Human Papillary Thyroid Carcinoma Cell Research Articles

RDM1 gene overexpression represents a therapeutic target in papillary thyroid carcinoma.

RAD52 motif containing 1 (RDM1) encodes the RAD52 protein involved in DNA double-strand break repair and recombination events. However, the importance of RDM1 in papillary thyroid carcinoma (PTC) is largely unknown. In the present study, we examined the role of RDM1 in thyroid cancer. The RDM1 expression in PTC patients was examined using immunohistochemistry. The expression levels of RDM1 mRNA in thyroid cancer cells were measured by quantitative real-time PCR (qRT-PCR). Lentivirus-mediated small interfering RNAs (siRNAs) were used to knock down the RDM1 expression in the K1 and TPC1 cells. Then, changes in the RDM1 target gene expression were determined by qRT-PCR and Western blot. Cell proliferation was examined by a high content screening assay. Cell cycle distribution and apoptosis were detected by flow cytometric analysis and MTT analysis. We showed that the RDM1 expression was higher in PTC tissue compared to pericarcinous tissue. RDM1 mRNA was found to be expressed by qRT-PCR. Using a lentivirus-based RNA interference (RNAi) approach, the RDM1 expression was significantly inhibited. The inhibition of RDM1 expression by RNAi significantly impaired cell proliferation, increased apoptosis and arrested cells in the G2/M phase. These data showed that RDM1 was highly expressed in PTC tissue and thyroid cancer cell lines. Moreover, RDM1 may play an important role in cell proliferation, cell cycle distribution and apoptosis of human PTC cells.

Loss of c-KIT expression in thyroid cancer cells

Papillary thyroid carcinoma is the most frequent histologic type of thyroid tumor. Few studies investigated the role of c-KIT expression in thyroid tumors, suggesting a role for this receptor and its ligand in differentiation and growth control of thyroid epithelium and a receptor loss following malignant transformation. We investigated and correlated c-KIT expression levels and two known markers of thyrocytes differentiation, PAX8 and TTF-1, in malignant and benign cytological thyroid samples. Moreover, we performed functional studies on human papillary thyroid carcinoma cell line to associated c-KIT expression to thyrocytes differentiation and tumor proliferation. c-KIT and PAX8 expression resulted higher in benign samples compared to the malignant ones, and the expression levels of these two genes were significantly correlated to each other. We also observed that c-KIT overexpression led to an increase of PAX8 expression level together with a decrease of proliferation. Furthermore, c-KIT overexpressing cells showed a regression of typical morphological features of malignancy. Taken together these results suggest that c-KIT could be involved in the differentiation of thyroid cells and in tumor progression.

Down-regulation of microRNA-146b-5p repress proliferation of thyroid carcinoma cells by enhancing autophagy activity

Objective To investigate the influence of autophagy on proliferation of human papillary thyroid carcinoma cells (TPC-1) repressed by down-regulation of microRNA (miRNA, miR)-146b-5p. Methods TPC-1 cells were transient transfected by Lipofectmine 2000, and then cells were devided into four groups: as-miR, as-NC, co-transfection (as-miR-146b-5p+ siBeclin1) and co-transfection for control (as-miR-146b-5p+ siNC). Then the transfection efficiency was determined by invert fluorescence microscope and real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR). Western blotting and RT-qPCR were used to analyzed the protein and mRNA levels of Beclin1 of the transfected cells, respectively. Transmission electron microscopy was used to evaluated the expression of autophagsome of the transfected cells. And cell counting kit-8 and colony formation assay were used to detected the proliferation of the transfected cells. Results Compared with those treated with as-NC, miR-146b-5p expression was decreased to (0.380±0.021), and the protein and mRNA levels of Beclin1 were increased to (0.612±0.014), (0.413±0.005) respectively, and the absorbance at 72 h and amount of colony foci was decreased to (1.470±0.062, P=0.007), (29.000±3.610)% (P=0.031) respectively, and the autophagsome expression was significantly increased in TPC-1 cells treated with as-miR-146b-5p after 24 h. Compared with those co-transfected with as-miR-146b-5p+ siNC, the protein and mRNA levels of Beclin1 were decreased to (0.286±0.027), (0.265±0.025, P=0.006) respectively, and the absorbance at 72 h and amount of colony foci was increased to (2.564±0.050), (49.000±2.821)% respectively (P=0.027), and autophagsome expression was significantly decreased in TPC-1 cells co-transfected with as-miR-146b-5p+ siBeclin1 after 36 h. Conclusion Down-regulation of miR-146b-5p inhibit the viability of TPC-1 cells via strengthening autophagy activity. Key words: MicroRNA-146b-5p; Papillary thyroid carcinoma; Atophagy; Beclin1

