Target For Thyroid Cancer Research Articles

TFCP2L1, a potential differentiation regulator, predicts favorable prognosis and dampens thyroid cancer progression.

Thyroid cancer has an overwhelming incidence in the population. Thus, there is an urgent need to understand the underlying mechanism of its occurrence and development, which may provide new insights into therapeutic strategies. The role and mechanism of TFCP2L1 in regulating the progression of thyroid cancer remains unclear. Public databases and clinical samples were used to detect the expression of TFCP2L1 in cancer and non-cancer tissues. Kaplan-Meier and Cox regression analyses were used to compare the differences in survival probability of the TFCP2L1 highly expressing group and the TFCP2L1 lowly expressing group. Functional assays were used to evaluate the biological effect of TFCP2L1 on thyroid cancer cells. RNA sequencing and enrichment analyses were used to find out pathways that were activated or inactivated by TFCP2L1. We demonstrated that TFCP2L1 was significantly downregulated in thyroid cancer. Decreased expression of TFCP2L1 was associated with malignant clinicopathological characteristics. Kaplan-Meier and Cox regression analyses indicated that thyroid tumor patients with low TFCP2L1 expression presented shorter disease-free interval and progression-free interval. Additionally, TFCP2L1 expression was positively correlated with thyroid differentiation degree. Overexpression of TFCP2L1 in thyroid cancer cells inhibited cell growth and motility in vitro, and tumorigenicity and metastasis in vivo. Mechanistically, the NF-κB signaling pathway was found inactivated by overexpressing TFCP2L1. Our results suggest that TFCP2L1 is a tumor suppressor and potential differentiation regulator, and might be a potential therapeutic target in thyroid cancer.

Coexisting RET/PTC and TERT Promoter Mutation Predict Poor Prognosis but Effective RET and MEK Targets in Thyroid Cancer.

To investigate the role of coexisting RET/PTC rearrangement and TERT promoter mutation in the prognosis and therapeutic targeting in papillary thyroid cancer (PTC). A total of 669 PTC patients with complete clinical follow-up and genetic data were pooled from thyroid cancer datasets TCGA, MSK MetTropism, and MSK-IMPACT, from whom 163 patients (112 women and 47 men, 4 unknown) with wild-type BRAF/RAS were identified, with median age (IQR) of 46.00 (33.00, 61.00) years and median follow-up time (IQR) of 16.13 (8.09, 27.91) months for comparative genotype cohort analysis of mortality. There was a significant concurrence index between RET/PTC and TERT promoter mutations, being 2.040 (95% CI 1.110-3.747, P = 0.023). Mortality occurred in 5/100 (5%) patients harboring neither mutation, 2/18 (11.1%) patients harboring TERT promoter mutation alone, 0/31 (0%) patients harboring RET/PTC alone, and 7/14 (50%) patients harboring both genetic alterations, corresponding to HRs (95% CI) of 1 (Reference), 2.469 (0.405-14.02), 3.296e-09 (0-inf), and 9.019 (2.635-30.87), respectively, which remained essentially unchanged after adjustment for patient race, sex, and age. Similar results were observed with BRAF/RAS and TERT promoter mutations. Mechanistically, RET/PTC used the MAP kinase pathway to upregulate the mutated TERT, but not the wild-type TERT, and, correspondingly, targeting RET and MEK could suppress mutated TERT but not the wild-type TERT. Coexisting RET/PTC and TERT promoter mutation identify PTC as a unique clinical entity with high mortality, providing new implications for genetic-based prognostication and potential therapeutic targeting of RET and MEK guided by RET/PTC and TERT status.

COL4A2 enhances thyroid cancer cell proliferation through the AKT pathway.

