Differentiated Thyroid Carcinoma Cell Research Articles

PSAT275 A Rare Case of Thyroid-Stimulating Immunoglobulin-Induced Thyrotoxicosis in Poorly Differentiated Metastatic Thyroid Cancer

Abstract We report case of a rare of hyperthyroidism secondary to functional metastatic thyroid carcinoma, which is an infrequent phenomenon that can be challenging to diagnose and treat, as low thyroid-stimulating hormone (TSH) levels can suppress the development and growth of differentiated thyroid carcinoma cells. Previous studies have reported that hyperfunctioning thyroid carcinoma may present as autonomous functioning thyroid nodules (AFTN) within the thyroid gland, or as functioning lesions in metastatic foci, which is our case. Functional thyroid carcinomas are capable of absorbing iodine, as well as synthesizing and releasing thyroxine, are often associated with follicular thyroid carcinomas. Potential mechanisms for the thyrotoxicosis include a large aggregate tumor mass, as well as the presence of thyroid-stimulating immunoglobulins (TSIs) that are able to stimulate the thyroid-stimulating hormone (TSH) receptors of the thyroid carcinoma. In this clinical case, patient presented with high titers of TSIs, and metastatic thyroid carcinoma, with persistent hyperthyroidism after thyroidectomy and with a remarkable radioactive iodine treatment response. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Retraction Note to: Inhibition of microRNA‑875‑5p promotes radioiodine uptake in poorly differentiated thyroid carcinoma cells by upregulating sodium-iodide symporter.

Retraction Note to: Inhibition of microRNA‑875‑5p promotes radioiodine uptake in poorly differentiated thyroid carcinoma cells by upregulating sodium-iodide symporter.

C/EBPβ mediates anti-proliferative effects of 1,25(OH)2D on differentiated thyroid carcinoma cells.

Differentiated thyroid carcinoma (DTC) is the most common endocrine malignancy and highly expresses the receptor for 1,25-dihydroxyvitamin D (1,25(OH)2D). However, it is unclear whether 1,25(OH)2D regulates DTC proliferation and differentiation. Here, we found that 1,25(OH)2D3 inhibited proliferation but not differentiation of the DTC cells. Notably, CYP27B1was elevated in DTC cells and 25-hydroxyvitamin D3 (25(OH)D3) reduced DTC cell proliferation. Knockdown of VDR did not affect the anti-proliferative effects of 1,25(OH)2D3. However, knockdown of CCAAT enhancer-binding protein β (C/EBPβ)abolished 1,25(OH)2D3-suppressed DTC cell proliferation. In addition, 1,25(OH)2D3 induced phosphorylation and translocation of C/EBPβto the nucleus from the cytoplasm. However, inhibition of p38 mitogen-activated protein kinases (MAPK) abrogated 1,25(OH)2D3-induced phosphorylation and nuclear translocation of C/EBPβas well as 1,25(OH)2D3-suppressed DTC cell proliferation. Knockdown of C/EBPβreduced the expression of Notch3. Knockdown of Notch3 blocked 1,25(OH)2D3-suppressed DTC cell proliferation. In the DTC cell-derived xenograft SCID mouse, knockdown of C/EBPβmarkedly increased tumor growth and proliferation and decreased apoptosis. In DTC patients, C/EBPβwas predominantly located in the cytoplasm of DTC cells in the tumor tissue when compared with adjacent non-cancerous tissue in which C/EBPβis located in the nucleus. In conclusion, C/EBPβstimulated Notch3signaling via the p38 MAPK-dependent pathway mediates the inhibitory effect of 1,25(OH)2D on DTC cell proliferation.

Vitamin D receptor regulates proliferation and differentiation of thyroid carcinoma via the E-cadherin-β-catenin complex.

