Prosapogenin A induces GSDME-dependent pyroptosis of anaplastic thyroid cancer through vacuolar ATPase activation-mediated lysosomal over-acidification.

Anaplastic thyroid cancer (ATC) is among the most aggressive and metastatic malignancies, often resulting in fatal outcomes due to the lack of effective treatments. Prosapogenin A (PA), a bioactive compound prevalent in traditional Chinese herbs, has shown potential as an antineoplastic agent against various human tumors. However, its effects on ATC and the underlying mechanism remain unclear. Here, we demonstrate that PA exhibits significant anti-ATC activity both in vitro and in vivo by inducing GSDME-dependent pyroptosis in ATC cells. Mechanistically, PA promotes lysosomal membrane permeabilization (LMP), leading to the release of cathepsins that activate caspase 8/3 to cleave GSDME. Remarkably, PA significantly upregulates three key functional subunits of V-ATPase-ATP6V1A, ATP6V1B2, and ATP6V0C-resulting in lysosomal over-acidification. This over-acidification exacerbates LMP and subsequent lysosomal damage. Neutralization of lysosomal lumen acidification or inhibition/knockdown of these V-ATPase subunits attenuates PA-induced lysosomal damage, pyroptosis and growth inhibition of ATC cells, highlighting the critical role for lysosomal acidification and LMP in PA's anticancer effects. In summary, our findings uncover a novel link between PA and lysosomal damage-dependent pyroptosis in cancer cells. PA may act as a V-ATPase agonist targeting lysosomal acidification, presenting a new potential therapeutic option for ATC treatment.

Ophiopogonin D' inhibited tumour growth and metastasis of anaplastic thyroid cancer by modulating JUN/RGS4 signalling.

Anaplastic thyroid cancer (ATC), an aggressive malignancy with virtually 100% disease-specific mortality, has long posed a formidable challenge in oncology due to its resistance to conventional treatments and the severe side effects associated with current regimens such as doxorubicin chemotherapy. Consequently, there was urgent need to identify novel candidate compounds that could provide innovative therapeutic strategies for ATC. Ophiopogonin D' (OPD'), a triterpenoid saponin extracted, yet its roles in ATC has not been reported. Our data demonstrated that OPD' potently inhibited proliferation and metastasis of ATC cells, promoting cell cycle arrest and apoptosis. Remarkably, OPD' impeded growth and metastasis of ATC in vitro and in vivo, displaying an encouraging safety profile. Regulator of G-protein signalling 4 (RGS4) expression was significantly up-regulated in ATC compared to normal tissues, and this upregulation was suppressed by OPD' treatment. Mechanistically, we elucidated that the transcription factor JUN bound to the RGS4 promoter, driving its transactivation. However, OPD' interacted with JUN, attenuating its transcriptional activity and thereby disrupting RGS4 overexpression. In summary, our research revealed that OPD' bound with JUN, which in turn resulted in the suppression of transcriptional activation of RGS4, thereby eliciting cell cycle arrest and apoptosis in ATC cells. These findings could offer promise in the development of high-quality candidate compounds for treatment in ATC.

Selective anti-tumor activity of glutathione-responsive abasic site trapping agent in anaplastic thyroid carcinoma.

Anaplastic thyroid carcinoma (ATC) is a rare but highly aggressive thyroid cancer with poor prognosis. Killing cancer cells by inducing DNA damage or blockage of DNA repair is a promising strategy for chemotherapy. It is reported that aldehyde-reactive alkoxyamines can capture the AP sites, one of the most common DNA lesions, and inhibit apurinic/apyrimidinic endonuclease 1(APE1)-mediated base excision repair (BER), leading to cell death. Whether this strategy can be employed for ATC treatment is rarely investigated. The aim of this study is to exploit GSH-responsive AP site capture reagent (AP probe-net), which responses to the elevated glutathione (GSH) levels in the tumor micro-environment (TME), releasing reactive alkoxyamine to trap AP sites and block the APE1-mediated BER for targeted anti-tumor activity against ATC. In vitro experiments, including MTT andγ-H2AX assays, demonstrate their selective cytotoxicity towards ATC cells over normal thyroid cells. Flow cytometry analysis suggests that AP probe-net arrests the cell cycle in the G2/M phase and induces apoptosis. Western blotting (WB) results show that the expression of apoptotic protein increased with the increased concentration of AP probe-net. Further in vivo experiments reveal that the AP probe-net has a good therapeutic effect on subcutaneous tumors of the ATC cells. In conclusion, taking advantage of the elevated GSH in TME, our study affords a new strategy for targeted chemotherapy of ATC with high selectivity and reduced adverse effects.

