Murilo Vieira Geraldo

MicroRNAs miR-146-5p and let-7f as prognostic tools for aggressive papillary thyroid carcinoma: a case report

Papillary thyroid cancer (PTC) is the most incident histotype of thyroid cancer. A certain fraction of PTC cases (5%) are irresponsive to conventional treatment, and refractory to radioiodine therapy. The current prognostic factors for aggressiveness are mainly based on tumor size, the presence of lymph node metastasis, extrathyroidal invasion and, more recently, the presence of the BRAFT1799A mutation. MicroRNAs (miRNAs) have been described as promising molecular markers for cancer as their deregulation is observed in a wide range of tumors. Recent studies indicate that the over-expression of miR-146b-5p is associated with aggressiveness and BRAFT1799A mutation. Furthermore, down-regulation of let-7f is observed in several types of tumors, including PTC. In this study, we evaluated the miR146b-5p and let-7f status in a young male patient with aggressive, BRAFT1799A-positive papillary thyroid carcinoma, with extensive lymph node metastases and short-time recurrence. The analysis of miR-146b-5p and let-7f expression revealed a distinct pattern from a cohort of PTC patients, suggesting caution in evaluating miRNA expression data as molecular markers of PTC diagnosis and prognosis.

MiRNA-146b-5p upregulates migration and invasion of different Papillary Thyroid Carcinoma cells

BackgroundTumor invasiveness is directly related to the ability of tumor cells to migrate and invade surrounding tissues, usually degrading extracellular matrix. Despite significant progress in the knowledge about migration and invasion, there is much more to elucidate about their regulatory mechanisms, especially in cancer cells. MicroRNAs (miRs) were recently described as important regulators of migration. Differential expression of miRs in cancer is frequently associated with progression, invasion and metastasis. In papillary thyroid carcinoma (PTC), miR-146b-5p is highly expressed and positively correlated to the degree of malignancy.MethodsThis study aimed to investigate the role of miR-146b-5p on the migratory and invasive behaviors of thyroid cells, using a non tumor rat thyroid follicular cell line (PCCl3) transfected with the miR-146b-5p genomic region, and two PTC cell lines (TPC-1 and BCPAP, bearing distinct oncogenic backgrounds), which express high levels of miR-146b-5p, after miR-146b inhibition by antagomiR and miR-146b overexpression by mimics-miR. Migration and invasion were studied by time-lapse and transwell assays (with and without Matrigel®). Gelatin degradation assays were also employed, as well as F-actin staining.ResultsMigration and invasion of PCCl3 were increased 2-3x after miR-146b-5p overexpression (10X) and large lamellipodia were evident in those cells. After miR-146b-5p inhibition, TPC-1 and BCPAP migration and invasion were significantly reduced, with cells showing several simultaneous processes and low polarity. Gelatin degradation was inhibited in TPC-1 cells after inhibition of miR-146b-5p, but was unaffected in BCPAP cells, which did not degrade gelatin. The inhibition of miR-146b-5p in PCCl3 also inhibited migration and invasion, and additional (exogenous) overexpression of this miR in TPC-1 and BCPAP cells increased migration and invasion, without effects on cell morphology or gelatin degradation. The overexpression of SMAD4 in BCPAP cells, a validated target of miR-146b-5p and key protein in the TGF-β signaling pathway, inhibited migration similarly to the effects observed with the antagomiR 146b-5p.ConclusionsmiR-146b-5p positively regulates migration and invasion of thyroid normal and tumor follicular cells (independently from their original mutation, either BRAF or RET/PTC), through a mechanism that involves the actin cytoskeleton but not an increased capacity of matrix degradation.

Integrated Analysis of Thyroid Cancer Public Datasets Reveals Role of Post-Transcriptional Regulation on Tumor Progression by Targeting of Immune System Mediators

