Thyroid cancer is one of the few malignancies that are increasing in incidence. Recent advances have improved our understanding of its pathogenesis; these include the identification of genetic alterations that activate a common effector pathway involving the RET-Ras-BRAF signalling cascade, and other unique chromosomal rearrangements. Some of these have been associated with radiation exposure as a pathogenetic mechanism. Defects in transcriptional and post-transcriptional regulation of adhesion molecules and cell-cycle control elements seem to affect tumour progression. This information can provide powerful ancillary diagnostic tools and can also be used to identify new therapeutic targets.

Background:The roles of ESRP1 and ESRP2 during carcinogenesis remain unknown. Results: ESRPs are up-regulated during carcinogenesis but down-regulated in invasive fronts. ESRP1 suppresses expression of the Rac1b isoform, whereas ESRP2 represses epithelial-mesenchymal transition-inducing transcription factors. Conclusion: ESRP1 and ESRP2 suppress cell motility through distinct transcriptional and/or post-transcriptional mechanisms. Significance: Our findings reveal a novel molecular network that regulates cancer cell motility.

We investigated the frequency of RAS mutations in follicular thyroid tumors from a large number of cases obtained from a single institute. The predominance of NRAS codon 61 mutations as a feature of carcinomas indicates that the diagnosis of adenoma alongside the presence of this mutation should be made cautiously. Our study raises the possibility that follicular adenomas with the RAS mutations have an inherent malignant potential; however, the clinical significance of this finding should be further investigated in more patients and over a longer follow-up period.

Runx2/Cbfa1 is a member of the Runt-related transcription factor family and is an essential regulator of osteoblast/ chondrocyte differentiation. Recently, aberrant expression of Runx2 and its oncogenic functions have been identified in the progression and metastasis of human cancers. In this study, we investigated the expression profile of Runx family genes in normal thyroid tissue, non-neoplastic but abnormal thyroid tissue, various types of thyroid tumors and representative human thyroid carcinoma cell lines. Using reverse transcriptase-PCR and western blotting, we found that Runx2 was consistently upregulated in papillary carcinomas (PCs) and thyroid carcinoma cell lines compared with normal thyroid tissue. With immunohistochemistry, we observed negative or focal immunoreactivity of Runx2 in the nuclei of normal thyroid follicular cells. None of the non-neoplastic thyroid tissues, including Graves' thyroid and adenomatous goiter, had diffuse positivity of Runx2. Expression of Runx2 in benign follicular adenomas varied from negative to diffusely positive. Meanwhile, all malignant thyroid tumors showed some Runx2 immunopositivity. It was diffuse and intense in 83% (19/23) of PCs, 71% (5/7) of follicular carcinomas (FCs) and 40% (4/10) of undifferentiated carcinomas (UCs). In thyroid carcinoma cell lines, the MEK inhibitor U0126 suppressed Runx2, suggesting an association of the MAPK/ERK pathway with Runx2 regulation. Effective silencing of Runx2 by short interfering RNA (siRNA) demonstrated downregulation of EMT-related molecules (SNAI2, SNAI3 and TWIST1), MMP2 and vasculogenic factors (VEGFA and VEGFC) in thyroid carcinoma cells. We also confirmed that Runx2 silencing suppresses thyroid carcinoma cell invasion in transwell assays. In conclusion, this study provides insight into the potential molecular mechanism of thyroid cancer invasion. Our data suggest that enhanced Runx2 is functionally linked to tumor invasion and metastasis of thyroid carcinoma by regulating EMT-related molecules, matrix metalloproteinases and angiogenic/lymphangiogenic factors.