DNA methylation at the 5 position of cytosine (5-mC) is a key epigenetic mark that is involved in various biological and pathological processes. 5-mC can be converted to 5-hydroxymethylcytosine (5-hmC) by the ten-eleven translocation (TET) family of DNA hydroxylases. Increasing evidence suggests that large-scale loss of 5-hmC is an epigenetic hallmark of several human cancers. However, the value of 5-hmC in diagnosis and prognosis of human cancers, including gastric cancer (GC), remains largely unknown. The aim of this study is to determine 5-hmC levels in GCs and explore its association with clinicopathological characteristics and clinical outcome of GC patients. Using immunohistochemistry (IHC) and dot-blot assays, we demonstrated that 5-hmC was dramatically decreased in GCs compared with matched normal tissues. We also found a strong link between decreased 5-hmC and the reduction of TET1 gene expression, but not TET2 or 3, suggesting that decreased TET1 expression might be one of the mechanisms underlying 5-hmC loss in GCs. Wilcoxon tests showed that 5-hmC content was significantly associated with most of clinicopathological characteristics, such as tumor size (P = 0.016), Bormman type (P < 0.0001), tumor invasion (P = 0.001), TNM stage (P < 0.0001), the number of lymph nodes metastasis (P = 0.002), and survival status (P < 0.0001). It is noteworthy that decreased 5-hmC was significantly associated with poor survival of GC patients. Collectively, our findings indicate that decreased 5-hmC may be crucial to the clinical pathology of GC and is a strong and independent poor prognostic factor in GCs.

Head and neck squamous cell cancer (HNSCC) is estimated to be the sixth most common malignant tumor worldwide. Of which, laryngeal cancer is the second most common HNSCC.1 The definite cause of laryngeal cancer is not yet determined, although some risk factors, such as tobacco and alcohol consumption, genetic and epigenetic alterations are believed to be linked with the development of this disease. 2,3Telomerase reverse transcriptase (TERT) gene, which encodes the catalytic subunit of telomerase, has been demonstrated to be up-regulated in human cancers, contributing to carcinogenesis. 4 Recently, two recurrent somatic mutations (1,295,228 C>T and 1,295,250 C>T, hereafter named C228T and C250T, respectively) in the TERT gene promoter have been frequently reported in various human cancers, including melanoma (71%), thyroid cancer (22-51%), bladder cancer (84.6%) and glioblastoma (83.8%). [5][6][7][8] In contrast, a very low frequency of these mutations has been found in certain cancers, particularly in esophageal squamous cell carcinoma (1.6%) and gastric cancer (0.7%).8-10 Importantly, these two mutations conferred a 2-to 4-fold increase in TERT transcriptional activity.5 Moreover, they have been demonstrated to be absent in benign tumors and normal subjects, implicating their potentially critical roles in human carcinogenesis. Although a previous study showed frequent TERT promoter mutations in head and neck cancers especially tongue cancer

Epithelial-mesenchymal transition (EMT), a crucial step in disease progression, plays a key role in tumor metastasis. N-cadherin, a well-known EMT marker, acts as a major oncogene in diverse cancers, whereas its functions in thyroid cancer remains largely unclear. This study was designed to explore the biological roles and related molecular mechanism of N-cadherin in thyroid tumorigenesis. Quantitative RT-PCR (qRT-PCR) and immunohistochemistry assays were used to evaluate N-cadherin expression. A series of in vitro studies such as cell proliferation, colony formation, cell cycle, apoptosis, migration and invasion assays were performed to determine the effect of N-cadherin on malignant behavior of thyroid cancer cells. Our results showed that N-cadherin was significantly upregulated in papillary thyroid cancers (PTCs) as compared with non-cancerous thyroid tissues. N-cadherin knockdown markedly inhibited cell proliferation, colony formation, cell migration and invasion, and induced cell cycle arrest and apoptosis. On the other hand, ectopic expression of N-cadherin promoted thyroid cancer cell growth and invasiveness. Mechanically, our data demonstrated that tumor-promoting role of N-cadherin in thyroid cancer was closely related to the activities of the MAPK/Erk, the phosphatidylinositol-3-kinase (PI3K)/Akt and p16/Rb signaling pathways in addition to affecting the EMT process. Altogether, our findings suggest that N-cadherin promotes thyroid tumorigenesis by modulating the activities of major signaling pathways and EMT process, and may represent a potential therapeutic target for this cancer.

BackgroundThyroid nodules with indeterminate cytological features on fine needle aspiration biopsy specimens (FNABs) have a ~20% risk of thyroid cancer. BRAF V600E mutation and DNA methylation are useful markers to distinguish malignant thyroid neoplasm from benign. The aim of this study was to determine whether combined detection of BRAF V600E mutation and methylation markers on FNABs could improve the diagnostic accuracy of thyroid cancer.MethodsUsing pyrosequencing and quantitative methylation-specific PCR (Q-MSP) methods, FNABs from 79 and 38 patients with thyroid nodules in training and test groups, respectively, were analyzed for BRAF V600E mutation and gene methylation.ResultsBRAF V600E mutation was found in 30/42 (71.4%) and 14/20 (70%) FNABs in training and test groups, respectively. All BRAF V600E -positive samples were histologically diagnosed as papillary thyroid cancer (PTC) after thyroidectomy. As expected, BRAF mutation was not found in all benign nodules. Moreover, we demonstrated that the five genes, including CALCA, DAPK1, TIMP3, RAR-beta and RASSF1A, were aberrantly methylated in FNABs. Of them, methylation level of DAPK1 in PTCs was significantly higher than that in benign samples (P <0.0001). Conversely, methylation level of RASSF1A in PTCs was significantly lower than that in benign samples (P =0.003). Notably, compared with BRAF mutation testing alone, combined detection of BRAF mutation and methylation markers increased the diagnostic sensitivity and accuracy of PTC with excellent specificity.ConclusionOur data have demonstrated that combine analysis of BRAF mutation and DNA methylation markers on FNABs may be a useful strategy to facilitate the diagnosis of malignant thyroid neoplasm, particularly PTC.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/6080878071149177.

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