Altered expression of key players in vitamin D metabolism and signaling in malignant and benign thyroid tumors

1,25-Dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), the active form of vitamin D, mediates antitumor effects in various cancers. The expression of key players in vitamin D signaling in thyroid tumors was investigated. Vitamin D receptor (VDR) and CYP27B1 and CYP24A1 (respectively activating and catabolizing vitamin D) expression was studied (RT-PCR, immunohistochemistry) in normal thyroid, follicular adenoma (FA), differentiated thyroid cancer (DTC) consisting of the papillary (PTC) and follicular (FTC) subtype, and anaplastic thyroid cancer (ATC). VDR, CYP27B1, and CYP24A1 expression was increased in FA and DTC compared with normal thyroid. However, in PTC with lymph node metastasis, VDR and CYP24A1 were decreased compared with non-metastasized PTC. In ATC, VDR expression was often lost, whereas CYP27B1/CYP24A1 expression was comparable to DTC. Moreover, ATC with high Ki67 expression (>30%) or distant metastases at diagnosis was characterized by more negative VDR/CYP24A1/CYP27B1 staining. In conclusion, increased expression of key players involved in local 1,25(OH)(2)D(3) signaling was demonstrated in benign and differentiated malignant thyroid tumors, but a decrease was observed for local nodal and especially distant metastasis, suggesting a local antitumor response of 1,25(OH)(2)D(3) in early cancer stages. These findings advocate further studies with 1,25(OH)(2)D(3) and analogs in persistent and recurrent iodine-refractory DTC.     

Expression of proteins: D1 cyclin and Ki-67 in papillary thyroid carcinomas

The aim of the study was an evaluation of expression of D1 cyclin and Ki-67 proteins in tissue of human papillary thyroid carcinoma (PTC) in a group of papillary microcarcinomas and in a group of PTC with a degree of staging higher than pT1a in TNM classification. We performed immunohistochemical staining and found no statistical differences between groups. These results suggest that changes of expression of D1 cyclin are an early event in tumorigenesis.     

Cellular and molecular effects of vitamin D on carcinogenesis

Epidemiologic data suggest that the incidence and severity of many types of cancer inversely correlates with indices of vitamin D status. The vitamin D receptor (VDR) is highly expressed in epithelial cells at risk for carcinogenesis including those resident in skin, breast, prostate and colon, providing a direct molecular link by which vitamin D status impacts on carcinogenesis. Consistent with this concept, activation of VDR by its ligand 1,25-dihydroxyvitamin D (1,25D) triggers comprehensive genomic changes in epithelial cells that contribute to maintenance of the differentiated phenotype, resistance to cellular stresses and protection of the genome. Many epithelial cells also express the vitamin D metabolizing enzyme CYP27B1 which enables autocrine generation of 1,25D from the circulating vitamin D metabolite 25-hydroxyvitamin D (25D), critically linking overall vitamin D status with cellular anti-tumor actions. Furthermore, pre-clinical studies in animal models has demonstrated that dietary supplementation with vitamin D or chronic treatment with VDR agonists decreases tumor development in skin, colon, prostate and breast. Conversely, deletion of the VDR gene in mice alters the balance between proliferation and apoptosis, increases oxidative DNA damage, and enhances susceptibility to carcinogenesis in these tissues. Because VDR expression is retained in many human tumors, vitamin D status may be an important modulator of cancer progression in persons living with cancer. Collectively, these observations have reinforced the need to further define the molecular actions of the VDR and the human requirement for vitamin D in relation to cancer development and progression.     

Lipopolysaccharide negatively modulates vitamin D action by down-regulating expression of vitamin D-induced VDR in human monocytic THP-1 cells

Vitamin D3, an important seco-steroid hormone for the regulation of body calcium homeostasis, promotes immature myeloid precursor cells to differentiate into monocytes/macrophages. Vitamin D receptor (VDR) belongs to a nuclear receptor super-family that mediates the genomic actions of vitamin D3 and regulates gene expression by binding with vitamin D response elements in the promoter region of the cognate gene. Thus by regulating gene expression, VDR plays an important role in modulating cellular events such as differentiation, apoptosis, and growth. Here we report lipopolysaccharide (LPS), a bacterial toxin; decreases VDR protein levels and thus inhibits VDR functions in the human blood monocytic cell line, THP-1. The biologically active form of vitamin D3, 1alpha,25-dihydroxy vitamin D3 [1,25(OH)2D3], induced VDR in THP-1 cells after 24 h treatment, and LPS inhibited 1,25(OH)2D3-mediated VDR induction. However, LPS and 1,25(OH)2D3 both increased VDR mRNA levels in THP-1 cells 20 h after treatment, as observed by real time RT-PCR. Moreover, LPS plus 1,25(OH)2D3 action on VDR mRNA level was additive and synergistic. A time course experiment up to 60 h showed an increase in VDR mRNA that was not preceded with an increase in VDR protein levels. Although the proteasome pathway plays an important role in VDR degradation, the proteasome inhibitor lactacystin had no effect on the LPS-mediated down-regulation of 1,25(OH)2D3 induced VDR levels. Reduced VDR levels by LPS were accompanied by decreased 1,25(OH)2D3/VDR function determined by VDR responsive 24-hydroxylase (CYP24) gene expression. The above results suggest that LPS impairs 1,25(OH)2D3/VDR functions, which may negatively affect the ability of 1,25(OH)2D3 to induce myeloid differentiation into monocytes/macrophages.     