RASSF10 is Epigenetically Inactivated and Suppresses Cell Proliferation and Induces Cell Apoptosis by Activating the p53 Signalling Pathway in Papillary Thyroid Carcinoma Cancer

Objectives: We aimed to confirm whether RASSF10 activated the p53 signalling pathway, thereby modulating cell proliferation, migration, invasion, and apoptosis in papillary thyroid carcinoma (PTC) cells. Methods: A total of 108 PTC tissue samples and normal adjacent tissues were obtained. RT-PCR and Western blotting analyses were performed to detect RASSF10 expression, and methylation levels of RASSF10 were estimated by methylation-specific PCR (MSP). We also detected the expression and methylation status of RASSF10 in both a human PTC cell line (K1) and a normal thyroid cell line (FRTL5). After transfection of cells with empty vector pcDNA3.1, pcDNA3.1-RASSF10, p53 siRNA and shRASSF10, Coulter counter, colony-formation, wound healing, Transwell and flow cytometry analyses were performed to examine the role of RASSF10 in cell proliferation, migration, invasion, and apoptosis. Finally, the expression of p53, p21, Bcl-2 and Bax were detected using Western Blotting analyses. Results: RASSF10 expression in PTC tissues was significantly lower and hyper-methylated compared to normal adjacent tissues. In addition, RASSF10 was significantly down-regulated and hyper-methylated in K1 cells compared to FRTL5 cells. In addition, suppressed proliferation and significantly induced apoptosis of K1 cells were observed after transfection with pcDNA3.1-RASSF10 (P < 0.05). Furthermore, RASSF10 activated the p53 signalling pathway and regulated the expression of p53, p21, Bcl-2 and Bax. Furthermore, p53 siRNA could antagonize the effects of RASSF10 in K1 cells. Conclusions: RASSF10 induces apoptosis in PTC cells by activating the p53 signalling pathway, indicating its role as a treatment target for PTC.

Combretastatin A4 Regulates Proliferation, Migration, Invasion, and Apoptosis of Thyroid Cancer Cells via PI3K/Akt Signaling Pathway.

BackgroundCombretastatin A4 (CA4) is a potential therapeutic candidate for a variety of human cancer treatments. However, the inhibitive effects of CA4 on thyroid cancer cells are still not well-clarified. This study aimed to investigate the potential effect of CA4 on thyroid cancer cells, as well as underlying mechanism.Material/MethodsHuman thyroid papillary carcinoma cell line TPC1 was pre-treated with 5 concentrations of CA4 (0, 1, 2, 5, or 10 μM) for 2 h. Cell proliferation was determined by 3-(4, 5-dimethyl-2- thiazolyl)-2, 5-diphenyl -2-H-tetrazolium bromide (MTT) assay. Cell migration and invasion were detected by a modified Boyden chamber assay. Moreover, cell apoptosis was detected by terminal deoxynucleotidyl (TUNEL) staining assay and flow cytometry method. Western blot analysis was performed to determine the expression changes of epithelial-mesenchymal transition (EMT)-related proteins and phosphatidylinositol-3-kinase/serine/threonine kinase (PI3K/Akt) signaling pathway proteins.ResultsCA4 significantly inhibited the cell proliferation, migration, and invasion, and significantly promoted cell apoptosis in a dose-dependent manner compared with the control group. The EMT-related protein levels of N-Cadherin, Vimentin, Snail1, Slug, Twist1, and ZEB1 were significantly decreased by CA4, while E-cadherin had no significant difference compared with the control group. Moreover, PI3K/Akt signaling pathway protein levels of p-PI3K and p-Akt were significantly decreased, whereas PI3K and Akt had no significant differences compared with the control group.ConclusionsCA4 can inhibit proliferation, migration, and invasion and promote apoptosis of TPC1 cells. These effects might be through the PI3K/Akt signaling pathway. CA4 may be a potential therapeutic target for the treatment of thyroid cancer.

