Stimulated Raman Scattering Microscopy Reveals Aberrant Triglyceride Accumulation in Lymphatic Metastasis of Papillary Thyroid Carcinoma.

Lipid metabolic alterations are known to play a crucial role in cancer metastasis. As a key hub in lipid metabolism, intracellular neutral lipid accumulation in lipid droplets (LDs) has become a signature of aggressive human cancers. Nevertheless, it remains unclear whether lipid accumulation displays distinctive features in metastatic lesions compared to the primary ones. Here, we integrated multicolor stimulated Raman scattering (SRS) imaging with confocal Raman spectroscopy on the same platform to quantitatively analyze the amount and composition of LDs in intact human thyroid tissues in situ without any processing or labeling. Inspiringly, we found aberrant accumulation of triglycerides (TGs) in lymphatic metastases but not in normal thyroid, primary papillary thyroid carcinoma (PTC), or normal lymph node. In addition, the unsaturation degree of unsaturated TGs was significantly higher in the lymphatic metastases from patients diagnosed with late-stage (T3/T4) PTC compared to those of patients diagnosed with early-stage (T1/T2) PTC. Furthermore, both public sequencing data analysis and our RNA-seq transcriptomic experiment showed significantly higher expression of alcohol dehydrogenase-1B (ADH1B), which is critical to lipid uptake and transport, in lymphatic metastases relative to the primary ones. In summary, these findings unravel the lipid accumulation as a novel marker and therapeutic target for PTC lymphatic metastasis that has a poor response to the regular radioactive iodine therapy.

CircPHGDH downregulation decreases papillary thyroid cancer progression through miR-122-5p/PKM2 axis.

BACKGROUND: Although papillary thyroid carcinoma (PTC) has a favorable prognosis, it could affect patient life quality and become a serious threat because of invasion and metastasis. Many investigations have suggested that circular RNAs (circRNAs) are involved in different cancer regulations. Nevertheless, circRNAs role in invasive PTC remains unclear. METHODS: In the present investigation, next-generation sequencing was applied to explore abnormal circRNA expression. The expression of circRNA phosphoglycerate dehydrogenase (circPHGDH) in PTC cell lines and tissues were examined. Then, we investigated regulatory mechanism and circPHGDH downstream targets using bioinformatics analysis and luciferase reporting analysis. Then transwell migration, Cell Counting Kit-8 (CCK8) and 5-ethynyl-2'-deoxyuridine (EdU) assays were used for cells migration and proliferation analysis. In vivo metastasis and tumorigenesis assays were also employed to evaluate the circPHGDH role in PTC. RESULTS: The data showcased that circPHGDH expression increased in both PTC cell lines and tissues, which suggested that circPHGDH functions in PTC progression. circPHGDH downregulation suppressed PTC invasion and proliferation in both in vivo and in vitro experiments. Bioinformatics and luciferase reporter results confirmed that both microRNA (miR)-122-5p and pyruvate kinase M2 subtype (PKM2) were downstream targets of circPHGDH. PKM2 overexpression or miR-122-5p suppression reversed PTC cell invasion and proliferation post silencing circPHGDH by restoring aerobic glycolysis. CONCLUSION: Taken together, our research found that circPHGDH downregulation reduced PTC progression via miR-122-5p/PKM2 axis regulation mediated by aerobic glycolysis.

Case report: A rare combination of aldosterone-secreting adrenocortical carcinoma and papillary thyroid carcinoma with Graves' disease.

Adrenocortical carcinoma (ACC) is a rare malignancy originating in the adrenal glands, aldosterone-producing ACC, even rarer. Papillary thyroid carcinoma (PTC), by contrast, accounts for the majority of thyroid carcinomas. We herein describe the first reported case of a female with comorbidities of aldosterone-producing ACC, PTC, and Graves' Disease(GD). The patient achieved transient clinical remission following adrenalectomy. However, three months later, aldosterone-producing ACC lung metastases emerged. Subsequently, within another three-month interval, she developed thyroid eye disease(TED). The patient died roughly one year after the adrenal operation. Exome sequencing did not reveal associations between aldosterone-producing ACC, PTC, and GD, and the underlying concurrence mechanism has yet to be elucidated. Further research of similar cases are needed to confirm potential links between the three pathologies.

