Regulator of G protein signaling 5 is highly expressed in parathyroid tumors and inhibits signaling by the calcium-sensing receptor

The molecular mechanisms responsible for aberrant calcium signaling in parathyroid disease are poorly understood. The loss of appropriate calcium-responsive modulation of PTH secretion observed in parathyroid disease is commonly attributed to decreased expression of the calcium-sensing receptor (CaSR), a G protein-coupled receptor. However, CaSR expression is highly variable in parathyroid adenomas, and the lack of correlation between CaSR abundance and calcium-responsive PTH kinetics indicates that mechanisms independent of CaSR expression may contribute to aberrant calcium sensing in parathyroid disease. To gain a better understanding of parathyroid tumors and the molecular determinants that drive parathyroid adenoma development, we performed gene expression profiling on a panel of 64 normal and neoplastic parathyroid tissues. The microarray data revealed high-level expression of genes known to be involved in parathyroid biology (PTH, VDR, CGA, CaSR, and GCM2). Moreover, our screen identified regulator of G protein signaling 5 (RGS5) as a candidate inhibitor of CaSR signaling. We confirmed RGS5 to be highly expressed in parathyroid adenomas relative to matched-pair normal glands. Transient expression of RGS5 in cells stably expressing CaSR resulted in dose-dependent abrogation of calcium-stimulated inositol trisphosphate production and ERK1/2 phosphorylation. Furthermore, we found that RGS5-nullizygous mice display reduced plasma PTH levels, an outcome consistent with attenuated opposition to CaSR activity. Collectively, these data suggest that RGS5 can act as a physiological regulator of calcium sensing by CaSR in the parathyroid gland. The abnormally elevated expression of RGS5 observed in parathyroid adenomas could thus represent a novel mechanism of CaSR desensitization in patients with primary hyperparathyroidism.     

Changes in gene expression in the course of proliferative processes in the parathyroid gland

The aim of this study was to investigate the changes in expression pattern of the most important genes connected with apoptosis in proliferative apoptotic lesions (hyperplasia, adenoma), applying cDNA microarray technique, in order to promote the possible diagnostic or therapeutic utilisation of any difference in gene expression compared to the healthy (normal) parathyroid gland. Samples were taken from surgically removed 2 hyperplasias, 2 adenomas and 2 normal parathyroid glands. The Apoptosis Gene Array (Superarray) was used. This contains 112 genes, in tetraspot arrangement. The probes measured 250-600 base pairs. Streptavidin was bound to the array. CDP Star TM chemiluminescent substrate was used for detection. The samples deriving from hyperplasia or adenoma were compared to samples from normal parathyroid glands. The following genes were overexpressed in both hyperplasia and adenoma: CHEK1, ATM, BCL-XL, FAS, TNF, cIAP1, TRAIL, FADD, CASP 4,5,6,8, CD120b, CD137, LTA, TANK, TARF2, CAD, LIGHTR, DR3LG. CASP1,10, BFAR, BOD, BCL2L2, TRANCE were underexpressed in both hyperplasia and adenoma. Genes overexpressed only in hyperplasia were: MDM2, MCL1, BCL2A1, BLK, RIPK2, CD40LG, TRAF5, HUS1, BNIP3. Underexpressed only in hyperplasia: BOK, CIDEA, TRAF1, TRIP. Overexpressed only in adenoma: APOLLON, RIPK1, LTB, LTBR, CASP2,13, cIAP2, CIDEB. Underexpressed only in adenoma: TRAF4 and FASLG. Overexpresion or underexpression meant 1.5-fold difference from normal average values. As a result of this study, both pro-apoptotic and antiapoptotic genes were identified in hyperplasia and adenoma of the parathyroid gland. It seems that increased proliferation is connected also with increased apoptotic activity, but tumor cell candidates are able to survive, by activation of signal pathways resulting in overexpresion of anti-apoptotic genes.     

Endothelin receptors in human parathyroid gland.

We studied whether specific receptors for endothelins (ETs) exist in human parathyroid tissues and whether ETs may have any effect on secretion of PTH from parathyroid cells. Binding studies using [125I]ET-1 to the parathyroid membranes obtained from patients with hyperparathyroidism (2 adenomas, 2 hyperplasias) revealed that ET-1 competitively inhibited the binding of [125I]ET-1 to the membranes (the apparent Kd: 62 +/- 18 pM), whereas ET-3 showed biphasic and less steep inhibition curve than ET-1 in all tissue membranes examined. Northern blot analysis of poly(A)+ RNA from the parathyroid adenoma clearly demonstrated gene expression of both ETA and ETB receptors as well as preproET-1. ET-1 inhibited basal PTH secretion from dispersed adenoma cells more potently than ET-3. The present study clearly demonstrates the presence of both ETA and ETB receptor subtypes in human parathyroid tissues through which ETs may modulate PTH secretion in an autocrine and/or paracrine manner.     