Metformin reduces glycometabolism of papillary thyroid carcinoma in vitro and in vivo.

More aggressive thyroid cancer cells show a higher activity of glycometabolism. Targeting cancer cell metabolism has emerged as a novel approach to prevent or treat malignant tumors. Glucose metabolism regulation effect of metformin in papillary thyroid cancer was investigated in the current study. Human papillary thyroid carcinoma (PTC) cell lines BCPAP and KTC1 were used. Cell viability was detected by CCK8 assay. Glucose uptake and relative gene expression were measured in metformin (0-10 mM for 48 h)-treated cells by 18F-FDG uptake assay and western blotting analysis, respectively. MicroPET/CT imaging was performed to detect 18F-FDG uptake in vivo After treatment with metformin at 0, 2.5, 5 and 10 mM for 48 h, the ratio of p-AMPK to total AMPK showed significant rising in a dose-dependent manner in both BCPAP and KTC1, whereas p-AKT and p-mTOR expression level were downregulated. 18F-FDG uptake reduced after metformin treatment in a dose-dependent manner, corresponding to the reduced expression level of HK2 and GLUT1 in vitro Xenograft model of PTC using BCPAP cells was achieved successfully. MicroPET/CT imaging showed that in vivo 18F-FDG uptake decreased after treatment with metformin. Immunohistochemistry staining further confirmed the reduction of HK2 and GLUT1 expression in the tumor tissue of metformin-treated PTC xenograft model. In conclusion, metformin could reduce glucose metabolism of PTC in vitro and in vivo Metformin, by targeting glycometabolism of cancer cells, could be a promising adjuvant therapy alternative in the treatment modality of advanced thyroid carcinoma.

Abstract 3393: miR-34b: A regulator of VEGF-A, Notch1 and Bcl-2 in thyroid carcinoma

Abstract Background: Thyroid cancer is the most common endocrine malignancy accounting for &amp;gt;91% of endocrine malignancy and 1.8% of all recently distinguished cancer reports, with an incidence continuing to rise globally in recent decades and current treatment strategies are not potent enough for patients. Therefore, novel and more effective treatment are outstandingly required. New strategy for treatment is target therapy, which not only hold cancer-specific expression but also limits side effects. miR-34b as part of p53 tumor suppressor network, plays crucial role in many physiological and pathological processes including cancer initiation, tumor progression and cancer angiogenesis process. Objectives: In this study, we evaluate the functional roles of miR-34b in 2 thyroid cancer cell lines for its potential in modulating angiogenesis and proliferation in thyroid malignancies. Methods: Expression levels of miR-34b was determined in metastasizing human papillary thyroid carcinoma (B-CPAP) and human undifferentiated thyroid carcinomas (MB-1) cell lines by qPCR. Exogenous miR-34b was transfected to thyroid cancer cell lines to investigate its effect on predominant genes involved in angiogenesis, cell cycle and apoptosis regulation including VEGF-A and Bcl-2 and Notch1. Confocal laser scanning microscopy (CLSM) and western blot techniques were performed to illustrate the protein expression changes. To demonstrate the perturbation of cell cycle and apoptosis pathways through exogenous miR-34b, fluorescence-activated cell sorting (FACS) was performed. Results: Significant underexpression of miR-34b was established in B-CPAP and MB-1 cell lines while outstanding overexpression of VEGF-A, Bcl-2 and Notch1 were detected. After transfection with miR-34b, significant drop in concentration of VEGF-A, Bcl-2 and Notch1 were noticed compared with controls in CLSM and western blot analysis (p&amp;lt; 0.05). Cell cycle analysis demonstrated that 48 hours after ectopic induction of miR-34b, significant impairment in proliferation of B-CPAP and MB-1 was induced through arresting cancer cell proliferation in G0-G1 phase (14.27% ±3.50 for B-CPAP and 13.61% ±0.16 for MB-1) (p&amp;lt;0.05). Apoptosis assay also revealed that miR-34b, induced cell death by increasing early and late apoptosis events, compared with controls (2.20% ±0.16 for B-CPAP and 7.87% ±0.92 for MB-1) (p&amp;lt;0.05). Conclusion: These results pave the way that miR-34b may be involved in balancing tumour angiogenesis, cell proliferation and apoptosis in thyroid cancer. These could potentially occur via direct modulation of downstream targets such as VEGF-A, Bcl-2 and Notch1 for their role in those events. The future of this research will investigate the regulatory role of miR-34b in Papillary and undifferentiated thyroid carcinoma through larger scale in vivo and clinical trial studies which shall potentially improve the clinical presentation of aggressive malignancies. Citation Format: Hamidreza Maroof, Ali Salajegheh, Alfred KY Lam. miR-34b: A regulator of VEGF-A, Notch1 and Bcl-2 in thyroid carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3393.