Thyroid cancer has the fastest rising incidence among cancers, especially for differentiated thyroid carcinoma (DTC). Although the prognosis of DTC is relatively good, if it changes to anaplastic thyroid carcinoma (ATC), the prognosis will be very poor. The prognosis of DTC is largely depending on the degree of cell differentiation and proliferation. However, whether the vitamin D receptor (VDR) plays a role in regulating the proliferation and the differentiation of DTC cells is unclear. In the present study, we found that VDR was upregulated in DTC tissues compared to the adjacent non-cancerous tissue. Knockdown of VDR increased proliferation and decreased differentiation proliferation in DTC cells in vitro as well as DTC cell-derived xenografts in vivo. In contrast, overexpression of VDR had an opposite effect. Knockdown of E-cadherin abolished VDR-induced suppression of proliferation and enhancement of differentiation of the DTC cells. Knockdown of β-catenin partially reversed the effect of the VDR knockdown. VDR increases the levels of E-cadherin in the plasma membrane and decreases the levels of β-catenin in the nucleus. VDR binds to E-cadherin and β-catenin in the plasma membrane of the DTC cell. Taken together, VDR inhibits DTC cell proliferation and promotes differentiation via regulation of the E-cadherin/β-catenin complex, potentially representing novel clues for a therapeutic strategy to attenuate thyroid cancer progression.

Upregulated SLC27A2/FATP2 in differentiated thyroid carcinoma promotes tumor proliferation and migration.

BackgroundDifferentiated thyroid carcinoma (DTC) accounts for the vast majority of thyroid cancer (TC) cases. The rapidly increasing incidence of TC requires the urgent identification of new diagnostic and therapeutic targets. Solute carrier family 27 member 2 (SLC27A2/FATP2) plays an essential role in lipid biosynthesis and fatty acid transport. Recent studies have confirmed its involvement in a variety of diseases, including cancer.MethodsIn this study, the expression of SLC27A2 was analyzed in cancer and paracancerous tissue samples from 98 thyroid cancer patients, and we performed ROC analysis to confirm the diagnostic value. CCK8, Transwell, and other methods were used to study its effect on DTC, and the mechanism of SLC27A2 was investigated by RNA sequencing and Western blot.ResultsThe expression of SLC27A2 was upregulated in both DTC tissues and cell lines and was correlated with clinical progression. In vitro studies further confirmed that SLC27A2 knockdown attenuated the proliferation and invasion of DTC cells. Through RNA sequence analysis and gene set enrichment analysis, we found that the MAPK pathway is the main downstream signaling pathway for the regulation by SLC27A2. SLC27A2 affects cell proliferation and differentiation by inducing changes in the proto‐oncogene C‐FOS.ConclusionsOur results show that SLC27A2 plays an important role in tumor proliferation and migration, providing a new putative target for the diagnosis and treatment of TC.

Targeting SHP2 Sensitizes Papillary Thyroid Cancer Cells to MEK Inhibitors

Background: Pharmacologic targeting of components of the MAPK/ERK pathway in differentiated thyroid carcinoma (DTC) is often limited due to the development of adaptive resistance. However, the detailed mechanism of MEK inhibitor (MEKi) resistance is not fully understood. Methods: RNA-seq of the constructed MEKi-resistant DTC cell line BCPAP-R (compared with the BCPAP line) was performed to investigate the intrinsic mechanism of drug resistance. Colony formation assays, cell viability assays, and cell cycle analysis were performed, and various murine models, including xenograft models, long-term MEKi-treated models, and transgenic model were used to evaluate the treatment effect of combination therapy (SHP099 and selumetinib). Findings: MEKi-resistant models were constructed successfully, in which multiple receptor tyrosine kinases (RTKs) signaling pathways and Src-homology 2 domain-containing phosphatase 2 (SHP2) were activated in MEKi-resistant cells. Given the physiological role of SHP2 as the downstream target of many RTKs, we first found that blockade of SHP2 enhanced the sensitivity to MEKi in constructed MEKi-resistant thyroid cancer models (including constructed cell lines and a long-term MEKi-treated murine model). Interestingly, we also found that compared with MEKi treatment alone, MEKi in combination with an SHP2 inhibitor markedly suppressed the reactivation of the MEK/ERK pathway; thus, the addition of the SHP2 inhibitor significantly improved the anti-tumor effects of MEKi. The synergistic suppression of DTC upon treatment with both inhibitors was futher confirmed in xenograft models and transgenic models. Interpretation: RTKs activation leads to reactivation of the MAPK pathway and resistance to MEKi in DTC, which is reversed by SHP2 blockade. As a novel active inhibitor of SHP2, SHP099 in combination with selumetinib is a promising therapeutic approach for advanced DTC and MEKi-resistant one. Funding Statement: This work was partially supported by grants from the National Natural Science Foundation of China (GRANT no. 81872169), Tianjin Key Research and Development Program Science and Technology Support Key Projects (grant no. 17YFZCSY00690), and Tianjin Municipal Science and Technology Project (grant no. 19JCYBJC27400). Declaration of Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Ethics Approval Statement: All animal experiments were approved by the Tianjin Medical University Cancer Institute and the Hospital Animal Care and Use Committee and performed according to the IACUC protocol.