Disrupting glycolysis and DNA repair in anaplastic thyroid cancer with nucleus-targeting platinum nanoclusters.

Cancer cells rely on aerobic glycolysis and DNA repair signals to drive tumor growth and develop drug resistance. Yet, fine-tuning aerobic glycolysis with the assist of nanotechnology, for example, dampening lactate dehydrogenase (LDH) for cancer cell metabolic reprograming remains to be investigated. Here we focus on anaplastic thyroid cancer (ATC) as an extremely malignant cancer with the high expression of LDH, and develop a pH-responsive and nucleus-targeting platinum nanocluster (Pt@TAT/sPEG) to simultaneously targets LDH and exacerbates DNA damage. Pt@TAT/sPEG effectively disrupts LDH activity, reducing lactate production and ATP levels, and meanwhile induces ROS production, DNA damage, and apoptosis in ATC tumor cells. We found Pt@TAT/sPEG also blocks nucleotide excision repair pathway and achieves effective tumor cell killing. In an orthotopic ATC xenograft model, Pt@TAT/sPEG demonstrates superior tumor growth suppression compared to Pt@sPEG and cisplatin. This nanostrategy offers a feasible approach to simultaneously inhibit glycolysis and DNA repair for metabolic reprogramming and enhanced tumor chemotherapy.

PFKFB3 facilitates cell proliferation and migration in anaplastic thyroid carcinoma via the WNT/ß-catenin signaling pathway.

PURPOSE: Despite the involvement of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase3 (PFKFB3) in the proliferation and metastasis of diverse tumor types, its biological functions and related molecular mechanisms in anaplastic thyroid carcinoma (ATC) remain largely unclear. METHODS: Datasets from the Gene Expression Omnibus, the Cancer Genome Atlas and immunohistochemistry (IHC) analyses were employed to measure the expression level of PFKFB3 in ATC. A series of assays were performed to analyze the role of PFKFB3 and its inhibitor KAN0438757 in ATC cell proliferation and migration. Furthermore, Western blotting (WB), IHC and luciferase reporter assay were conducted to investigate the potential mechanisms underlying the involvement of PFKFB3 and KAN0438757 in ATC. Additionally, we established a subcutaneous xenograft tumor model in nude mice to evaluate the in vivo tumor growth. RESULTS: PFKFB3 exhibited a significant increase in its expression level in ATC tissues. The overexpression of PFKFB3 resulted in the stimulation of ATC cell proliferation and migration. Furthermore, this overexpression was associated with the elevated expression levels of p-AKT (ser473), p-GSK3α/ß (ser21/9), nuclear ß-catenin, fibronectin1 (FN1), matrix metallopeptidase 9 (MMP-9) and cyclin D1. It also promoted the nuclear translocation of ß-catenin and the transcription of downstream molecules. Conversely, contrasting results were observed with the downregulation or KAN0438757-mediated inhibition of PFKFB3 in ATC cells. The selective AKT inhibitor MK2206 was noted to reverse the increased expression of p-AKT (ser473) and p-GSK3α/ß (ser21/9) induced by PFKFB3 overexpression. The level of lactate was increased in PFKFB3-overexpressing ATC cells, while the presence of KAN0438757 inhibited lactate production. Moreover, the simultaneous use of PFKFB3 downregulation and KAN0438757 was found to suppress subcutaneous tumor growth in vivo. CONCLUSION: PFKFB3 can enhance ATC cell proliferation and migration via the WNT/ß-catenin signaling pathway and plays a crucial role in the regulation of aerobic glycolysis in ATC cells.