Dihydrotanshinone I exhibits antitumor effects via ß-catenin downregulation in papillary thyroid cancer cell lines.

Thyroid cancer is the most common endocrine carcinoma and, among its different subtypes, the papillary subtype (PTC) is the most frequent. Generally, PTCs are well differentiated, but a minor percentage of PTCs are characterized by a worse prognosis and more aggressive behavior. Phytochemicals, naturally found in plant products, represent a heterogeneous group of bioactive compounds that can interfere with cell proliferation and the regulation of the cell cycle, taking part in multiple signaling pathways that are often disrupted in tumor initiation, proliferation, and progression. In this work, we focused on 15,16-dihydrotanshinone I (DHT), a tanshinone isolated from Salvia miltiorrhiza Bunge (Danshen). We first evaluated DHT biological effect on PTC cells regarding cell viability, colony formation ability, and migration capacity. All of these parameters were downregulated by DHT treatment. We then investigated gene expression changes after DHT treatment by performing RNA-seq. The analysis revealed that DHT significantly reduced the Wnt signaling pathway, which plays a role in various diseases, including cancer. Finally, we demonstrate that DHT treatment decreases protein levels of ß-catenin, a final effector of canonical Wnt signaling pathway. Overall, our data suggest a possible use of this nutraceutical as an adjuvant in the treatment of aggressive papillary thyroid carcinoma.

The emerging role and clinical significance of circRNAs in papillary thyroid cancer.

Papillary thyroid cancer (PTC) is the most common type of thyroid malignancy, and its global incidence has been gradually increasing. For advanced PTC, the mortality rates are also increasing yearly. Despite advancements in diagnosis and treatment, some advanced PTC exhibit aggressive behaviors, leading to a poor prognosis. CircRNAs are a class of non-coding RNAs characterized by a covalently closed loop structure. Their stability and abundance have positioned them as promising diagnostic and prognostic biomarkers. Numerous studies have identified dysregulated circRNAs in PTC tissues and cell lines, suggesting their involvement in PTC initiation and progression. In this review, we provide an overview of circRNAs and systematically discuss their role in PTC. CircRNAs affect cancer progression by regulating the Wnt/ß-catenin, PI3K/AKT, MAPK pathways, and others. Furthermore, circRNAs have been implicated in PTC metastasis and chemoresistance. We highlight their potential value as diagnostic markers, therapeutic targets, and prognostic indicators. In conclusion, circRNAs play a critical role in PTC, and dysregulated circRNAs influence multiple signaling pathways and cellular processes involved in tumorigenesis and metastasis. It represents a promising avenue for advancing the diagnosis, management, and treatment of PTC.

Spatial transcriptomics reveals prognosis-associated cellular heterogeneity in the papillary thyroid carcinoma microenvironment.

BACKGROUND: Papillary thyroid carcinoma (PTC) is the most common malignant endocrine tumour, and its incidence and prevalence are increasing considerably. Cellular heterogeneity in the tumour microenvironment is important for PTC prognosis. Spatial transcriptomics is a powerful technique for cellular heterogeneity study. METHODS: In conjunction with a clinical pathologist identification method, spatial transcriptomics was employed to characterise the spatial location and RNA profiles of PTC-associated cells within the tissue sections. The spatial RNA-clinical signature genes for each cell type were extracted and applied to outlining the distribution regions of specific cells on the entire section. The cellular heterogeneity of each cell type was further revealed by ContourPlot analysis, monocle analysis, trajectory analysis, ligand-receptor analysis and Gene Ontology enrichment analysis. RESULTS: The spatial distribution region of tumour cells, typical and atypical follicular cells (FCs and AFCs) and immune cells were accurately and comprehensively identified in all five PTC tissue sections. AFCs were identified as a transitional state between FCs and tumour cells, exhibiting a higher resemblance to the latter. Three tumour foci were shared among all patients out of the 13 observed. Notably, tumour foci No. 2 displayed elevated expression levels of genes associated with lower relapse-free survival in PTC patients. We discovered key ligand-receptor interactions, including LAMB3-ITGA2, FN1-ITGA3 and FN1-SDC4, involved in the transition of PTC cells from FCs to AFCs and eventually to tumour cells. High expression of these patterns correlated with reduced relapse-free survival. In the tumour immune microenvironment, reduced interaction between myeloid-derived TGFB1 and TGFBR1 in tumour focus No. 2 contributed to tumourigenesis and increased heterogeneity. The spatial RNA-clinical analysis method developed here revealed prognosis-associated cellular heterogeneity in the PTC microenvironment. CONCLUSIONS: The occurrence of tumour foci No. 2 and three enhanced ligand-receptor interactions in the AFC area/tumour foci reduced the relapse-free survival of PTC patients, potentially leading to improved prognostic strategies and targeted therapies for PTC patients.

