1 interacts with eIF2α and is required for resolution of the ER stress response in pancreatic tissue.

Nuclear protein 1 (NUPR1) is a stress response protein overexpressed upon cell injury in virtually all organs including the exocrine pancreas. Despite NUPR1's well-established role in the response to cell stress, the molecular and structural machineries triggered by NUPR1 activation remain largely debated. In this study, we uncover a new role for NUPR1, participating in the unfolded protein response (UPR) and the integrated stress response. Biochemical results and ultrastructural morphological observations revealed alterations in the UPR of acinar cells of germline-deleted NUPR1 murine models, consistent with the inability to restore general protein synthesis after stress induction. Bioinformatic analysis of NUPR1-interacting partners showed significant enrichment in translation initiation factors, including eukaryotic initiation factor (eIF) 2α. Co-immunoprecipitation and proximity ligation assays confirmed the interaction between NUPR1 and eIF2α and its phosphorylated form (p-eIF2α). Furthermore, our data suggest loss of NUPR1 in cells results in maintained eIF2α phosphorylation and evaluation of nascent proteins by click chemistry revealed that NUPR1-depleted PANC-1 cells displayed a slower poststress protein synthesis recovery when compared to wild-type. Combined, these data propose a novel role for NUPR1 in the integrated stress response pathway, at least partially through promoting efficient PERK branch activity and resolution through a unique interaction with eIF2α.

The molecular and gene/miRNA expression profiles of radioiodine resistant papillary thyroid cancer.

BACKGROUND: Papillary thyroid cancer (PTC) is the most frequent endocrine tumor. Radioiodine (RAI) treatment is highly effective in these tumors, but up to 60% of metastatic cases become RAI-refractory. Scanty data are available on either the molecular pattern of radioiodine refractory papillary thyroid cancers (PTC) or the mechanisms responsible for RAI resistance. METHODS: We analyzed the molecular profile and gene/miRNA expression in primary PTCs, synchronous and RAI-refractory lymph node metastases (LNMs) in correlation to RAI avidity or refractoriness. We classified patients as RAI+/D+ (RAI uptake/disease persistence), RAI-/D+ (absent RAI uptake/disease persistence), and RAI+/D- (RAI uptake/disease remission), and analyzed the molecular and gene/miRNA profiles, and the expression of thyroid differentiation (TD) related genes. RESULTS: A different molecular profile according to the RAI class was observed: BRAFV600E cases were more frequent in RAI-/D+ (P = 0.032), and fusion genes in RAI+/D+ cases. RAI+/D- patients were less frequently pTERT mutations positive, and more frequently wild type for the tested mutations/fusions. Expression profiles clearly distinguished PTC from normal thyroid. On the other hand, in refractory cases (RAI+/D+ and RAI-/D+) no distinctive PTC expression patterns were associated with either tissue type, or RAI uptake, but with the driving lesion and BRAF-/RAS-like subtype. Primary tumors and RAI-refractory LNMs with BRAFV600E mutation display transcriptome similarity suggesting that RAI minimally affects the expression profiles of RAI-refractory metastases. Molecular profiles associated with the expression of TPO, SLC26A4 and TD genes, that were found more downregulated in BRAFV600E than in gene fusions tumors. CONCLUSIONS: The present data indicate a different molecular profile in RAI-avid and RAI-refractory metastatic PTCs. Moreover, BRAFV600E tumors displayed reduced differentiation and intrinsic RAI refractoriness, while PTCs with fusion oncogenes are RAI-avid but persistent, suggesting different oncogene-driven mechanisms leading to RAI refractoriness.

