Antonella Verrienti

The adiponectin gene SNP+276G>T associates with early-onset coronary artery disease and with lower levels of adiponectin in younger coronary artery disease patients (age ≤50 years)

Adiponectin, an adipocyte-derived protein, is an essential modulator of insulin sensitivity and several studies suggest an important role of adiponectin in the processes leading to atherosclerosis, thus indicating the adiponectin gene as a potential candidate for coronary artery disease (CAD). In the present study we have studied the association between two single nucleotide polymorphisms (SNPs) (+45T>G and +276 G>T) of the adiponectin gene and CAD, looking also into the possible influence of these SNPs on adiponectin plasma levels. The SNPs were analysed in a first cohort of 595 subjects, 325 with CAD and 270 matched controls. We observed a significant association (p<0.001) between the SNP +276G>T in the adiponectin gene and CAD. In multivariate analysis, carriers of the +276G>T SNP had an odds ratio (OR) for CAD of 4.99 (p<0.0007). A strong interaction between the +276G>T SNP and age was also present (OR, 1.03; p<0.0001). The increase in CAD risk was most evident among individuals with early-onset CAD (age ≤50 years), whereas in older CAD subjects other factors, and not the adiponectin SNP, were the major determinants. Furthermore, in CAD subjects with early-onset disease this SNP was also a significant determinant of lower levels of serum adiponectin levels. This association resulted independent from the other variables known to be associated with CAD in our population, including sex, body mass index, high-density lipoprotein and Homeostasis Model Assessment for insulin resistance. To confirm the results the +276G>T SNP was analysed in a second cohort of CAD and controls. The difference between CAD and controls in the +276G>T SNP frequencies showed a similar trend as before, although not significant. The combination of the two cohorts (1,046 subjects: 580 CAD and 466 controls) showed a statistically significant association, particularly in CAD subjects with early-onset of disease. In addition, we confirmed that in younger CAD subjects the SNP was a significant determinant of lower levels of adiponectin. In view of these results, it could be speculated that the adiponectin gene variant, or a mutation in linkage with it, determines lower adiponectin gene expression, causing in turn an increased risk to develop insulin resistance, atherosclerosis and cardiovascular disease. The significant association of the adiponectin gene in subjects with early-onset CAD also suggests that that genetic factors for late-onset diseases may exert a greater influence in younger persons, when other risk factors are not as prevalent as in older age groups.

Serologic and genetic markers of celiac disease: A sequential study in the screening of first degree relatives

Objectives: The prevalence of celiac disease (CD) among the relatives and the complications of an undiagnosed CD prompted us to identify a useful disease screening strategy. Methods: We studied 441 first degree relatives of 208 CD patients by immunoglobulin (Ig)A antiendomysium antibodies (EMA) and radioimmunoprecipitation assay (RIA) IgA antitransglutaminase autoantibodies (TGAA). Of these, 364 were typed for human leukocyte antigen-DRB1, -DQA1, and -DQB1 genes by the polymerase chain reaction sequence specific primers method. It was suggested to the autoantibody-positive subjects that they should undergo intestinal biopsy. Results: TGAA were positive in 46 of 439 relatives, EMA in 38; intestinal lesions related to CD were present in 40 subjects. We also found two immunodeficient fathers with duodenal villous atrophy. In three serology-positive subjects, permission for intestinal biopsy was refused; for another three serology-positive cases, duodenal mucosa was normal. Thus, the strict CD prevalence resulted 9.5%, the enlarged prevalence 10.9%. The DQ2/DQ8 heterodimers were carried in 231 of 364 subjects and in 38 of 40 biopsy-proven celiac patients. Three DQ2-positive parents became positive to the serology during a long-lasting follow-up. Conclusions: On the basis of a carefully conducted study, CD prevalence in our series was seen as very high. These data suggest an accurate algorithm to select candidates for intestinal biopsy among CD high-risk subjects. First, an evaluation of the sensitive RIA TGAA and of total IgA (in IgA deficiency RIA IgG anti-tissue transglutaminase assay) should be performed. Then, an evaluation of the TGAA and the genetic study would be advisable 2 to 3 years later in negative subjects. Those carrying the DQ2/DQ8 heterodimers should continue the serologic follow-up; the others need a clinical follow-up.