CircNRCAM up-regulates NRCAM to promote papillary thyroid carcinoma progression.

PURPOSE: Papillary Thyroid Carcinoma (PTC) is the most prevalent subtype of Thyroid Carcinoma (THCA), a type of malignancy in the endocrine system. According to prior studies, Neural Cell Adhesion Molecule (NRCAM) has been found to be up-regulated in PTC and stimulates the proliferation and migration of PTC cells. However, the specific mechanism of NRCAM in PTC cells is not yet fully understood. Consequently, this study aimed to investigate the underlying mechanism of NRCAM in PTC cells, the findings of which could provide new insights for the development of potential treatment targets for PTC. METHODS AND RESULTS: Bioinformatics tools were utilized and a series of experiments were conducted, including Western blot, colony formation, and dual-luciferase reporter assays. The data collected indicated that NRCAM was overexpressed in THCA tissues and PTC cells. Circular RNA NRCAM (circNRCAM) was found to be highly expressed in PTC cells and to positively regulate NRCAM expression. Through loss-of-function assays, both circNRCAM and NRCAM were shown to promote the proliferation, invasion, and migration of PTC cells. Mechanistically, this study confirmed that precursor microRNA-506 (pre-miR-506) could bind with m6A demethylase AlkB Homolog 5 (ALKBH5), leading to its m6A demethylation. It was also discovered that circNRCAM could competitively bind to ALKBH5, which restrained miR-506-3p expression and promoted NRCAM expression. CONCLUSION: In summary, circNRCAM could up-regulate NRCAM by down-regulating miR-506-3p, thereby enhancing the biological behaviors of PTC cells.

Targeting Nrf2 to treat thyroid cancer.

Oxidative stress (OS) is recognized as a contributing factor in the development and progression of thyroid cancer. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a pivotal transcription factor involved in against OS generated by excessive reactive oxygen species (ROS). It governs the expression of a wide array of genes implicated in detoxification and antioxidant pathways. However, studies have demonstrated that the sustained activation of Nrf2 can contribute to tumor progression and drug resistance in cancers. The expression of Nrf2 was notably elevated in papillary thyroid cancer tissues compared to normal tissues, indicating that Nrf2 may play an oncogenic role in the development of papillary thyroid cancer. Nrf2 and its downstream targets are involved in the progression of thyroid cancer by impacting the prognosis and ferroptosis. Furthermore, the inhibition of Nrf2 can increase the sensitivity of target therapy in thyroid cancer. Therefore, Nrf2 appears to be a potential therapeutic target for the treatment of thyroid cancer. This review summarized current data on Nrf2 expression in thyroid cancer, discussed the function of Nrf2 in thyroid cancer, and analyzed various strategies to inhibit Nrf2.

Unraveling the role of the mitochondrial one-carbon pathway in undifferentiated thyroid cancer by multi-omics analyses.