Evidencing a Pancreatic Ductal Adenocarcinoma Subpopulation Sensitive to the Proteasome Inhibitor Carfilzomib.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with a survival rate less than 5%. Multiple chemotherapeutic drugs have been tested to improve patient prognosis; however, the clinical efficacy of these treatments is low. One of the most controversial family of drugs are the proteasome inhibitors, which have displayed promising effects in preclinical studies, but low clinical performance. Here, we unravel a specific transcriptomic signature that discriminates a subgroup of patients sensitive to the proteasome inhibitor carfilzomib. EXPERIMENTAL DESIGN: First, we identified a subpopulation of PDAC-derived primary cells cultures (PDPCC) sensitive to the proteasome inhibitor carfilzomib. Then, we selected a transcriptomic signature that predicts carfilzomib chemosensitivity using independent component analysis on the transcriptome of PDPCC. Finally, we validated the signature in an independent cohort of PDAC biopsy-derived pancreatic organoids. RESULTS: Sensitive phenotype was characterized by a high expression of genes related with a cornified/squamous pathway and a downregulation of epithelial-mesenchymal transition genes. Interestingly, carfilzomib-sensitive transcriptomic profile did not show any association with the proteasome activity but strongly correlates with ATF4 and CHOP expression, which are key markers of the unfolded protein response and critical to trigger the cell death program. Concordantly, sensitive phenotype showed a high level of the de novo RNA and protein synthesis compared with the resistant one and, most important, cell death induced by carfilzomib is dependent of the translational activity. CONCLUSIONS: We demonstrate the existence of a carfilzomib-sensitive PDAC subgroup with a specific transcriptomic phenotype that could explain the biological reason for this responsiveness.

Development and Validation of a Self-Determination Theory-Based Measure of Motivation to Exercise and Diet in Children.

Objective: To develop and test the factorial structure of a new self-determination theory-based measure of behavioral regulation in children. Methods: Five hundred ninety 590 (F = 51.7%) children aged 7 to 11 years completed the Motivation to Exercise and Diet (MED-C) questionnaire, which comprises 16 items (eight for exercise and eight for diet) grouped into eight factors (five motivations and three needs). Psychometric testing included confirmatory factor analysis and internal consistency. Measurement invariance analyses were also performed to evaluate whether the factorial structure of the MED-C was equivalent for gender (male vs. female), age (≤9 vs. ≥10 years), and the perception of having at least one parent with overweight or obesity (yes vs. no). Results: Factorial analysis confirmed an acceptable factors solution for the MED-C and a good fit to the data for both the exercise and the diet subscales assessed independently. The maximal reliability coefficient revealed good reliability for the exercise and the diet subscales. Moreover, the MED-C factor structure was invariant across group comparisons. Discussion: Findings support the construct validity and reliability of the MED-C. Therefore, it represents the first validated instrument simultaneously measuring motivational regulation and psychological need satisfaction in the context of children's exercise and diet. Considering the goodness of these results, scale percentile ranks of the total score distribution as well as the z score and the T score were provided for clinical and research purposes. Conclusion: The MED-C might support the understanding of motivations and needs of children with weight problems and assist their process of behavioral change in primary and secondary prevention programs. Psychological factors represent, in fact, potential targets for interventions to increase children's motivation to exercise and diet.

Cancer Associated Fibroblasts and Senescent Thyroid Cells in the Invasive Front of Thyroid Carcinoma.

Thyroid carcinoma (TC) comprises several histotypes with different aggressiveness, from well (papillary carcinoma, PTC) to less differentiated forms (poorly differentiated and anaplastic thyroid carcinoma, PDTC and ATC, respectively). Previous reports have suggested a functional role for cancer-associated fibroblasts (CAFs) or senescent TC cells in the progression of PTC. In this study, we investigated the presence of CAFs and senescent cells in proprietary human TCs including PTC, PDTC, and ATC. Screening for the driving lesions BRAFV600E and N/H/KRAS mutations, and gene fusions was also performed to correlate results with tumor genotype. In samples with unidentified drivers, transcriptomic profiles were used to establish a BRAF- or RAS-like molecular subtype based on a gene signature derived from The Cancer Genome Atlas. By using immunohistochemistry, we found co-occurrence of stromal CAFs and senescent TC cells at the tumor invasive front, where deposition of collagen (COL1A1) and expression of lysyl oxidase (LOX) enzyme were also detected, in association with features of local invasion. Concurrent high expression of CAFs and of the senescent TC cells markers, COL1A1 and LOX was confirmed in different TC histotypes in proprietary and public gene sets derived from Gene Expression Omnibus (GEO) repository, and especially in BRAF mutated or BRAF-like tumors. In this study, we show that CAFs and senescent TC cells co-occur in various histotypes of BRAF-driven thyroid tumors and localize at the tumor invasive front.

