The current role of targeted therapies to induce radioiodine uptake in thyroid cancer

hsa_circ_0004846 enhances the malignant phenotype of papillary thyroid carcinoma cells via the miR‑142‑3p/PELI1 axis

Circular RNAs (circRNAs) are closely associated with human tumorigenesis; however, whether hsa_circ_0004846 serves a role in the progression of papillary thyroid carcinoma (PTC) remains unclear. Therefore, the present study aimed to investigate the effect of hsa_circ_0004846 on PTC. The results demonstrated that circ_0004846 was abnormally upregulated in PTC tissues and thyroid cancer cell lines (BCPAP, TPC-1 and IHH-4). Furthermore, hsa_circ_0004846-overexpressing or -depleted PTC cell lines (TPC-1 and IHH-4) were constructed using a lentiviral vector system. Notably, hsa_circ_0004846 overexpression markedly promoted cell proliferation, migration and invasion, as evidenced by activation of the PI3K/AKT pathway and the upregulation of vimentin, a class-III intermediate filament, which acts by regulating cell attachment and migration. However, hsa_circ_0004846 knockdown displayed the opposite effects. Mechanistically, the regulatory association among hsa_circ_0004846, microRNA (miR)-142-3p and Pellino E3 ubiquitin protein ligase 1 (PELI1) was validated using a dual-luciferase reporter assay. Specifically, the results demonstrated that hsa_circ_0004846 could sponge miR-142-3p, and the expression levels of miR-142-3p were negatively associated with those of hsa_circ_0004846. In addition, PELI1, a cancer-related E3 ubiquitin ligase, was identified as a downstream target of the hsa_circ_0004846/miR-142-3p axis in PTC. Therefore, PELI1 silencing could reverse the hsa_circ_0004846-induced malignant phenotype of PTC cells. Taken together, the results of the current study highlighted the effect of the hsa_circ_0004846/miR-142-3p/PELI1 regulatory network on PTC progression, thus providing a promising target for PTC treatment.

CircRNA ITCH Inhibits Epithelial-Mesenchymal Transformation and Promotes Apoptosis in Papillary Thyroid Carcinoma via miR-106a-5p/JAZF1 Axis

Circular RNA ITCH (circ-ITCH) is implicated in papillary thyroid carcinoma (PTC) development. Nevertheless, the more detailed molecular mechanism remains uncovered. The transcriptional level of circ-ITCH was tested via quantitative real-time PCR. Transwell assay was introduced to assess the migrative and invasive abilities of cells. RNA interference technology was employed to reduce the level of circ-ITCH as well as JAZF1 in PTC cells. Western blot assay was utilized to reveal the content of JAZF1 and proteins related to epithelial-mesenchymal transformation (EMT) progression. Circ-ITCH was downregulated in PTC tissues as well as cells. Overexpression of circ-ITCH suppressed EMT, migration, invasion, facilitated apoptosis in PTC cells, while silencing circ-ITCH exhibited reversed effects. Additionally, miR-106a-5p was the target of circ-ITCH and negatively regulated through circ-ITCH. MiR-106a-5p mimic partly eliminated the influences of overexpressed circ-ITCH in PTC cells. Moreover, JAZF1 could interact with miR-106a-5p, then it was regulated via circ-ITCH. Silencing JAZF1 partially counteracted the role of circ-ITCH in PTC cells progress. This study uncovered that circ-ITCH suppressed the development of PTC cells at least partly by mediating miR-106a-5p/JAZF1 network.

Regulation of iodine-glucose flip-flop in SW1736 anaplastic thyroid cancer cell line

AIMS AND BACKGROUND

The alternative manner of iodide and glucose uptake found in different types of thyroid cancer, referred to flip-flop. ATC cells indicate low iodide uptake and high glucose uptake, which lack the morphology and genetic characteristics of well-differentiated tumors and become increasingly invasive. Importance placed on the discovery of innovative multi-targeted medicines to suppress the dysregulated signaling in cancer. In this research, we aimed to clarify molecular mechanism of Rutin as a phytomedicine on anaplastic thyroid cancer cell line based on iodide and glucose uptake.

MATERIAL METHODS

The MTT test was employed to test cell viability. Iodide uptake assay was performed using a spectrophotometric assay to determine iodide uptake in SW1736 cells based on Sandell-Kolthoff reaction. For glucose uptake detection, ''GOD-PAP'' enzymatic colorimetric assay was applied to measure the direct glucose levels inside of the cells. Determination of NIS, GLUT1 and 3 mRNA expression in SW1736 cells was performed by qRT-PCR. Determination of NIS, GLUT1 and 3 protein levels in SW1736 cells was performed by western blotting.

RESULTS

According to our results, Rutin inhibited the viability of SW1736 cells in a time- and dose-dependent manner. Quantitative Real-time RT-PCR analysis exposed that NIS mRNA levels were increased in Rutin treated group compared to the control group. Accordingly, western blot showed high expression of NIS protein and low expression of GLUT 1 and 3 in Rutin treated SW1736 cell line. Rutin increased iodide uptake and decreased glucose uptake in thyroid cancer cell line SW1736 compared to control group.

CONCLUSION

Multiple mechanisms point to Rutin's role as a major stimulator of iodide uptake and inhibitor of glucose uptake, including effects at the mRNA and protein levels for both NIS and GLUTs, respectively. Here in, we described the flip-flop phenomenon as a possible therapeutic target for ATC. Moreover, Rutin is first documented here as a NIS expression inducer capable of restoring cell differentiation in SW1736 cell line. It also be concluded that GLUTs as metabolic targets can be blocked specifically by Rutin for thyroid cancer prevention and treatment.

CircPCNXL2 promotes papillary thyroid carcinoma progression by regulating fatty acid metabolism induced by anabolic enzyme ACC1

Papillary thyroid cancer (PTC) is an endocrine malignant tumor with a rapidly increasing incidence in recent years. Although the disease prognosis is good in general, there are still some patients with local invasion, distant metastasis and recurrence, which make treatment difficult. This study aimed to investigate the effect of a novel circRNA, circPCNXL2, on the progression of PTC and to explore its underlying mechanism in PTC. In this study, we found that the expression of circPCNXL2 was upregulated in PTC, which was positively correlated with the proliferation of PTC, and knockdown of circPCNXL2 enhanced the cell cycle arrest of PTC and promoted cell apoptosis. Further research revealed that circPCNXL2 can interact with ACC1, a key enzyme of cellular lipid metabolism, and then promote cell growth by affecting the de novo synthesis of fatty acids. Mechanistically, circPCNXL2 enhances the protein activity of ACC1 by reducing ACC1 phosphorylation of ser 79, thereby promoting the formation of fatty acids such as free fatty acids and triglycerides in cells to meet the energy metabolism needs of cells and promote cell growth. In a nude mouse subcutaneous tumorigenesis model, knockdown of circPCNXL2 inhibited the growth of PTC tumors while high levels of circPCNXL2 expression promoted tumor proliferation. This study revealed that circPCNXL2 regulates PTC lipid metabolism by enhancing the protein activity of ACC1 and identified a novel signaling pathway, the circPCNXL2-ACC1 axis, that can be targeted for the treatment of PTC.

Comparison of gasless transaxillary endoscopic thyroidectomy, endoscopic thyroidectomy via areola approach and conventional open thyroidectomy in patients with unilateral papillary thyroid carcinoma

BACKGROUND

Gasless transaxillary endoscopic thyroidectomy (GTET) and endoscopic thyroidectomy via the areola approach (ETA) have emerged as minimally invasive surgical techniques for managing papillary thyroid carcinoma (PTC). This study aimed to assess the surgical efficacy of endoscopic thyroidectomy (ET) as compared to conventional open thyroidectomy (COT) in PTC patients.

METHODS

Between 2020 and 2022, 571 PTC patients underwent unilateral thyroidectomy accompanied by ipsilateral central lymph node dissection. This cohort comprised 72 patients who underwent GTET, 105 ETA, and 394 COT. The analysis encompassed a comprehensive examination of patient clinicopathologic characteristics and postoperative complaints. Furthermore, the learning curve of GTET was evaluated using the cumulative summation (CUSUM) method.

RESULTS

Patients in the ET group exhibited a lower mean age and a higher proportion of female individuals. Operation time in the ET group was significantly longer. No significant differences were observed in the incidence of postoperative complications among the three groups. With regard to postoperative complaints reported three months after surgery, GTET demonstrated superior alleviation of anterior chest discomfort and swallowing difficulties. Patients who underwent ET reported significantly higher cosmetic satisfaction levels. Additionally, the learning curve of GTET was 27 cases, and the operation time during the mature phase of the learning curve exhibited a significant reduction when compared to ETA.