Knockdown of circ_NEK6 Decreased 131I Resistance of Differentiated Thyroid Carcinoma via Regulating miR-370-3p/MYH9 Axis.

Radioresistance is a crucial factor for the failure of iodine 131 (131I)-based radiotherapy for differentiated thyroid carcinoma (DTC). This study aimed to explore the effect of circ_NEK6 on the development of 131I resistance in DTC and its potential mechanism. In this study, we demonstrated that circ_NEK6 expression was significantly elevated in 131I-resistant DTC tissues and cell lines. Knockdown of circ_NEK6 significantly repressed 131I resistance via inhibiting cell proliferation, migration, invasion abilities, and inducing cell apoptosis and DNA damage in 131I-resistant DTC cells. Mechanistically, knockdown of circ_NEK6 suppressed 131I resistance in DTC by upregulating the inhibitory effect of miR-370-3p on the expression of myosin heavy chain 9 (MYH9). In vivo experiments showed that circ_NEK6 inhibition aggravated 131I radiation-induced inhibition of xenograft tumor growth. Taken together, knockdown of circ_NEK6 repressed 131I resistance in DTC cells by regulating the miR-370-3p/MYH9 axis, indicating that circ_NEK6 may act as a potential biomarker and therapeutic target for DTC patients with 131I resistance.

Inhibition of microRNA-875-5p promotes radioiodine uptake in poorly differentiated thyroid carcinoma cells by upregulating sodium-iodide symporter.

Poorly differentiated thyroid carcinoma (PDTC) is an endocrine malignancy that is challenging to treat due to its limited radioiodine uptake. microRNAs (miRNAs or miRs) have been shown to be useful in treating many types of tumors, including PDTC. This study aims to evaluate the potential effect of miR-875-5p on the radioiodine uptake of PDTC and to clarify the underlying mechanisms. Expression of miR-875-5p and sodium-iodide symporter (NIS) in tissues and cell lines was determined using RT-qPCR. The binding relationship between miR-875-5p and NIS was predicted through in silico analysis and verified by dual-luciferase reporter gene assay. A series of miR-875-5p mimic, miR-875-5p inhibitor, shRNA against NIS, and overexpressed NIS plasmids were introduced into PDTC cells. We then evaluated the cell viability, colony formation, apoptosis, and radioiodine uptake of each PDTC sample via CCK-8 assay, clonogenic assay, flow cytometry, and γ counter, respectively. miR-875-5p was found to be highly expressed, but NIS was poorly expressed in DTC tissues and PDTC cell lines. NIS was verified to be a target gene of miR-875-5p. Upregulation of miR-875-5p was found to induce PDTC cell proliferation, and reduce apoptosis and radioiodine uptake in vitro through down-regulation of NIS. In an in vivo orthotopic model, the enhancement of miR-875-5p led to the reduction of NIS expression and radioiodine uptake in the thyroid tumors. Altogether, the findings of the current study suggest that down-regulated miR-875-5p expression could promote its target gene NIS to increase radioiodine uptake in PDTC, constituting a preventive strategy against PDTC.

Therapeutic Delivery of miR-143 Targeting Tumor Metabolism in Poorly Differentiated Thyroid Cancer Xenografts and Efficacy Evaluation Using 18F-FDG MicroPET-CT.