Silencing of long noncoding RNA RP11-476D10.1 enhances apoptosis and autophagy while inhibiting proliferation of papillary thyroid carcinoma cells via microRNA-138-5p-dependent inhibition of LRRK2

The distant metastasis in papillary thyroid carcinoma (PTC) is a major threat for PTC patients. Moreover, the involvement of long noncoding RNAs (lncRNAs) in the regulation of PTC progression has been extensively investigated. The aim of this study was to underscore whether lncRNA RP11-476D10.1 affects the proliferation, apoptosis and autophagy of PTC cells. Initially, we determined that lncRNA RP11-476D10.1 and LRRK2 were highly expressed in PTC cells. Meanwhile, through experimentation, miR-138-5p was confirmed to bind with lncRNA RP11-476D10.1 and LRRK2. It was also revealed that lncRNA RP11-476D10.1 downregulated the miR-138-5p expression, thereby upregulating the LRRK2 expression. After that, PTC cells were transfected with siRNA against RP11-476D10.1, or inhibitor or mimic of miR-138-5p to evaluate the influence of lncRNA RP11-476D10.1 on the PTC cell proliferation, apoptosis, and autophagy in vitro and on the tumor formation ability in vivo. The results showed that silenced lncRNA RP11-476D10.1 or overexpressed miR-138-5p enhanced the apoptosis and autophagy of PTC cells while reducing cell proliferation, with increased levels of Bax, LC3B, and Beclin1 and decreased Bcl-2 level were observed. The inhibitory role of silenced lncRNA RP11-476D10.1 role in the PTC development was further verified by the reduced tumor formation ability in nude mice. Our results demonstrated that lncRNA RP11-476D10.1 could bind to miR-138-5p and promote LRRK2 expression. Moreover, the silencing of lncRNA RP11-476D10.1 may inhibit the development of PTC, highlighting a novel insight for the development of superior therapeutic targets for PTC treatment.     

Nuclear vitamin D receptor expression is associated with improved survival in non-small cell lung cancer

Vitamin D has been shown to have anti-proliferative effects in a wide variety of cancers including lung cancer. The anticancer effects of vitamin D are mediated primarily by its active metabolite, 1,25-dihydroxyvitamin D (calcitriol), through vitamin D receptor (VDR) signaling. However, thus far there have been no studies evaluating the association between VDR expression and survival outcome in lung cancer. Using immunohistochemical analysis, we evaluated VDR expression, separately in the nucleus and cytoplasm, in lung cancer samples from 73 non-small cell lung carcinoma (NSCLC) patients with no prior therapy, and investigated the association between VDR expression and overall survival (OS). Cox proportional hazard models were used for our primary analyses. There were 44 deaths during a median follow-up of 51 months (range 13-93 months). High nuclear VDR expression was associated with improved OS after adjusting for age, gender, stage, smoking status, and histology (adjusted hazard ratio, 0.36; 95% confidence interval, 0.17-0.79). There was no association between cytoplasmic VDR expression and OS. Our results suggest that nuclear VDR status may be a prognostic marker in NSCLC. Future large studies to replicate our findings and to assess the impact of VDR gene polymorphisms on VDR expression are required as therapies targeting the vitamin D signaling pathway may be influenced by VDR status in the target lung cancer tissue.     