'Palaeoshellomics' reveals the use of freshwater mother-of-pearl in prehistory.

The extensive use of mollusc shell as a versatile raw material is testament to its importance in prehistoric times. The consistent choice of certain species for different purposes, including the making of ornaments, is a direct representation of how humans viewed and exploited their environment. The necessary taxonomic information, however, is often impossible to obtain from objects that are small, heavily worked or degraded. Here we propose a novel biogeochemical approach to track the biological origin of prehistoric mollusc shell. We conducted an in-depth study of archaeological ornaments using microstructural, geochemical and biomolecular analyses, including 'palaeoshellomics', the first application of palaeoproteomics to mollusc shells (and indeed to any invertebrate calcified tissue). We reveal the consistent use of locally-sourced freshwater mother-of-pearl for the standardized manufacture of 'double-buttons'. This craft is found throughout Europe between 4200-3800 BCE, highlighting the ornament-makers' profound knowledge of the biogeosphere and the existence of cross-cultural traditions.

Senescent thyrocytes and thyroid tumor cells induce M2-like macrophage polarization of human monocytes via a PGE2-dependent mechanism.

BACKGROUND: Thyroid carcinoma includes several variants characterized by different biological and clinical features: from indolent microcarcinoma to undifferentiated and aggressive anaplastic carcinoma. Inflammation plays a critical role in thyroid tumors. Conditions predisposing to cancer, as well as oncogene activity, contribute to the construction of an inflammatory microenvironment that facilitates thyroid tumor progression. Moreover, oncogene-induced senescence, a mechanism tightly connected with inflammation, and able to restrain or promote cancer progression, is involved in thyroid cancer. The interactions between thyroid tumor cells and the microenvironment are not completely clarified. METHODS: We characterize in vitro the interplay between macrophages and senescent thyrocytes and tumor-derived cell lines, modeling early and late thyroid tumor stages, respectively. Purified peripheral blood-derived human monocytes were exposed to thyroid cell-derived conditioned medium (CM) and assessed for phenotype by flow cytometry. The factors secreted by thyroid cells and macrophages were identified by gene expression analysis and ELISA. The protumoral effect of macrophages was assessed by wound healing assay on K1 thyroid tumor cells. The expression of PTGS2 and M2 markers in thyroid tumors was investigated in publicly available datasets. RESULTS: Human monocytes exposed to CM from senescent thyrocytes and thyroid tumor cell lines undergo M2-like polarization, showing high CD206 and low MHC II markers, and upregulation of CCL17 secretion. The obtained M2-like macrophages displayed tumor-promoting activity. Among genes overexpressed in polarizing cells, we identified the prostaglandin-endoperoxide synthase enzyme (PTGS2/COX-2), which is involved in the production of prostaglandin E2 (PGE2). By using COX-2 inhibitors we demonstrated that the M2-like polarization ability of thyroid cells is related to the production of PGE2. Co-expression of PTGS2 and M2 markers is observed a significant fraction of human thyroid tumors. CONCLUSIONS: Our results demonstrate that both senescent thyrocytes and thyroid tumor cell lines trigger M2-like macrophage polarization that is related to PGE2 secretion. This suggests that the interaction with the microenvironment occurs at both early and late thyroid tumor stages, and favors tumor progression. The co-expression of PTGS2 gene and M2 markers in human thyroid carcinoma highlights the possibility to counteract tumor growth through COX-2 inhibition.

Mitosis perturbation by MASTL depletion impairs the viability of thyroid tumor cells.