CONCLUSIONS

The findings of this study affirm the safety and feasibility of employing GTET and ETA for the surgical management of PTC. GTET presents an attractive surgical option, particularly for patients with unilateral PTC who place a premium on cosmetic outcomes.

Computational screening and functional tuning of chemically stable metal organic frameworks for I2/CH3I capture in humid environments

High chemical stability is of vital significance in rendering metal organic frameworks (MOFs) as promising adsorbents for capturing leaked radioactive nuclides, under real nuclear industrial conditions with high humidity. In this work, grand canonical Monte Carlo (GCMC) and density functional theory (DFT) methods have been employed to systematically evaluate I2/CH3I capture performances of 21 experimentally confirmed chemically stable MOFs in humid environments. Favorable structural factors and the influence of hydrophilicity for iodine capture were unveiled. Subsequently, the top-performing MIL-53-Al with flexible tunability was functionalized with different functional groups to achieve the better adsorption performance. It has been revealed that the adsorption affinity and pore volume were two major factors altered by the functionalization of polar functional groups, which collectively influenced the iodine adsorption properties. In general, this work has screened the chemically stable high-performance MOF iodine adsorbents and provided comprehensive insights into the key factors affecting I2/CH3I uptake and separation in humid environments.

Progranulin promoted the proliferation, metastasis, and suppressed apoptosis via JAK2-STAT3/4 signaling pathway in papillary thyroid carcinoma

BACKGROUND

Progranulin (PGRN), a glycoprotein secreted by a wide range of epithelial cells and plays an important role in inflammatory mechanisms and tumor progression. In this study, the expression, and functions of PGRN in papillary thyroid carcinoma (PTC) was examined to explore the potential pathogenesis of PTC.

METHODS

Western blotting and qRT-PCR were used to detect the relationship between PGRN expression and clinicopathological characteristics of patients with PTC. PTC cell lines with PGRN overexpression and with PGRN knockdown were established to explore their effects on the biological behavior. Western blotting was used to detect the changes of relevant molecules and JAK2-STAT3/4 signaling pathway. Moreover, rescue experiments validated the involvement of the JAK2-STAT3/4 signaling pathway. And statistical analyses were analyzed using SPASS 21.0 and graph generation were performed using GraphPad Prism 8.0.

RESULTS

PGRN was overexpressed in PTC tissue and increased by 75% at mRNA level and 161% at relative protein level in the patients with lymph node metastasis compared to without lymph node metastasis. Besides, PGRN regulated and promoted PTC cell proliferation, migration, invasion, and inhibited cell apoptosis. With PGRN overexpressed, relevant molecules including the expression of BCL2/BAX, BCL2/BAD, CyclinD1, MMP2, vimentin and N-cadherin were increased, the expression level of E-cadherin was decreased, and the phosphorylation of JAK2 and STAT3/4 were increased. JAK inhibitor (JSI-124) rescued these changes of PTC cells induced by overexpressed PGRN.

CONCLUSIONS

These findings revealed that PGRN promote the progression of PTC through the JAK2-STAT3/4 pathway, and PGRN could be served as a potential therapeutic target for PTC.

ALKBH5-induced circular RNA NRIP1 promotes glycolysis in thyroid cancer cells by targeting PKM2

Although circular RNAs (circRNAs) are involved in cell proliferation, differentiation, apoptosis, and invasion, the underlying regulatory mechanisms of circRNAs in thyroid cancer have not been fully elucidated. This article aimed to study the role of circRNA regulated by N6-methyladenosine modification in papillary thyroid cancer (PTC). Quantitative real-time PCR, western blotting, and immunohistochemistry were used to investigate the expressions of circRNA nuclear receptor-interacting protein 1 (circNRIP1) in PTC tissues and adjacent noncancerous thyroid tissues. In vitro and in vivo assays were carried out to assess the effects of circNRIP1 on PTC glycolysis and growth. The N6-methyladenosine mechanisms of circNRIP1 were evaluated by methylated RNA immunoprecipitation sequencing, luciferase reporter gene, and RNA stability assays. Results showed that circNRIP1 levels were significantly upregulated in PTC tissues. Furthermore, elevated circNRIP1 levels in PTC patients were correlated with high tumor lymph node metastasis stage and larger tumor sizes. Functionally, circNRIP1 significantly promoted glycolysis, PTC cell proliferation in vitro, and tumorigenesis in vivo. Mechanistically, circNRIP1 acted as a sponge for microRNA (miR)-541-5p and miR-3064-5p and jointly upregulated pyruvate kinase M2 (PKM2) expression. Knockdown of m⁶ A demethylase α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5) significantly enhanced circNRIP1 m⁶ A modification and upregulated its expression. These results show that ALKBH5 knockdown upregulates circNRIP1, thus promoting glycolysis in PTC cells. Therefore, circNRIP1 can be a prognostic biomarker and therapeutic target for PTC by acting as a sponge for oncogenic miR-541-5p and miR-3064-5p to upregulate PKM2 expression.

The Emerging Role of m6A Modification in Endocrine Cancer

With the development of RNA modification research, N6-methyladenosine (m6A) is regarded as one of the most important internal epigenetic modifications of eukaryotic mRNA. It is also regulated by methylase, demethylase, and protein preferentially recognizing the m6A modification. This dynamic and reversible post-transcriptional RNA alteration has steadily become the focus of cancer research. It can increase tumor stem cell self-renewal and cell proliferation. The m6A-modified genes may be the primary focus for cancer breakthroughs. Although some endocrine cancers are rare, they may have a high mortality rate. As a result, it is critical to recognize the significance of endocrine cancers and identify new therapeutic targets that will aid in improving disease treatment and prognosis. We summarized the latest experimental progress in the m6A modification in endocrine cancers and proposed the m6A alteration as a potential diagnostic marker for endocrine malignancies.

MicroRNA-203a-3p may prevent the development of thyroid papillary carcinoma via repressing MAP3K1 and activating autophagy

Background

Papillary thyroid carcinoma (PTC) grows slowly but has a great risk of metastasis. MicroRNAs are well known as vital tumor‐related gene regulators. In PTC, the role of miR‐203a‐3p and the underlying mechanisms remain not completely understood.

Methods

We conducted CCK8 assay, wound healing assay, transwell experiment and flow cytometry analyses to investigate the function of miRNA‐203a‐3p. The interaction of miRNA‐203a‐3p with its gene MAP3K1 was characterized by quantitative real‐time polymerase chain reaction, western blotting and luciferase assay.

Results

We found that the levels of miRNA‐203a‐3p were statistically decreased in PTC tissues. When mimics were delivered to TPC‐1 and KTC‐1 cells to upregulate miR‐203a‐3p, it was observed that cell proliferation, metastatic abilities and cell cycle process were prevented but cell apoptosis was enhanced. Furthermore, we proved the interaction between MAP3K1 and miR‐203a‐3p. Intriguingly, similar to miR‐203a‐3p mimics, siMAP3K1 showed a tumor‐suppressive effect, and this effect could be reversed when miR‐203a‐3p was simultaneously inhibited. Finally, selected autophagy‐linked proteins such as LC3 Beclin‐1 were detected and found to be increased when miR‐203a‐3p was upregulated or MAP3K1 was inhibited.

Conclusion

Overall, miR‐203a‐3p inhibits the oncogenic characteristics of TPC‐1 and KTC‐1 cells via suppressing MAP3K1 and activating autophagy. Our findings might enrich the understanding and the therapeutic strategies of PTC.

Circ_0059354 aggravates the progression of papillary thyroid carcinoma by elevating ARFGEF1 through sponging miR-766-3p

BACKGROUND

Circular RNAs (circRNAs) have been identified as vital players in tumors, including papillary thyroid carcinoma (PTC). The purpose of this study is to explore the functions of circ_0059354 on PTC development.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to examine the levels of circ_0059354, microRNA-766-3p (miR-766-3p) and ADP ribosylation factor guanine nucleotide exchange factor 1 (ARFGEF1). Cell Counting Kit-8 (CCK-8) assay and colony formation assay were proceeded for cell proliferation ability. Transwell assay was conducted for cell migration and invasion. Tube formation assay was employed to examine the angiogenesis ability. Flow cytometry analysis was adopted for cell apoptosis. Western blot assay was conducted for protein levels. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were utilized to verify the relationships among circ_0059354, miR-766-3p and ARFGEF1. The murine xenograft model was constructed to analyze the function of circ_0059354 in vivo.