A novel de novo germ‐line V292M mutation in the extracellular region of RET in a patient with phaeochromocytoma and medullary thyroid carcinoma: functional characterization

Context  In multiple endocrine neoplasia (MEN), rearranged during transfection (RET), gene testing has been extensively exploited to characterize tumour aggressiveness and optimize the diagnostic and clinical management.

PDE5 expression in human thyroid tumors and effects of PDE5 inhibitors on growth and migration of cancer cells

Recent studies have revealed in normal thyroid tissue the presence of the transcript of several phosphodiesterases (PDEs), enzymes responsible for the hydrolysis of cyclic nucleotides. In this work, we analyzed the expression of PDE5 in a series of human papillary thyroid carcinomas (PTCs) presenting or not BRAF V600E mutation and classified according to ATA risk criteria. Furthermore, we tested the effects of two PDE5 inhibitors (sildenafil, tadalafil) against human thyroid cancer cells. PDE5 gene and protein expression were analyzed in two different cohorts of PTCs by real-time PCR using a TaqMan micro-fluid card system and Western blot. MTT and migration assay were used to evaluate the effects of PDE5 inhibitors on proliferation and migration of TPC-1, BCPAP, and 8505C cells. In a first series of 36 PTCs, we found higher expression levels of PDE5A in tumors versus non-tumor (normal) tissues. PTCs with BRAF mutation showed higher levels of mRNA compared with those without mutation. No significant differences were detected between subgroups with low and intermediate ATA risk. Upregulation of PDE5 was also detected in tumor tissue proteins. Similar results were obtained analyzing the second cohort of 50 PTCs. Moreover, all tumor tissues with high PDE5 levels showed reduction of Thyroglobulin, TSH receptor, Thyroperoxidase, and NIS transcripts. In thyroid cancer cells in vitro, sildenafil and tadalafil determined a reduction of proliferation and cellular migration. Our findings demonstrate for the first time an overexpression of PDE5 in PTCs, and the ability of PDE5 inhibitors to block the proliferation of thyroid cancer cells in culture, therefore, suggesting that specific inhibition of PDE5 may be proposed for the treatment of these tumors.

Overexpression of genes involved in miRNA biogenesis in medullary thyroid carcinomas with RET mutation

Abnormal expression of non-coding micro RNA (miRNA) has been described in medullary thyroid carcinoma (MTC). Expression of genes encoding factors involved in miRNA biogenesis results often deregulated in human cancer and correlates with aggressive clinical behavior. In this study, expression of four genes involved in miRNA biogenesis (DICER, DROSHA, DCGR8, and XPO5) was investigated in 54 specimens of MTC. Among them, 33 and 13 harbored RET and RAS mutations, respectively. DICER, DGCR8, and XPO5 mRNA levels were significantly overexpressed in MTC harboring RET mutations, in particular, in the presence of RET634 mutation. When MTCs with RET and RAS mutations were compared, only DGCR8 displayed a significant difference, while MTCs with RAS mutations did not show significant differences with respect to non-mutated tumors. We then attempted to correlate expression of miRNA biogenesis genes with tumor aggressiveness. According to the TNM status, MTCs were divided in two groups and compared (N0 M0 vs. N1 and/or M1): for all four genes no significant difference was detected. Cell line experiments, in which expression of a RET mutation is silenced by siRNA, suggest the existence of a causal relationship between RET mutation and overexpression of DICER, DGCR8, and XPO5 genes. These findings demonstrate that RET- but not RAS-driven tumorigenic alterations include abnormalities in the expression of some important genes involved in miRNA biogenesis that could represent new potential markers for targeted therapies in the treatment of RET-mutated MTCs aimed to restore the normal miRNA expression profile.