MAPK and SHH pathways modulate type 3 deiodinase expression in papillary thyroid carcinoma.

Type 3 deiodinase (DIO3, D3) is reactivated in human neoplasias. Increased D3 levels in papillary thyroid carcinoma (PTC) have been associated with tumor size and metastatic disease. The objective of this study is to investigate the signaling pathways involved in DIO3 upregulation in PTC. Experiments were performed in human PTC cell lines (K1 and TPC-1 cells) or tumor samples. DIO3 mRNA and activity were evaluated by real-time PCR and ion-exchange column chromatography respectively. Western blot analysis was used to determine the levels of D3 protein. DIO3 gene silencing was performed via siRNA transfection. DIO3 mRNA levels and activity were readily detected in K1 (BRAF(V6) (0) (0E)) and, at lower levels, in TPC-1 (RET/PTC1) cells (P<0.007 and P=0.02 respectively). Similarly, DIO3 mRNA levels were higher in PTC samples harboring the BRAF(V600E) mutation as compared with those with RET/PTC1 rearrangement or negative for these mutations (P<0.001). Specific inhibition of BRAF oncogene (PLX4032, 3 μM), MEK (U0126, 10-20 μM) or p38 (SB203580, 10-20 μM) signaling was associated with decreases in DIO3 expression in K1 and TPC-1 cells. Additionally, the blockage of the sonic hedgehog (SHH) pathway by cyclopamine (10 μM) resulted in markedly decreases in DIO3 mRNA levels. Interestingly, siRNA-mediated DIO3 silencing induced decreases on cyclin D1 expression and partial G1 phase cell cycle arrest, thereby downregulating cell proliferation. In conclusion, sustained activation of the MAPK and SHH pathways modulate the levels of DIO3 expression in PTC. Importantly, DIO3 silencing was associated with decreases in cell proliferation, thus suggesting a D3 role in tumor growth and aggressiveness.

15-Deoxy-Δ(12,14)-prostaglandin J2 Induces Apoptosis and Upregulates SOCS3 in Human Thyroid Cancer Cells.

The cyclopentenone prostaglandin 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) is a natural ligand of peroxisome proliferator-activated receptor gamma (PPAR-γ) and a potential mediator of apoptosis in cancer cells. In the present study, we evaluated the effect of 15d-PGJ2 in human thyroid papillary carcinoma cells (TPC-1) using different doses of 15d-PGJ2 (0.6 to 20 μM) to determine IC50 (9.3 μM) via the MTT assay. The supernatant culture medium of the TPC-1 cells that was treated either with 15d-PGJ2 or with vehicle (control) for 24 hours was assessed for IL-6 secretion via CBA assay. RT-qPCR was used to evaluate mRNA expression of IL-6, SOCS1, SOCS3, and STAT3. TPC-1 cells treated with 15d-PGJ2 decreased the secretion and expression of IL-6 and STAT3, while it increased SOCS1 and SOCS3. Overall, we demonstrated that 15d-PGJ2 downregulated IL-6 signaling pathway and led TPC-1 cells into apoptosis. In conclusion, 15d-PGJ2 shows the potential to become a new therapeutic approach for thyroid tumors.

MicroRNA-663 suppresses cell invasion and migration by targeting transforming growth factor beta 1 in papillary thyroid carcinoma.