RESULTS

Circ_0059354 level was abnormally increased in PTC tissues and cells. Functionally, circ_0059354 silencing suppressed cell proliferation, migration, invasion and angiogenesis and facilitated apoptosis in PTC cells. Circ_0059354 was identified to sponge miR-766-3p, which directly targeted ARFGEF1. Moreover, circ_0059354 directly targeted miR-766-3p to positively regulated ARFGEF1 expression. MiR-766-3p inhibition reversed circ_0059354 knockdown-mediated effect of PTC cell malignant behaviors. Overexpression of miR-766-3p restrained the malignant behaviors of PTC cells, whereas ARFGEF1 elevation reversed the effects. Additionally, circ_0059354 deficiency blocked tumor growth in vivo.

CONCLUSION

Circ_0059354 served as an oncogene in PTC progression through regulating miR-766-3p/ARFGEF1 axis.

Targeting IGF2BP2 Promotes Differentiation of Radioiodine Refractory Papillary Thyroid Cancer via Destabilizing RUNX2 mRNA

Simple Summary

Differentiation therapy is one of the most promising treatment approaches for radioiodine refractory papillary thyroid cancer (RR-PTC). In this study, we found that insulin-like growth factor 2 mRNA-binding protein 2 promoted dedifferentiation of PTC via integrating to 3′-untranslated regions of runt-related transcription factor 2, which bound to the promoter region of sodium/iodide symporter, downregulating its expression.

Abstract

N6-methyladenosine (m6A) regulators play an important role in multiple biological and pathological processes of radioiodine refractory papillary thyroid cancer (RR-PTC). However, the function of m6A regulators in differentiation of RR-PTC remains unclear. In this study, online data, clinical samples, and RR-PTC cell lines (K1 and TPC1) were used to identify the m6A regulators that contributed to the differentiation of RR-PTC. Insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) was found to be associated with thyroid-specific genes in online data analyses, and metastatic PTCs with high expression of IGF2BP2 were prone to be ¹³¹I-nonavid in clinical analyses. Furthermore, targeting IGF2BP2 increased ¹²⁵I uptake in RR-PTC cell lines and enhanced the sodium/iodide symporter (NIS) expression. Mechanistically, IGF2BP2 bound to the m6A modification site of runt-related transcription factor 2 (RUNX2) 3′-UTR and enhanced the RUNX2 mRNA stability. Moreover, RUNX2 could bind to the promoter region of NIS to block the differentiation of RR-PTC. Together, these results demonstrated that IGF2BP2 represents a diagnostic marker for RR-PTC, suggesting a novel differentiation therapeutic strategy of targeting IGF2BP2.

FTO suppresses glycolysis and growth of papillary thyroid cancer via decreasing stability of APOE mRNA in an N6-methyladenosine-dependent manner

Background

N6-methyladenosine (m⁶A) modification is the most common chemical modification in mammalian mRNAs, and it plays important roles by regulating several cellular processes. Previous studies report that m⁶A is implicated in modulating tumorigenesis and progression. However, dysregulation of m⁶A modification and effect of m⁶A demethylase fat-mass and obesity-associated protein (FTO) on glucose metabolism has not been fully elucidated in papillary thyroid cancer (PTC).

Methods

Quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry were performed to explore the expression profile of FTO in PTC tissues and adjacent non-cancerous thyroid tissues. Effects of FTO on PTC glycolysis and growth were investigated through in vitro and in vivo experiments. Mechanism of FTO-mediated m⁶A modification was explored through transcriptome-sequencing (RNA-seq), methylated RNA immunoprecipitation sequencing (MeRIP-seq), MeRIP-qPCR, luciferase reporter assays, RNA stability assay and RNA immunoprecipitation assay.

Results

FTO expression was significantly downregulated in PTC tissues. Functional analysis showed that FTO inhibited PTC glycolysis and growth. Further analyses were conducted to explore FTO-mediated m⁶A modification profile in PTC cells and Apolipoprotein E (APOE) was identified as the target gene for FTO-mediated m⁶A modification using RNA-seq and MeRIP-seq. FTO knockdown significantly increased APOE mRNA m⁶A modification and upregulated its expression. FTO-mediated m⁶A modification of APOE mRNA was recognized and stabilized by the m⁶A reader IGF2BP2. The findings showed that APOE also promoted tumor growth through glycolysis in PTC. Analysis showed that FTO/APOE axis inhibits PTC glycolysis by modulating IL-6/JAK2/STAT3 signaling pathway.

Conclusion

FTO acts as a tumor suppressor to inhibit tumor glycolysis in PTC. The findings of the current study showed that FTO inhibited expression of APOE through IGF2BP2-mediated m⁶A modification and may inhibit glycolytic metabolism in PTC by modulating IL-6/JAK2/STAT3 signaling pathway, thus abrogating tumor growth.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02254-z.

CircRNA circTIAM1 promotes papillary thyroid cancer progression through the miR-646/HNRNPA1 signaling pathway

Papillary thyroid cancer (PTC) is a common endocrine tumor with a rapidly increasing incidence in recent years. Although the majority of PTCs are relatively indolent and have a good prognosis, a certain proportion is highly aggressive with lymphatic metastasis, iodine resistance, and easy recurrence. Circular RNAs (circRNAs) are a class of noncoding RNAs that are linked to a variety of tumor processes in several cancers, including PTC. In the current study, circRNA high-throughput sequencing was performed to identify alterations in circRNA expression levels in PTC tissues. circTIAM1 was then selected because of its increased expression in PTC and association with apoptosis, proliferation, and migration of PTC cells in vitro and in vivo. Mechanistically, circTIAM1 acted as a sponge of microRNA-646 and functioned in PTC by targeting miR-646 and heterogeneous ribonucleoprotein A1. Fluorescence in situ hybridization and dual-luciferase reporter assays further confirmed these connections. Overall, our results reveal an important oncogenic role of circTIAM1 in PTC and may represent a potentially therapeutic target against PTC progression.

BRAF Inhibitors Induce Feedback Activation of RAS Pathway in Thyroid Cancer Cells

BRAF^V600E is the most frequent oncogenic mutation identified in papillary thyroid cancer (PTC). In PTC patients who do not respond to standard treatment, BRAF inhibitors are currently tested as alternative strategies. However, as observed for other targeted therapies, patients eventually develop drug resistance. The mechanisms of BRAF inhibitors response are still poorly understood in a thyroid cancer (TC) context. In this study, we investigated in BRAF^V600E mutated TC cell lines the effects of Vemurafenib and Dabrafenib, two BRAF inhibitors currently used in a clinical setting. We assessed cell proliferation, and the expression and activity of the thyroid function related transporter NIS following the treatment with BRAF inhibitors. In addition, we investigated the global gene expression by microarray, the relevant modulated biological processes by gene set enrichment analysis (GSEA), and TC specific gene signatures related to MAPK pathway activation, thyroid differentiation, and transcriptional profile associated with BRAF^V600E or RAS mutation. We found that both inhibitors induce antiproliferative and redifferentiative effects on TC cells, as well as a rewiring of the MAPK pathway related to RAS signaling. Our results suggest a possible mechanism of drug response to the BRAF inhibitors Vemurafenib or Dabrafenib, supporting very recent findings in TC patients treated with targeted therapies.

Circular RNA circWDR27 Promotes Papillary Thyroid Cancer Progression by Regulating miR-215-5p/TRIM44 Axis

Purpose

This study was to explore the biological roles and underlying mechanism of circRNA WD repeat domain 27 (circWDR27).

Methods

The expression of circWDR27, microRNA-215-5p (miR-215-5p) and tripartite motif containing 44 (TRIM44) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays were employed to detect cell proliferation. Flow cytometry was used to determine cell apoptosis and cell cycle distribution. Cell migration and invasion abilities were examined by wound healing and transwell assays. The protein levels of matrix metalloproteinase 2 (MMP2), MMP9 and TRIM44 were analyzed by Western blot assay. The relationship between miR-215-5p and circWDR27 or TRIM44 was predicted by bioinformatics tools and confirmed using dual-luciferase reporter assay. Mouse xenograft model was established to examine the role of circWDR27 in vivo.

Results

CircWDR27 and TRIM44 were highly expressed while miR-215-5p was lowly expressed in PTC tissues and cells. Knockdown of circWDR27 suppressed cell proliferation and metastasis and induced cell cycle arrest and apoptosis in PTC cells. Moreover, miR-215-5p was a direct target of circWDR27, and its inhibition reversed the suppressive effect of circWDR27 knockdown on PTC cell progression. In addition, miR-215-5p directly targeted TRIM44, and miR-215-5p exerted its anti-cancer role in PTC cells by targeting TRIM44. Furthermore, circWDR27 positively regulated TRIM44 expression by sponging miR-215-5p. Importantly, knockdown of circWDR27 suppressed tumor growth in vivo by upregulating miR-215-5p and downregulating TRIM44.