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.

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.

Targeting PEAK1 sensitizes anaplastic thyroid carcinoma cells harboring BRAFV600E to Vemurafenib by Bim upregulation.

Pseudopodium-enriched atypical kinase 1 (PEAK1) has been demonstrated to be upregulated in human malignancies and cells. Enhanced PEAK1 expression facilitates tumor cell survival and chemoresistance. However, the role of PEAK1 inhibition to anaplastic thyroid carcinoma cell (ATC) and vemurafenib resistance is still unknown. Here, we observed that targeting PEAK1 inhibited cell viability and colony formation, but not cell apoptosis in both of the 8505C and Hth74 cells in vitro. Targeting PEAK1 sensitized 8505C and Hth74 cells to vemurafenib by inducing cell apoptosis, and thereby decreasing cell viability. Mechanistically, vemurafenib treatment upregulated PEAK1 expression. Combined PEAK1 depletion and Vemurafenib treatment upregulated Bim expression. Targeting PEAK1 sensitized vemurafenib-induced apoptosis by upregulating Bim. In conclusion, vemurafenib resistance in ATC cells harboring BRAFV600E is associated with PEAK1 activation, resulting in the inhibition of pro-apoptotic Bim protein. Therefore, targeting PEAK1 may be an effective strategy to sensitize ATC harboring BRAFV600E to vemurafenib.

Ibuprofen inhibits anaplastic thyroid cells in vivo and in vitro by triggering NLRP3-ASC-GSDMD-dependent pyroptosis.

Pyroptosis is a novel type of proinflammatory programmed cell death that is associated with inflammation, immunity, and cancer. Anaplastic thyroid carcinoma (ATC) has a high fatality rate, and there is no effective or standard treatment. The disease progresses rapidly and these tumors can invade the trachea and esophagus, leading to breathing and swallowing difficulties. Hence, new treatment methods are greatly needed. Ibuprofen is a common drug that can exert antitumor effects in some cancers. In this study, we demonstrated in vitro and in vivo that ibuprofen can induce ATC pyroptosis. Hence, we treated C643 and OCUT-2C ATC cells with ibuprofen and found that several dying cells presented the characteristic morphological features of pyroptosis, such as bubble-like swelling and membrane rupture, accompanied by activation of ASC and NLRP3 and cleavage of GSDMD. Along with the increased release of LDH, ibuprofen treatment promoted apoptosis and inhibited viability, invasion, and migration. However, overexpression of GSDMD significantly inhibited ibuprofen-induced pyroptosis. In vivo, research has demonstrated that thyroid tumor growth in nude mice can be suppressed by ibuprofen-induced pyroptosis in a dose-dependent manner. In this research, we explored a new mechanism by which ibuprofen inhibits ATC growth and progression and highlighted its promise as a therapeutic agent for ATC.

Epigenetic inhibition of CTCF by HN1 promotes dedifferentiation and stemness of anaplastic thyroid cancer.

Anaplastic thyroid cancer (ATC) is one of the deadliest cancers, whose important malignant feature is dedifferentiation. Chromatin remodeling is critical for tumorigenesis and progression, while its roles and regulator in facilitating dedifferentiation of ATC had been poorly understood. In our study, an emerging function of hematological and neurological expressed 1 (HN1) in promoting dedifferentiation of ATC cells was uncovered. HN1 expression was negatively correlated with the thyroid differentiation markers both at mRNA and protein level. Knockdown of HN1 in ATC cells effectively upregulated the thyroid differentiation markers and impeded the sphere formation capacity, accompanying with the loss of cancer stemness. In contrast, overexpression of HN1 drove the gain of stemness and the loss of thyroid differentiation markers. Nude mouse and zebrafish xenograft models showed that inhibition of HN1 in ATC cells effectively hindered tumor growth due to the loss of cancer stemness. Further study showed that HN1 was negatively correlated with CTCF in an independent thyroid-cancer cohort, and inhibition of HN1 enhanced the expression of CTCF in ATC cells. Overexpression of CTCF significantly reversed the dedifferentiation phenotypes of ATC cells, whereas simultaneously inhibiting HN1 and CTCF was unable to recover the level of thyroid differentiation markers. The combination of ATAC-seq and ChIP-seq analysis confirmed that CTCF regulated genes relating with thyroid gland development through influencing their chromatin accessibility. HN1 inhibited the acetylation of H3K27 at the promoter of CTCF by recruiting HDAC2, thereby inhibiting the transcriptional activation of CTCF. These findings demonstrated an essential role of HN1 in regulating the chromatin accessibility of thyroid differentiation genes during ATC dedifferentiation.