The role of the serine/glycine metabolic pathway (SGP) has recently been demonstrated in tumors; however, the pathological relevance of the SGP in thyroid cancer remains unexplored. Here, we perform metabolomic profiling of 17 tumor-normal pairs; bulk transcriptomics of 263 normal thyroid, 348 papillary, and 21 undifferentiated thyroid cancer samples; and single-cell transcriptomes from 15 cases, showing the impact of mitochondrial one-carbon metabolism in thyroid tumors. High expression of serine hydroxymethyltransferase-2 (SHMT2) and methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) is associated with low thyroid differentiation scores and poor clinical features. A subpopulation of tumor cells with high mitochondrial one-carbon pathway activity is observed in the single-cell dataset. SHMT2 inhibition significantly compromises mitochondrial respiration and decreases cell proliferation and tumor size in vitro and in vivo. Collectively, our results highlight the importance of the mitochondrial one-carbon pathway in undifferentiated thyroid cancer and suggest that SHMT2 is a potent therapeutic target.

Ruxolitinib induces apoptosis and pyroptosis of anaplastic thyroid cancer via the transcriptional inhibition of DRP1-mediated mitochondrial fission.

Anaplastic thyroid carcinoma (ATC) has a 100% disease-specific mortality rate. The JAK1/2-STAT3 pathway presents a promising target for treating hematologic and solid tumors. However, it is unknown whether the JAK1/2-STAT3 pathway is activated in ATC, and the anti-cancer effects and the mechanism of action of its inhibitor, ruxolitinib (Ruxo, a clinical JAK1/2 inhibitor), remain elusive. Our data indicated that the JAK1/2-STAT3 signaling pathway is significantly upregulated in ATC tumor tissues than in normal thyroid and papillary thyroid cancer tissues. Apoptosis and GSDME-pyroptosis were observed in ATC cells following the in vitro and in vivo administration of Ruxo. Mechanistically, Ruxo suppresses the phosphorylation of STAT3, resulting in the repression of DRP1 transactivation and causing mitochondrial fission deficiency. This deficiency is essential for activating caspase 9/3-dependent apoptosis and GSDME-mediated pyroptosis within ATC cells. In conclusion, our findings indicate DRP1 is directly regulated and transactivated by STAT3; this exhibits a novel and crucial aspect of JAK1/2-STAT3 on the regulation of mitochondrial dynamics. In ATC, the transcriptional inhibition of DRP1 by Ruxo hampered mitochondrial division and triggered apoptosis and GSDME-pyroptosis through caspase 9/3-dependent mechanisms. These results provide compelling evidence for the potential therapeutic effectiveness of Ruxo in treating ATC.

SIRT7 promotes the proliferation and migration of anaplastic thyroid cancer cells by regulating the desuccinylation of KIF23.

OBJECTIVE: This study was designed to investigate the regulatory effects of kinesin family member (KIF) 23 on anaplastic thyroid cancer (ATC) cell viability and migration and the underlying mechanism. METHODS: Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to analyze the levels of KIF23 in ATC cells. Besides, the effects of KIF23 and sirtuin (SIRT) 7 on the viability and migration of ATC cells were detected using cell counting kit-8, transwell and wound healing assays. The interaction between SIRT7 and KIF23 was evaluated by co-immunoprecipitation (Co-IP) assay. The succinylation (succ) of KIF23 was analyzed by western blot. RESULTS: The KIF23 expression was upregulated in ATC cells. Silencing of KIF23 suppressed the viability and migration of 8505C and BCPAP cells. The KIF23-succ level was decreased in ATC cells. SIRT7 interacted with KIF23 to inhibit the succinylation of KIF23 at K537 site in human embryonic kidney (HEK)-293T cells. Overexpression of SIRT7 enhanced the protein stability of KIF23 in HEK-293T cells. Besides, overexpression of KIF23 promoted the viability and migration of 8505C and BCPAP cells, which was partly blocked by silenced SIRT7. CONCLUSIONS: SIRT7 promoted the proliferation and migration of ATC cells by regulating the desuccinylation of KIF23.

PLK1 and FoxM1 expressions positively correlate in papillary thyroid carcinoma and their combined inhibition results in synergistic anti-tumor effects.

