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Astrid Kehlen

Publications and source records attributed to Astrid Kehlen.

12 recordsLinked to original sources
PubMed2006

Fetal microchimerism in Hashimoto's thyroiditis: a quantitative approach.

OBJECTIVE: Fetal microchimerism (MCH) has been implicated in the etiology of autoimmune diseases such as autoimmune thyroiditis. The goal of the study was to reliably estimate the number of fetal engrafted cells and to further investigate factors influencing the development of MCH. METHODS: Quantitative real-time PCR amplification using Y-chromosome specific (DYS14) and autosomal (beta-globin) loci was performed on thyroid gland specimens. Furthermore, we compared the distribution of ABO and rhesus systems in mothers with and without blood MCH in relation to the blood groups of the children. RESULTS: MCH was detected in eight of 21 Hashimoto patients in a frequency range of 15 to 4900 male cells per 100,000 total cells (median 97 cells), but in none of 17 healthy thyroid glands. In a third group, consisting of 18 nodular goiters, only one sample was positive (182 male cells/100,000 total cells). No woman who had not had a prior pregnancy with a male fetus showed MCH. Mothers both with and without MCH showed the same rate of mother/child incompatibilities for the ABO and rhesus systems. CONCLUSIONS: The percentage of microchimeric cells varies to a great extent in Hashimoto's thyroiditis, and this phenomenon can occur in nodular goiter in rare instances, but it appears to be absent from normal thyroid glands. Nevertheless, the biological significance of MCH remains unclear. Moreover, we have concluded that the tested blood group systems (as opposed to their role in graft vs host disease after transplantations) have no effect on fetal MCH.

ABO Blood-Group System↗
PubMed2005

Chromatin inactivation precedes de novo DNA methylation during the progressive epigenetic silencing of the RASSF1A promoter.

Epigenetic inactivation of the RASSF1A tumor suppressor by CpG island methylation was frequently detected in cancer. However, the mechanisms of this aberrant DNA methylation are unknown. In the RASSF1A promoter, we characterized four Sp1 sites, which are frequently methylated in cancer. We examined the functional relationship between DNA methylation, histone modification, Sp1 binding, and RASSF1A expression in proliferating human mammary epithelial cells. With increasing passages, the transcription of RASSF1A was dramatically silenced. This inactivation was associated with deacetylation and lysine 9 trimethylation of histone H3 and an impaired binding of Sp1 at the RASSF1A promoter. In mammary epithelial cells that had overcome a stress-associated senescence barrier, a spreading of DNA methylation in the CpG island promoter was observed. When the RASSF1A-silenced cells were treated with inhibitors of DNA methyltransferase and histone deacetylase, binding of Sp1 and expression of RASSF1A reoccurred. In summary, we observed that histone H3 deacetylation and H3 lysine 9 trimethylation occur in the same time window as gene inactivation and precede DNA methylation. Our data suggest that in epithelial cells, histone inactivation may trigger de novo DNA methylation of the RASSF1A promoter and this system may serve as a model for CpG island inactivation of tumor suppressor genes.

Cell Line, Tumor↗
PubMed2005

Expression of the epidermal growth factor seven-transmembrane member CD97 correlates with grading and staging in human oral squamous cell carcinomas.

INTRODUCTION: The oral squamous cell carcinoma (OSCC) is the sixth most common malignant tumor worldwide. No significant better progress has been made in the treatment of OSCCs during the last decades. The heterodimeric CD97 protein is a epidermal growth factor seven-transmembrane family member and was identified as a dedifferentiation marker in thyroid carcinomas. Nothing is known about CD97 in OSCCs. MATERIAL AND METHODS: Employing UV-laser microdissection, CD97 and its ligand CD55 were investigated in normal oral mucosa and OSCCs (n = 78) by multiplex reverse transcription-PCR. Frozen sections were investigated by immunohistochemistry. The effects of retinoic acid and sodium butyrate on the CD97/CD55 expression in OSCC cell lines were determined by quantitative PCR, immunocytochemistry, and flow cytometry. RESULTS: Weak CD97 transcripts were expressed in normal mucosa and normal basal epithelial cells revealed specific CD97 immunostaining. Strong CD97 transcripts were detected in pT(3)/T(4) and G3/G4 OSCC tissues, whereas pT(1)/T(2) and G1/G2 carcinomas revealed weak CD97 transcript levels. A weak CD97 immunostaining was observed in pT(1)/T(2) and G1/G2 tumors. By contrast, intensive CD97 immunostaining was detected in pT(3)/T(4) OSCCs and G3/G4 lesions. CD55 gene expression was low in normal mucosa. All OSCCs, irrespective of stage and grading, displayed strong CD55 immunostaining. Sodium butyrate and retinoic acid inhibited CD97 mRNA and protein in OSCC cell lines. Interestingly, CD55 was up-regulated by both substances. CONCLUSION: We identified CD97 as a novel marker of dedifferentiated OSCC. Interaction of CD97 and CD55 may facilitate adhesion of OSCC cells to surrounding surfaces that would result in metastases and bad prognosis.

