Background: MicroRNAs (miRNAs) are involved in the pathogenesis of human cancers, including medullary thyroid carcinoma (MTC). The aim of this study was to test the hypothesis that different miRNA profiles are related to RET status and prognosis in patients with hereditary MTC (hMTC) and sporadic MTC (sMTC). Methods: We analyzed the expression of nine miRNAs (miR-21, miR-127, miR-154, miR-224, miR-323, miR-370, miR-9*, miR-183, and miR-375) by quantitative real-time-polymerase chain reaction in 34 cases of sMTC, 6 cases of hMTC, and 2 cases of C-cell hyperplasia (CCH). We also analyzed the immunohistochemical expression of PDCD4, an miR-21 gene target. sMTC (n = 34) was genotyped for somatic RET and RAS mutations. Disease status was defined on the basis of the concentration of serum calcitonin at the latest follow-up and other parameters as indicated in the results. Results: MTC and CCH were both characterized by a significant overexpression of the whole set of miRNAs (the increase being 4.2-fold for miR-21, 6.7-fold for miR-127, 8.8-fold for miR-154, 6.6-fold for miR-224, 5.8-fold for miR-323, 6.1-fold for miR-370, 13-fold for miR-9*, 6.7-fold for miR-183, and 10.1 for miR-375, p < 0.0001). PDCD4 expression was significantly downregulated in MTC samples, consistent with miR-21 upregulation. Significantly lower miR-127 levels were observed in sMTC carrying somatic RET mutations in comparison to sMTC carrying a wild-type RET. In sMTC and familial MTC, the miR-224 upregulation correlated with the absence of node metastases, lower stages at diagnosis, and with biochemical cure during follow-up. Conclusions: miRNAs are significantly dysregulated in MTC, and this dysregulation is probably an early event in C-cell carcinogenesis. miR-224 upregulation could represent a prognostic biomarker associated with a better outcome in MTC patients.

Gender-specific bCT and sCT cutoffs for the identification of C-cell hyperplasia and/or MTC have been defined. The bCT and sCT were found to have a similar accuracy, indicating that serum CT assays with improved functional sensitivity may likely decrease the relevance of the stimulation test in several conditions. Finally, systematic cardiac monitoring confirms the safety of the Ca test.

Sporadic medullary thyroid carcinoma (MTC) harbors RET gene somatic mutations in up to 50 % of cases, and RAS family gene mutations occur in about 10 %. A timely and comprehensive characterization of molecular alterations is needed to improve MTC diagnostic stratification and design-tailored therapeutic approaches. Twenty surgically resected sporadic MTCs, previously analyzed for RET mutations by Sanger sequencing using DNA from formalin-fixed paraffin-embedded samples, were investigated for intragenic mutations in 50 cancer-associated genes applying a multigene Ion AmpliSeq next-generation sequencing (NGS) technology. Thirteen (65 %) MTCs harbored a RET mutation; 10 were detected at both Sanger and NGS sequencing, while 3 undetected by Sanger were revealed by NGS. One of the 13 RET-mutated cases also showed an F354L germline mutation in STK11. Of the seven RET wild-type MTCs, four cases (57.1 %) harbored a RAS mutation: three in HRAS (all Q61R) and one in KRAS (G12R). The three remaining MTCs (15 %) resulted as wild-type for all the 50 cancer-related genes. Follow-up was available in all but one RET-mutated case. At the end of follow-up, 7 of 12 (58 %) RET-mutated patients had relapsed, while the 4 RAS-mutated MTC patients were disease-free. Two of the three patients with MTC wild-type for all 50 genes relapsed during the follow-up period. Detection of mutations by NGS has the potential to improve the diagnostic stratification of sporadic MTC.

Objective: Medullary thyroid carcinoma (MTC) derives from the parafollicular C cells, being sporadic in 75% of cases and familial in 25%, due to RET proto-oncogene germinal mutations. In sporadic forms, stage at diagnosis is the most important negative prognostic factor. The aim of this study was to evaluate the prognostic impact of molecular and immunohistochemical markers in sporadic MTC. Design and methods: We studied 60 patients with sporadic MTC. For each case, we sought RET somatic mutations in the primary cancer and in lymph node metastases. The primary cancer also underwent immunohistochemical examination for Ki-67. Results: A somatic RET mutation was found in 38% of patients, being M918T in 52% of them. We observed a statistically significant association between RET mutations and male gender (P!0.01), tumor size (P!0.05), lymph nodes (P!0.05) and distant metastases (P!0.001), advanced stage (P!0.05), increased risk of persistent disease (PZ0.01), and low overall survival (P!0.01). High Ki-67 levels were similarly associated with extra-thyroid spread (P!0.05), lymph nodes (P!0.05) and distant metastases (P!0.001), advanced stage (PZ0.01), and low overall survival (PZ0.01). Combining somatic RET analysis with Ki-67 assessment seems to be useful for increasing the specificity of Ki-67 assessment alone and identifying patients with a more aggressive cancer: in our series, only the patients who died during the follow-up had both a somatic RET mutation and a Ki-67 expression level O50 cells/mm 2 . Conclusions: The combined evaluation of RET and Ki-67 could act as an adjuvant prognostic marker useful for ameliorating the initial risk stratification of patients with sporadic MTC.European Journal of Endocrinology 164 971-976

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