Poorly differentiated thyroid carcinoma cells tend to be more aggressive and show enhanced glucose uptake which could be exploited for anti-cancer strategy. Previously, we identified hexokinase 2 (HK2) as a direct target of miR-143. In our current study, the effects of miR-143 on glucose metabolism and tumor biological behavior were investigated in FTC-133 cells which is a poorly differentiated thyroid carcinoma (PDTC). Additionally, tumor-bearing mice xenografts of PDTC were constructed, with encapsulated miR-143 agomir being administered intravenously. 18F-FDG microPET-CT scanning was used for the evaluation of therapeutic efficacy. The tumor-restrained effect of miR-143 was demonstrated in PDTC. Furthermore, microPET/CT imaging exhibited a reduction of 18F-FDG uptake in tumors, corresponding to the downregulated expression of HK2 in tissues. In summary, our results suggest that miR-143 can be an alternative treatment for PDTC and the specific assessment of therapeutic response to miR-143 can be achieved by 18F-FDG microPET/CT in advanced thyroid carcinoma xenografts.

Research progress on low iodine preparation for radioactive iodine therapy in differentiated thyroid carcinoma

Normal thyroid follicular epithelial cells and differentiated thyroid carcinoma (DTC) cells have the unique ability to take up iodine under the stimulation of thyroid stimulating hormone (TSH) via a membrane-based sodium/iodide symporter (NIS). Depleting plasma iodine concentration and ensuring sufficient amount of 131I uptake into remnant or cancer cells serve as the basis for radioactive iodine (RAI) therapy. Knowledge of the importance of low iodine preparation contributes to RAI therapy for DTC patients. This review summarizes the optimal extent, duration and impact of low iodine preparation on outcomes of RAI therapy. Key words: Thyroid neoplasms; Radiotherapy; Iodine radioisotopes; Trends

Thermotherapy for Na+/I− symporter-expressing cancer using anti-Na+/I− symporter antibody-conjugated magnetite nanoparticles

Surgery, followed by remnant ablation with radioactive iodine (I-131), is used for treating differentiated thyroid carcinoma (DTC) as the sodium–iodine (Na-I) symporter (NIS) is highly expressed in the thyroid and DTC cells. Our aim was to investigate the feasibility of using anti-NIS antibody-conjugated magnetite nanoparticles (NIS-MNPs) as a diagnostic and therapeutic agent for DTC by studying NIS-MNP in an NIS over-expressing HeLa (HeLa-NIS) cell line and a subcutaneous HeLa-NIS tumor-bearing mouse model. Immunofluorescence was used to determine if NIS-MNP could bind to HeLa-NIS, and its therapeutic effect was investigated using HeLa-NIS cells after alternating magnetic field (AMF) irradiation. Magnetic resonance imaging (MRI) was performed to visualize the normal thyroid gland of nude mice after intravenous injection of NIS-MNP. NIS-MNPs were injected into the cancer nodules of the mouse model, which were irradiated under AMF for 1h twice at 24-h intervals. Accumulation of NIS-MNP was examined using MRI and tumor volume was measured over seven days. Results showed that NIS-MNP bound effectively to the surface of HeLa-NIS cells, and AMF inhibited growth of NIS-MNP-treated HeLa-NIS cells. Normal thyroid glands of mice were enhanced by NIS-MNP treatment in T2-weighted MRI. Inhibition of tumor growth was observed after AMF irradiation in the NIS-MNP group. In conclusion, NIS-MNP is a feasible diagnostic and therapeutic tool for localizing and treating NIS-expressing tumors such as DTC when coupled with AMF irradiation.

In vitro studies of DNA damage and repair mechanisms induced by BNCT in a poorly differentiated thyroid carcinoma cell line.

Boron neutron capture therapy (BNCT) for aggressive tumors is based on nuclear reaction [10B (n, α) 7Li]. Previously, we demonstrated that BNCT could be applied for the treatment of undifferentiated thyroid carcinoma. The aim of the present study was to describe the DNA damage pattern and the repair pathways that are activated by BNCT in thyroid cells. We analyzed γH2AX foci and the expression of Ku70, Rad51 and Rad54, main effector enzymes of non-homologous end joining (NHEJ) and homologous recombination repair (HRR) pathways, respectively, in thyroid follicular carcinoma cells. The studied groups were: (1) C [no irradiation], (2) gamma [60Co source], (3) N [neutron beam alone], (4) BNCT [neutron beam plus 10µg 10B/ml of boronphenylalanine (10BPA)]. The total absorbed dose was always 3Gy. The results showed that the number of nuclear γH2AX foci was higher in the gamma group than in the N and BNCT groups (30min-24h) (p < 0.001). However, the focus size was significantly larger in BNCT compared to other groups (p < 0.01). The analysis of repair enzymes showed a significant increase in Rad51 and Rad54 mRNA at 4 and 6h, respectively; in both N and BNCT groups and the expression of Ku70 did not show significant differences between groups. These findings are consistent with an activation of HRR mechanism in thyroid cells. A melanoma cell line showed different DNA damage pattern and activation of both repair pathways. These results will allow us to evaluate different blocking points, to potentiate the damage induced by BNCT.