Conclusion

CircWDR27 accelerates PTC progression via regulating miR-215-5p/TRIM44 axis, providing a potential therapeutic target for PTC.

Circular RNA circ-NCOR2 accelerates papillary thyroid cancer progression by sponging miR-516a-5p to upregulate metastasis-associated protein 2 expression

Objective

Papillary thyroid cancer (PTC) is one of the most prevalent endocrine malignancies and the fifth most common cancer in women. Circular RNAs (circRNAs) have been shown to play vital functions in cancers, but few studies have focused on the functions and mechanism of dysregulated circRNAs in PTC.

Methods

Quantitative reverse transcription PCR was used to measure circ-NCOR2 levels in PTC tissues and cell lines. The functions of circ-NCOR2 in PTC were examined by analysis using the cell counting kit-8, clone forming, flow cytometry, and Transwell experiments. Bioinformatic analysis and dual luciferase reporter gene testing were used to identify the mechanisms of circ-NCOR2.

Results

Circ-NCOR2 overexpression was observed in PTC tissues and cells. Silenced or overexpressed expression of circ-NCOR2 strikingly attenuated or facilitated, respectively, the growth, migration, and invasion of PTC cells. Mechanistically, miR-615a-5p was identified as the target of circ-NCOR2. Moreover, circ-NCOR2 enhanced the expression of metastasis-associated protein 2 (MTA2) by sponging miR-615a-5p, thereby facilitating PTC cell progression.

Conclusions

Taken together, our findings reveal a novel circ-NCOR2/miR-615a-5p/MTA2 axis in PTC, which could become a potential therapeutic target for this disease.

Molecular mechanisms of radioactive iodine refractoriness in differentiated thyroid cancer: Impaired sodium iodide symporter (NIS) expression owing to altered signaling pathway activity and intracellular localization of NIS

The advanced, metastatic differentiated thyroid cancers (DTCs) have a poor prognosis mainly owing to radioactive iodine (RAI) refractoriness caused by decreased expression of sodium iodide symporter (NIS), diminished targeting of NIS to the cell membrane, or both, thereby decreasing the efficacy of RAI therapy. Genetic aberrations (such as BRAF, RAS, and RET/PTC rearrangements) have been reported to be prominently responsible for the onset, progression, and dedifferentiation of DTCs, mainly through the activation of mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT signaling pathways. Eventually, these alterations result in a lack of NIS and disabling of RAI uptake, leading to the development of resistance to RAI therapy. Over the past decade, promising approaches with various targets have been reported to restore NIS expression and RAI uptake in preclinical studies. In this review, we summarized comprehensive molecular mechanisms underlying the dedifferentiation in RAI-refractory DTCs and reviews strategies for restoring RAI avidity by tackling the mechanisms.

The direct miR-874-3p-target FAM84A promotes tumor development in papillary thyroid cancer

With the improvement in diagnostic technology, the incidence of thyroid cancer (TC) is on the rise. Papillary thyroid carcinoma (PTC) is the most common pathological type of thyroid cancer; therefore, it is important to explore some valuable molecular targets to improve the treatment and prognosis of PTC. Studies have shown that family with sequence similarity 84, member A (FAM84A) is involved in the development of various tumors. However, the role of FAM84A in PTC remains unknown. Herein, we explored the biological function and specific molecular mechanism of FAM84A in PTC. Results indicated that FAM84A was upregulated in PTC tissues and cells. In addition, patients with higher FAM84A expression tended to possess larger tumor size, higher lymph node metastasis rate, and advanced TNM stage. Further studies indicated that downregulation of FAM84A could inhibit the development of PTC in vitro and in vivo by repressing the epithelial–mesenchymal transition (EMT) and Wnt/β‐catenin signaling pathway. Moreover, FAM84A was confirmed to be negatively regulated by tumor suppressor miR‐874‐3p. In conclusion, our findings suggest that FAM84A may act as a potential diagnostic and therapeutic target for PTC.

Alternative splicing events implicated in carcinogenesis and prognosis of thyroid gland cancer

Alternative splicing (AS), a critical post-transcriptional regulatory mechanism, expands gene expression patterns, thereby leading to increased protein diversity. Indeed, more than 95% of human genes undergo alternative splicing events (ASEs). In this study, we drew an all-around AS profile of thyroid cancer cells based on RNA-seq data. In total, there were 45,150 AS in 10,446 thyroid cancer cell genes derived from 506 patients, suggesting that ASEs is a common process in TC. Moreover, 1819 AS signatures were found to be significantly associated with the overall survival (OS) of TC patients. Kaplan–Meier survival analyses suggested that seven types of ASEs were associated with poor prognosis of TC (P < 0.05). Among them, exon skipping (ES) was the most common, with alternate promoter (AP) and alternate terminator (AT) coming second and third, respectively. Our results indicated that acceptor sites (AA) (AUC: 0.937), alternate donor sites (AD) (AUC: 0.965), AT (AUC: 0.964), ES (AUC: 0.999), mutually exclusive exons (ME) (AUC: 0.999), and retained intron (RI) (AUC: 0.837) exhibited an AUC greater than 0.6. In addition, age and risk score (All) were risk factors for TC patients. We also evaluated whether TC-ASEs are regulated by various splicing factors (SFs). We found that the expression of 90 SFs was associated with 469 ASEs and OS of TC patients. Our findings provide an insight into the role of spliceosomes in TC, which may offer novel perspectives in tumor research.

hsa_circ_0001018 promotes papillary thyroid cancer by facilitating cell survival, invasion, G1/S cell cycle progression, and repressing cell apoptosis via crosstalk with miR-338-3p and SOX4

We identified a novel interactome, circ_0001018/miR-338-3p/SOX4, in papillary thyroid cancer (PTC), and we intended to confirm the regulatory relationship between the three and to study the effects of the three in PTC. The bioinformatics method was used to screen out the circular RNA and mRNA of interest. A cellular fractionation assay and fluorescence in situ hybridization (FISH) assay were conducted to prove that circ_0001018 and CCT4 (the host gene of circ_0001018) mRNA primarily localized in the cytoplasm of PTC cell lines. By qRT-PCR analysis, the expression of circ_0001018 and SOX4 mRNA was found upregulated while the expression of miR-338-3p was found downregulated in PTC tissues and cells. circ_0001018 silence significantly inhibited the tumor growth in xenografted nude mice. A series of cytological experiments such as a Cell Counting Kit-8 (CCK-8) assay, a 5-ethynyl-2′-deoxyuridine (EdU) assay, cell cycle profiling, wound healing, a transwell assay, and cell apoptosis were conducted and showed that circ_0001018 and SOX4 promoted cell proliferation, migration, and invasion, inhibited cell apoptosis, and reduced the cell cycle arrest at the G₁ phase in PTC cells. Compared with circ_0001018 and SOX4, miR-338-3p held the opposite function. The regulatory relationship between circ_0001018 and miR-338-3p, and between miR-338-3p and SOX4 mRNA, was validated using a luciferase reporter gene assay and/or RNA immunoprecipitation (RIP assay). Our findings showed that circ_0001018 acted as the tumor promoter via sponging miR-338-3p to elevate SOX4 expression level in PTC. Importantly, this novel circ_0001018/miR-338-3p/SOX4 axis has the potential to be considered as a therapy target for PTC.

CREB3 Transactivates lncRNA ZFAS1 to Promote Papillary Thyroid Carcinoma Metastasis by Modulating miR-373-3p/MMP3 Regulatory Axis

The incidence rate of thyroid carcinoma ranks ninth among human malignancies, and it accounts for the most frequent malignancy in endocrine-related tumors. This study aimed to investigate the role of long noncoding RNA (lncRNA) ZFAS1 in the metastasis of papillary thyroid carcinoma (PTC) and the potential molecular mechanisms. Both ZFAS1 and MMP3 were highly expressed in thyroid carcinoma and PTC cell, as measured by the q-PCR and TCGA database. In addition, ZFAS1 induced TPC-1 metastasis through inducing the epithelial-mesenchymal transition (EMT) process. Besides, ZFAS1 knockdown by siRNA induced miR-373-3p expression and reduced MMP3 expression, as quantified by q-PCR and Western blotting. According to the luciferase assay, both ZFAS1 and MMP3 were classified as the direct targets of miR-373-3p. However, MMP3 itself did not affect ZFAS1. Using the online prediction tool, CREB3 was predicted as the transcription factor (TF) of ZFAS1 that contained two binding sites on its promoter region, and CREB3 was positively correlated with ZFAS1 in thyroid carcinoma cohorts. Results from the dual-luciferase assay and ChIP-qPCR indicated that both the two binding sites were essential for the transcription of ZFAS1. In conclusion, CREB3 activated lncRNA ZFAS1 at the transcriptional level to promote PTC metastasis by modulating miR-373-3p/MMP3.