促甲状腺激素并非甲状腺乳头状癌发生发展的关键因素

目的:血清促甲状腺激素(TSH)在甲状腺乳头状癌(PTC)中的作用及机制尚不明确,本研究主要探讨TSH对甲状腺细胞系及乳头状癌细胞系的作用。方法:体外培养人甲状腺细胞系和乳头状癌细胞系,分别给予不同剂量(0 mU/L、5 mU/L及20 mU/L)的TSH干预。通过MTS及流式细胞术,观察TSH对甲状腺及乳头状癌细胞系增殖和细胞周期的作用;通过RNA-seq、ELISA检测TSH对细胞因子的影响;通过实时荧光定量PCR及Western blot寻找潜在的作用靶点。结果:MTS及流式细胞术结果显示,TPC-1和Nthy-ori-3-1细胞经TSH干预后增殖指数下降,20 mU/L浓度的TSH干预组细胞周期缩短。ELISA结果显示TPC-1中TSH下调CXCL8,上调CXCL10,而CXCL12的表达无明显变化。在Nthy-ori-3-1细胞中CXCL8和CXCL10的表达也观察到类似的结果,但CXCL12表达受到TSH的抑制。TSH可使Nthy-ori-3-1和Bcpap细胞中细胞命运决定因子(DACH1)的表达呈剂量依赖性上调,且TSH可抑制Bcpap中BRAF(V600E)以及Nthy-ori-3-1和TPC-1中BRAF的表达。结论:综上所述,我们并未发现TSH对甲状腺癌细胞有明显的促肿瘤作用。相反,本研究提示TSH可能呈部分抗癌作用。因此,TSH对甲状腺的致癌作用仍有待进一步研究。     

The deubiquitinase OTUB1 fosters papillary thyroid carcinoma growth through EYA1 stabilization

Deubiquitinating enzyme OTU domain-containing ubiquitin aldehyde-binding proteins 1 (OTUB1) has been shown to have an essential role in multiple carcinomas. However, the function of OTUB1 in papillary thyroid cancer (PTC) and the underlying mechanisms regulating PTC cells proliferation remain poorly understood. In this study, OTUB1 was significantly upregulated in papillary thyroid carcinoma tissues and cells. Through in vitro and in vivo experiments, knockdown of OTUB1 suppressed PTC cells growth whereas OTUB1 overexpression enhanced the proliferation ability of PTC cells. Moreover, the eyes absent homologue 1 (EYA1) was recognized as a potential target of OTUB1 through mass spectrometry analysis, and we further verified that EYA1 protein level was positively correlated with OTUB1 expression in PTC cells and clinical samples. Mechanistically, OTUB1 could interact with EYA1 directly and deubiquitinate EYA1 to stabilize it. At last, EYA1 was found to play an essential role in OTUB1-derived PTC cells growth. Overall, our investigation reveals that OTUB1 is a previously unrecognized oncogenic factor in PTC cells proliferation and suggests that OTUB1 might be a novel therapeutic target in PTC.     

Vitamin D and the regulation of placental inflammation

The vitamin D-activating enzyme 1α-hydroxylase (CYP27B1) and vitamin D receptor (VDR) support anti-inflammatory responses to vitamin D in many tissues. Given the high basal expression of CYP27B1 and VDR in trophoblastic cells from the placenta, we hypothesized that anti-inflammatory effects of vitamin D may be particularly important in this organ. Pregnant wild type (WT) mice i.p. injected with LPS showed elevated expression of mouse Cyp27b1 (4-fold) and VDR (6-fold). Similar results were also obtained after ex vivo treatment of WT placentas with LPS. To assess the functional impact of this, we carried out ex vivo studies using placentas -/- for fetal (trophoblastic) Cyp27b1 or VDR. Vehicle-treated -/- placentas showed increased expression of IFN-γ and decreased expression of IL-10 relative to +/+ placentas. LPS-treated -/- placentas showed increased expression of TLR2, IFN-γ, and IL-6. Array analyses identified other inflammatory factors that are dysregulated in Cyp27b1(-/-) versus Cyp27b1(+/+) placentas after LPS challenge. Data highlighted enhanced expression of IL-4, IL-15, and IL-18, as well as several chemokines and their receptors, in Cyp27b1(-/-) placentas. Similar results for IL-6 expression were observed with placentas -/- for trophoblastic VDR. Finally, ex vivo treatment of WT placentas with the substrate for Cyp27b1, 25-hydroxyvitamin D(3), suppressed LPS-induced expression of IL-6 and the chemokine Ccl11. These data indicate that fetal (trophoblastic) vitamin D plays a pivotal role in controlling placental inflammation. In humans, this may be a key factor in placental responses to infection and associated adverse outcomes of pregnancy.     

