Anaplastic Thyroid Cancer Xenografts Research Articles

Tenascin-C potentiates Wnt signaling in thyroid cancer.

Tenascin-C (TNC) is a secreted extracellular matrix protein that is highly expressed during embryonic development and re-expressed during wound healing, inflammation, and neoplasia. Studies in developmental models suggest that TNC may regulate the Wnt signaling pathway. Our lab has shown high levels of Wnt signaling and TNC expression in anaplastic thyroid cancer (ATC), a highly lethal cancer with an abysmal ∼3-5 month median survival. Here, we investigated the role of TNC in facilitating ligand-dependent Wnt signaling in thyroid cancer. We utilized bulk RNA-sequencing from three independent multi-institutional thyroid cancer patient cohorts. TNC expression was spatially localized in patient tumors with RNA in situ hybridization. The role of TNC was investigated in vitro using Wnt reporter assays and in vivo with a NOD.PrkdcscidIl2rg-/- mouse ATC xenograft tumor model. TNC expression was associated with aggressive thyroid cancer behavior, including anaplastic histology, extrathyroidal extension, and metastasis. Spatial localization of TNC in patient tissue demonstrated a dramatic increase in expression within cancer cells along the invasive edge, adjacent to Wnt ligand-producing fibroblasts. TNC expression was also increased in areas of intravascular invasion. In vitro, TNC bound Wnt ligands and potentiated Wnt signaling. Finally, in an ATC mouse model, TNC increased Wnt signaling, tumor burden, invasion, and metastasis. Altogether, TNC potentiated ligand driven Wnt signaling and promotes cancer cell invasion and metastasis in a mouse model of thyroid cancer. Understanding the role of TNC and its interaction with Wnt ligands could lead to the development of novel biomarkers and targeted therapeutics for thyroid cancer.

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.

BUB1/KIF14 complex promotes anaplastic thyroid carcinoma progression by inducing chromosome instability.

Chromosome instability (CIN) is a common contributor driving the formation and progression of anaplastic thyroid cancer (ATC), but its mechanism remains unclear. The BUB1 mitotic checkpoint serine/threonine kinase (BUB1) is responsible for the alignment of mitotic chromosomes, which has not been thoroughly studied in ATC. Our research demonstrated that BUB1 was remarkably upregulated and closely related to worse progression-free survival. Knockdown of BUB1 attenuated cell viability, invasion, migration and induced cell cycle arrests, whereas overexpression of BUB1 promoted the cell cycle progression of papillary thyroid cancer cells. BUB1 knockdown remarkably repressed tumour growth and tumour formation of nude mice with ATC xenografts and suppressed tumour metastasis in a zebrafish xenograft model. Inhibition of BUB1 by its inhibitor BAY-1816032 also exhibited considerable anti-tumour activity. Further studies showed that enforced expression of BUB1 evoked CIN in ATC cells. BUB1 induced CIN through phosphorylation of KIF14 at serine1292 (Ser1292 ). Overexpression of the KIF14ΔSer1292 mutant was unable to facilitate the aggressiveness of ATC cells when compared with that of the wild type. Collectively, these findings demonstrate that the BUB1/KIF14 complex drives the aggressiveness of ATC by inducing CIN.

Selection, characterization and in vivo evaluation of novel CD44v6-targeting antibodies for targeted molecular radiotherapy