ATF2-Induced lncRNA GAS8-AS1 Promotes Autophagy of Thyroid Cancer Cells by Targeting the miR-187-3p/ATG5 and miR-1343-3p/ATG7 Axes

Long non-coding RNAs (lncRNAs) play an essential regulatory role in multiple cancers. However, the role of lncRNAs in papillary thyroid carcinoma (PTC) is still unknown. Here, GAS8-AS1, a novel lncRNA that is significantly downregulated in PTC, was selected for further investigation. The roles of GAS8-AS1 in PTC cells were verified by gain- and loss-of-function experiments. The functional mechanism of GAS8-AS1 on the microRNA (miR)-187-3p/ATG5 axis and miR-1343-3p/ATG7 axis in PTC cells was evaluated using bioinformatics analysis, luciferase reporter assay, Cell Counting Kit-8 (CCK-8) assay, immunohistochemistry analysis, transmission electron microscopy, and immunofluorescence. We found that GAS8-AS1 was downregulated in PTC tissues and cell lines. In patients with PTC, low GAS8-AS1 expression was associated with higher tumor-node-metastasis (TNM) stage and lymph node metastasis (LNM). Functionally, GAS8-AS1 significantly promoted autophagy and inhibited PTC cell proliferation in vitro and promoted tumorigenesis in vivo. Mechanistically, GAS8-AS1 acted as a sponge of miR-187-3p and miR-1343-3p and upregulated ATG5 and ATG7 expression, respectively. The transcription factor ATF2 regulated GAS8-AS1 by binding to the GAS8-AS1 promoter. In conclusion, upregulation of ATF2 activated GAS8-AS1-promoted autophagy of PTC cells by sponging oncogenic miR-187-3p and miR-1343-3p and upregulating the expression of ATG5 and ATG7, respectively, making GAS8-AS1 a potential prognostic biomarker and therapeutic target for PTC.

Long non-coding RNA AGAP2-AS1 increases the invasiveness of papillary thyroid cancer

Papillary thyroid cancer (PTC) is considered a low hazard endocrine system cancer, but a considerable number of patients have poor prognosis because of lymph node metastasis and invasion of surrounding tissues. In this study, we analyzed the expression and function of the long non-coding RNA (lncRNA) AGAP2-AS1 in PTC. We found that AGAP2-AS1 expression was significantly higher in human PTC tissues than adjacent noncancerous tissues (n=110; p<0.01) and correlated with lymph node metastasis (p=0.01) and tumor-node-metastasis stage (p=0.006). AGAP2-AS1 downregulation decreased migration and invasion by PTC cells, and reduced expression of matrix metalloproteinase-2 (MMP2). AGAP2-AS1 upregulated MMP2 expression by competitively binding to microRNA-425-5p. In addition, miR-424-5p expression was decreased in PTC tissues and correlates negatively with the AGAP2-AS1 levels. These results demonstrate that AGAP2-AS1 expression is significantly elevated in PTC tissues and that, by binding to miRNA-425-5p, it upregulates the MMP2 expression, thereby increasing the invasiveness and migration capacity of PTC cells.

Novel therapeutic options for radioiodine-refractory thyroid cancer: redifferentiation and beyond

PURPOSE OF REVIEW

Radioiodine-refractory thyroid cancers represent the main cause of thyroid cancer-related death. At present, targeted therapies with multikinase inhibitors represent a unique therapeutic tool, though they have limited benefit on patient survival and severe drug-associated adverse events. This review summarizes current treatment strategies for radioiodine-refractory thyroid cancer and focuses on novel approaches to redifferentiate thyroid cancer cells to restore responsiveness to radioiodine administration.

RECENT FINDINGS

We summarize and discuss recent clinical trial findings and early data from real-life experiences with multikinase-inhibiting drugs. Possible alternative strategies to traditional redifferentiation are also discussed.

SUMMARY

The current review focuses primarily on the major advancements in the knowledge of the pathophysiology of iodine transport and metabolism and the genetic and epigenetic alterations occurring in thyroid neoplasia as described using preclinical models. Results of clinical studies employing new compounds to induce thyroid cancer cell redifferentiation by acting against specific molecular targets are also discussed. Finally, we describe the current scenario emerging from such findings as well as future perspectives.

Decreased expression of TNFRSF12A in thyroid gland cancer predicts poor prognosis: A study based on TCGA data

Thyroid cancer (TC) is the most well-known endocrine neoplasia as well as a common malignant tumor in the head and neck. Our study was designed to assess the prognostic meaningful of TNFRSF12A expression in TC dependent on data acquired from TCGA and so as to increase further knowledge into the biological pathways involved in TC pathogenesis related TNFRSF12A.Information on gene expression and comparing clinical data were identified and downloaded from TCGA. Gene set enrichment analysis (GSEA) created an arranged list of all genes indicated by their connection with TNFRSF12A expression.Our study cohort included 370 (73.1%) female and 136 (26.9%) male patients. The scatter plot and paired plot showed the difference of TNFRSF12A expression between normal and tumor samples (P < .01). The univariate analysis suggested that TNFRSF12A-low associated essentially with age (HR: 1.15; 95%CI: 1.08-1.22; P < .01), stage (HR: 2.79; 95%CI: 1.43-5.46; I vs IV; P = .003) and tumor stage (HR: 2.39; 95%CI: 1.08-5.30; P = .031). The GSEA results show that type II diabetes mellitus, pantothenate and CoA biosynthesis, adipocytokine signaling pathway, PPAR signaling pathway, mTOR signaling pathway, insulin signaling pathway, are enriched in TNFRSF12A low expression phenotype.TNFRSF12A expression may be a potential useful prognostic molecular biomarker of bad survival in thyroid cancer, in addition, PPAR signaling pathway, insulin signaling pathway, mTOR signaling pathway may be the key pathway controlled by TNFRSF12A in thyroid cancer. Further experimental ought to be performed to demonstrate the biologic effect of TNFRSF12A.

Long noncoding RNA SNHG22 increases ZEB1 expression via competitive binding with microRNA-429 to promote the malignant development of papillary thyroid cancer

Long noncoding RNA termed small nucleolar RNA host gene 22 (SNHG22) is a crucial regulator in epithelial ovarian carcinoma. Nevertheless, the regulatory functions of SNHG22 in papillary thyroid cancer (PTC) progression and its mechanisms of action remain poorly defined. Therefore, the present study aimed to investigate the role of SNHG22 in the malignant phenotype of PTC and determine whether SNHG22 regulates PTC progression via a ceRNA mechanism. SNHG22 expression in PTC was detected using reverse transcription-quantitative polymerase chain reaction analysis. The biological actions of SNHG22 silencing in PTC cells were evaluated both in vitro (using Cell Counting Kit-8 assay, flow cytometry analysis, and cell migration and invasion assays) and in vivo (using tumorigenicity assay). Herein, high SNHG22 expression was observed in PTC tissues and cell lines. This high SNHG22 level was closely associated with unfavorable clinicopathological characteristics and worse overall survival in patients with PTC. SNHG22 knockdown effectively suppressed PTC cell proliferation, migration, and invasion in vitro; accelerated cell apoptosis; and hindered tumor growth in vivo. Mechanistic experiments revealed that SNHG22 directly interacts with microRNA-429 (miR-429) as an miRNA sponge and positively modulates ZEB1 expression. Rescue assays found that miR-429 inhibition or ZEB1 upregulation can offset the actions of SNHG22 knockdown in PTC cells. In sum, SNHG22, miR-429, and ZEB1 form an interactive regulatory network with cancer-promoting roles in PTC cells, suggesting that the SNHG22/miR-429/ZEB1 pathway is a novel diagnostic and therapeutic target.