Thyroid cancer (THCA) is the most common malignant tumor in endocrine system and the incidence has been increasing worldwide. And the number of patients dying from THCA has also gradually risen because the incidence continues to increase, so the mechanisms related to effective targets is necessary to improve the survival. This study was to preliminarily investigate the effects of the COL4A2 gene on the regulation of thyroid cancer (THCA) cell proliferation and the associated pathways. Bioinformatics analysis revealed that COL4A2 was closely associated with cancer development. COL4A2 expression in THCA tissues was analyzed using immunohistochemistry, and survival information was determined via Kaplan‒Meier curves. The expression of COL4A2 and AKT pathway-related genes were analyzed using qPCR and western blot analyses. Colony formation as well as CCK-8 assays exhibited the cell proliferation level and cell activity, respectively. Downstream of COL4A2 was identified by Gene set enrichment analysis (GSEA). The effects of the COL4A2 and AKT pathways on THCA tumor growth in vivo were determined using a mouse model. Bioinformatics analysis exhibited that COL4A2 plays a significant role in cancer and that the AKT pathway is downstream of COL4A2. THCA patients with high COL4A2 expression had shorter recurrence-free survival. Upregulation of COL4A2 gene expression in 2 THCA cell lines promoted tumor cell growth and activity. The use of AKT pathway blockers also restrained the growth and activity of the 2 THCA cell lines. The use of AKT pathway blockers reduced tumor volume and mass and prolonged mouse survival. COL4A2 can promote the growth as well as development of THCA through the AKT pathway and COL4A2 could be used as a target for THCA.

Abstract C012: Exploring thrombospondin-1 variant and splicing factors as potential diagnostic biomarkers and therapeutic targets in thyroid cancer

Abstract Thyroid cancer is the most common type of cancer affecting the thyroid gland, accounting for 11.8% of all cancer cases in Korea as of 2020. The majority of thyroid cancer cases belong to the papillary thyroid cancer (PTC) subtype. Diagnostic methods for thyroid cancer include blood tests, ultrasound examinations, fine needle aspiration cytology (FNAC), PET/CT scans, and others. However, distinguishing between different subtypes of thyroid cancer, such as follicular variant of papillary thyroid carcinoma (FVPTC), follicular adenoma (FA), and follicular thyroid carcinoma (FTC), remains challenging, often leading to unnecessary surgeries for patients. In this study, antibody arrays were used to analyze tumor and adjacent normal tissues from thyroid cancer patients. Thrombospondin 1 (TSP1), was found to be more highly expressed in tumor tissue compared to normal tissue. TSP1 is a glycoprotein with diverse biological functions that can either inhibit or promote tumorigenesis depending on the context. The researchers discovered a transcriptional variant of TSP1 (TSP1V) generated by intron retention (IR), which was more highly expressed in normal tissue compared to tumor tissue. Overexpression of TSP1V in thyroid cancer cells resulted in the secretion of the protein into the medium or its deposition in the extracellular matrix (ECM). TSP1V exhibited anti-cancer properties, inhibiting proliferation, migration, invasion, colony formation, and spheroid formation of thyroid cancer cells in vitro. It also suppressed tumor growth in a mouse experiment. The researchers explored the TGF-β pathway, a well-known signaling pathway associated with TSP1, and found that TSP1V inhibited the phosphorylation of Smad2 and FAK, unlike TSP1 wild-type (TSP1W). To investigate the mechanism behind TSP1V's generation through IR, we examined splicing factors. RBM5 overexpression inhibited IR induced by anti-cancer compounds, while RBM5 knockdown increased IR. Sulindac sulfide, one of the compounds tested, increased IR by inhibiting the phosphorylation of RBM5. Additionally, trans-chalcone was found to increase IR by demethylating DNA. Trans-chalcone also reduced the expression of TSP1W, DNMT3b, and MeCP2 in a time-dependent manner. The study concluded by analyzing tumor and adjacent normal tissues from patients with follicular neoplasm (FN), including benign thyroid nodule (BTN) and differentiated thyroid carcinoma (DTC). We also observed significant differences in the ratio of TSP1V to TSP1W. These findings provide evidence that secreted proteins like TSP1 have the potential to serve as diagnostic biomarkers and therapeutic targets for thyroid cancer. Moreover, the study enhances our understanding of the molecular mechanisms underlying the anti-cancer activities of these proteins. Citation Format: Yukyung Hong, Ilju Kim, Hyunjin Moon, Jaehak Lee, Pattawika Lertpatipanpong, Chang Hwan Ryu, Junsun Ryu, Seung Joon Baek. Exploring thrombospondin-1 variant and splicing factors as potential diagnostic biomarkers and therapeutic targets in thyroid cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C012.

Tumor-associated macrophages as a potential therapeutic target in thyroid cancers.