MicroRNA-663 (miR-663) has been detected in a large variety of tumor types; however, it still holds both tumor suppressive and oncogenic roles in different tumor types. The miRNA-CHIP microarray assay revealed downregulation of miR-663 in papillary thyroid carcinoma (PTC); however, the effect of miR-663 on PTC cell invasion and migration remains unknown. Accordingly, this study aimed to investigate the potential involvement of miR-663 in PTC. In this study, miR-663 expression level was measured via quantitative real-time PCR in 91 pairs of human PTC and adjacent normal tissues and in two human PTC cell lines. The effect of miR-663 on PTC cell invasion and migration were studied by transwell and wound healing assays. In addition, the miR-663 target was searched and the underlying mechanism was clarified by reporter assay and rescue experiment. The current study confirmed that miR-663 expression was inhibited in PTC tissue samples and PTC cell lines. There were statistically significant differences in expression of miR-663 with regard to age and tumor size. Upregulation of miR-663 suppressed PTC cell invasion and migration. Further study showed that transforming growth factor beta 1 (TGFβ1) was the direct target of miR-663 and mediated the effect of miR-663 on PTC development. By targeting TGFβ1, miR-663 efficiently regulates the expression of epithelial-mesenchymal transition (EMT) markers and matrix metalloproteinases (MMPs). The data indicated that miR-663 may suppress tumor invasion and migration by targeting TGFβ1 and regulate EMT progress of PTC cells.

Over-expression of microRNA-375 inhibits papillary thyroid carcinoma cell proliferation and induces cell apoptosis by targeting ERBB2

MicroRNAs (miRs) played important roles in the cell proliferation, apoptosis and other biological processes in cancer. In the present study we found that miR-375 was significantly down-regulated in human papillary thyroid carcinoma (PTC) tissues and cell lines. In this study we try to investigate the biological activity of miR-375 in human PTC cells and try to find the potential target of miR-375. Our study indicated that over-expression of miR-375 could inhibit the PTC cells proliferation and this inhibition was caused by the induction of cell apoptosis. In vivo animal study indicated that over-expression of miR-375 could significantly decrease the migration and invasion of human PTC cell in vivo. These results exhibit over-expression of miR-375 in human PTC cells could inhibit the process of human PTC. Further study demonstrated ERBB2 was a direct target of miR-375, over-expression of miR-375 decrease the both mRNA and protein expression of ERBB2 in human PTC cells. These data indicate miR-375 play important roles in the process and development of human PTC. These finds suggested that appropriate application of miR-375 regulation might be a new sight for the treatment of human PTC in the future.

FAM172A protein promotes the proliferation of human papillary thyroid carcinoma cells via the p38 mitogen-activated protein kinase pathway.

Family with sequence similarity 172, member A (FAM172A), was cloned from human aortic tissues and confirmed in our previous study in 2009, however, its functions remain to be fully elucidated. In our previous studies, the protein expression of FAM172A in human aortic smooth muscle cells was found to be upregulated by high glucose in a concentration‑ and time‑dependent manner. Several reports have shown that insulin resistance is associated with papillary thyroid carcinoma (PTC). Thus, in the present study, the protein expression levels of FAM172A in human papillary thyroid carcinoma were investigated, and the effect of the FAM172A protein on the proliferation of IHH‑4 human papillary thyroid carcinoma cells, and its potential molecular underlying mechanisms were examined. Immunohistochemistry and western blotting demonstrated that the protein expression of FAM172A in papillary thyroid carcinoma tissues was not only significantly higher than that in noncancerous tissues adjacent to the carcinoma tissues, but it was also markedly higher than that in normal thyroid and thyroid adenoma tissues. Overexpression of the FAM172A protein activated the p38 MAPK pathway, but not the PI3K and AMPK pathways, in the IHH‑4 cells. In addition, overexpression of the FAM172A protein accelerated IHH‑4 cell proliferation, compared with the control group, and the pro‑proliferative effect of FAM172A protein on IHH4 cells was markedly attenuated by SB202190, an inhibitor of p38 MAPK. Taken together, these results suggest that the FAM172A protein is expressed at high levels in human PTC, which may promote cell proliferation via activation of the p38 MAPK signaling pathway, and be involved in the pathogenesis of PTC.

Expression of Pax8 is decreased and bortezomib does not increase the iodine uptake in thyroid carcinoma cells.