Calcitriol enhances Doxorubicin-induced apoptosis in papillary thyroid carcinoma cells via regulating VDR/PTPN2/p-STAT3 pathway

There is increasing evidence that vitamin D deficiency is the risk factor for multiple diseases, such as immune disorder, cardiovascular disease and cancer. Calcitriol is the active form of vitamin D with beneficial effects on anti‐cancer by binding vitamin D receptor (VDR). The primary aim of this study was to investigate the role of Calcitriol on papillary thyroid carcinoma (PTC) and explore the possible mechanism. We found nuclear VDR expression in PTC samples was negatively correlated with STAT3 hyperphosphorylation that indicated worse PTC clinicopathologic characteristics. Calcitriol treatment up‐regulated VDR and protein tyrosine phosphatase N 2 (PTPN2) expression, down‐regulated signal transducers and activators of transcription (STAT3) phosphorylation and thereby facilitating chemotherapy drug Doxorubicin‐induced apoptosis in PTC cell lines. However, the apoptosis‐promoting effect of Calcitriol and Doxorubicin co‐treatment was abrogated by STAT3 hyperphosphorylation, indicating suppression of STAT3 phosphorylation was essential for combined treatment of Calcitriol and Doxorubicin in PTC. Together, these results suggested that Calcitriol reinforced the sensitivity of PTC cells to Doxorubicin by regulating VDR/PTPN2/p‐STAT3 signalling pathway.

Circular RNA circFOXM1 Plays a Role in Papillary Thyroid Carcinoma by Sponging miR-1179 and Regulating HMGB1 Expression

Circular RNAs (circRNAs) are a class of noncoding RNAs broadly expressed in cells of various species. However, the molecular mechanisms that link circRNAs with progression of papillary thyroid carcinoma (PTC) are not well understood. In the present study, we attempted to provide a novel basis for targeted therapy for PTC from the aspect of the circRNA-microRNA (miRNA)-mRNA interaction. We investigated the expression of circRNAs in five paired PTC tissues and normal tissues by microarray analysis. The circRNA microarray assay followed by qRT-PCR was used to verify the differential expression of circFOXM1 (hsa_circ_0025033), which is located at chr12: 2966846-2983691 and derived from FOXM1. The spliced length of circFOXM1 is 3410 nt. The qRT-PCR analysis was to investigate the expression pattern of circFOXM1 in PTC tissues and cell lines. Then, the effects of circFOXM1 on tumor growth were assessed in PTC in vitro and in vivo. Furthermore, bioinformatics online programs predicted, and the luciferase reporter assay was used to validate the association of circFOXM1 and miR-1179 in PTC cells. In this study, circFOXM1 was observed to be upregulated in PTC tissues and cell lines. circFOXM1 downregulation inhibited tumor growth of PTC in vitro and in vivo. Bioinformatics analysis predicted that there is a circFOXM1/miR-1179/high-mobility group box 1 (HMGB1) axis in PTC. A dual luciferase reporter system validated the direct interaction of circFOXM1, miR-1179, and HMGB1. In summary, our study demonstrated that circFOXM1 modulates cancer progression through the miR-1179/HMGB1 pathway in PTC. Our findings indicate that circFOXM1 may serve as a promising therapeutic target for the treatment of PTC patients.

Hsa_circ_0039411 promotes tumorigenesis and progression of papillary thyroid cancer by miR-1179/ABCA9 and miR-1205/MTA1 signaling pathways

Papillary thyroid cancer (PTC) is a common malignancy in endocrine system worldwide. Increasing evidence has shown that dysregulation of circular RNAs (circRNAs) could contribute to PTC tumorigenesis. The aims of this project are to investigate the potential role and molecular mechanism of hsa_circ_0039411 in PTC. In the project, RT-qPCR was performed to measure the expression profile of hsa_circ_0039411 in PTC tissues and cells. Cell counting kit-8, clonogenic, flow cytometric, and transwell experiments were used to identify the biological role of hsa_circ_0039411 on PTC cell progression. Bioinformatics methods, along with the dual-luciferase reporter test, was used to identify the potential mechanism of hsa_circ_0039411. Hsa_circ_0039411 was identified as enhanced in PTC tissues/cells. Gain-of-function experiments indicated that hsa_circ_0039411 facilitated PTC cell growth, migration, and invasion and inhibited cell apoptosis. Knockdown of hsa_circ_0039411 caused the opposite effects mentioned above. The mechanism exploration showed that hsa_circ_0039411 functioned as a sponge for miR-1179 and miR-1205 to elevate ATP-binding cassette transporter A9 (ABCA9) and metastasis-associated 1 (MTA1) expression at the post-transcriptional level, respectively. Further investigation confirmed that the functions of hsa_circ_0039411 are dependent on its modulation of ABCA9 and MTA1 in PTC cells. This study uncovered a mechanism of hsa_circ_0039411 in PTC, which might act as a novel therapeutic target for PTC.

Long non-coding RNA UCA1 exerts growth modulation by miR-15a in human thyroid cancer TPC-1 cells

Thyroid cancer is widely diagnosed as malignancy in endocrine system. This study attempted to validate UCA1 possessed modulatory function on cell proliferation and epithelial mesenchymal transition (EMT) in human thyroid cancer cell line TPC-1. Ectopic expression of UCA1 was induced in TPC-1 cells by transfection. CCK-8 assays were employed to value cell viability. Cell apoptosis analysis was conducted through flow cytometry. We found that overexpressed UCA1 strongly promoted cell proliferation. However, the knockdown of UCA1 suppressed cell proliferation and induced obvious cell apoptosis. Besides, cell EMT was promoted by overexpressed UCA1 and was inhibited by the knockdown of UCA1. Further study revealed that miR-15a level in TPC-1 cells was suppressed by overexpressed UCA1. Simultaneous overexpression of UCA1 and miR-15a partly alleviated UCA1-induced growth, identifying that miR-15a was a possible target of UCA1. At last, the Hippo and JNK signal pathways were activated by overexpressed UCA1 but were then weakened by the adding of miR-15a. In conclusion, our study revealed UCA1/miR-15a axis implicated in thyroid cancer cells EMT, exposing a novel mechanism of thyroid cancer progression.

MicroRNA-592 suppresses the malignant phenotypes of thyroid cancer by regulating lncRNA NEAT1 and downregulating NOVA1

Numerous studies have demonstrated that various microRNAs (miRs) are aberrantly expressed in thyroid cancer and play critical roles in thyroid cancer malignancy. The aberrant expression of miR‑592 has frequently been reported in multiple human cancer types; however, its expression profile and functions in thyroid cancer remain poorly understood. Reverse transcription‑quantitative polymerase chain reaction was carried out to determine the expression profile of miR‑592 in thyroid cancer tissues and cell lines. The regulatory effects of miR‑592 upregulation on thyroid cancer cell proliferation, migration, and invasion in vitro, and tumor growth in vivo were investigated using a CCK‑8 assay, migration and invasion assays, and a xenograft tumor model, respectively. Furthermore, the mechanisms underlying miR‑592‑mediated suppression of the aggressive phenotypes of thyroid cancer cells were explored in detail. The results indicated that miR‑592 was significantly downregulated in thyroid cancer samples, and its downregulation was associated with lymph node metastasis and tumor‑node‑metastasis stage. Patients with thyroid cancer and low miR‑592 expression exhibited shorter overall survival than patients with high miR‑592 expression. Overexpression of miR‑592 resulted in decreased cell proliferation, migration, and invasion in thyroid cancer. In addition, neuro‑oncological ventral antigen 1 (NOVA1) was identified as a novel target gene of miR‑592 in thyroid cancer cells. Furthermore, ectopic NOVA1 expression may effectively abolish the tumor‑suppressing effects of miR‑592 overexpression in thyroid cancer cells. Notably, the lncRNA NEAT1 was proposed to function as a sponge of miR‑592 in thyroid cancer cells, thereby regulating NOVA1 expression. Finally, resuming miR‑592 expression significantly impaired thyroid cancer tumor growth in vivo. The results indicated that the NEAT1/miR‑592/NOVA1 pathway may play regulatory roles in thyroid cancer malignancy in vitro and in vivo. Our findings may provide novel insight into the pathogenesis of thyroid cancer. Therefore, this pathway may be an effective target for treating patients with this disease.

microRNA-564 inhibits the aggressive phenotypes of papillary thyroid cancer by directly targeting astrocyte-elevated gene-1