Molecular radiotherapy combines the advantages of systemic administration of highly specific antibodies or peptides and the localized potency of ionizing radiation. A potential target for molecular radiotherapy is the cell surface antigen CD44v6, which is overexpressed in numerous cancers, with limited expression in normal tissues. The aim of the present study was to generate and characterize a panel of human anti-CD44v6 antibodies and identify a suitable candidate for future use in molecular radiotherapy of CD44v6-expressing cancers. Binders were first isolated from large synthetic phage display libraries containing human scFv and Fab antibody fragments. The antibodies were extensively analyzed through in vitro investigations of binding kinetics, affinity, off-target binding, and cell binding. Lead candidates were further subjected to in vivo biodistribution studies in mice bearing anaplastic thyroid cancer xenografts that express high levels of CD44v6. Additionally, antigen-dependent tumor uptake of the lead candidate was verified in additional xenograft models with varying levels of target expression. Interestingly, although only small differences were observed among the top antibody candidates in vitro, significant differences in tumor uptake and retention were uncovered in in vivo experiments. A high-affinity anti-CD44v6 lead drug candidate was identified, mAb UU-40, which exhibited favorable target binding properties and in vivo distribution. In conclusion, a panel of human anti-CD44v6 antibodies was successfully generated and characterized in this study. Through comprehensive evaluation, mAb UU-40 was identified as a promising lead candidate for future molecular radiotherapy of CD44v6-expressing cancers due to its high affinity, excellent target binding properties, and desirable in vivo distribution characteristics.

ICAM1 antibody drug conjugates exert potent antitumor activity in papillary and anaplastic thyroid carcinoma

Treatment options for anaplastic thyroid cancer (ATC) and refractory papillary thyroid carcinoma (PTC) are limited and outcomes remain poor. In this study, we determined via bioinformatic expression analyses and immunohistochemistry staining that intercellular adhesion molecule-1(ICAM1) is an attractive target for ATC and PTC. We designed and engineered two ICAM1-directed antibody-drug conjugate (I1-MMAE and I1-DXd), both of which potently and selectively ablate multiple human ATC and PTC cell lines without affecting non-plastic cells invitro. Furthermore, I1-MMAE and I1-DXd mediated a potent tumor regression in ATC and PTC xenograft models. To develop a precision medicine, we also explored magnetic resonance imaging (MRI) as a non-invasive biomarker detection method to quantitatively map ICAM1 antigen expression in heterogeneous thyroid tumors. Taken together, this study provides a strong rationale for the further development of I1-MMAE and I1-DXd as promising therapeutic candidates to treat advanced PTC and ATC.

TIM3 Expression in Anaplastic-Thyroid-Cancer-Infiltrating Macrophages: An Emerging Immunotherapeutic Target.

Anaplastic thyroid cancer (ATC) is a clinically aggressive form of undifferentiated thyroid cancer with limited treatment options. Immunotherapy for patients with ATC remains challenging. Tumor-associated macrophages (TAMs) constitute over 50% of ATC-infiltrating cells, and their presence is associated with a poor prognosis. Consequently, the development of new therapies targeting immune checkpoints in TAMs is considered a promising therapeutic approach for ATC. We have previously shown that soluble factors secreted by ATC cells induced pro-tumor M2-like polarization of human monocytes by upregulating the levels of the inhibitory receptor TIM3. Here, we extended our observations on ATC-cell-induced xenograft tumors. We observed a large number of immune cells infiltrating the ATC xenograft tumors. Significantly, 24-28% of CD45+ immune cells were macrophages (CD11b+ F4/80+). We further showed that 40% of macrophages were polarized toward a M2-like phenotype, as assessed by CD206 expression and by a significant increase in the Arg1/iNOS (M2/M1) ratio. Additionally, we found that ATC xenograft tumors had levels of TIM3 expression when determined by RT-PCR and immunofluorescence assays. Interestingly, we detected the expression of TIM3 in macrophages in ATC tumors by flow cytometry assays. Furthermore, TIM3 expression correlated with macrophage marker expression in human ATC. Our studies show that TIM3 is a newly identified immune checkpoint in macrophages. Since TIM3 is known as a negative immune regulator, it should be considered as a promising immunotherapeutic target for ATC.

Blocking CDK7-Mediated NOTCH1-cMYC Signaling Attenuates Cancer Stem Cell Activity in Anaplastic Thyroid Cancer.