HOXD9/miR-451a/PSMB8 axis is implicated in the regulation of cell proliferation and metastasis via PI3K/AKT signaling pathway in human anaplastic thyroid carcinoma.

Anaplastic thyroid carcinoma (ATC) is a deadly disease with a poor prognosis. Thus, there is a pressing need to determine the mechanism of ATC progression. The homeobox D9 (HOXD9) transcription factor has been associated with numerous malignancies but its role in ATC is unclear. In the present study, the carcinogenic potential of HOXD9 in ATC was investigated. We assessed the differential expression of HOXD9 on cell proliferation, migration, invasion, apoptosis, and epithelial-mesenchymal transition (EMT) in ATC and explored the interactions between HOXD9, microRNA-451a (miR-451a), and proteasome 20S subunit beta 8 (PSMB8). In addition, subcutaneous tumorigenesis and lung metastasis in mouse models were established to investigate the role of HOXD9 in ATC progression and metastasis in vivo. HOXD9 expression was enhanced in ATC tissues and cells. Knockdown of HOXD9 inhibited cell proliferation, migration, invasion, and EMT but increased apoptosis in ATC cells. The UCSC Genome Browser and JASPAR database identified HOXD9 as an upstream regulator of miR-451a. The direct binding of miR-451a to the untranslated region (3'-UTR) of PSMB8 was established using a luciferase experiment. Blocking or activation of PI3K by LY294002 or 740Y-P could attenuate the effect of HOXD9 interference or overexpression on ATC progression. The PI3K/AKT signaling pathway was involved in HOXD9-stimulated ATC cell proliferation and EMT. Consistent with in vitro findings, the downregulation of HOXD9 in ATC cells impeded tumor growth and lung metastasis in vivo. Our research suggests that through PI3K/AKT signaling, the HOXD9/miR-451a/PSMB8 axis may have significance in the control of cell proliferation and metastasis in ATC. Thus, HOXD9 could serve as a potential target for the diagnosis of ATC.

Thyroid hormone receptor α1: a novel regulator of thyroid cancer cell differentiation.

Thyroid hormone receptor α1 (TRα1) mediates the genomic actions of thyroid hormone (T3). The biology of TRα1 in growth and development has been well studied, but the functional role of TRα1 in cancers remains to be elucidated. Analysis of the human thyroid cancer database of The Cancer Genome Atlas (TCGA) showed that THRA gene expression is lost in highly dedifferentiated anaplastic thyroid cancer (ATC). We, therefore, explored the effects of TRα1 on the progression of ATC. We stably expressed TRα1 in two human ATC cell lines, THJ-11T (11T-TRα1 #2, #7, and #8) and THJ-16T (16T-TRα1 #3, #4, and #8) cells. We found that the expressed TRα1 inhibited ATC cell proliferation and induced apoptosis. TCGA data showed that THRA gene expression was best correlated with the paired box gene 8 (PAX8). Consistently, we found that the PAX8 expression was barely detectable in parental 11T and 16T cells. However, PAX8 gene expression was elevated in 11T- and 16T-TRα1-expressing cells at the mRNA and protein levels. Using various molecular analyses, we found that TRα1 directly regulated the expression of the PAX8 gene. Single-cell transcriptomic analyses (scRNA-seq) demonstrated that TRα1 functions as a transcription factor through multiple signaling pathways to suppress tumor growth. Importantly, scRNA-seq analysis showed that TRα1-induced PAX8, via its transcription program, shifts the cell landscape of ATC toward a differentiated state. The present studies suggest that TRα1 is a newly identified regulator of thyroid differentiation and could be considered as a potential therapeutic target to improve the outcome of ATC patients.