Post-translational Regulation of Radioactive Iodine Therapy Response in Papillary Thyroid Carcinoma.

Radioactive iodine (RAI) is the mainstay of treatment for differentiated thyroid carcinoma (DTC). Nevertheless, the mechanism of RAI resistance that occurs in many patients with DTC remains unknown. We aimed to elucidate the role of post-translational regulation of radioiodine uptake. We analyzed the expression pattern of the ribosomal glycosylphosphatidylinositol transamidase (GPIT) complex in freshly excised tumors from 10 patients with DTC. We used functional RAI uptake assays to assess the role of GPIT in iodine uptake both in vivo and in vitro. The effects of MEK inhibition on the GPIT subunit PIGU and the sodium iodide symporter (NIS) were assessed in three DTC cell lines and in four human DTC biopsies. We used a multivariable logistic regression model to study the role of PIGU in the response to RAI treatment in advanced DTC. All statistical tests were two-sided. Expression profiling of different GPIT complex subunits revealed statistically significantly lower expression of PIGU in papillary carcinomas than in matched normal thyroid tissue (P < .001). Expression of PIGU in the K1 human papillary carcinoma cell line resulted in a robust increase in NIS glycosylation and trafficking to the cell membrane, accompanied by a robust increase in I125 uptake both in vitro (465 200 ± 56 343 vs 1236 ± 156 counts per million, P < .001) and in vivo (128 945 ± 28 556 vs 7963 ± 192 counts per million, P < .001, n = 5 mice per group). Treatment with the MEK inhibitors U0126 and PD302 rescued PIGU expression. Finally, the PIGU expression levels in tumors of 18 patients with recurrent DTC were associated with a biochemical response to RAI treatment (hazard ratio = 8.06, 95% confidence interval = 3.72 to 12.3, P = .001). We showed that downregulation of PIGU in DTC determines NIS function and RAI avidity. This represents a novel mechanism for RAI resistance.

99mTc-EDDA/HYNIC-TOC in the diagnosis of differentiated thyroid carcinoma refractory to radioiodine treatment.

In majority of cases of differentiated thyroid carcinoma (DTC), the ablative radioiodine treatment shows high efficacy. In a small number of patients, mechanism of selective iodine uptake by the DTC cells is insufficient and alternative methods of diagnosis and treatment are needed. As demonstrated in vitro, DTC cells show expression of somatostatin recep-tors. Radiolabeled somatostatin analogs are widely used in the diagnosis of neuroendocrine tumors. The aim of the study was to evaluate the utility of peptide receptor scintigraphy with the use of 99mTc-EDDA/HYNIC-TOC in the diagnosis of DTC in patients with elevated thyroglobulin concentrations (Tg), negative WBS and no effect of the consecutive radioiodine therapies. Whole body scintigraphy as well as SPECT of neck and chest were performed 3 and 24 h after i.v. administration of 740 MBq 99mTc-EDDA/HYNIC-TOC. The obtained images were compared with other radionuclide and ra-diological imaging methods. Forty-three patients with DTC after surgery and ablative radioiodine treatment with negative WBS and elevated Tg were qualified. Patients' age: 18-83 years (mean 58.0). SRS showed foci of tracer accumulation in 29 cases (67.4%). Sensitivity was 69.0% specificity 78.6%. SRS correctly identified local recurrence in 8 pts., metastatic lymph nodes in 19 pts., lung metastases in 12 pts. and bone metastases in 5 pts. SRS showed high sensitivity in the detection of metastatic lymph nodes (100%) and bone metastases (83.3%) and lung metastases (63.2%). Positive SRS was found in pts. with higher Tg concentrations (130 ± 144 vs. 30 ± 54 ng/ml). Scintigraphy with the use of the studied technetium-99m-labeled somatostatin analog is useful in the evaluation of patients with advanced DTC. It shows relatively good sensitivity and specificity but not high enough to be recommended as a routine imaging method. The role of somatostatin receptor scintigraphy in DTC is complementary to other imaging modalities.