Background: Anaplastic thyroid cancer (ATC) is an aggressive solid cancer in humans with few treatment options. Recent studies suggest that aberrant gene transcription could contribute to aggressive ATC progression. To test this hypothesis, we assessed if blocking cyclin-dependent protein 7 (CDK7) activity could impede ATC progression through attenuation of cancer stem cell (CSC) activity. Methods: We treated cell lines isolated from human ATC (THJ-11T and -16T) and xenograft mice induced by these cells with the CDK7 inhibitor THZ1. Through integrative transcriptome analyses we found that the NOTCH1-cMYC signaling axis was a potential target of CDK7 inhibition in ATC. To determine the regulatory action of NOTCH1-cMYC signaling in CSC maintenance, we evaluated the effect of a selective NOTCH1 inhibitor, crenigacestat, on CSC capacities in ATC. Results: THZ1 markedly inhibited proliferation of ATC cells and xenograft tumor growth by blocking cell cycle progression and inducing apoptosis. NOTCH1 was sensitive to suppressive transcription mediated by CDK7 inhibition and was highly enriched in tumorspheres from ATC cells. Treatment of ATC cells with either crenigacestat or THZ1 blocked formation of tumorspheres, decreased aldehyde dehydrogenase activity, and suppressed in vivo initiation and growth of tumors induced by ATC cells, indicating that NOTCH1 was a critical regulator of CSC activity in ATC. Furthermore, we demonstrated that cMYC was a downstream target of NOTCH1 signaling that collaboratively maintained CSC activity in ATC. Of note, genomic analysis showed that low CDK7 expression contributed to longer disease-free survival of thyroid cancer patients. Conclusions: NOTCH1 is a newly identified CSC regulator. Targeting NOTCH1-cMYC signaling is a promising therapeutic strategy for ATC.

Potent antitumor activity of novel taxoids in anaplastic thyroid cancer.

Anaplastic thyroid cancer (ATC) is the most aggressive form of thyroid cancers and it is rapidly fatal without any effective therapeutic regimens. There are some clinical trials showing that paclitaxel-based chemotherapy for ATC can achieve a relatively high response rate and low incidence of adverse reaction. The aim of this study was to evaluate potential therapeutic activity of novel taxoids in ATC cells. We evaluated antitumor activity of five novel 3'-difluorovinyltaxoids (DFV-taxoids) in anaplastic thyroid cancer cells by a series of in vitro and in vivo experiments. Besides, we also explored the potential mechanism underlying the difference among the taxoids and paclitaxel by molecular docking and tubulin polymerization assays. Our data showed that these novel DFV-taxoids were more effective than paclitaxel in ATC cell lines and xenografts, as reflected by the inhibition of cell proliferation, colony formation and tumorigenic potential in nude mice, and the induction of G2/M phase arrest and cell apoptosis. Using tubulin polymerization assays and molecular docking analysis, we found that these DFV-taxoids promoted more rapid polymerization of β-tubulin than paclitaxel. Our data demonstrate that these novel taxoids exhibit stronger antitumor activity in ATC cells than paclitaxel, thereby providing a promising therapeutic strategy for the patients with ATC.

Augmentation of lenvatinib efficacy by topical treatment of miR-634 ointment in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the most lethal types of human tumors. Lenvatinib can improve the disease control and prognosis in patients with ATC. However, there is an unmet need to develop a therapeutically safer and non-invasive strategy that improves the efficacy of lenvatinib for advanced ATC tumors, which grow larger close to the skin. We previously demonstrated that the topical application of an ointment incorporating tumor suppressive microRNA (TS-miR), miR-634, is a useful strategy as a TS-miR therapeutics. Here, we found that the overexpression of miR-634 synergistically increased lenvatinib-induced cytotoxicity by concurrently downregulating multiple genes related to cytoprotective processes, including ASCT2, a glutamine transporter, in ATC cell lines. Furthermore, the topical application of a miR-634 ointment on subcutaneous tumors effectively augmented the anti-tumor effects of lenvatinib in an ATC xenograft mouse model. Thus, we propose topical treatment of a miR-634 ointment as a rational strategy for improving lenvatinib-based therapy for ATC.

Efficacy of adavosertib therapy against anaplastic thyroid cancer.