Macrophages are important precursor cell types of the innate immune system and bridge adaptive immune responses through the antigen presentation system. Meanwhile, macrophages constitute substantial portion of the stromal cells in the tumor microenvironment (TME) (referred to as tumor-associated macrophages, or TAMs) and exhibit conflicting roles in the development, invasion, and metastasis of thyroid cancer (TC). Moreover, TAMs play a crucial role to the behavior of TC due to their high degree of infiltration and prognostic relevance. Generally, TAMs can be divided into two subgroups; M1-like TAMs are capable of directly kill tumor cells, and recruiting and activating other immune cells in the early stages of cancer. However, due to changes in the TME, M2-like TAMs gradually increase and promote tumor progression. This review aims to discuss the impact of TAMs on TC, including their role in tumor promotion, gene mutation, and other factors related to the polarization of TAMs. Finally, we will explore the M2-like TAM-centered therapeutic strategies, including chemotherapy, clinical trials, and combinatorial immunotherapy.

Targeting the inward rectifier potassium channel 5.1 in thyroid cancer: artificial intelligence-facilitated molecular docking for drug discovery

BackgroundRecurrent and metastatic thyroid cancer is more invasive and can transform to dedifferentiated thyroid cancer, thus leading to a severe decline in the 10-year survival. The thyroid-stimulating hormone receptor (TSHR) plays an important role in differentiation process. We aim to find a therapeutic target in redifferentiation strategies for thyroid cancer.MethodsOur study integrated the differentially expressed genes acquired from the Gene Expression Omnibus database by comparing TSHR expression levels in the Cancer Genome Atlas database. We conducted functional enrichment analysis and verified the expression of these genes by RT-PCR in 68 pairs of thyroid tumor and paratumor tissues. Artificial intelligence-enabled virtual screening was combined with the VirtualFlow platform for deep docking.ResultsWe identified five genes (KCNJ16, SLC26A4, TG, TPO, and SYT1) as potential cancer treatment targets. TSHR and KCNJ16 were downregulated in the thyroid tumor tissues, compared with paired normal tissues. In addition, KCNJ16 was lower in the vascular/capsular invasion group. Enrichment analyses revealed that KCNJ16 may play a significant role in cell growth and differentiation. The inward rectifier potassium channel 5.1 (Kir5.1, encoded by KCNJ16) emerged as an interesting target in thyroid cancer. Artificial intelligence-facilitated molecular docking identified Z2087256678_2, Z2211139111_1, Z2211139111_2, and PV-000592319198_1 (-7.3 kcal/mol) as the most potent commercially available molecular targeting Kir5.1.ConclusionThis study may provide greater insights into the differentiation features associated with TSHR expression in thyroid cancer, and Kir5.1 may be a potential therapeutic target in the redifferentiation strategies for recurrent and metastatic thyroid cancer.

Challenges and Strategies to Combat Resistance Mechanisms in Thyroid Cancer Therapeutics.

Background: BRAFV600E and N/H/K RAS mutations and oncogenic kinase fusions involving neurotrophin tyrosine receptor kinase (NTRK), RET, anaplastic lymphoma kinase (ALK), and ROS1 have been identified as actionable targets in thyroid cancer. These driver alterations lead to oncogene addiction, which has been successfully exploited through tyrosine kinase inhibitors. Acquired resistance may develop following an initial response requiring a therapeutic pivot to new therapies. Summary: Several pathways for development of acquired resistance have been identified. These encompass acquired on-target gene mutation impeding drug activity and upregulation of bypass kinase signaling pathways leading to tumor progression. Biopsy of resistant lesions (liquid or tissue) and subsequent molecular analysis can assist with new therapeutic strategies. Conclusions: Progression-free survival is curtailed by developing acquired resistance. To minimize this therapeutic liability, clinicians must be anticipatory in identifying the drivers and characterizing mechanisms of on-target resistance.

Epigenetic Targets and Their Inhibitors in Thyroid Cancer Treatment.

Although biologically targeted therapies based on key oncogenic mutations have made significant progress in the treatment of locally advanced or metastatic thyroid cancer, the challenges of drug resistance are urging us to explore other potentially effective targets. Herein, epigenetic modifications in thyroid cancer, including DNA methylation, histone modifications, non-coding RNAs, chromatin remodeling and RNA alterations, are reviewed and epigenetic therapeutic agents for the treatment of thyroid cancer, such as DNMT (DNA methyltransferase) inhibitors, HDAC (histone deacetylase) inhibitors, BRD4 (bromodomain-containing protein 4) inhibitors, KDM1A (lysine demethylase 1A) inhibitors and EZH2 (enhancer of zeste homolog 2) inhibitors, are updated. We conclude that epigenetics is promising as a therapeutic target in thyroid cancer and further clinical trials are warranted.