Papillary thyroid carcinoma (PTC) is a well-differentiated thyroid tumor that accounts for approximately 80% of thyroid cancer cases. On other hand, anaplastic thyroid carcinoma (ATC) is a less frequent, but aggressive subtype, with poor prognosis. MicroRNAs (miRNAs), small non-coding RNAs, have emerged as potent post-transcriptional regulators of gene expression, which modulate the expression of cancer-related genes. Computational analyses estimate that a single miRNA may modulate hundreds of mRNA targets and, at the same time, cooperate with others to regulate one single mRNA transcript. Due to the large number of predicted targets and possible interactions, only a small number of miRNAs have characterized biological roles, and the panorama of miRNA-mediated regulation in thyroid cancer remains to be understood. Taking into consideration the large amount of gene expression data deposited in public databases we aligned miRNA target prediction and gene expression data from public PTC and ATC datasets to construct a network of post-transcriptional regulation in thyroid cancer. After a gene set enrichment analysis we identified signaling pathways and biological processes potentially modulated by the miRNAs deregulated in PTC and ATC. Our results show miRNA-mRNA interaction that could contribute with the de-regulation of key tumor-host mediators, such as extra-cellular matrix molecules, interleukins and interleukin receptors, which could drive a more aggressive behavior and tumor progression. Moreover, our analysis through The Cancer Genome Atlas (TCGA) database revealed that aberrant expression of ECM and cytokines genes is frequent in PTC and is associated with aggressive behavior and decreased overall survival rate. In conclusion, we shed light on the post-transcriptional regulation of gene expression in differentiated and undifferentiated thyroid cancers, revealing a potential role of miRNAs in modulation of tumor-host interaction molecules, particularly ECM molecules and immune system mediators, which could stimulate crosstalk between tumors and the immune system to generate a more aggressive behavior. We propose a novel putative miRNA:mRNA network that could lead to a new path toward functional studies.

Down-regulation of 14q32-encoded miRNAs and tumor suppressor role for miR-654-3p in papillary thyroid cancer

Papillary thyroid carcinoma (PTC) is the most prevalent malignant neoplasia of the thyroid gland. A fraction of PTC cases show loss of differentiation and aggressive behavior, with radioiodine therapy resistance and metastasis. Although microRNAs (miRNAs) emerged as promising molecular markers for PTC, their role in the loss of differentiation observed during PTC progression remains to be fully understood. We performed the large-scale analysis of miRNA expression during PTC progression in BRAFT1799A-transgenic animals (Tg-Braf) and thyroid cancer cell lines and identified the marked downregulation of several miRNAs from the region 14q32. Data from The Cancer Genome Atlas (TCGA) confirmed the global downregulation of miRNAs from the 14q32 region in human PTC. The regulatory network potentially suppressed by these miRNAs suggests that key cancer-related biological processes such as cell proliferation, adhesion, migration and angiogenesis. Among the downregulated miRNAs, we observed that miR-654-3p levels decrease with long-term PTC progression in Tg-Braf mice and inversely correlate with EMT. The in vitro restoration of miR-654-3p decreased cell proliferation and migration and induced reprogramming of metastasis-related genes, suggesting a tumor suppressor role for this miRNA. In conclusion, we show global downregulation of 14q32-encoded miRNAs in an in vivo model of PTC progression. The potential circuitry in which these miRNAs are involved suggests that these miRNAs could play a key role in the pathophysiology of PTC and therefore be relevant for the development of new therapeutic strategies.

Abstract B234: Large scale analysis of miRNA expresion and in silico prediction of regulatory networks in thyroid cancer progression.