Wee1 is a kinase that regulates the G2/M progression by the inhibition of CDK1, which is critical for ensuring DNA damage repair before initiation of mitotic entry. Targeting Wee1 may be a potential strategy in the treatment of anaplastic thyroid cancer, a rare but lethal disease. The therapeutic effects of adavosertib, a Wee1 inhibitor for anaplastic thyroid cancer was evaluated in this study. Adavosertib inhibited cell growth in three anaplastic thyroid cancer cell lines in a dose-dependent manner. Cell cycle analysis revealed cells were accumulated in the G2/M phase. Adavosertib induced caspase-3 activity and led to apoptosis. Adavosertib monotherapy showed significant retardation of the growth of two anaplastic thyroid cancer tumor models. The combination of adavosertib with dabrafenib and trametinib revealed strong synergism in vitro and demonstrated robust suppression of tumor growth in vivo in anaplastic thyroid cancer xenograft models with BRAFV600E mutation. The combination of adavosertib with either sorafenib or lenvatinib also demonstrated synergism in vitro and had strong inhibition of tumor growth in vivo in an anaplastic thyroid cancer xenograft model. No appreciable toxicity appeared in mice treated with either a single agent or combination treatment. Our findings suggest adavosertib holds the promise for the treatment of patients with anaplastic thyroid cancer.

Synergistic anticancer activity of sorafenib, paclitaxel, and radiation therapy on anaplastic thyroid cancer in vitro and in vivo.

This study aimed to investigate the antitumor activity of paclitaxel with radiation and sorafenib in anaplastic thyroid cancer (ATC) cells in vitro and in vivo. The 8505C ATC cell line was exposed to radiation, sorafenib, and paclitaxel each or in combination. The effects of combined treatment on the cell cycle and intracellular signaling pathways were assessed using flow cytometry and western blot analysis. An ATC cell line xenograft model was used to examine antitumor activity in vivo. Radiation, paclitaxel plus sorafenib synergistically decreased cell viability in ATC cells and significantly increased apoptotic cell death. The combination of paclitaxel, sorafenib with radiation reduced the antiapoptotic factor in ATC. This combination therapy significantly reduced the tumor volume and increased survival in the ATC xenograft model. These results suggest that the combination of radiation and paclitaxel plus sorafenib has significant anticancer activity in preclinical models.

REG\u03b3 ablation impedes dedifferentiation of anaplastic thyroid carcinoma and accentuates radio-therapeutic response by regulating the Smad7-TGF-\u03b2 pathway

Anaplastic thyroid cancer (ATC) is the most aggressive human thyroid malignancy, characterized by dedifferentiation and resistance to radioiodine therapy. The underlying mechanisms regulating ATC dedifferentiation are largely unknown. Here, we show that REGγ, a noncanonical proteasome activator highly expressed in ATC, is an important regulator of differentiation in ATC cells. Ablation of REGγ significantly restored expression of thyroid-specific genes, enhanced iodine uptake, and improved the efficacy of 131I therapy in ATC xenograft models. Mechanistically, REGγ directly binds to the TGF-β signaling antagonist Smad7 and promotes its degradation, leading to the activation of the TGF-β signal pathway. With gain- and loss-of-function studies, we demonstrate that Smad7 is an important mediator for the REGγ function in ATC cell dedifferentiation, which is supported by expression profiles in human ATC tissues. It seems that REGγ impinges on repression of thyroid-specific genes and promotion of tumor malignancy in ATC cells by activating the TGF-β signal pathway via degradation of Smad7. Thus, REGγ may serve as a novel therapeutic target for allowing radioiodine therapy in anaplastic thyroid cancer patients with poor prognosis.

Novel Dual-Action Targeted Nanomedicine in Mice With Metastatic Thyroid Cancer and Pancreatic Neuroendocrine Tumors.