Fundamental treatment for papillary thyroid carcinoma (PTC) involves total or subtotal thyroidectomy. Iodine-131 (131I) is routinely utilized to target remnant thyroid cancer and metastasis after thyroidectomy. The effectiveness of other therapeutic modalities remains unsatisfactory; thus, these patients have a poor prognosis. The manner in which the ability of 131I uptake can be improved is vital for their prognosis. Bortezomib has been used as a re-differentiation agent for the treatment of patients with multiple myeloma; however, little is reported about the role of bortezomib in thyroid cancer. To evaluate the therapeutic potential of bortezomib in a human PTC cell line, expression of paired-box 8 (Pax8) protein was determined using Western blot in PTC, normal thyroid, and anaplastic/undifferentiated thyroid carcinoma (ATC) cells. The expression of Pax8 protein in PTC cells pretreated with bortezomib was determined using the same method. Iodine uptake was determined using 131I radioactivity assay. The level of Pax8 protein in normal thyroid cells was significantly higher than in PTC (P < 0.05) and ATC cells (P < 0.05); its expression in PTC cells was also significantly higher than in ATC cells (P < 0.05). The PTC cells in the bortezomib-treated group showed a higher expression of Pax8 protein than the control group (P < 0.05). These findings indicate that bortezomib can increase the expression of Pax8, but does not significantly increase the iodine uptake of PTC cells.

MiR-183 regulates biological behavior in papillary thyroid carcinoma by targeting the programmed cell death 4.

Numerous studies have demonstrated that microRNAs (miRNAs) play vital roles in papillary thyroid carcinoma (PTC). The aim of the present study was to examine the expression levels of miR-183 in PTC and investigate whether its potential roles involved targeting the programmed cell death 4 (PDCD4). Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to examine the expression levels of miR-183 in 38 PTC specimens and 4 PTC cell lines. MTT, colony formation, wound-healing and Transwell invasion assays, and flow cytometry were conducted to explore the potential functions of miR-183 in human TPC1 papillary thyroid carcinoma cells. The dual-luciferase reporter assay was performed to validate whether PDCD4 was a direct target of miR-183. The effects of modulating miR-183 on endogenous levels of PDCD4 were subsequently confirmed via RT-qPCR and western blotting. Functional assays were used to indicate the roles of endogenous PDCD4 in TPC1. The results showed the miR-183 expression levels were significantly upregulated in PTC specimens and cell lines (P<0.05). Overexpression of miR-183 in TPC1 promoted cell proliferation, migration, invasion and decreased apoptosis. The dual-luciferase reporter assay confirmed that PDCD4 was a direct target of miR-183. RT-qPCR and western blotting showed that miR-183 negatively regulated PDCD4 protein expression but had no impact on mRNA expression of PDCD4. Knockdown of PDCD4 expression in TPC1 cells significantly enhanced cell proliferation, migration, invasion and inhibited apoptosis. The results of the present study suggested that miR-183 acts as a papillary thyroid carcinoma oncogene through the negative regulation of PDCD4 protein expression at the post-transcriptional levels. Therefore, targeting miR-183 provides a novel strategy for the diagnosis and treatment of patients with PTC.

Multiple functional variants in long-range enhancer elements contribute to the risk of SNP rs965513 in thyroid cancer

The [A] allele of SNP rs965513 in 9q22 has been consistently shown to be highly associated with increased papillary thyroid cancer (PTC) risk with an odds ratio of ∼1.8 as determined by genome-wide association studies, yet the molecular mechanisms remain poorly understood. Previously, we noted that the expression of two genes in the region, forkhead box E1 (FOXE1) and PTC susceptibility candidate 2 (PTCSC2), is regulated by rs965513 in unaffected thyroid tissue, but the underlying mechanisms were not elucidated. Here, we fine-mapped the 9q22 region in PTC and controls and detected an ∼33-kb linkage disequilibrium block (containing the lead SNP rs965513) that significantly associates with PTC risk. Chromatin characteristics and regulatory element signatures in this block disclosed at least three regulatory elements functioning as enhancers. These enhancers harbor at least four SNPs (rs7864322, rs12352658, rs7847449, and rs10759944) that serve as functional variants. The variant genotypes are associated with differential enhancer activities and/or transcription factor binding activities. Using the chromosome conformation capture methodology, long-range looping interactions of these elements with the promoter region shared by FOXE1 and PTCSC2 in a human papillary thyroid carcinoma cell line (KTC-1) and unaffected thyroid tissue were found. Our results suggest that multiple variants coinherited with the lead SNP and located in long-range enhancers are involved in the transcriptional regulation of FOXE1 and PTCSC2 expression. These results explain the mechanism by which the risk allele of rs965513 predisposes to thyroid cancer.