Disulfiram/Cu Kills and Sensitizes BRAF-Mutant Thyroid Cancer Cells to BRAF Kinase Inhibitor by ROS-Dependently Relieving Feedback Activation of MAPK/ERK and PI3K/AKT Pathways

BRAFV600E, the most common genetic alteration, has become a major therapeutic target in thyroid cancer. Vemurafenib (PLX4032), a specific inhibitor of BRAFV600E kinase, exhibits antitumor activity in patients with BRAFV600E-mutated thyroid cancer. However, the clinical benefit of PLX4032 is often limited by short-term response and acquired resistance via heterogeneous feedback mechanisms. Disulfiram (DSF), an alcohol-aversion drug, shows potent antitumor efficacy in a copper (Cu)-dependent way. However, its antitumor activity in thyroid cancer and its effect on cellular response to BRAF kinase inhibitors remain unclear. Antitumor effects of DSF/Cu on BRAFV600E-mutated thyroid cancer cells and its effect on the response of these cells to BRAF kinase inhibitor PLX4032 were systematically assessed by a series of in vitro and in vivo functional experiments. The molecular mechanism underlying the sensitizing effect of DSF/Cu on PLX4032 was explored by Western blot and flow cytometry assays. DSF/Cu exhibited stronger inhibitory effects on the proliferation and colony formation of BRAFV600E-mutated thyroid cancer cells than DSF treatment alone. Further studies revealed that DSF/Cu killed thyroid cancer cells by ROS-dependent suppression of MAPK/ERK and PI3K/AKT signaling pathways. Our data also showed that DSF/Cu strikingly increased the response of BRAFV600E-mutated thyroid cancer cells to PLX4032. Mechanistically, DSF/Cu sensitizes BRAF-mutant thyroid cancer cells to PLX4032 by inhibiting HER3 and AKT in an ROS-dependent way and subsequently relieving feedback activation of MAPK/ERK and PI3K/AKT pathways. This study not only implies potential clinical use of DSF/Cu in cancer therapy but also provides a new therapeutic strategy for BRAFV600E-mutated thyroid cancers.

A Review and In Silico Analysis of Tissue and Exosomal Circular RNAs: Opportunities and Challenges in Thyroid Cancer.

Simple SummaryThyroid cancer is the most common endocrine neoplasm. Recently, knowledge of the molecular genetic changes of thyroid cancer has dramatically improved. Understanding the roles of these molecular changes in thyroid cancer tumorigenesis and progression is essential in developing a successful treatment strategy and improving disease outcomes. As a family of non-coding RNAs, circular RNAs (circRNAs) have been involved in several aspects of the physiological and pathological processes of the cells. The roles of circRNAs in cancer development and progress are evident. In the current review, we aimed to explore the clinical potential of circRNAs as potential diagnostic, prognostic, and therapeutic targets in thyroid cancer. Furthermore, screening the genome-wide circRNAs and performing functional enrichment analyses for all associated dysregulated circRNAs in thyroid cancer have been done. Given the unique advantages circRNAs have, such as superior stability, higher abundance, and presence in different body fluids, this family of non-coding RNAs could be promising diagnostic and prognostic biomarkers and potential therapeutic targets for thyroid cancer.Thyroid cancer (TC) is the most common endocrine tumor. The genetic and epigenetic molecular alterations of TC have become more evident in recent years. However, a deeper understanding of the roles these molecular changes play in TC tumorigenesis and progression is essential in developing a successful treatment strategy and improving patients’ prognoses. Circular RNAs (circRNAs), a family of non-coding RNAs, have been implicated in several aspects of carcinogenesis in multiple cancers, including TC. In the current review, we aimed to explore the clinical potential of circRNAs as putative diagnostic, prognostic, and therapeutic targets in TC. The current analyses, including genome-wide circRNA screening and functional enrichment for all deregulated circRNA expression signatures, show that circRNAs display atypical contributions, such as sponging for microRNAs, regulating transcription and translation processes, and decoying for proteins. Given their exceptional clinical advantages, such as higher stability, wider abundance, and occurrence in several body fluids, circRNAs are promising prognostic and theranostic biomarkers for TC.

Expression of epithelial membrane protein (EMP) 1, EMP 2, and EMP 3 in thyroid cancer.