Expression of TGF-β1, SNAI1 and MMP-9 is associated with lymph node metastasis in papillary thyroid carcinoma

TGF-β1, SNAI1 and MMP-9 are implicated in tumor invasion and metastasis. The purpose of this study was to examine TGF-β1, SNAI1 and MMP-9 expression in papillary thyroid carcinoma (PTC), and to assess association of TGF-β1, SNAI1 and MMP-9 expression with several clinicopathological indicators of PTC. TGF-β1, SNAI1 and MMP-9 protein expression in 83 PTCs and their matched normal thyroid specimens were analyzed using immunohistochemistry. The mRNA expression levels of TGF-β1, SNAI1 and MMP-9 in 12 fresh PTC specimens with lymph node metastasis (LNM), 12 fresh PTC specimens without LNM and their matched normal thyroid specimens were assessed by real-time RT-PCR. The results showed that the mRNA and protein expression levels of TGF-β1, SNAI1 and MMP-9 were significantly higher in PTCs than in their matched normal thyroid tissues. There were not significant differences in TGF-β1, SNAI1 and MMP-9 protein expression relative to age, gender, tumor size and TNM stage, except for MMP-9 whose protein expression correlated with tumor size. However, high mRNA and protein expression levels of TGF-β1, SNAI1 and MMP-9 were significantly correlated with LNM. Furthermore, TGF-β1, SNAI1 and MMP-9 protein expression were significantly correlated with one another. Concomitant expression of any two or all of the three molecules had stronger correlation with LNM than did each alone. Collectively, the present results indicate that immunohistochemical and real-time RT-PCR evaluation of TGF-β1, SNAI1 and MMP-9 expression in PTC may be useful to predict the risk of LNM in PTC patients.     

MMP-11 promotes papillary thyroid cell proliferation and invasion via the NF-κB pathway

Papillary thyroid carcinoma (PTC) is the most common form of thyroid cancer, and its incidence is on the rise. It has been reported that some matrix metalloproteinases (MMPs) are abnormally expressed in PTC and can be used as diagnostic markers. However, few studies have explored the underlying mechanisms by which MMPs promote tumor progression. In this study, we used microarray analysis to compare the variations of gene expression within the PTC cell populations and their adjacent normal tissues and found that MMP-11 was the most differentially expressed MMP. To investigate the role of MMP-11 in the mediation of thyroid cancer cell development, pEnter-MMP-11 plasmid, and MMP-11 small interfering RNA were applied to up- and downregulate MMP-11 expression of in cultured PTC cell lines K1 and BCPAP. The results suggested that the levels of proliferation and migration of cells transfected with MMP-11 siRNA were significantly reduced, while the levels in MMP-11-plasmid-transfected cells were increased. In terms of the mechanism, experimental data showed that the change in cyclin D1 is consistent with MMP-11 expression, which may explain the changes in proliferation. In addition, Western blot assay was conducted to analyze the p65 and activated (phospho-) p65 protein levels concomitant with MMP-11 adjustments. Variations in intracellular MMP-11 significantly altered the amount of phospho-p65 in thyroid cells, while p65 knockdown did not affect MMP-11 expression. These results suggest that MMP-11 is located upstream of p65 and regulates its activity. Interestingly, the data for the Transwell assay suggested that MMP-11 regulatory migration is also associated with the NF-κB p65 signaling pathway. In conclusion, this report describes the important role of MMP-11 in the regulation of thyroid cell proliferation and migration. Mechanistic studies have shown that cyclin D1 and p65 are important mediators in the processes, which provides a new way to study the mechanism of MMPs promoting the progression of thyroid cancer.     

The classic receptor for 1alpha,25-dihydroxy vitamin D3 is required for non-genomic actions of 1alpha,25-dihydroxy vitamin D3 in osteosarcoma cells

1alpha,25-dihydroxy vitamin D3 has a major role in the regulation of the bone metabolism as it promotes the expression of key bone-related proteins in osteoblastic cells. In recent years it has become increasingly evident that in addition to its well-established genomic actions, 1alpha,25-dihydroxy vitamin D3 induces non-genomic responses by acting through a specific plasma membrane-associated receptor. Results from several groups suggest that the classical nuclear 1alpha,25-dihydroxy vitamin D3 receptor (VDR) is also responsible for these non-genomic actions of 1alpha,25-dihydroxy vitamin D3. Here, we have used siRNA to suppress the expression of VDR in osteoblastic cells and assessed the role of VDR in the non-genomic response to 1alpha,25-dihydroxy vitamin D3. We report that expression of the classic VDR in osteoblasts is required to generate a rapid 1alpha,25-dihydroxy vitamin D3-mediated increase in the intracellular Ca(2+) concentration, a hallmark of the non-genomic actions of 1alpha,25-dihydroxy vitamin D3 in these cells.