Co-inhibition of glutaminolysis and one-carbon metabolism promotes ROS accumulation leading to enhancement of chemotherapeutic efficacy in anaplastic thyroid cancer.

Anaplastic thyroid cancer (ATC) is one of the most aggressive tumors with an extremely poor prognosis. Based on the several biological features related to glutamine metabolism in ATC, we hypothesized glutaminolysis inhibition induces cell death in ATC cells. However, glutamine metabolism inhibition triggered cell growth arrest independent of cell death in ATC, suggesting that other signaling pathways avoid glutamine metabolism inhibition-induced stress exist. To investigate the functional mechanism against glutamine metabolism inhibition, we conducted mRNA and ATAC-Sequencing data analysis and found that glutamine deprivation increased ATF4-mediated one-carbon metabolism. When we inhibited PHGDH, the first rate-limiting enzyme for one-carbon metabolism, cell growth arrest was promoted upon glutamine metabolism inhibition by accumulating intracellular ROS. We next observed that the co-inhibition of glutamine and one-carbon metabolism could augment the anticancer effects of drugs used in patients with ATC. Finally, single-cell RNA sequencing analysis revealed that one-carbon metabolism was strengthened through the evolutionary process from PTC to ATC. Collectively, our data demonstrate that one-carbon metabolism has a potential role of modulation of cell fate in metabolic stress and can be a therapeutic target for enhancing antitumor effects in ATC.

Autophagic blockade potentiates anlotinib-mediated ferroptosis in anaplastic thyroid cancer.

Anlotinib-mediated angiogenic remodeling was delineated in various tumors. Meanwhile, we previously showed that anlotinib inhibited tumor angiogenesis in anaplastic thyroid cancer (ATC). However, the potential role of anlotinib on cell lethality in ATC remains an enigma. Herein, we found that anlotinib inhibited the viability, proliferation, and migration of KHM-5M, C643, and 8505C cells in a dose-dependently manner. Under anlotinib treatment, PANoptosis (pyroptosis, apoptosis, and necroptosis) markers were not changed; however, ferroptosis targets (transferrin, HO-1, FTH1, FTL, and GPX4) were significantly downregulated. ROS levels also increased in a concentration-dependent manner after anlotinib treatment in KHM-5M, C643, and 8505C cells. In addition, protective autophagy was activated in response to anlotinib, and autophagic blockade potentiated anlotinib-mediated ferroptosis and antitumor effects in vitro and in vivo. Our new discovery identified autophagy-ferroptosis signaling pathway which provides mechanistic insight into anlotinib-mediated cell death, and synergistic combination therapy may help develop new ATC treatment strategies.

BRAFV600E restructures cellular lactylation to promote anaplastic thyroid cancer proliferation.