Recurrence of Differentiated Thyroid Carcinoma During Full TSH Suppression: Is the Tumor Now Thyroid Hormone Dependent?

Well-standardized primary treatment and long-term management of differentiated thyroid carcinoma (DTC) include lowering or suppression of host thyrotropin (TSH) with exogenous L-thyroxine (T4). This treatment recognizes the trophic action of TSH on DTC cells. Suppression of endogenous TSH with T4 is continued in recurrent disease. However, T4 can induce proliferation of follicular and papillary thyroid carcinoma cell lines and of other human carcinoma cells. The proliferative mechanism is initiated at a cell surface receptor for T4 on integrin αvβ3, a receptor by which the hormone also inhibits p53-dependent apoptosis in tumor cells. In recurrent DTC with satisfactory suppression of endogenous TSH, we discuss here the possibility that the tumor is no longer TSH dependent and that T4 has become a critical growth factor for the cancer.

Efficacy of lentiviral-mediated transfection of hTSHR in poorly differentiated thyroid carcinoma cell line

Dedifferentiated thyroid cancer is often incurable because it does not respond to radioiodine. This study aimed to investigate iodide uptake and the expressions of thyroid-specific molecules after the transfection of human thyrotropin receptor (hTSHR) gene in poorly differentiated follicular thyroid cancer cell line (FTC-133). pGC-FU-hTSHR-GFP-lentivirus and pGC-FU-GFP-lentivirus were added into FTC-133 cells respectively. The parental cells were defined as the blank group. Cells transduced with pGC-FU-GFP and pGC-FU-hTSHR-GFP were defined as the control group and experimental group respectively. The efficiency of transfection was observed under a fluorescence microscope. (125)I uptake by FTC-133 was analyzed by measuring the radioactivity. Real time-PCR, western blotting and radioimmunoassay were applied to detect the expressions of mRNAs and proteins of Na(+)/I(-) symporter (NIS), thyroid-stimulating hormone receptor (TSHR), thyroid peroxidase (TPO) and thyroglobulin (Tg) in FTC-133. The green fluorescence was present in 80% of the transduced cells under fluorescence microscope. The iodine uptake of cells transduced with pGC-FU-TSHR-GFP was 3.3 times higher than that in the other two groups (P<0.01). NIS, TSHR, TPO and Tg had been significantly up-regulated in the experimental group as compared to the control group (P<0.01) and the blank group (P<0.01). The hTSHR transfection in FTC-133 improved the expression of thyroid-specific molecules including TSHR, NIS, TPO and Tg and radioiodide uptake.

Differentiated thyroid carcinomas may elude the immune system by B7H1 upregulation

B7H1 is consistently associated with inhibition of the immune system in many solid tumors. However, there is no report about its impact on differentiated thyroid carcinoma (DTC) presentation, aggressiveness, or evolution. Aiming to investigate the role of B7H1 in DTC and correlate this protein with other tumor-infiltrating immune cells, we studied 407 thyroid nodule tissue samples including 293 from DTC patients, all managed according to a same standard protocol. In addition, we obtained 5 normal and 114 benign thyroid lesions. Eighteen out of the 253 papillary thyroid carcinomas were paired with respective metastatic lymph node tissues. B7H1 (CD274) protein expression was assessed by immunohistochemistry and the gene expression was quantified by real-time PCR. Malignant tissues displayed a more intense B7H1 staining and higher mRNA levels than benign tissues (both P<0.0001). We observed a positive linear correlation between higher age at diagnosis and B7H1 mRNA levels (P=0.02896). Elevated levels of B7H1 protein were associated with the presence of CD4+, CD8+, CD20+, and FoxP3+ lymphocytes (all P<0.05); tumor-associated macrophages (P<0.0001); and the presence of myeloid-derived suppressor cells (P=0.03256). Stage II-IV patients presented higher B7H1 mRNA levels than stage I cases (P=0.03522). On the contrary, a decreased expression of B7H1 protein was observed in lymph node metastasis (P=0.0152). In conclusion, our data demonstrate that B7H1 expression is associated with features of aggressiveness, suggesting that this is an immune evasion mechanism of DTC cells.