Expression of parathyroid hormone-related protein (PTHrP) in parathyroid tissue under normal and pathological conditions

Parathyroid hormone-related protein (PTHrP), a factor responsible for malignancy associated hypercalcemia, plays a physiological roles such as bone development and placental calcium transport. The expression of PTHrP in adult human parathyroid tissues under normal and pathological conditions was analyzed. By immunohistochemistry, PTHrP expression was detected in 86% of normal parathyroid (12/14 cases), 74% of adenomas (14/19) and 89% of hyperplasia secondary to chronic renal failure (16/18). PTHrP protein was observed mainly in the cytoplasm of oxyphil cells, consistent with the localization of its mRNA demonstrated by in situ hybridization. The rate of PTHrP-positive cells was higher in areas consisting of oxyphil cells than in those of non-oxyphil cells, regardless of whether the parathyroid was normal or pathological. In the normal parathyroid, an age-related increase in PTHrP expression was observed with a relative increase in oxyphil cells, reflecting aging and deterioration of parathyroid tissue. In adenoma, cases with a predominance of oxyphil cells expressed PTHrP, whereas clear cell adenoma did not. In secondary hyperplasia, the rate of PTHrP-expressing cells was higher than in normal parathyroid or adenoma, with varying levels of expression among nodules. We speculate that PTHrP could act through the paracrine/autocrine mechanism to regulate proliferation and differentiation of normal and neoplastic parathyroid cells.     

Fine needle aspiration cytology of cystic parathyroid lesions. A cytomorphologic overlap with cystic lesions of the thyroid

Three cases of palpable cystic parathyroid nodules examined by fine needle aspiration (FNA) cytology are reported. Two of the three aspirates were incorrectly identified as thyroid neoplasms due to the presence of papillary clusters or microfollicles and grossly golden-brown cyst fluid. Histologic examination of these two nodules revealed partially cystic parathyroid adenomas. Aspirated material from the third patient yielded clear watery fluid, which was correctly identified as consistent with a parathyroid cyst. The diagnostic difficulties in the differentiation of parathyroid adenoma from thyroid carcinoma or adenoma are discussed, as is the utilization of assays for parathyroid hormone in making the FNA diagnosis of parathyroid lesions.     

Identification of differentially expressed microRNAs by microarray: a possible role for microRNA genes in pituitary adenomas

MicroRNAs (miRNAs) are small non-coding RNAs that control gene expression by targeting mRNA. It has been demonstrated that miRNA expression is altered in many human cancers, suggesting that they may play a role in human neoplasia. To determine whether miRNA expression is altered in pituitary adenomas, we analyzed the entire miRNAome in 32 pituitary adenomas and in 6 normal pituitary samples by microarray and by Real-Time PCR. Here, we show that 30 miRNAs are differentially expressed between normal pituitary and pituitary adenomas. Moreover, 24 miRNAs were identified as a predictive signature of pituitary adenoma and 29 miRNAs were able to predict pituitary adenoma histotype. miRNA expression could differentiate micro- from macro-adenomas and treated from non-treated patient samples. Several of the identified miRNAs are involved in cell proliferation and apoptosis, suggesting that their deregulated expression may be involved in pituitary tumorigenesis. Predictive miRNAs could be potentially useful diagnostic markers, improving the classification of pituitary adenomas.     

配子体自交不亲和植物花粉S基因研究进展

配子体自交不亲和植物的自交不亲和性是由雌蕊自交不亲和因子和花粉自交不亲和因子相互作用的结果。目前已经分离和鉴定了雌蕊自交不亲和基因及其表达产物。最近从金鱼草、Prumusdulcis、梅等植物中分离的F-box基因,它具有花粉S基因特点,即在花药、成熟的花粉和花粉管中特异表达;在基因位置上,与S-RNase基因紧密连锁;不同物种或同一物种不同品种F-box基因间核苷酸和氨基酸序列上存在高度多态性。通过分子生物学方法和杂交授粉试验证明所分离的F-box基因是花粉自交不亲和基因,但目前尚未分离出该类基因相应的表达蛋白。主要综述了配子体自交不亲和植物花粉自交不亲和基因的发现、基因的结构、雌蕊自交不亲和因子和花粉自交不亲和因子相互作用的模型。     

Global and gene-specific promoter methylation analysis in primary hyperparathyroidism