Anaplastic thyroid cancer (ATC) is a rare but fatal cancer with BRAF mutation ranging from 30 to 50%. Histone lysine lactylation represents a novel epigenetic mark that translates cellular metabolic signals into transcriptional regulation. It is not clear whether the Warburg effect can promote the proliferation of ATC with BRAFV600E mutation via metabolite-mediated histone lactylation. Our study aimed at illustrating how BRAFV600E restructures the cellular protein lactylation landscape to boost ATC proliferation, and determining whether blockade of protein lactylation can sensitize mutant ATC to BRAFV600E inhibitors. Western blotting was used to evaluate lactylation status. Aerobic glycolysis was intervened by adding cell-permeable ethyl lactate or using metabolic inhibitors. Chromatin immunoprecipitation and RT-qPCR were applied to analyze the expression of growth-related genes. Different chemical inhibitors were used to inhibit BRAFV600E and other enzymes. ATC cell line-derived xenograft model was employed to examine the efficacy of mono and combinatorial therapies. The results showed that aerobic glycolysis in ATC increased global protein lactylation via improving cellular lactate availability. In particular, lactylation on Histone 4 Lysine 12 residue (H4K12La) activated the expression of multiple genes essential for ATC proliferation. Furthermore, oncogenic BRAFV600E boosted glycolytic flux to restructure the cellular lactylation landscape, leading to H4K12La-driven gene transcription and cell cycle deregulation. Accordingly, the blockade of cellular lactylation machinery synergized with BRAFV600E inhibitor to impair ATC progression both in vitro and in vivo. Our results demonstrated an extra beneficial effect of aerobic glycolysis on ATC, revealing a novel metabolism-epigenetics axis suitable for combinatorial therapy with BRAFV600E inhibition.

Modulation of EZH2 Activity Induces an Antitumoral Effect and Cell Redifferentiation in Anaplastic Thyroid Cancer.

Anaplastic thyroid cancer (ATC) is a rare and lethal form of thyroid cancer that requires urgent investigation of new molecular targets involved in its aggressive biology. In this context, the overactivation of Polycomb Repressive Complex 2/EZH2, which induces chromatin compaction, is frequently observed in aggressive solid tumors, making the EZH2 methyltransferase a potential target for treatment. However, the deregulation of chromatin accessibility is yet not fully investigated in thyroid cancer. In this study, EZH2 expression was modulated by CRISPR/Cas9-mediated gene editing and pharmacologically inhibited with EZH2 inhibitor EPZ6438 alone or in combination with the MAPK inhibitor U0126. The results showed that CRISPR/Cas9-induced EZH2 gene editing reduced cell growth, migration and invasion in vitro and resulted in a 90% reduction in tumor growth when EZH2-edited cells were injected into an immunocompromised mouse model. Immunohistochemistry analysis of the tumors revealed reduced tumor cell proliferation and less recruitment of cancer-associated fibroblasts in the EZH2-edited tumors compared to the control tumors. Moreover, EZH2 inhibition induced thyroid-differentiation genes' expression and mesenchymal-to-epithelial transition (MET) in ATC cells. Thus, this study shows that targeting EZH2 could be a promising neoadjuvant treatment for ATC, as it promotes antitumoral effects in vitro and in vivo and induces cell differentiation.

Type 2 deiodinase is expressed in anaplastic thyroid carcinoma and its inhibition causes cell senescence.

Anaplastic thyroid cancer (ATC) is a rare thyroid tumor that frequently originates from the dedifferentiation of a well-differentiated papillary or follicular thyroid cancer. Type 2 deiodinase (D2), responsible for the activation of the thyroid hormone thyroxine into tri-iodothyronine (T3), is expressed in normal thyroid cells and its expression is strongly downregulated in papillary thyroid cancer. In skin cancer, D2 has been associated with cancer progression, dedifferentiation, and epithelial-mesenchymal transition. Here, we show that D2 is highly expressed in anaplastic compared to papillary thyroid cancer cell lines and that D2-derived T3 is required for ATC cell proliferation. D2 inhibition is associated with G1 growth arrest and induction of cell senescence, together with reduced cell migration and invasive potential. Finally, we found that mutated p5372R(R248W), frequently found in ATC, is able to induce D2 expression in transfected papillary thyroid cancer cells. Our results show that the action of D2 is crucial for ATC proliferation and invasiveness, providing a potential new therapeutic target for the treatment of ATC.

The curcumin analogue PAC has potent anti-anaplastic thyroid cancer effects.