Background: Accumulating evidence has revealed that an increasing number of microRNAs (miRNAs) are dysregulated in papillary thyroid cancer (PTC) and that their dysregulation plays an important role in PTC onset and progression. Reportedly, miRNA-564 (miR-564) is downregulated in several types of human cancer. However, its expression profile and specific functions in PTC remain unclear to date. Methods: In this study, we used reverse transcription-quantitative polymerase chain reaction to detect miR-564 expression in PTC tissues and cell lines. Further, the regulatory roles of miR-564 in the malignant development of PTC in vitro and in vivo were examined using a series of functional experiments. In addition, the possible underlying mechanisms and signaling pathways involved were investigated. Results: We demonstrated that miR-564 expression markedly decreased in PTC tissues and cell lines, and this decrease correlated with the lymph node metastasis and tumor-node-metastasis stage. miR-564 upregulation significantly inhibited cell proliferation, migration, and invasion and induced cell apoptosis in vitro as well as hindered tumor growth in vivo. Furthermore, astrocyte-elevated gene-1 (AEG-1) was identified as a direct target gene of miR-564 in PTC cells. Its expression was upregulated and inversely correlated with miR-564 expression in clinically PTC tissues. Additionally, the silencing of AEG-1 expression could imitate the action of miR-564 overexpression in PTC cells. Remarkably, the restoration of AEG-1 expression partially abolished the tumor-suppressing effects induced by a miR-564 upregulation in PTC cells. Ectopic miR-564 expression deactivated the PTEN/Akt pathway in PTC cells in vitro and in vivo. Conclusion: Overall, the findings of the current study suggest that miR-564 is a tumor-suppressive miRNA that exerts crucial roles in the development and progression of PTC. Therefore, this miRNA might be a promising candidate target in the anticancer treatment of patients with PTC.

MAPK Inhibitors Enhance HDAC Inhibitor-Induced Redifferentiation in Papillary Thyroid Cancer Cells Harboring BRAF V600E: An In Vitro Study

Clinical efficacy of redifferentiation therapy with histone deacetylase inhibitor (HDACi) for lethal radioiodine-refractory papillary thyroid cancer (RR-PTC) is urgently needed to be improved. Given that the impairment of histone acetylation is a mechanism in BRAF^V600E-mitogen-activated protein kinase (MAPK)-induced aberrant silencing of thyroid iodine-metabolizing genes, dual inhibition of HDAC and MAPK may produce a more favorable effect. In this study, we treated BRAF^V600E-mutant (BCPAP and K1) and BRAF-wild-type (BHP 2-7) cells with HDACi (panobinostat) and MAPK inhibitor (dabrafenib or selumetinib), alone or in combination, and we tested the expression of iodine- and glucose-metabolizing genes, radioiodine uptake and efflux, and toxicity. We found that panobinostat alone increased iodine-metabolizing gene expression, promoted radioiodine uptake and toxicity, and suppressed GLUT1 expression in all the cells. However, MAPKi (dabrafenib or selumetinib) induced these effects only in BRAF^V600E-mutant cells. Combined treatment with panobinostat and MAPKi (dabrafenib or selumetinib) displayed a more robust BRAF^V600E-dependent redifferentiation effect than panobinostat alone via further improving the acetylation level of histone at the sodium-iodide symporter (NIS) promoter. In conclusion, MAPK inhibitors enhance HDACi-induced redifferentiation in PTC cells harboring BRAF^V600E, warranting animal and clinical trials.

Upregulated circular RNA circ_0025033 promotes papillary thyroid cancer cell proliferation and invasion via sponging miR-1231 and miR-1304

Recent evidence revealed that circular RNAs (circRNAs) are key regulators for tumorigenesis. However, their roles in papillary thyroid cancer (PTC) is not fully understood. In the current work, the differentially expressed circRNAs between PTC tissues and adjacent noncancerous tissue samples were screened by circRNA microarray. We further selected the highest expressed circRNA (circ_0025033) in tumorous tissues for the study. qRT-PCR was used to measure the level of circ_0025033 in PTC tissue samples and cell lines. Gain/loss of function assays were carried out to determine the effect of circ_0025033 on cell viability, clone-forming, apoptosis, migration and invasion. Dual-luciferase reporter assays were conducted to investigate the mechanisms of circ_0025033 in PTC. The data showed that circ_0025033 aggravated cell proliferation, migration and invasion and inhibited cell apoptosis. Additionally, circ_0025033 could directly sponge miR-1231 and miR-1304 in PTC cells. Furthermore, the oncogenic role of circ_0025033 is dependent on its suppression of miR-1231 and miR-1304. Collectively, this work uncovers a novel signal of circ_0025033/miR-1231/miR-1304 involved in PTC initiation and progression.

CircRNA circ-ITCH suppresses papillary thyroid cancer progression through miR-22-3p/CBL/β-catenin pathway

While recent evidence has uncovered that circular RNAs (circRNAs) are vital regulators of carcinogenesis, their role in papillary thyroid cancer (PTC) is not clearly understood. In this study, we reveal that lower levels of circRNA circ-ITCH are expressed in PTC tissues than in normal adjacent tissues. Gain-of-functional assays show that circ-ITCH overexpression suppresses PTC cell proliferation and invasion and promotes apoptosis in vitro. Overexpression of circ-ITCH also leads to impaired tumor growth in vivo. Bioinformatics analysis and luciferase reporter assays demonstrate that circ-ITCH sponges miR-22-3p to upregulate the expression of CBL, an E3 ligase of nuclear β-catenin. Elevated levels of CBL suppress activation of the Wnt/β-catenin pathway and consequently attenuates PTC progression. In summary, our study reveals a novel signaling pathway of circ-ITCH/miR-22-3p/CBL/β-catenin involved in PTC development and progression.

NEAT1_2 functions as a competing endogenous RNA to regulate ATAD2 expression by sponging microRNA-106b-5p in papillary thyroid cancer

Nuclear paraspeckle assembly transcript 1 (NEAT1), a long non-coding RNA (lncRNA), is a core structural component of paraspeckles and is essential for paraspeckle formation. NEAT1 comprises two different isoforms: NEAT1_1 (3.7 kb) and NEAT1_2 (23 kb). Recently, NEAT1 has been shown to have oncogenic roles and to facilitate tumorigenesis in various human cancers. However, the function of NEAT1 in papillary thyroid cancer (PTC) is not well understood. The relative expression levels of NEAT1_2, ATPase family AAA domain-containing protein 2 (ATAD2), and microRNA-106b-5p (miR-106b-5p) were assessed via quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Four PTC cell lines were used to detect the relative expression of NEAT1_2. The effects of NEAT1_2 on PTC cells were studied by RNA interference approaches in vitro. The effects of NEAT1_2 on downstream proteins were detected by western blotting. The underlying mechanism was clarified by a rescue experiment, and three dual-luciferase reporter assays. NEAT1_2 expression was markedly increased in PTC tissues and the PTC cell lines (K1 and TPC1). The relative expression level of NEAT1_2 was positively associated with TNM stage and tumor size. NEAT1_2 knockdown led to a significant inhibition of growth and metastasis, and induced apoptosis in PTC cells. Knockdown of NEAT1_2 significantly inhibited malignant biological behavior by downregulating the oncogene ATAD2. In addition, NEAT1_2 could act as a competing endogenous RNA to regulate the expression of ATAD2 through downregulating miR-106b-5p. Taken together, our results indicated that NEAT1_2 is overexpressed in PTC. NEAT1_2 could function as a competing endogenous RNA to regulate ATAD2 expression by sponging miR-106b-5p in PTC. Targeting NEAT1_2 could be a promising therapeutic strategy for patients with PTC.

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.

miR-451a is underexpressed and targets AKT/mTOR pathway in papillary thyroid carcinoma

Papillary Thyroid Carcinoma (PTC) is the most frequent thyroid cancer. Although several PTC-specific miRNA profiles have been reported, only few upregulated miRNAs are broadly recognized, while less consistent data are available about downregulated miRNAs. In this study we investigated miRNA deregulation in PTC by miRNA microarray, analysis of a public dataset from The Cancer Genome Atlas (TCGA), literature review and meta-analysis based on a univocal miRNA identifier derived from miRBase v21. A list of 18 miRNAs differentially expressed between PTC and normal thyroid was identified and validated in the TCGA dataset. Furthermore, we compared our signature with miRNA profiles derived from 15 studies selected from literature. Then, to select possibly functionally relevant miRNA, we integrated our miRNA signature with those from two in vitro cell models based on the PTC-driving oncogene RET/PTC1. Through this strategy, we identified commonly deregulated miRNAs, including miR-451a, which emerged also by our meta-analysis as the most frequently reported downregulated miRNA. We showed that lower expression of miR-451a correlates with aggressive clinical-pathological features of PTC as tall cell variant, advanced stage and extrathyroid extension. In addition, we demonstrated that ectopic expression of miR-451a impairs proliferation and migration of two PTC-derived cell lines, reduces the protein levels of its recognized targets MIF, c-MYC and AKT1 and attenuates AKT/mTOR pathway activation.