Epigenetic mechanisms involved in primary hyperparathyroidism are poorly understood as studies are limited. In order to understand the role of aberrant DNA promoter methylation in the pathogenesis of parathyroid tumors, we have quantified the CpG island promoter methylation density of several candidate genes including APC (promoter 1A and 1B), β-catenin (CTNNB1), CASR, CDC73/HRPT2, MEN1, P16 (CDKN2A), PAX1, RASSF1A, SFRP1 and VDR in 72 parathyroid tumors and 3 normal parathyroid references using bisulfite pyrosequencing. Global methylation levels were assessed for LINE-1. We also compared methylation levels with gene expression levels measured by qRT-PCR for genes showing frequent hypermethylation. The adenomas displayed frequent hypermethylation of APC 1A (37/66; 56%), RASSF1A (34/66; 52%) and β-catenin (19/66; 29%). One of the three atypical adenomas was hypermethylated for APC 1A. The three carcinomas were hypermethylated for RASSF1A and SFRP1, and the latter was only observed in this subtype. The global methylation density was similar in tumors (mean 70%) and parathyroid reference samples (mean 70%). In general, hypermethylated genes had reduced expression in the parathyroid adenomas using qRT-PCR. Among the adenomas, methylation of APC 1A correlated with adenoma weight (r = 0.306, p < 0.05). Furthermore, the methylation status of RASSF1A correlated with each of APC 1A (r = 0.289, p < 0.05) and β-catenin (r = 0.315, p < 0.01). Our findings suggest a role for aberrant DNA promoter methylation of APC 1A, β-catenin and RASSF1A in a subset of parathyroid tumors.     

A proteomic approach to study parathyroid glands

Parathyroid tumours are heterogeneous and in some cases the diagnosis may be difficult using histological features. In this study we used a two-dimensional electrophoresis (2D)/mass spectrometry (MS)-based approach to examine the global changes of parathyroid adenoma tissues protein profile compared to the parathyroid normal tissues. Validation of protein expression was performed by immunoblotting using specific antibodies. Ingenuity software was used to identify the biological processes to which these proteins belong and to construct a potential network. A total of 30 proteins were found to be differentially expressed, of which 22 resulted in being over-expressed. Proteins identified by 2D/MS/MS proteomics were classified into functional categories and a major change (≥ 2-fold) in terms of expression was found in proteins involved in response to biotic stimuli, cell organization and signal transduction. After Ingenuity analysis, 14-3-3 ζ/δ appears to be a key protein in the network of parathyroid adenoma, where it is linked to other proteins such as annexin A2, B box and SPRY domain-containing protein (BSPRY), p53 and epidermal growth factor receptor (EGFR). Our results suggest that the proteomic approach was able to differentiate the protein profiles of normal parathyroid and parathyroid adenoma and identify a panel of proteins which are differentially expressed. The functional role of these proteins in the network of intracellular pathways is discussed.     

Common miRNAs,candidate genes and their interaction network across four subtypes of epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is categorized into four major histological subtypes such as clear cell carcinoma (CCC), endometrioid carcinoma (EC), mucinous carcinoma (MC), and serous carcinoma (SC). Heterogeneity of the EOC leads to different clinical outcomes of the disease, although all the subtypes are originated from the same layer of tissue. Therefore, it is of interest to identify the common candidate genes, miRNA and their interaction network in four the subtypes of EOC. A comparative gene expression analysis identified 248 common differentially expressed genes (DEGs) in the four subtypes of EOC. Identified common DEGs were found to be enriched in cancer specific pathways. A protein-protein interaction (PPI) network of the common DEGs were constructed, and subsequent module and survival analyses identified seven key candidate genes (CCNB1, CENPM, CEP55, RACGAP1, TPX2, UBE2C, and ZWINT). We also documented 10 key candidate miRNAs (hsa-mir-16-5p, hsa-mir-23b-3p, hsa-mir-34a-5p, hsa-mir-103a-3p, hsa-mir-107, hsa-mir-124-3p, hsa-mir-129-2-3p, hsa-mir-147a, hsa-mir-205-5p, and hsa-mir-195-5p) linked to the candidate genes. These derived data find application in the understanding of EOC.     