Development and characterization of six new human papillary thyroid carcinoma cell lines.

Cell lines are a widely used tool in cancer research. However, despite the relatively high incidence of papillary thyroid carcinoma (PTC), there are only four PTC cell lines available for international research audience. The objective of this study was to establish and characterize new PTC cell lines that represent primary tumor biology. Surgical specimens were obtained to generate PTC cell lines. Short tandem repeat profiling was used to confirm the uniqueness of the cell lines against databases of known cell lines and mutations were assessed using Sequenom. The expression of thyroid-specific genes was examined using real-time PCR. Tumorigenicity was determined using an orthotopic thyroid xenograft tumor mouse model. Six PTC cell lines (five conventional PTCs and one follicular variant of PTC) were generated and found to be unique when compared by short tandem repeat profiling against databases of all existing cell lines. The five conventional PTC cell lines carry the BRAF V600E mutation and the follicular variant of PTC cell line had an NRAS mutation. Five of the six cell lines had a mutation in the promoter of the human telomerase reverse transcriptase gene. None of the cell lines have RET/PTC rearrangements. Three cell lines were tumorigenic in the orthotopic thyroid xenograft tumor mouse model. These five characterized conventional PTC cell lines and the unique follicular variant of PTC cell line should be valuable reagents for thyroid cancer research. The three tumorigenic cell lines can be used for in vivo testing of targeted therapeutic and novel agents.

Identification of a novel germline FOXE1 variant in patients with familial non-medullary thyroid carcinoma (FNMTC).

The familial forms of non-medullary thyroid carcinoma (FNMTC) represent approximately 5 % of thyroid neoplasms. Nine FNMTC susceptibility loci have been mapped; however, only the DICER1 and SRGAP1 susceptibility genes have been identified. The transcription factors NKX2-1, FOXE1, PAX8, and HHEX are involved in the morphogenesis and differentiation of the thyroid. Recent studies have identified NKX2-1 germline mutations in FNMTC families. However, the role of high-penetrant FOXE1 variants in FNMTC etiology remains unclear. The aim of this study was to investigate the role of FOXE1 germline mutations in the pathogenesis of FNMTC. We searched for molecular changes in the FOXE1 gene in the probands from 60 Portuguese families with FNMTC. In this series, we identified nine polymorphisms and one variant (c.743C>G, p.A248G) which was not previously described. This variant, which involved an amino acid residue conserved in evolution, segregated with disease in one family, and was also detected in an apparently unrelated case of sporadic NMTC. Functional studies were performed using rat normal thyroid cells (PCCL3) clones and human papillary thyroid carcinoma cell line (TPC-1) pools, expressing the wild type and mutant (p.A248G) forms of FOXE1. In these experiments, we observed that the p.A248G variant promoted cell proliferation and migration, suggesting that it may be involved in thyroid tumorigenesis. Additionally, somatic p.V600E BRAF mutations were also detected in the thyroid tumors of two members of the family carrying the p.A248G variant. This study represents the first evidence of involvement of a germline FOXE1 rare variant in FNMTC etiology and suggests that mutations in MAPK pathway-related genes may contribute to tumor development in these familial cases.

Establishment of nude mice xenograft model of papillary thyroid carcinoma with the ability of 99mTc-intake