Foxp3 expression is associated with aggressiveness in differentiated thyroid carcinomas

OBJECTIVES:Forkhead box P3 (FoxP3) expression has been observed in human cancer cells but has not yet been reported in thyroid cells. We investigated the prognostic significance of both FoxP3 expression and intratumoral FoxP3+ lymphocyte infiltration in differentiated thyroid carcinoma cells.METHODS:We constructed a tissue microarray with 385 thyroid tissues, including 266 malignant tissues (from 253 papillary thyroid carcinomas and 13 follicular carcinomas), 114 benign lesions, and 5 normal thyroid tissues.RESULTS:We determined the expression of FoxP3 in both tumor cells and tumor-infiltrating lymphocytes using immunohistochemical techniques. Cellular expression of FoxP3 was evident in 71% of benign and 91.9% of malignant tissues. The nuclear and cytoplasmic expression patterns were quantified separately. A multivariate logistic regression analysis indicated that cytoplasmic FoxP3 expression is an independent risk factor for thyroid malignancy. Cytoplasmic FoxP3 staining was inversely correlated with patient age. Nuclear FoxP3 staining was more intense in younger patients and in tumors presenting with metastasis at diagnosis. FoxP3+ lymphocytes were more frequent in tumors smaller than 2 cm, those without extrathyroidal invasion, and in patients with concurrent chronic lymphocytic thyroiditis.CONCLUSIONS:We demonstrated FoxP3 expression in differentiated thyroid carcinoma cells and found evidence that this expression may exert an important influence on several features of tumor aggressiveness.

REGγ is a strong candidate for the regulation of cell cycle, proliferation and the invasion by poorly differentiated thyroid carcinoma cells

REGγ is a proteasome activator that facilitates the degradation of small peptides. Abnormally high expression of REGγ has been observed in thyroid carcinomas. The purpose of the present study was to explore the role of REGγ in poorly differentiated thyroid carcinoma (PDTC). For this purpose, small interfering RNA (siRNA) was introduced to down-regulate the level of REGγ in the PDTC cell line SW579. Down-regulation of REGγ at the mRNA and protein levels was confirmed by RT-PCR and Western blot analyses. FACS analysis revealed cell cycle arrest at the G1/S transition, the MTT assay showed inhibition of cell proliferation, and the Transwell assay showed restricted cell invasion. Furthermore, the expression of the p21 protein was increased, the expression of proliferating cell nuclear antigen (PCNA) protein decreased, and the expression of the p27 protein was unchanged as shown by Western blot analyses. REGγ plays a critical role in the cell cycle, proliferation and invasion of SW579 cells. The alteration of p21 and PCNA proteins related to the down-regulation of REGγ suggests that p21 and PCNA participate in the process of REGγ regulation of cell cycle progression and cell proliferation. Thus, targeting REGγ has a therapeutic potential in the management of PDTC patients.

Overexpression of DEP domain containing mTOR-interacting protein correlates with poor prognosis in differentiated thyroid carcinoma

DEP domain containing mammalian target of rapamycin (mTOR)-interacting protein (DEPTOR), a recently identified mTOR-interacting protein, is a novel candidate oncogene. Previous studies reveal that high DEPTOR expression is required to maintain PI3K and Akt activation and to inhibit apoptosis. However, its significance in differentiated thyroid carcinoma (DTC) is not yet known. The present study verifies the mRNA and protein expression of DEPTOR in five cell lines, DTC tissues and normal adjacent tissues. Tissue microarrays of 114 DTC patients were used to detect DEPTOR protein expression. The assessment of DEPTOR levels demonstrated that DEPTOR in DTC cells and tissues was significantly increased compared with normal cells and adjacent normal tissues. DEPTOR protein expression was significantly associated with lymph node status, extrathyroid extension and distant metastasis. Patients exhibiting high DEPTOR expression were statistically susceptible to earlier recurrence and poorer survival than those with low expression. Univariate and multivariate analyses showed that DEPTOR expression was an independent prognostic factor for DTC recurrence. In conclusion, our data indicate DEPTOR as a novel prognostic marker for DTC.