Purpose Epithelial membrane protein (EMP) 1, EMP2, and EMP3 are expressed in various types of tumors and have been reported to be involved in carcinogenesis. In this study, we aimed to investigate the expression of these proteins in primary and metastatic thyroid cancer and its clinical implication. Methods EMP1, EMP2, and EMP3 immunohistochemistry was performed using tissue microarrays of 545 primary thyroid carcinomas [338 papillary thyroid carcinoma (PTC), 111 follicular carcinoma (FC), 69 medullary carcinoma (MC), 23 poorly differentiated carcinoma (PDC), and 4 anaplastic carcinoma (AC)] and 59 recurrent or metastatic PTCs. Results EMP1 showed high expression in AC, PTC, FC (P<0.001), and EMP2 was highly expressed in AC (P<0.001). EMP1 and EMP2 were not expressed in stromal cells. Expression of EMP3 in tumor cells [EMP3 (T)] was higher in PDC, PTC, and AC (P<0.001), and expression in stromal cells [EMP3 (S)] was observed only in AC and PTC (P=0.001). The expression of EMP1 (P=0.002) and EMP3 (T) (P<0.001) was higher in conventional PTC than in follicular variant PTC. PTC with BRAF V600E mutation showed higher expression of EMP1 (P<0.001), EMP3 (T) (P<0.001), and EMP3 (S) (P=0.012) than PTC without BRAF V600E mutation. In the PTC without BRAF V600E mutation group, expression of EMP3 (S) was associated with shorter disease free survival (P=0.004). Metastatic PTC showed higher EMP2 (3.4% vs. 0%, P=0.022) and lower EMP3 (T) (44.1% vs. 66%, P=0.001) than primary PTC. Conclusions Expression of EMP1, EMP2, and EMP3 is different according to the subtypes of thyroid cancer. Further studies are needed to determine their role as prognostic markers and treatment target in thyroid cancer.

Pralsetinib for patients with advanced or metastatic RET-altered thyroid cancer (ARROW): a multi-cohort, open-label, registrational, phase 1/2 study

Oncogenic alterations in RET represent important therapeutic targets in thyroid cancer. We aimed to assess the safety and antitumour activity of pralsetinib, a highly potent, selective RET inhibitor, in patients with RET-altered thyroid cancers. ARROW, a phase 1/2, open-label study done in 13 countries across 71 sites in community and hospital settings, enrolled patients 18 years or older with RET-altered locally advanced or metastatic solid tumours, including RET-mutant medullary thyroid and RET fusion-positive thyroid cancers, and an Eastern Co-operative Oncology Group performance status of 0-2 (later limited to 0-1 in a protocol amendment). Phase 2 primary endpoints assessed for patients who received 400 mg once-daily oral pralsetinib until disease progression, intolerance, withdrawal of consent, or investigator decision, were overall response rate (Response Evaluation Criteria in Solid Tumours version 1.1; masked independent central review) and safety. Tumour response was assessed for patients with RET-mutant medullary thyroid cancer who had received previous cabozantinib or vandetanib, or both, or were ineligible for standard therapy and patients with previously treated RET fusion-positive thyroid cancer; safety was assessed for all patients with RET-altered thyroid cancer. This ongoing study is registered with clinicaltrials.gov, NCT03037385, and enrolment of patients with RET fusion-positive thyroid cancer was ongoing at the time of this interim analysis. Between Mar 17, 2017, and May 22, 2020, 122 patients with RET-mutant medullary and 20 with RET fusion-positive thyroid cancers were enrolled. Among patients with baseline measurable disease who received pralsetinib by July 11, 2019 (enrolment cutoff for efficacy analysis), overall response rates were 15 (71%) of 21 (95% CI 48-89) in patients with treatment-naive RET-mutant medullary thyroid cancer and 33 (60%) of 55 (95% CI 46-73) in patients who had previously received cabozantinib or vandetanib, or both, and eight (89%) of nine (95% CI 52-100) in patients with RET fusion-positive thyroid cancer (all responses confirmed for each group). Common (≥10%) grade 3 and above treatment-related adverse events among patients with RET-altered thyroid cancer enrolled by May 22, 2020, were hypertension (24 patients [17%] of 142), neutropenia (19 [13%]), lymphopenia (17 [12%]), and anaemia (14 [10%]). Serious treatment-related adverse events were reported in 21 patients (15%), the most frequent (≥2%) of which was pneumonitis (five patients [4%]). Five patients [4%] discontinued owing to treatment-related events. One (1%) patient died owing to a treatment-related adverse event. Pralsetinib is a new, well-tolerated, potent once-daily oral treatment option for patients with RET-altered thyroid cancer. Blueprint Medicines.