Primary Hyperparathyroidism: Comparing Between Solid and Cystic Adenomas and the Efficacy of Ultrasound and Single-Photon Emission Computed Tomography in their Diagnosis

Objective: Primary hyperparathyroidism (PHPT) is a disorder that results from abnormal functioning of the parathyroid glands. The purpose of this study was to compare cystic and solid adenomas by analyzing different variables associated with PHPT and parathyroid adenomas (age, calcium, phosphorus, and parathyroid hormone &lsqb;PTH] levels, adenoma volume) while comparing the efficacy of ultrasound and single-photon emission computed tomography in differentiating between both types of adenoma.Methods: From 152 patients diagnosed with PHPT between January 2013 and 2014, only 109 patients who had positive ultrasonographic findings for single parathyroid adenoma were included in the study.Results: A total of 26 patients had cystic adenomas and 83 patients had solid adenomas. Sestamibi (MIBI) was negative in 50% of the cystic adenoma group and 27.7% of the solid adenoma group, with an overall technetium-MIBI efficacy of 67%. Age, phosphorus level, and adenoma volume were significantly higher in patients with cystic adenomas (P = .001, P = .02, and P = .02, respectively), whereas calcium and PTH levels were significantly higher in patients with solid adenomas (P = .02, P = .038, respectively). MIBI had a significant correlation with PTH levels (P = .031) and adenoma volume (P = .05) only in patients with solid adenomas. No significant correlation was found between sex and type of parathyroid adenoma.Conclusion: The current study is the first to compare age, PTH levels, and adenoma volume between cystic and solid adenoma patients, providing more information for the poorly understood pathology of cystic adenomas. Our findings showed that age and calcium and PTH levels are significantly higher in patients with solid adenomas, whereas adenoma volume and phosphorus levels are significantly higher in patients with cystic adenomas.Abbreviations: BMD = bone mineral density GFR = glomerular filtration rate iPTH = intact parathyroid hormone MIBI = sestamibi PHPT = primary hyperparathyroidism PTH = parathyroid hormone SPECT = single-photon emission computed tomography Tc = technetium US = ultrasound     

Protein–protein interaction and SNP analysis in intraductal papillary mucinous neoplasm

Intraductal papillary mucinous neoplasm (IPMN) is a type of tumor that grows within the pancreatic ducts. It is a progress from hyperplasia to intraductal adenoma (IPMA), to noninvasive carcinoma, and ultimately to invasive carcinoma (IPMC). The objective of this study was to explore the molecular mechanism of the progression from IPMA to IPMC. By using the GSE19650 affymetrix microarray data accessible from Gene Expression Omnibus (GEO) database, we first identified the differentially expressed genes (DEGs) between IPMA and IPMC, followed by the protein–protein interaction and single-nucleotide polymorphism (SNP) analysis of the DEGs. Our study identified thousands of DEGs which involved regulation of cell cycle and apoptosis in this progression from IPMA to IPMC. Protein–protein interaction network construction found that MYC, IL6ST, NR3C1, CREBBP, GATA1 and LRP1 might play an important role in the progression. Furthermore, the SNP analysis confirmed the association between BRAC1 and pancreas cancer. In conclusion, our data provide a comprehensive bioinformatics analysis of genes and pathways which may be involved in the progression of IPMN from IPMA to IPMC.     

Aberrant DNA methylation of WNT pathway genes in the development and progression of CIMP-negative colorectal cancer

The WNT signaling pathway has an essential role in colorectal carcinogenesis and progression, which involves a cascade of genetic and epigenetic changes. We aimed to analyze DNA methylation affecting the WNT pathway genes in colorectal carcinogenesis in promoter and gene body regions using whole methylome analysis in 9 colorectal cancer, 15 adenoma, and 6 normal tumor adjacent tissue (NAT) samples by methyl capture sequencing. Functional methylation was confirmed on 5-aza-2′-deoxycytidine-treated colorectal cancer cell line datasets. In parallel with the DNA methylation analysis, mutations of WNT pathway genes (APC, β-catenin/CTNNB1) were analyzed by 454 sequencing on GS Junior platform. Most differentially methylated CpG sites were localized in gene body regions (95% of WNT pathway genes). In the promoter regions, 33 of the 160 analyzed WNT pathway genes were differentially methylated in colorectal cancer vs. normal, including hypermethylated AXIN2, CHP1, PRICKLE1, SFRP1, SFRP2, SOX17, and hypomethylated CACYBP, CTNNB1, MYC; 44 genes in adenoma vs. NAT; and 41 genes in colorectal cancer vs. adenoma comparisons. Hypermethylation of AXIN2, DKK1, VANGL1, and WNT5A gene promoters was higher, while those of SOX17, PRICKLE1, DAAM2, and MYC was lower in colon carcinoma compared to adenoma. Inverse correlation between expression and methylation was confirmed in 23 genes, including APC, CHP1, PRICKLE1, PSEN1, and SFRP1. Differential methylation affected both canonical and noncanonical WNT pathway genes in colorectal normal-adenoma-carcinoma sequence. Aberrant DNA methylation appears already in adenomas as an early event of colorectal carcinogenesis.