The advantages of nanomedicines include preferential delivery of the payload directly to tumor tissues. CYT-21625 is the novel, first-in-class gold nanomedicine designed to target tumor vasculature and cancer cells by specifically delivering recombinant human tumor necrosis factor alpha (rhTNF) and a paclitaxel prodrug. We analyzed TNF receptor expression in publicly available gene expression profiling data and in thyroid tissue samples. Mice with metastatic FTC-133 and 8505C xenografts and the MEN1 conditional knock-out mice were treated weekly with CYT-21625 and gold nanoparticles with rhTNF only (CYT-6091); controls included mice treated with either paclitaxel or saline. In vivo luciferase activity was used to assess the effects on tumor growth. Computed tomography, magnetic resonance imaging, and 18F-Fludeoxyglucose positron emission tomography were used to study tumor selectivity in mice with insulin-secreting pancreatic neuroendocrine tumors (PNETs). All statistical tests were two-sided. Anaplastic thyroid cancer (ATC) expressed statistically significantly higher levels of TNF receptor superfamily 1A and 1B messenger RNA (n = 11) and protein (n = 6) than control samples (n = 45 and 13, respectively). Mice (n = 5-7 per group) with metastatic ATC (P < .009) and FTC-133 xenografts (P = .03 at week 3, but not statistically significant in week 4 owing to reduced sample size from death in non-CYT-21625 groups) treated with CYT-21625 had a statistically significantly lower tumor burden. Treatment with CYT-21625 resulted in loss of CD34 expression in intratumoral vasculature, decreased proliferating cell nuclear antigen, and increased cleaved caspase-3. Intratumoral vascular leakage occurred only in mice with PNET and ATC treated with CYT-6091 and CYT-21625. CYT-6091 and CYT-21625 preferentially deposited in PNETs and statistically significantly decreased serum insulin levels (n = 3 per group, P < .001). There were no toxicities observed in mice treated with CYT-21625. CYT-21625 is effective in mice with PNETs and metastatic human thyroid cancer with no toxicities. Thus, CYT-21625 should be studied in patients with advanced PNETs and thyroid cancer.

A selective cyclin-dependent kinase 4, 6 dual inhibitor, Ribociclib (LEE011) inhibits cell proliferation and induces apoptosis in aggressive thyroid cancer

The RB-E2F1 pathway is an important mechanism of cell-cycle control, and deregulation of this pathway is one of the key factors contributing to tumorigenesis. Cyclin-dependent kinases (CDKs) and Cyclin D have been known to increase in aggressive thyroid cancer. However, there has been no study to investigate effects of a selective CDK 4/6 inhibitor, Ribociclib (LEE011), in thyroid cancer. Performing Western blotting, we found that RB phosphorylation and the expression of Cyclin D are significantly higher in papillary thyroid cancer (PTC) cell lines as well as anaplastic thyroid cancer (ATC) cell lines, compared with normal thyroid cell line and follicular thyroid cancer cell line. LEE011 dose-dependently inhibited RB phosphorylation and also decreased the expressions of its target genes such as FOXM1, Cyclin A1, and Myc in ATC. Furthermore, LEE011 induced cell cycle arrest in G0-G1 phase and cell apoptosis, and inhibited cell proliferation in ATC. Consistently, oral administration of LEE011 to ATC xenograft models strongly inhibited tumor growth with decreased expressions of pRB, pAKT and Ki-67, and also significantly increased tumor cell apoptosis. Taken together, our data support the rationale for clinical development of the CDK4/6 inhibitor as a therapy for patients with aggressive thyroid cancer.

Synergistic efficacy of irinotecan and sunitinib combination in preclinical models of anaplastic thyroid cancer

The identification of new therapeutic strategies is urgently needed for the management of patients affected by anaplastic thyroid cancer (ATC) due to their short survival and poor prognosis. Aim of the study was to determine the activity of the combination irinotecan/sunitinib on ATC cell growth in vitro and the antitumor effects in vivo. Proliferation assays were performed for 72 h on ATC cell lines exposed to the combination of SN-38, the active metabolite of irinotecan, and sunitinib. The simultaneous combination of sunitinib and SN-38, quantified by the combination index, determined a high synergism on ATC cells, increasing the intracellular concentrations of SN-38. Moreover, the synergistic combination greatly decreases the gene expression and the protein levels of vascular endothelial growth factor, colony stimulating factor 1 and ATP-binding cassette transporter G2 in ATC cells. A significant in vivo antitumor effect was observed in ATC xenografts with the simultaneous combination of irinotecan and sunitinib if compared to monotherapy. The simultaneous combination of irinotecan and sunitinib, in vitro and in vivo demonstrated a significant, synergistic ATC antitumor activity, suggesting a possible and rapid translation of this schedule into the clinics.