New advances in novel targets for thyroid cancer and thyroid cancer theragnostics

New advances in novel targets for thyroid cancer and thyroid cancer theragnostics

Identification of TNIK as a novel potential drug target in thyroid cancer based on protein druggability prediction.

Thyroid cancer is a common endocrine malignancy; however, surgery remains its primary treatment option. A novel targeted drug for the development and application of targeted therapy in thyroid cancer treatment remain underexplored.We obtained RNA sequence data of thyroid cancer from The Cancer Genome Atlas database and identified differentially expressed genes (DEGs). Then, we constructed co-expression network with DEGs and combined it with differentially methylation analysis to screen the key genes in thyroid cancer. PockDrug-Server, an online tool, was applied to predict the druggability of the key genes. Finally, we constructed protein-protein interaction (PPI) network to observe potential targeted drugs for thyroid cancer.We identified 3 genes correlated with altered DNA methylation level and oncogenesis of thyroid cancer. According to the druggable analysis and PPI network, we predicted TRAF2 and NCK-interacting protein kinase (TNIK) sever as the drug targeted for thyroid cancer. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that genes in protein-protein interaction network of TNIK enriched in mitogen-activated protein kinase signaling pathway. For drug repositioning, we identified a targeted drug of genes in PPI network.Our study provides a bioinformatics method for screening drug targets and provides a theoretical basis for thyroid cancer targeted therapy.

Tumor Cells and Cancer-Associated Fibroblasts: A Synergistic Crosstalk to Promote Thyroid Cancer.

Thyroid cancer is the most common endocrine malignancy. Although most thyroid cancer patients are successfully treated and have an excellent prognosis, a percentage of these patients will develop aggressive disease and, eventually, progress to anaplastic thyroid cancer. Since most patients with this type of aggressive thyroid carcinoma will die from the disease, new treatment strategies are urgently needed. Tumor cells live in a complex and dynamic tumor microenvironment composed of different types of stromal cells. Cancer-associated fibroblasts (CAFs) are one of the most important cell components in the tumor microenvironment of most solid tumors, including thyroid cancer. CAFs originate mainly from mesenchymal cells and resident fibroblasts that are activated and reprogrammed in response to paracrine factors and cytokines produced and released by tumor cells. Upon reprogramming, which is distinguished by the expression of different marker proteins, CAFs synthesize and secret soluble factors. The secretome of CAFs directly impacts different functions of tumor cells. This bi-directional interplay between CAFs and tumor cells within the tumor microenvironment ends up fostering tumor cancer progression. CAFs are therefore key regulators of tumor progression and represent an under-explored therapeutic target in thyroid cancer.

New Horizons: Emerging Therapies and Targets in Thyroid Cancer.

The treatment of patients with progressive metastatic follicular cell-derived and medullary thyroid cancers that do not respond to standard therapeutic modalities presents a therapeutic challenge. As a deeper understanding of the molecular drivers for these tumors has occurred and more potent and specific compounds are developed, the number of Food and Drug Administration (FDA)-approved treatments for thyroid cancer has expanded. In addition, with the advent of disease-agnostic target-directed FDA approvals an ever-broadening number of therapeutic options are available for clinicians and patients. However, to date, complete remissions are rare, the average durations of response are relatively modest, and toxicities are common. These factors accentuate the need for further understanding of the mechanisms of resistance that result in treatment failures, the development of biomarkers that can improve patient selection for treatment earlier in the disease process, and the continued need for new therapeutic strategies. In this article, recent approvals relevant to thyroid cancer will be discussed along with selected new potential avenues that might be exploited for future therapies.