Polo-like kinase 1 (PLK1; also known as serine/threonine-protein kinase PLK1) serves as a central player in cell proliferation, exerting critical regulatory roles in mitotic processes and cell survival. We conducted an analysis of PLK1 protein expression in a large cohort of samples from papillary thyroid carcinoma (PTC) patients and examined its functional significance in PTC cell lines, both in vitro and in vivo. PLK1 overexpression was noted in 54.2% of all PTC and was significantly associated with aggressive clinicopathological parameters; it was also found to be an independent prognostic marker for shorter recurrence-free survival. Given the significant association between PLK1 and forkhead box protein M1 (FoxM1), and their concomitant overexpression in a large proportion of PTC samples, we explored their correlation and their combined inhibitions in PTC in vitro and in vivo. Inhibition of PLK1 expression indeed suppressed cell proliferation, leading to cell cycle arrest and apoptosis in PTC cell lines. Significantly, the downregulation of PLK1 reduced the self-renewal capability of spheroids formed from PTC cells. Immunoprecipitation analysis shows that PLK1 binds to FoxM1 and vice versa in vitro. Mechanistically, PLK1 knockdown suppresses FoxM1 expression, whereas inhibition of FoxM1 does not affect PLK1 expression, which suggests that PLK1 acts through the FoxM1 pathway. The combined treatment of a PLK1 inhibitor (volasertib) and a FoxM1 inhibitor (thiostrepton) demonstrated a synergistic effect in reducing PTC cell growth in vitro and delaying tumor growth in vivo. This study highlights the important role of PLK1 in PTC tumorigenesis and prognosis. It also highlights the synergistic therapeutic potential of dual-targeting PLK1 and FoxM1 in PTC, unveiling a potential innovative therapeutic strategy for managing aggressive forms of PTC.

Circulating small extracellular vesicle-based miRNA classifier for follicular thyroid carcinoma: a diagnostic study.

BACKGROUND: The diagnosis of follicular thyroid carcinoma (FTC) prior to surgery remains a major challenge in the clinic. METHODS: This multicentre diagnostic study involved 41 and 150 age- and sex-matched patients in the training cohort and validation cohort, respectively. The diagnostic properties of circulating small extracellular vesicle (sEV)-associated and cell-free RNAs were compared by RNA sequencing in the training cohort. Subsequently, using a quantitative real-time polymerase chain reaction (qRT‒PCR) assay, high-quality candidates were identified to construct an RNA classifier for FTC and verified in the validation cohort. The parallel expression, stability and influence of the RNA classifier on surgical strategy were also investigated. RESULTS: The diagnostic properties of sEV long RNAs, cell-free long RNAs and sEV microRNAs (miRNAs) were comparable and superior to those of cell-free miRNAs in RNA sequencing. Given the clinical application, the circulating sEV miRNA (CirsEV-miR) classifier was developed from five miRNAs based on qRT‒PCR data, which could well identify FTC patients (area under curve [AUC] of 0.924 in the training cohort and 0.844 in the multicentre validation cohort). Further tests revealed that the CirsEV-miR score was significantly correlated with the tumour burden, and the levels of sEV miRNAs were also higher in sEVs from the FTC cell line, organoid and tissue. Additionally, circulating sEV miRNAs remained constant after different treatments, and the addition of the CirsEV-miR classifier as a biomarker improves the current surgical strategy. CONCLUSIONS: The CirsEV-miR classifier could serve as a noninvasive, convenient, specific and stable auxiliary test to help diagnose FTC following ultrasonography.

Forward Genetic Screens Identify Mechanisms of Resistance to Small-Molecule Lactate Dehydrogenase Inhibitors.

Altered metabolism is a hallmark of cancer; however, it has been difficult to specifically target metabolism in cancer for therapeutic benefit. Cancers with genetically defined defects in metabolic enzymes constitute a subset of cancers where targeting metabolism is potentially accessible. Hürthle cell carcinoma of the thyroid (HTC) tumors frequently harbor deleterious mitochondrial DNA (mtDNA) mutations in subunits of complex I of the mitochondrial electron transport chain (ETC). Previous work has shown that HTC models with deleterious mtDNA mutations exhibit mitochondrial ETC defects that expose lactate dehydrogenase (LDH) as a therapeutic vulnerability. Here, we performed forward genetic screens to identify mechanisms of resistance to small-molecule LDH inhibitors. We identified two distinct mechanisms of resistance: upregulation of an LDH isoform and a compound-specific resistance mutation. Using these tools, we demonstrate that the anticancer activity of LDH inhibitors in cell line and xenograft models of complex I mutant HTC is through on-target LDH inhibition.