Epigenetic-related gene expression profile in medullary thyroid cancer revealed the overexpression of the histone methyltransferases EZH2 and SMYD3 in aggressive tumours

Epigenetic control of gene expression plays a major influence in the development and progression of many cancer types. Aim of the present study was to investigate the expression of epigenetic regulators in a large cohort of medullary thyroid carcinomas (MTC), correlating the data with the clinical outcome and mutational status of the patients. Taqman Low Density Arrays (TLDAs) were used to analyze expression levels of several genes involved in the epigenetic control of transcription in a series of 54 MTCs. The patients cohort included 13 familial MTCs and 41 sporadic forms; 33 hosted a RET mutation and 13 a RAS somatic mutation. The expression profiling revealed in the more aggressive diseases (i.e. occurrence of metastases; persistent disease; disease-related death) a significant increase of EZH2 and SMYD3 gene expression. The increased levels of EZH2 and SMYD3 did not correlate significantly with mutational status of RET or RAS genes. Thus, the histone methyltransferases EZH2 and SMYD3 mRNA expression may represent useful prognostic biomarkers tailoring the most appropriate follow-up and timing of therapeutic approaches.

BRAFV600E mutation and expression of proangiogenic molecular markers in papillary thyroid carcinomas

OBJECTIVE Tyrosine kinase inhibitors (TKIs) are evaluated for treatment of radioiodine refractory thyroid cancer. Their effects in this setting are based on blockade of proangiogenic signaling mediated by receptors for vascular endothelial growth factors (VEGFs) and platelet-derived growth factors (PDGF). Most TKIs also block other cancer-relevant kinases, such as B-type Raf kinase (BRAF), which are constitutively activated in approximately half of papillary thyroid carcinomas (PTCs), but the impact of these effects is not clear. DESIGN The aim of our study was to investigate the impact of BRAF(V600E) on proangiogenic gene expression and microvascular features of PTCs. METHODS mRNA levels for VEGFA, VEGF receptors, and coreceptors (VEGFRs 1, 2, and 3, neuropilin-1), and PDGF receptor β (PDGFRβ or PDGFRB) were measured with real-time PCR in BRAF(V600E) (n=55) and wild-type BRAF (BRAF-wt; n=35) PTCs. VEGF and VEGFR protein expression and microvessel densities (MVD) and lymphatic vessel densities (LVDs) were assessed by immunohistochemistry in 22 of the 90 PTCs (including 11 BRAF(V600E) cases). Angiogenic gene expression was also studied in vitro after induction/silencing of the BRAF(V600E) mutation in thyrocyte lines. RESULTS Transcript levels of proangiogenic factors were significantly lower in BRAF(V600E) PTCs versus BRAF-wt PTCs (P<0.0001), but MVD and LVDs were not significantly different. VEGFA mRNA levels in thyroid cell lines decreased when BRAF(V600E) mutation was induced (P=0.01) and increased when it was silenced (P=0.01). CONCLUSIONS Compared with BRAF-wt PTCs, those harboring BRAF(V600E) exhibit downregulated VEGFA, VEGFR, and PDGFRβ expression, suggesting that the presence of BRAF mutation does not imply a stronger prediction of response to drugs targeting VEGF and PDGFB signaling pathways.

Sunitinib exerts only limited effects on the proliferation and differentiation of anaplastic thyroid cancer cells

BACKGROUND Novel molecularly targeted drugs are undergoing preclinical and clinical testing to assess their efficacy against refractory thyroid carcinomas. The multikinase inhibitor Sunitinib has been shown to inhibit the kinase activity of the RET oncogene and reduce proliferation in differentiated thyroid cancer cells harboring the RET/PTC rearrangement. In this study, we evaluated its effects in human cell lines derived from differentiated (TPC-1) and anaplastic (8505C, CAL-62, and C643) thyroid cancers. METHODS The cells exposed to various concentrations of Sunitinib were examined for: (1) cell viability and presence of apoptosis, analyzed by cell counts, MTT assay, trypan blue exclusion assay, western blotting, and immunofluorescence; (2) expression of cyclin D1 and phosphorylated and nonphosphorylated extracellular signal-regulated kinase (ERK) and Akt proteins, analyzed by western blotting; and (3) transcription of genes encoding thyrocyte differentiation markers (thyroid-stimulating hormone receptor, sodium/iodide symporter, thyroglobulin, and thyroperoxidase) and proangiogenic factors (vascular endothelial growth factor A, platelet-derived growth factors A and B), measured by quantitative reverse transcriptase-polymerase chain reaction. RESULTS Exposure to nanomolar concentrations of Sunitinib significantly reduced cell viability in only TPC-1 cells, and this effect was paralleled by reduction of cyclin D1 levels. Western blotting revealed reduced phosphorylation of ERK and Akt after 3 and 6 hours of drug exposure. In contrast, the growth of 8505C, CAL-62, and C-643 cells was significantly reduced only by micromolar concentrations of Sunitinib, mainly due to induced necrotic rather than apoptotic death. In these cells, Sunitinib exerted a few significant effects on the transcription of angiogenic factors or thyrocyte differentiation markers. CONCLUSIONS Sunitinib has little or no effect on the growth or differentiation of anaplastic thyroid cancer cells, thus suggesting that it is unlikely to be effective in the treatment of anaplastic thyroid cancer.