Effects of roniciclib in preclinical models of anaplastic thyroid cancer

Many human cancers have altered cyclin-dependent kinase activity. Inhibition of cyclin-dependent kinases may arrest cell cycle progression and represents an important strategy in the treatment of malignancies. We evaluated the therapeutic effects of roniciclib, a cyclin-dependent kinase inhibitor, as a treatment for anaplastic thyroid cancer. Roniciclib inhibited anaplastic thyroid cancer cell proliferation in a dose-dependent manner. Roniciclib activated caspase-3 activity and induced apoptosis. Cell cycle progression was arrested in G2/M phase. In vivo, the growth of anaplastic thyroid cancer xenograft tumors was retarded by roniciclib treatment without evidence of toxicity. These data provide a rationale for further clinical evaluation using roniciclib in the treatment of patients with anaplastic thyroid cancer.

Combining doxorubicin-nanobubbles and shockwaves for anaplastic thyroid cancer treatment: preclinical study in a xenograft mouse model.

Anaplastic thyroid cancer is one of the most lethal diseases, and a curative therapy does not exist. Doxorubicin, the only drug approved for anaplastic thyroid cancer treatment, has a very low response rate and causes numerous side effects among which cardiotoxicity is the most prominent. Thus, doxorubicin delivery to the tumor site could be an import goal aimed to improve the drug efficacy and to reduce its systemic side effects. We recently reported that, in human anaplastic thyroid cancer cell lines, combining doxorubicin-loaded nanobubbles with extracorporeal shock waves, acoustic waves used in lithotripsy and orthopedics without side effects, increased the intracellular drug content and in vitro cytotoxicity. In the present study, we tested the efficacy of this treatment on a human anaplastic thyroid cancer xenograft mouse model. After 21 days, the combined treatment determined the greatest drug accumulation in tumors with consequent reduction of tumor volume and weight, and an extension of the tumor doubling time. Mechanistically, the treatment induced tumor apoptosis and decreased cell proliferation. Finally, although doxorubicin caused the increase of fibrosis markers and oxidative stress in animal hearts, loading doxorubicin into nanobubbles avoided these effects preventing heart damage. The improvement of doxorubicin anti-tumor effects together with the prevention of heart damage suggests that the combination of doxorubicin-loaded nanobubbles with extracorporeal shock waves might be a promising drug delivery system for anaplastic thyroid cancer treatment.

Targeting MYC as a Therapeutic Intervention for Anaplastic Thyroid Cancer.

Recent studies showed that transcription of the MYC gene is driven by the interaction of bromodomain and extraterminal domain (BET) proteins with acetylated histones on chromatin. JQ1, a potent inhibitor that effectively disrupts the interaction of BET proteins with acetylated histones, preferentially suppresses transcription of the MYC gene. We recently reported that JQ1 decreased thyroid tumor growth and improved survival in a mouse model of anaplastic thyroid cancer (ATC) by targeting MYC transcription. The role of MYC in human ATC and whether JQ1 can effectively target MYC as a treatment modality have not been elucidated. To understand the underlying molecular mechanisms of JQ1, we evaluated its efficacy in human ATC cell lines and xenograft models. We determined the effects of JQ1 on proliferation and invasion in cell lines and xenograft tumors. We identified key regulators critical for JQ1-affected proliferation and invasion of tumor cells. JQ1 markedly inhibited proliferation of four ATC cell lines by suppression of MYC and elevation of p21and p27 to decrease phosphorylated Rb and delay cell cycle progression from the G0/G1 phase to the S phase. JQ1 blocked cell invasion by attenuating epithelial-mesenchymal transition signals. These cell-based studies were further confirmed in xenograft studies in which the size and rate of tumor growth were inhibited by JQ1 via inhibition of p21-cyclin/cyclin-dependent kinase-Rb-E2F signaling. These results suggest targeting of the MYC protein could be a potential treatment modality for human ATC for which effective treatment options are limited.