SHMT2 promotes papillary thyroid cancer metastasis through epigenetic activation of AKT signaling.

Cancer cells alter their metabolism and epigenetics to support cancer progression. However, very few modulators connecting metabolism and epigenetics have been uncovered. Here, we reveal that serine hydroxymethyltransferase-2 (SHMT2) generates S-adenosylmethionine (SAM) to epigenetically repress phosphatase and tensin homolog (PTEN), leading to papillary thyroid cancer (PTC) metastasis depending on activation of AKT signaling. SHMT2 is elevated in PTC, and is associated with poor prognosis. Overexpressed SHMT2 promotes PTC metastasis both in vitro and in vivo. Proteomic enrichment analysis shows that AKT signaling is activated, and is positively associated with SHMT2 in PTC specimens. Blocking AKT activation eliminates the effects of SHMT2 on promoting PTC metastasis. Furthermore, SHMT2 expression is negatively associated with PTEN, a negative AKT regulator, in PTC specimens. Mechanistically, SHMT2 catalyzes serine metabolism and produces activated one-carbon units that can generate SAM for the methylation of CpG islands in PTEN promoter for PTEN suppression and following AKT activation. Importantly, interference with PTEN expression affects SHMT2 function by promoting AKT signaling activation and PTC metastasis. Collectively, our research demonstrates that SHMT2 connects metabolic reprogramming and epigenetics, contributing to the poor progression of PTC.

CMTM 6 promotes the development of thyroid cancer by inhibiting NIS activity through activating the MAPK signaling pathway.

Thyroid cancer is the most common type of endocrine cancer. Chemokine-like factor (CKLF)-like MARVEL transmembrane domain containing 6 (CMTM6) is recognized as one of its potential immunotherapy targets. The purpose of this study was to investigate the role and molecular mechanism of CMTM6 in regulating the development of thyroid cancer cells. In this study, expression levels of CMTM6 and the sodium/iodide symporter (NIS) were detected by qRT-PCR. Additionally, colony formation assay and flow cytometry were used to detect cell proliferation and apoptosis, while expression levels of various proteins were assessed using Western blotting. Further, the apoptosis and invasion capacity of cells were investigated by scratch and transwell experiments. Finally, the effect of CMTM6 on the epithelial-mesenchymal transition (EMT) of thyroid cancer cells was determined by immunofluorescence assay, which measured the expression levels of epithelial and mesenchymal phenotypic markers. The results of qRT-PCR experiments showed that CMTM6 was highly expressed in thyroid cancer tissues and cells. In addition, knockdown of CMTM6 expression significantly increased NIS expression. Function experiments demonstrated that small interfering (si)-CMTM6 treatment inhibited the proliferation, migration, invasion, and EMT of thyroid cancer cells, while promoting apoptosis of FTC133 cells. Furthermore, mechanistic studies showed that mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) phosphorylation were inhibited by si-CMTM6, as demonstrated by Western blot experiments. In conclusion, our findings demonstrated the role of CMTM6 in the metastasis of thyroid cancer. Briefly, CMTM6 exerts its tumor-promoting effect through the MAPK signaling pathway and could potentially be used as a valuable biomarker for thyroid cancer diagnosis and prognosis.

Genetic alterations in thyroid cancer mediating both resistance to BRAF inhibition and anaplastic transformation.