Even if thyroid tumors are generally curable, a fraction will develop resistance to therapy and progress towards undifferentiated forms, whose treatment remains a demanding challenge. To identify potential novel targets for treatment of thyroid cancer, in a previous study using siRNA-mediated functional screening, we identified several genes that are essential for the growth of thyroid tumor, but not normal cells. Among the top-ranking hits, we found microtubule associated serine/threonine kinase-like (MASTL), which is known to play an essential role in mitosis regulation, and is also involved in the DNA damage response. Herein, we examine the effects of MASTL depletion on growth and viability of thyroid tumor cells. MASTL depletion impaired cell proliferation and increased the percentage of cells presenting nuclear anomalies, which are indicative of mitotic catastrophe. Furthermore, MASTL depletion was associated with enhanced DNA damage. All these effects eventually led to cell death, characterized by the presence of apoptotic markers. Moreover, MASTL depletion sensitized thyroid tumor cells to cisplatin. Our results demonstrate that MASTL represents vulnerability for thyroid tumor cells, which could be explored as a therapeutic target for thyroid cancer.

Isoform-selective HDAC1/6/8 inhibitors with an imidazo-ketopiperazine cap containing stereochemical diversity.

A series of hydroxamic acids linked by different lengths to a chiral imidazo-ketopiperazine scaffold were synthesized. The compounds with linker lengths of 6 and 7 carbon atoms were the most potent in histone deacetylase (HDAC) inhibition, and were specific submicromolar inhibitors of the HDAC1, HDAC6 and HDAC8 isoforms. A docking model for the binding mode predicts binding of the hydroxamic acid to the active site zinc cation and additional interactions between the imidazo-ketopiperazine and the enzyme rim. The compounds were micromolar inhibitors of the MV4-11, THP-1 and U937 cancer cell lines. Increased levels of histone H3 and tubulin acetylation support a cellular mechanism of action through HDAC inhibition.This article is part of a discussion meeting issue 'Frontiers in epigenetic chemical biology'.

Correction: miR-451a is underexpressed and targets AKT/mTOR pathway in papillary thyroid carcinoma.

[This corrects the article DOI: 10.18632/oncotarget.7262.].

Circulating miR-375 as a novel prognostic marker for metastatic medullary thyroid cancer patients.

This study aimed to identify circulating miRNAs as novel non-invasive biomarkers for prognosis and vandetanib response in advanced medullary thyroid cancer (MTC) patients. We prospectively recruited two independent cohorts of locally advanced/metastatic MTC patients including a subgroup of vandetanib-treated subjects: a discovery cohort (n = 20), including matched plasma/tissue samples (n = 17/20), and a validation cohort, yielding only plasma samples (n = 17). Plasma samples from healthy subjects (n = 36) and MTC patients in remission (n = 9) were used as controls. MTC (n = 17 from 8 patients included in discovery cohort) and non-neoplastic thyroid specimens (n = 3) were assessed by microarray profiling to identify candidate circulating miRNAs. qRT-PCR and in situ hybridization were carried out to validate the expression and localization of a selected miRNA within tissues, and qRT-PCR was also performed to measure miRNA levels in plasma samples. By microarray analysis, we identified 51 miRNAs differentially expressed in MTC. The most overexpressed miR, miR-375, was highly expressed by C cells compared to other thyroid cells, and more expressed in MTC than in reactive C-cell hyperplasia. MTC patients had significantly higher miR-375 plasma levels than healthy controls (P < 0.0001) and subjects in remission (P = 0.0004) as demonstrated by qRT-PCR analysis. miR-375 plasma levels were not predictive of vandetanib response, but, notably, high levels were associated with significantly reduced overall survival (HR 10.61, P < 0.0001) and were a strong prognostic factor of poor prognosis (HR 6.24, P = 0.00025) in MTC patients. Overall, our results unveil plasma miR-375 as a promising prognostic marker for advanced MTC patients, to be validated in larger cohorts.