Anaplastic thyroid carcinoma (ATC) is the rarest type of thyroid cancer, but is the common cause of death from these tumors. The aggressive behavior of ATC makes it resistant to the conventional therapeutic approaches. Thus, the present study was designed to evaluate the anti-ATC efficacy of the piperidone analogue of curcumin (PAC). We have shown that PAC induces apoptosis in thyroid cancer cells in a time-dependent fashion through the mitochondrial pathway. Immunoblotting analysis revealed that PAC suppressed the epithelial-to-mesenchymal transition (EMT) process in ATC cells by upregulating the epithelial marker E-cadherin and reducing the level of the mesenchymal markers N-cadherin, Snail, and Twist1. This anti-EMT effect was confirmed by showing PAC-dependent inhibition of the proliferation and migration abilities of ATC cells. Furthermore, PAC inhibited the AKT/mTOR pathway in ATC cells. Indeed, PAC downregulated mTOR and its downstream effectors p70S6K and 4E-BP1 more efficiently than the well-known mTOR inhibitor rapamycin. In addition to the promising in vitro anticancer efficacy, PAC significantly suppressed the growth of humanized thyroid tumor xenografts in mice. Together, these findings indicate that PAC could be considered as promising therapeutic agent for anaplastic thyroid carcinomas.

Reactivated thyroid hormone receptor ß attenuates anaplastic thyroid cancer (ATC) stem cell activity.

Anaplastic thyroid cancer (ATC) is one of the most aggressive solid cancers in humans, with limited treatment options. Recent studies suggest that cancer stem cell (CSC) activity contributes to therapeutic resistance and recurrence of ATC. We show that the expression of the endogenous thyroid hormone receptor ß gene (THRB) is silenced in ATC and demonstrate that the exogenously expressed TRß suppresses CSC activity. Decitabine is one of the demethylation agents to treat myelodysplastic syndrome and acute myeloid leukemia patients and is currently in clinical trials for hematopoietic malignancies and solid tumors. We aim to show that the re-expression of the endogenous THRB gene by decitabine can attenuate CSC activity to block ATC tumor growth. We treated ATC cell lines derived from human ATC tumors (11T and 16T cells) with decitabine and evaluated the effects of the reactivated endogenous TRß on CSC activity in vitro and in vivo xenograft models. We found that treatment of 11T and 16T cells with decitabine reactivated the expression of endogenous TRß, as evidenced by western blot and immunohistochemical analyses. The expressed TRß inhibited cell proliferation by arresting cells at the S phase, increased apoptotic cell death by upregulation of cleaved caspase-3, and markedly suppressed the expression of CSC regulators, including cMYC, ALDH, SOX2, CD44, and ß-catenin. Decitabine also inhibited xenograft tumor growth by suppressing CSC activity, inhibiting cancer cell proliferation, and increasing apoptosis. Our findings suggest that re-expression of the endogenous TRß is a novel therapeutic approach for ATC via suppression of CSC activity.

ASPM promotes migration and invasion of anaplastic thyroid carcinoma by stabilizing KIF11.

Abnormal spindle-like microcephaly-associated (ASPM) protein is crucial to the mitotic spindle function during cell replication and tumor progression in multiple tumor types. However, the effect of ASPM in anaplastic thyroid carcinoma (ATC) has not yet been understood. The present study is to elucidate the function of ASPM in the migration and invasion of ATC. ASPM expression is incrementally upregulated in ATC tissues and cell lines. Knockout (KO) of ASPM pronouncedly attenuates the migration and invasion of ATC cells. ASPM KO significantly reduces the transcript levels of Vimentin, N-cadherin, and Snail and increases E-cadherin and Occludin, thereby inhibiting epithelial-to-mesenchymal transition (EMT). Mechanistically, ASPM regulates the movement of ATC cells by inhibiting the ubiquitin degradation of KIF11 and thus stabilizing it via direct binding to it. Moreover, xenograft tumors in nude mice proved that KO of ASPM could ameliorate tumorigenesis and tumor growth accompanied by a decreased protein expression of KIF11 and an inhibition of EMT. In conclusion, ASPM is a potentially useful therapeutic target for ATC. Our results also reveal a novel mechanism by which ASPM inhibits the ubiquitin process in KIF11.