A subset of thyroid cancers present at advanced stage or with dedifferentiated histology and have limited response to standard therapy. Tumors harboring the BRAF V600E mutation may be treated with BRAF inhibitors; however, tumor response is often short lived due to multiple compensatory resistance mechanisms. One mode of resistance is the transition to an alternative cell state, which on rare occasions can correspond to tumor dedifferentiation. DNA sequencing and RNA expression profiling show that thyroid tumors that dedifferentiate after BRAF inhibition are enriched in known genetic alterations that mediate resistance to BRAF blockade, and may also drive tumor dedifferentiation, including mutations in the PI3K/AKT/MTOR (PIK3CA, MTOR), MAP/ERK (MET, NF2, NRAS, RASA1), SWI/SNF chromatin remodeling complex (ARID2, PBRM1), and JAK/STAT pathways (JAK1). Given these findings, recent investigations have evaluated the efficacy of dual-target therapies; however, continued lack of long-term tumor control illustrates the complex and multifactorial nature of these compensatory mechanisms. Transition to an immune-suppressed state is another correlate of BRAF inhibitor resistance and tumor dedifferentiation, suggesting a possible role for concurrent targeted therapy with immunotherapy. Investigations into combined targeted and immunotherapy are ongoing, but early results with checkpoint inhibitors, viral therapies, and CAR T-cells suggest enhanced anti-tumor immune activity with these combinations.

YTHDC2 Retards Cell Proliferation and Triggers Apoptosis in Papillary Thyroid Cancer by Regulating CYLD-Mediated Inactivation of Akt Signaling.

N6-Methyladenosine (m6A) mRNA methylation modification is regarded as an important mechanism involved in diverse physiological processes. YT521-B homology (YTH) domain family members are associated with the tumorigenesis of several cancers. However, the role of YTHDC2 in papillary thyroid cancer (PTC) progression remains unknown. Results showed that YTHDC1, YTHDF1, YTHDF2, and YTHDF3 showed no observable difference in thyroid cancer samples. YTHDC2 was significantly downregulated in thyroid cancer samples and cells. YTHDC2 inhibited cell proliferation in PTC cells. YTHDC2 elicited apoptosis in PTC cells, as demonstrated by the elevated expression of pro-apoptotic factors cl-caspase-3/caspase-3 and Bcl-2-associated (Bax), and the reduced anti-apoptotic B cell lymphoma-2 (Bcl-2) expression. There was a positive correlation between YTHDC2 and cylindromatosis (CYLD) expression based on GEPIA database. YTHDC2 increased CYLD expression in PTC cells. CYLD knockdown abolished the effects of YTHDC2 on PTC cell proliferation and apoptosis. Additionally, YTHDC2 inactivated the protein kinase B (Akt) pathway by increasing CYLD in PTC cells. Overall, YTHDC2 inhibited cell proliferation and induced apoptosis in PTC cells by regulating CYLD-mediated inactivation of Akt pathway.

MiR-138-5p Inhibits Thyroid Cancer Cell Growth and Stemness by Targeting TRPC5/Wnt/ß-Catenin Pathway.

MicroRNAs play a key role in the pathogenesis of many types of cancer, including thyroid cancer (TC). MiR-138-5p has been confirmed to be abnormally expressed in TC tissues. However, the role of miR-138-5p in TC progression and its potential molecular mechanism need to be further explored. In this study, quantitative real-time PCR was used to examine miR-138-5p and TRPC5 expression, and western blot analysis was performed to examine the protein levels of TRPC5, stemness-related markers, and Wnt pathway-related markers. Dual-luciferase reporter assay was used to assess the interaction between miR-138-5p and TRPC5. Cell proliferation, stemness, and apoptosis were examined using colony formation assay, sphere formation assay, and flow cytometry. Our data showed that miR-138-5p could target TRPC5 and its expression was negatively correlated with TRPC5 expression in TC tumor tissues. MiR-138-5p decreased proliferation, stemness, and promoted gemcitabine-induced apoptosis in TC cells, and this effect could be reversed by TRPC5 overexpression. Moreover, TRPC5 overexpression abolished the inhibitory effect of miR-138-5p on the activity of Wnt/ß-catenin pathway. In conclusion, our data showed that miR-138-5p suppressed TC cell growth and stemness via the regulation of TRPC5/Wnt/ß-catenin pathway, which provided some guidance for studying the potential function of miR-138-5p in TC progression.