A cyclin-dependent kinase inhibitor, dinaciclib in preclinical treatment models of thyroid cancer.

BackgroundWe explored the therapeutic effects of dinaciclib, a cyclin-dependent kinase (CDK) inhibitor, in the treatment of thyroid cancer.Materials and methodsSeven cell lines originating from three pathologic types of thyroid cancer (papillary, follicular and anaplastic) were studied. The cytotoxicity of dinaciclib was measured using a lactate dehydrogenase assay. The expression of proteins associated with cell cycle and apoptosis was assessed using Western blot analysis and immunofluorescence microscopy. Cell cycle distribution was measured by flow cytometry and immunofluorescence microscopy. Apoptosis and caspase-3 activity were measured by flow cytometry and fluorometric assay. Mice bearing flank anaplastic thyroid cancer (ATC) were treated with intraperitoneal injections of dinaciclib.ResultsDinaciclib inhibited thyroid cancer cell proliferation in a dose-dependent manner. Dinaciclib had a low median-effect dose (≤ 16.0 nM) to inhibit cell proliferation in seven thyroid cancer cell lines. Dinaciclib decreased CDK1, cyclin B1, and Aurora A expression, induced cell cycle arrest in the G2/M phase, and induced accumulation of prophase mitotic cells. Dinaciclib decreased Mcl-1, Bcl-xL and survivin expression, activated caspase-3 and induced apoptosis. In vivo, the growth of ATC xenograft tumors was retarded in a dose-dependent fashion with daily dinaciclib treatment. Higher-dose dinaciclib (50 mg/kg) caused slight, but significant weight loss, which was absent with lower-dose dinaciclib (40 mg/kg) treatment.ConclusionsDinaciclib inhibited thyroid cancer proliferation both in vitro and in vivo. These findings support dinaciclib as a potential drug for further studies in clinical trials for the treatment of patients with refractory thyroid cancer.

Potential anti-cancer effect of N-hydroxy-7-(2-naphthylthio) heptanomide (HNHA), a novel histone deacetylase inhibitor, for the treatment of thyroid cancer.

BackgroundThyroid cancer has been indicated to have a higher global proportion of DNA methylation and a decreased level of histone acetylation. Previous studies showed that histone gene reviser and epigenetic changes role significant parts in papillary and anaplastic thyroid cancer tumorigenesis. The goal of this research was to study the endoplasmic reticulum (ER) stress-mediated actions of the dominant histone deacetylase (HDAC) inhibitor, N-hydroxy-7-(2-naphthylthio) hepatonomide (HNHA), in thyroid cancer and to explore its effects on apoptotic cell death pathways.MethodsExperiments were achieved to conclude the effects of HNHA in papillary thyroid cancer (PTC) and anaplastic thyroid cancer (ATC) cell lines and xenografts, as compared with two other established HDAC inhibitors (SAHA; suberoylanilide hydroxamic acid and TSA; trichostatin A).ResultsApoptosis, which was induced by all HDAC inhibitors, was particularly significant in HNHA-treated cells, where noticeable B-cell lymphoma-2 (Bcl-2) suppression and caspase activation were observed both in vitro and in vivo. HNHA increased Ca2+ release from the ER to the cytoplasm. ER stress-dependent apoptosis was induced by HNHA, suggesting that it induced caspase-dependent apoptotic cell death in PTC and ATC. PTC and ATC xenograft studies demonstrated that the antitumor and pro-apoptotic effects of HNHA were greater than those of the established HDAC inhibitors. These HNHA activities reflected its induction of caspase-dependent and ER stress-dependent apoptosis on thyroid cancer cells.ConclusionsThe present study indicated that HNHA possibly provide a new clinical approach to thyroid cancers, including ATC.