Overall, our study provide both an updated overview of miRNA deregulation in PTC and the first functional evidence that miR-451a exerts tumor suppressor functions in this neoplasia.

Reintroducing the Sodium-Iodide Symporter to Anaplastic Thyroid Carcinoma

BACKGROUND

Anaplastic thyroid carcinoma (ATC), the most aggressive form of thyroid cancer, is unresponsive to radioiodine therapy. The current study aimed to extend the diagnostic and therapeutic application of radioiodine beyond the treatment of differentiated thyroid cancer by targeting the functional sodium-iodide symporter (NIS) to ATC.

METHODS

The study employed nanoparticle vectors (polyplexes) based on linear polyethylenimine (LPEI), shielded by polyethylene glycol (PEG) and coupled to the synthetic peptide GE11 as an epidermal growth factor receptor (EGFR)-specific ligand in order to target a NIS-expressing plasmid (LPEI-PEG-GE11/NIS) to EGFR overexpressing human thyroid carcinoma cell lines. Using ATC xenograft mouse models, transfection efficiency by ¹²³I scintigraphy and potential for systemic radioiodine therapy after systemic polyplex application were evaluated.

RESULTS

In vitro iodide uptake studies in SW1736 and Hth74 ATC cells, and, for comparison, in more differentiated follicular (FTC-133) and papillary (BCPAP) thyroid carcinoma cells demonstrated high transfection efficiency and EGFR-specificity of LPEI-PEG-GE11/NIS that correlated well with EGFR expression levels. After systemic polyplex injection, in vivo ¹²³I gamma camera imaging revealed significant tumor-specific accumulation of radioiodine in an SW1736 and an Hth74 xenograft mouse model. Radioiodine accumulation was found to be higher in SW1736 tumors, reflecting in vitro results, EGFR expression levels, and results from ex vivo analysis of NIS staining. Administration of ¹³¹I in LPEI-PEG-GE11/NIS-treated SW1736 xenograft mice resulted in significantly reduced tumor growth associated with prolonged survival compared to control animals.

CONCLUSIONS

The data open the exciting prospect of NIS-mediated radionuclide imaging and therapy of ATC after non-viral reintroduction of the NIS gene. The high tumor specificity after systemic application makes the strategy an attractive alternative for the treatment of highly metastatic ATC.

Evaluation of in vitro and in vivo activity of a multityrosine kinase inhibitor, AL3810, against human thyroid cancer

Thyroid cancer is the most common type of endocrine neoplasia. Despite recent breakthroughs in treatment of the disease, the treatment of advanced, progressive thyroid cancers remains challenging with limited therapeutic options available. In this study, we evaluated a novel and orally bioavailable small-molecule multiple tyrosine kinases inhibitor, AL3810, in preclinical models of thyroid cancer in vitro and in vivo. AL3810 (2-5 μmol/L) dose-dependently inhibited the proliferation of human thyroid cancer cell lines TT, SW579 and TPC-1 in vitro with IC₅₀ values ranging from 0.59 to 7.03 μmol/L. Specifically, this agent dose-dependently arrested the thyroid cancer cells in the G₁ phase and induced apoptosis. Furthermore, AL3810 dose-dependently inhibited the migration and invasion of SW579 and TPC-1 cells in vitro. In SW579 and TT xenograft models, oral administration of AL3810 (5-20 mg·kg^-1·d^-1) for 21 d potently inhibited the tumor growth; immunohistochemical staining revealed that the antitumor activity of AL3810 was closely correlated with its anti-angiogenesis effect, as evidenced by a dose-dependent reduction of microvessels in tumor tissues. To assess the therapeutic potential of AL3810 in treating thyroid cancer involving RET gene fusion, we showed that AL3810 (1-10 μmol/L) dose-dependently inhibited the proliferation of RET-driven Baf3 cell line Baf3-CCDC6-RET, and the auto-phosphorylation of RET in these cells. Our data suggest that AL3810 is a promising agent for the treatment of thyroid cancer.

Curcumin induces G2/M arrest, apoptosis, NF-κB inhibition, and expression of differentiation genes in thyroid carcinoma cells

PURPOSE

The therapy of unresectable advanced thyroid carcinomas shows unfavorable outcome. Constitutive nuclear factor-κB (NF-κB) activation in thyroid carcinomas frequently contributes to therapeutic resistance; the radioiodine therapy often fails due to the loss of differentiated functions in advanced thyroid carcinomas. Curcumin is known for its anticancer properties in a series of cancers, but only few studies have focused on thyroid cancer. Our aim was to evaluate curcumin's molecular mechanisms and to estimate if curcumin could be a new therapeutic option in advanced thyroid cancer.

METHODS

Human thyroid cancer cell lines TPC-1 (papillary), FTC-133 (follicular), and BHT-101 (anaplastic) were treated with curcumin. Using real-time PCR analysis, we investigated microRNA (miRNA) and mRNA expression levels. Cell cycle, Annexin V/PI staining, and caspase-3 activity analysis were performed to detect apoptosis. NF-κB p65 activity and cell proliferation were analyzed using appropriate ELISA-based colorimetric assay kits.

RESULTS

Treatment with 50 μM curcumin significantly increased the mRNA expression of the differentiation genes thyroglobulin (TG) and sodium iodide symporter (NIS) in all three cell lines and induced inhibition of cell proliferation, apoptosis, and decrease of NF-κB p65 activity. The miRNA expression analyses showed a significant deregulation of miRNA-200c, -21, -let7c, -26a, and -125b, known to regulate cell differentiation and tumor progression. Curcumin arrested cell growth at the G2/M phase.

CONCLUSIONS

Curcumin increases the expression of redifferentiation markers and induces G2/M arrest, apoptosis, and downregulation of NF-κB activity in thyroid carcinoma cells. Thus, curcumin appears to be a promising agent to overcome resistance to the conventional cancer therapy.

Emerging strategies for managing differentiated thyroid cancers refractory to radioiodine

Efficient treatment of radio refractory thyroid cancer is still a major challenge. The recent identification of genetic and epigenetic alterations present in almost all differentiated tumors has revealed novel molecular targets, which can hopefully be exploited to create new treatments for these tumors. This review looks briefly at some of the innovative strategies currently being investigated for the treatment the radioiodine-resistant thyroid cancers.

[What's new in follicular thyroid cancer management in 2014?]

The American Thyroid Association has presented new guidelines for the management of thyroid cancer. These guidelines tend to appreciate more accurately the individual risk of patients, to adapt accordingly the treatment and the follow up. The initial risk stratification has been completed, especially precising the risk of N1 patients, follicular thyroid cancers, and the prognostic impact of molecular markers. Indications, doses and modalities of radioiodine (RAI) have been reevaluated, restricting its utilization in order to avoid overtreatment of low risk patients. Moreover the response to initial treatment allows to restratify the risk of the patients, and to adapt the monitoring and the thyroid hormone therapy management. The risk of suppressive thyroid hormone therapy has also to be considered. Concerning advanced thyroid cancer, prognosis is mainly depending on its RAI sensitivity. The systemic treatment of progressive, threatening refractory cancers is nowadays based on targeted therapy. However none of these treatments has demonstrated an improvement in overall survival, and side effects are frequent. Fagin et al presented promising results concerning short term treatment with selective inhibitors of the MAPK pathway, able to partially restore RAI sensitivity of refractory lesions in murine models, and recently in human patients.

Phosphorus-32, a clinically available drug, inhibits cancer growth by inducing DNA double-strand breakage

Radioisotopes that emit electrons (beta particles), such as radioiodine, can effectively kill target cells, including cancer cells. Aqueous ³²P[PO₄] is a pure beta-emitter that has been used for several decades to treat non-malignant human myeloproliferative diseases. ³²P[PO₄] was directly compared to a more powerful pure beta-emitter, the clinically important ⁹⁰Y isotope. In vitro, ³²P[PO₄] was more effective at killing cells than was the more powerful isotope ⁹⁰Y (P ≤ 0.001) and also caused substantially more double-stranded DNA breaks than did ⁹⁰Y. In vivo, a single low-dose intravenous dose of aqueous elemental ³²P significantly inhibited tumor growth in the syngeneic murine cancer model (P ≤ 0.001). This effect is exerted by direct incorporation into nascent DNA chains, resulting in double-stranded breakage, a unique mechanism not duplicatable by other, more powerful electron-emitting radioisotopes. ³²P[PO₄] should be considered for human clinical trials as a potential novel anti-cancer drug.