CYP2S1 is a synthetic lethal target in BRAFV600E-driven thyroid cancers

BRAFV600E is the most common genetic alteration and has become a major therapeutic target in thyroid cancers; however, intrinsic feedback mechanism limited clinical use of BRAFV600E specific inhibitors. Synthetic lethal is a kind of interaction between two genes, where only simultaneously perturbing both of the genes can lead to lethality. Here, we identified CYP2S1 as a synthetic lethal partner of BRAFV600E in thyroid cancers. First, we found that CYP2S1 was highly expressed in papillary thyroid cancers (PTCs) compared to normal thyroid tissues, particularly in conventional PTCs (CPTCs) and tall-cell PTCs (TCPTCs), and its expression was positively associated with BRAFV600E mutation. CYP2S1 knockdown selectively inhibited cell proliferation, migration, invasion and tumorigenic potential in nude mice, and promoted cell apoptosis in BRAFV600E mutated thyroid cancer cells, but not in BRAF wild-type ones. Mechanistically, BRAFV600E-mediated MAPK/ERK cascade upregulated CYP2S1 expression by an AHR-dependent pathway, while CYP2S1 in turn enhanced transcriptional activity of AHR through its metabolites. This AHR/CYP2S1 feedback loop strongly amplified oncogenic role of BRAFV600E in thyroid cancer cells, thereby causing synthetic lethal interaction between CYP2S1 and BRAFV600E. Finally, we demonstrated CYP2S1 as a potential therapeutic target in both BRAFV600E-drived xenograft and transgenic mouse models by targetedly delivering CYP2S1-specific siRNA. Altogether, our data demonstrate CYP2S1 as a synthetic lethal partner of BRAFV600E in thyroid cancers, and indicate that targeting CYP2S1 will provide a new therapeutic strategy for BRAFV600E mutated thyroid cancers.

Downregulation of miR-140 is Correlated with Poor Prognosis and Progression of Thyroid Cancer.

The incidence of thyroid cancer is increasing rapidly and there is an urgent need to explore novel therapeutic targets for thyroid cancer. MiR-140 has been reported to affect the progression of various cancers, which makes it possible to play a role in thyroid cancer. This study aimed to investigate the expression and role of miR-140 in thyroid cancer. The expression of miR-140 was investigated by reverse transcription-quantitative polymerase chain reaction (qRT-PCR) in thyroid cancer tissues and cell lines. The prognostic value of miR- 140 in thyroid cancer was evaluated by Kaplan-Meier survival and Cox regression. Moreover, the effects of miR-140 on cell proliferation, migration, and invasion of thyroid cancer were investigated by CCK-8 and Transwell assay. MiR-140 was downregulated in thyroid cancer tissues and cells, which correlated with TNM stage and lymph node metastasis of patients. Patients with low miR-140 expression had a shorter survival time compared with that in patients with high miR-140 expression. Furthermore, miR-140 acts as an independent factor for the prognosis of thyroid cancer. Overexpression of miR-140 inhibited cell proliferation, migration, and invasion of thyroid cancer. MiR-140 can serve as a potential prognostic factor for patients with thyroid cancer and suppress the progression of thyroid cancer, which provides new insight for the therapeutic target for thyroid cancer.

Amino Acid Transporters as Potential Therapeutic Targets in Thyroid Cancer.

Thyroid cancer cells have a high amino acid demand for proliferation, invasion, and metastasis. Amino acids are taken up by thyroid cancer cells, both thyroid follicular cell and thyroid parafollicular cells (commonly called “C-cells”), via amino acid transporters. Amino acid transporters up-regulate in many cancers, and their expression level associate with clinical aggressiveness and prognosis. This is the review to discuss the therapeutic potential of amino acid transporters and as molecular targets in thyroid cancer.

Identification of PTK7 as a promising therapeutic target for thyroid cancer.

To evaluate the possible involvement of PTK7 in the progression of human thyroid cancer and assess its potential effects on the proliferation and apoptosis of thyroid cancer. Immunohistochemical (IHC) assays and clinical significance analysis were performed to explore the correlations between PTK7 expression and clinical characteristics of patients with thyroid cancer. Quantitative PCR assays and Immunoblot assays were performed to detect the expression of PTK7 in control or PTK7 shRNA plasmids transfected thyroid cancer cells. MTT assays were performed to detect the effects on the proliferation of thyroid cancer cells. Flow cytometry (FCM) assays were performed to assess the changes in cell apoptosis of thyroid cancer. Additionally, the effects of PTK7 on tumor growth were detected through in vivo tumor growth assays. PTK7 is highly expressed in human thyroid cancer tissues, and its expression levels are associated with the clinical characteristics, including TNM stage (p=0.015*), and intraglandular dissemination (p=0.024*) of patients with thyroid cancer. PTK7 ablation inhibits cell proliferation and stimulates cell apoptosis of thyroid cancer in vitro. Additionally, PTK7 contributes to tumor growth of thyroid cancer cells in mice. We demonstrated the involvement of PTK7in the progression of thyroid cancer, and therefore provided a novel and promising therapeutic target for thyroid cancer treatment.