We have recently reported that MicroRNAs (miR)-221 and miR-222 were up-regulated in human thyroid papillary carcinomas in comparison with the normal thyroid tissue. Bioinformatic analysis proposed the p27 Kip1 protein, a key regulator of cell cycle, as a candidate target for the miR-221/222 cluster. Here, we report that the enforced expression of miR-221 and miR-222 was able to reduce p27Kip1 protein levels in thyroid carcinoma and HeLa cells in the absence of significant changes in specific p27Kip1 mRNA levels. This effect is direct as miR-221 and miR-222 negatively regulate the expression of the 3 0 -untranslated region-based reporter construct from the p27 Kip1 gene, and is dependent on two target sites in this region. Consistent with these results, an enforced expression of the miR-221 and miR-222 induced the thyroid papillary carcinoma cell line (TPC-1) to progress to the S phase of the cell cycle. It is likely that the negative regulation of p27Kip1 by miR-221 and miR-222 might also have a role in vivo since we report an inverse correlation between miR-221 and miR-222 up-regulation and down-regulation of the p27 Kip1 protein levels in human thyroid papillary carcinomas. Therefore, the data reported here demonstrate that miR-221 and miR-222 are endogenous regulators of p27 Kip1 protein expression, and thereby, the cell cycle.

Thyroid carcinomas comprise a broad spectrum of tumors with different clinical behaviors. On the one side, there are occult papillary carcinomas (PTC), slow growing and clinically silent, and on the other side, rapidly growing anaplastic carcinomas (ATC), which are among the most lethal human neoplasms. We have analysed the microRNA (miR) profile of ATC in comparison to the normal thyroid using a microarray (miRNACHIP microarray). By this approach, we found an aberrant miR expression profile that clearly differentiates ATC from normal thyroid tissues and from PTC analysed in previous studies. In particular, a significant decrease in miR-30d, miR-125b, miR-26a and miR-30a-5p was detected in ATC in comparison to normal thyroid tissue. These results were further confirmed by northern blots, quantitative reverse transcription-PCR analyses and in situ hybridization. The overexpression of these four miRs in two human ATC-derived cell lines suggests a critical role of miR-125b and miR-26a downregulation in thyroid carcinogenesis, since a cell growth inhibition was achieved. Conversely, no effect on cell growth was observed after the overexpression of miR-30d and miR-30a-5p in the same cells. In conclusion, these data indicate a miR signature associated with ATC and suggest the miR deregulation as an important event in thyroid cell transformation.

The down-regulation of miR-25 and miR-30d could contribute to the process of thyroid cancer progression, leading to the development of anaplastic carcinomas targeting EZH2 mRNA.

PTCs in young patients display a low prevalence of the already identified oncogenic alterations. The increasing prevalence with age is mainly due to V600E BRAF mutation. There is no relation between tumor aggressiveness and BRAF mutation. There is a relation between the presence of RET/PTC (1 and 3) and the histological and clinical short-term aggressiveness of PTC in the population of young adults. Such a relation is not found in children and adolescents.

The high-mobility group A (HMGA, types 1 and 2) proteins are low-molecular-weight nuclear factors that orchestrate the assembly of nucleoprotein complexes involved in gene transcription, replication, and chromatin structure. HMGAs possess oncogenic activity [1,2] and proteins of type 1 (HMGA1) have been correlated to cellular invasiveness and drug-resistance in human malignancies.[3] In particular, blockage of expression of these proteins significantly enhances the responsiveness of tumor cell lines that are otherwise resistant to cytotoxic agents. Thus, phenotypic assays based on cells with reduced levels of HMGA are a possible tool for a rational search of novel compounds against tumors whose aggressiveness and resistance reduce the success of normal screening methods.Herein, we report the elucidation of the structure of mycalol (1), a novel polyoxygenated ether lipid that showed a promising in vitro specific activity against different cell lines derived from human anaplastic thyroid carcinoma (ATC), the most aggressive human thyroid gland malignancy.[4] Mycalol was identified by a novel screening method based on the parallel use of FRO cells, which are human ATC-derived cells with high constitutive levels of HMAG1, but not HMGA2, and FRO-asHMGA1 cells, a genetically modified population of FRO cells that stably express an anti-HMGA1 antisense construct that blocks HMGA1 synthesis.[5] The effects of extracts and fractions were measured on the paired cell lines by MTS proliferation assay.Mycalol was isolated from a chloroform extract of the sponge Mycale (Oxymycale) acerata Kirkpatrick 1907 collected along the coasts of Terra Nova Bay (Antarctica) during the Austral summer of 2005. The sponge, frozen soon after collection, was extracted with MeOH and fractionated according to a modified Kupchan method.[6] The chloroform extract showed no activity against FRO cells up to 50 mg mL À1 , but gave a good response (IC 50 = 7.5 mg mL À1 ) against HMGA1-silenced FRO cells (FRO-asHMGA), thus supporting the potential of a novel screening method based on HMGA-interference. Sequential steps of silica gel radial chromatography and reverse-phase HPLC (see the Supporting information) gave alkyl glyceryl ether 1 together with a number of minor compounds that are still under study. The HR-ESI+ MS spectrum of 1 showed a MÀNa + ion at m/z 573.3959, thus accounting for the molecular formula C 29 H 58 O 9 (calcd m/z 573.3979 for C 29 H 58 O 9 Na) and requiring only one formal unsaturation. Accordingly, 1 H and 13 C 2D NMR data indicated a C 27 linear structure with nine oxygenated carbons and an acetyl group (for full assignment, see the Supporting Information, Table S1). COSY spectra identified seven of these carbons as part of a glycerol moiety (H1' This methylene group showed scalar couplings with the diastereomeric protons at d 2.40 and d 2.16 (H 2 2), both also coupled to one of the oxymethine protons (d 4.18, H3) of the two gem-diol systems. Characterization and location of these groups were unambiguously accomplished by 2D NMR...