XL184 (cabozantinib) for medullary thyroid carcinoma.

Introduction: Intrathyroidal medullary thyroid carcinoma (MTC) can generally be cured by surgery, but distant metastases are often already present at diagnosis. Currently, there is no effective treatment for metastatic MTC. In these cases, consensus treatment guidelines explicitly recommend new experimental drugs. Several kinase inhibitors are now being tested for treatment of MTC in clinical trials and XL184, an oral, small-molecule multi-kinase inhibitor, seems to be one of the most promising of these compounds. Areas covered: We review preliminary data on the safety and efficacy of XL184 in metastatic MTC based on an extensive search of the literature, which included published articles, abstracts and website information. In particular, the review focuses on the rationale for using XL184 in advanced MTC. The compound has been specifically designed to target multiple signaling pathways, and this is expected to produce synergistic antitumor effects superior to those achieved by single-kinase inhibition. Preliminary results from the Phase I study of XL184 seem to support this hypothesis. Expert opinion: Multiple receptor tyrosine kinases (RTKs) are concomitantly activated in the same tumor. The blockade of a single RTK may engage compensatory signaling that maintains cell growth. Targeting multiple kinases might overcome both intrinsic and acquired resistance to antitumoral drugs.

BRAF V600E and risk stratification of thyroid microcarcinoma: a multicenter pathological and clinical study.

Studies from single institutions have analyzed BRAF in papillary microcarcinomas, sometimes with contradictory results. Most of them have provided limited integration of histological and clinical data. To obtain a comprehensive picture of BRAF V600E-mutated microcarcinomas and to evaluate the role of BRAF testing in risk stratification we performed a retrospective multicenter analysis integrating microscopical, pathological, and clinical information. Three hundred and sixty-five samples from 300 patients treated at six medical institutions covering different geographical regions of Italy were analyzed with central review of all cases. BRAF V600E statistical analysis was conducted on 298 microcarcinomas from 264 patients after exclusion of those that did not meet the required criteria. BRAF V600E was identified in 145/298 tumors (49%) including the following subtypes: 35/37 (95%, P<0.0001) tall cell and 72/114 (64%, P<0.0001) classic; conversely 94/129 follicular variant papillary microcarcinomas (73%, P<0.0001) were BRAF wild type. BRAF V600E-mutated microcarcinomas were characterized by markedly infiltrative contours (P<0.0001) with elongated strings of neoplastic cells departing from the tumor, and by intraglandular tumor spread (P<0.0001), typically within 5 mm of the tumor border. Multivariate analysis correlated BRAF V600E with specific microscopic features (nuclear grooves, optically clear nuclei, tall cells within the tumor, and tumor fibrosis), aggressive growth pattern (infiltrative tumor border, extension into extrathyroidal tissues, and intraglandular tumor spread), higher American Thyroid Association recurrence risk group, and non-incidental tumor discovery. The following showed the strongest link to BRAF V600E: tall cell subtype, many neoplastic cells with nuclear grooves or with optically clear nuclei, infiltrative growth, intraglandular tumor spread, and a tumor discovery that was non-incidental. BRAF V600E-mutated microcarcinomas represent a distinct biological subtype. The mutation is associated with conventional clinico-pathological features considered to be adverse prognostic factors for papillary microcarcinoma, for which it could be regarded as a surrogate marker. BRAF analysis may be useful to identify tumors (BRAF wild type) that have negligible clinical risk.