Introduction: Papillary thyroid carcinoma (PTC) is a well differentiated tumor that accounts for more than 80% of the thyroid cancer cases. Although PTC presents good prognosis, about 5% of the cases present a more aggressive behavior, evolving to poorly differentiated thyroid carcinoma (PDTC) and becoming refractory to chemo and radioiodine therapy. Recent studies indicate a positive correlation between the more aggressive PTC phenotype and the point mutation in B-RAF proto-oncogene BRAFT1799A. microRNAs (miRNAs), small non-coding RNAs involved in post-transcriptional gene regulation, emerged as promising molecular markers and targets for cancer therapy, including for PTC. However, the role of miRNAs in PTC progression remains unclear, particularly regarding to the dedifferentiation observed in the more aggressive PTCs. Materials: Transgenic FVB/N mice with thyroid-targeted expression of the oncogene BRAFT1799A, Tg-BRAF mice, which present locally invasive well-differentiated PTC at 5 weeks, and areas of poorly differentiated thyroid cancer after 12 weeks. Human thyroid cell lines N-Thy-ORI (normal), TPC-1 and BCPAP (PTC) and KTC-2 (PDTC). Results: To identify differentially expressed miRNAs related to loss of differentiation during progression of PTC, we performed large scale analysis of miRNA expression of thyroid glands extracted from Tg-BRAF mice with 1, 5, 12 and 30 weeks, and of 4 human thyroid cell lines presenting different degrees of differentiation. Experimental validation of 8 de-regulated miRNAs genes (5 up- and 3 down-regulated) confirmed the expression pattern observed in large scale analysis. Based on the hypothesis that these miRNAs could cooperate to regulate the same mRNA targets, we used in silico approaches and publicly available GEO-datasets from normal thyroid tissue, well and poorly differentiated thyroid carcinoma, to generate two regulatory networks of predicted targets of the differentially expressed miRNAs during PTC progression. Interestingly, Kegg orthology analysis of the resulting regulatory networks revealed that the subset of up-regulated miRNAs negatively regulates the PI3K-AKT signaling pathway, by repressing its downstream targets BCL2 and CREB1. On the other hand, the regulatory network regulated by under-expressed miRNAs potentially regulates RNA splicing and transport by regulating the RNA binding protein RBM8A. Additionally the MAPK and TGF-beta signaling pathways, important mediators of epithelial-to-mesenchymal transition and cell survival, respectively, are potentially regulated by under-expressed miRNAs by targeting TGF-beta receptor 2 and RAF1. Conclusion: Our large scale analysis followed by an in silico approach identified a potential regulatory network of post-transcriptional regulation that could explain the aggressive behavior of this subtype of PTC. Moreover, the further investigation of the disrupted regulatory networks in PTC, as well as the modulation of miRNA genes, could open up perspectives for the development of new therapeutic strategies for aggressive PTC. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B234. Citation Format: Murilo V. Geraldo, Edna T. Kimura. Large scale analysis of miRNA expresion and in silico prediction of regulatory networks in thyroid cancer progression. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B234.

Abstract 5592: Lack of association between AGTR1 (A168G and T825A) and ACE T5529C polymorphisms with breast cancer among Brazilian women

Background: Angiotensin II (AngII) exerts promitotic, pro-proliferative and angiogenic effects and the administration of angiotensin I-converting enzyme (ACE) inhibitors reduces tumor growth in animal models of cancer. AngII type 1 receptor (AGTR1) is found in a wide variety of normal tissues, increased expression is often found in the corresponding neoplastic tissues, suggesting that its overexpression is involved in carcinogenesis. In a previous study we observed that the ID genotype might be protective against breast cancer and also that the ACE (I/D) polymorphism is a possible target for developing genetic markers for breast cancer. Other authors have also observed the association of the ACE with breast cancer risk. To further test the hypothesis that AngII participates in breast carcinogenesis through AGTR1 and ACE, we examined genetic polymorphisms in the 5’-region of the AGTR1 gene (A-168G and T-825A) and in the ACE (T5529C) in relation to risk of breast cancer among Brazilian women. Methods: Genotyping was performed through Real Time PCR (A168G and T825A) or PCR-RFLP (T5529C) using genomic DNA extracted from buccal cells of subjects with or without breast cancer.Results: Patients with (case) or without (control) breast cancer aging from 30 to 90 years old were genotyped for A168G (n=516), and the following frequencies obtained for AA, AG and GG in % were, among cases: 63, 30, 07 and among controls: 64, 32, 04 (p = 0.89). For T825A (n=562), we determined the frequency of TT, TA and AA (in %, cases: 62, 33, 05; controls: 59, 33, 08; p = 0.68). At last, for ACE (T5529C) (n=272) these are the obtained frequencies for TT, TC and CC genotypes in %, among cases: 65, 23, 12 and among controls: 55, 29, 15 (p = 0.39). Conclusion: Our results suggest a lack of significant association between AGTR1 polymorphisms (A168G and T825A) with breast cancer risk in the Brazilian population, in contrast to a previous result among Chinese women, where an association of the AGTR1 polymorphisms with breast cancer has been reported. Regarding the ACE T5529C polymorphism, it also did not show any association with breast cancer risk in the present study, differently from the observed for another polymorphism of the same gene, the ACE (I/D). Therefore, the AGTR1 (A168G and T825A) and ACE (T5529C) variant genotypes do not appear to be related to risk of breast cancer among Brazilian women. Support: FAPESP. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5592. doi:10.1158/1538-7445.AM2011-5592