Objective To establish the nude mice xenograft model of papillary thyroid carcinoma with the ability to accumulate 99mTc,and to provide a tool for further study in both pathogenesis and radioactive iodine treatment of papillary thyroid carcinoma.Methods 1 × 107 cells in 200 μl suspension liquids of the human papillary thyroid carcinoma cell lines IHH-4 were inoculated into nine nude mice (five week-old female nude mice,BALB/c-nu/ nu).Tumor formation was recorded,and the size and morphology of tumor were observed by PET-CT.Emission computed tomography (ECT) was used to observe the function of 99mTc intake by xenografts.Results The percentage of the formation of xenografts in nude mice was 100.0％ (9/9).One week after the cells were injected into nude mice,visible tumors were formed.PET-CT performed by the fourth week demonstrated that tumor size was about 1.8 cm × 2.4 cm.Xenograft' image was displayed by ECT after 15 minutes of intraperitoneal injection of 99mTc.Conclusion The nude mice xenograft model of papillary thyroid carcinoma was successfully established by using the human papillary thyroid carcinoma cell lines IHH-4.The xenografts have the ability to accumulate 99mTc,thus providing a good animal model for the study of pathogenesis and radioactive iodine with treatment of papillary thyroid carcinoma. Key words: Papillary thyroid carcinoma; Tumors in nude mice model; 99mTc; Emission computed tomography

Adenovirus-mediated siRNA targeting NOB1 inhibits tumor growth and enhances radiosensitivity of human papillary thyroid carcinoma in vitro and in vivo.

NIN1/RPN12 binding protein 1 homolog (NOB1), a ribosome assembly factor, plays critical roles in tumor progression and development. Previously, we reported that overexpression of NOB1 is correlated with the prognosis of patients with papillary thyroid carcinoma (PTC). Little is known, however, concerning its role in PTC. The aims of the present study were to investigate the association of NOB1 expression with tumor growth and radiosensitivity of human PTC. A recombinant adenovirus expression vector carrying NOB1 was constructed and then infected into the human PTC cell line TPC-1. Cell proliferation, cell cycle distribution, apoptosis, migration and invasion in vitro and tumor growth in vivo were determined after downregulation of NOB1 by RNAi. Additionally, the in vitro and in vivo radiosensitivity of PTC cells was determined by clonogenic cell survival assay and a mouse xenograft model, respectively. The results showed that downregulation of NOB1 expression using RNAi in TPC-1 cells significantly inhibited cell proliferation, migration and invasion and induced cell apoptosis in vitro, and suppressed tumor growth in vivo, as well as enhanced the in vitro and in vivo radiosensitivity of PTC cells. Moreover, our results also showed that downregulation of NOB1 was able to significantly activate constitutive phosphorylation of p38 MAPK, which might contribute to the inhibition of PTC cell growth. These findings suggest that NOB1 may be a potential therapeutic target for the treatment of PTC.

Effects of iodine intake on the orthotopic nude mouse model of human papillary thyroid carcinoma cell line TPC-1

Objective To observe the effects of different iodine intake on the thyroid tumor growth and thyroid function in the orthotopic nude mice model of human papillary thyroid carcinoma (PTC) cell line TPC-1.Methods Human PTC cell line TPC-1 (2 × 105) was injected into the left thyroid gland of nude mice.After the operation,the nude mice were randomly divided into three groups:low iodine group (LI),normal iodine group (NI),and high iodine group(HI,50 folds of normal iodine) based on the iodine levels contained in their diet.4 and 12 weeks later,the nude mice were executed,then their thyroid tumors were removed and weighted.The levels of urinary iodine were measured with As3+-Ce4+ catalytic spectrophotometry using ammonium persulfate digestion method.The thyroid hormone level was detected using chemiluminescent immunoassay.The morphology and structure of thyroid tumor tissue was observed by microscope.Results The iodine intervention feeding was successful according to urinary iodine level of LI,NI,and HI groups,paralleled to their iodine intakes.However,the difference of the weight of thyroid tumor in three groups had no statistical significance(P＞0.05).At 4 weeks,compared with control group,the levels of thyroid hormones were normal in NI group,while lower T4 and normal T3 were found in LI group.However,T4 was higher and T3 was lower in HI group (P＜0.05).At 12 weeks,the levels of thyroid hormones all were decreased due to the enlargement of thyroid gland tumor in NI,LI and HI groups.T4 and T3 in LI group were the lowest among three groups,even T4 was below detection limit.T4 was normal and T3 was lower in HI group as compared to control group.Conclusion Iodine intake may not significantly affect tumor growth in the orthotopic nude mice model of human PTC cell line TPC-1,but it has a significant effect on the synthesis of thyroid hormones. Key words: Iodine ; Papillary thyroid carcinoma ; Orthotopic model