Adult↗
PubMed2005

INSL3 in the benign hyperplastic and neoplastic human prostate gland.

The human prostate gland is a well known source of H1 and H2 relaxin but information is lacking on the expression and potential role of the INSL3 peptide hormone within the prostate gland. In the present study we have investigated the expression of human INSL3 in patients with benign prostate hyperplasia (BPH), prostate intraepithelial neoplasia (PIN) and prostate carcinoma tissues. Of the prostate epithelial cells, strongest INSL3 expression was detected in the basal epithelial cell compartment. Weaker INSL3 mRNA expression and immunoreactive INSL3 production were observed in secretory epithelial cells and in interstitial smooth muscle cells. Prostate epithelial cells were also a source for transcripts encoding the INSL3 receptor LGR8 suggesting the presence of an autocrine/paracrine INSL3-LGR8 ligand-receptor system within the human prostate. Three human prostate carcinoma cell lines displayed differential gene activity for INSL3 and LGR8. While LNCaP was devoid of INSL3, the androgen-insensitive PC-3 and the stromal prostate cell line hPCP co-expressed INSL3 and LGR8 transcripts. In addition to expressing INSL3 mRNA, the LGR8-negative DU-145 also expressed an INSL3 splice form formerly demonstrated in thyroid carcinoma cells. When incubated with recombinant INSL3, PC-3 cells showed significantly increased intracellular cAMP levels indicating functional LGR8 receptors. INSL3 did not alter the proliferative or metabolic activity of PC-3 carcinoma cells. Instead, PC-3 responded to INSL3 with significantly enhanced tumor cell motility and a transcriptional down-regulation of ErbB receptors and EGF. All-trans-retinoic acid was demonstrated in PC-3 to up-regulate LGR8 gene activity in a dose- and time-dependent manner while having no effect on INSL3 gene activity. In conclusion, we have identified a functional INSL3-LGR8 ligand-receptor system in human prostate carcinoma cells.

Cell Line, Tumor↗
PubMed2004

Seasonal expression of INSL3 and Lgr8/Insl3 receptor transcripts indicates variable differentiation of Leydig cells in the roe deer testis.

Roe deer are seasonal breeders and show cyclic variation in testicular volume and cellular differentiation within the tubular and interstitial testis compartment. We have employed the roe deer as a model to elucidate the expression of the postpubertal Leydig cell marker INSL3 during seasonal changes in Leydig cell differentiation. Roe deer testis and serum samples were collected bimonthly throughout the complete reproductive cycle. Peak levels of testicular Insl3 mRNA and INSL3 immunoprotein were detected well before the onset of rut in April and coincided with the highest percentage of INSL3-positive cell number/square millimeter of testicular interstitial area. During the winter (December, February), roe deer INSL3 was exclusively detected in a subpopulation of alpha-actin-negative, spindle-shaped peritubular cells. Concordant with the increase in INSL3 production in April and 1 mo after the reported LH peak, a sharp increase in serum testosterone concentrations was observed. High serum testosterone concentrations coincided with the presence of detectable 17alpha-hydroxylase, mRNA and protein, in Leydig cells. Upregulation of INSL3 production in spring appeared to reflect LH-dependent differentiation of Leydig cells. The considerable changes in percentage of INSL3 immunopositive cells within the numerically constant interstitial cell population indicated cyclic seasonal de- and redifferentiation of Leydig cells. A complex functional role of the INSL3/LGR8 ligand-receptor system in the roe deer testis was suggested by the detection of specific hybridization signals for roe deer Lgr8 transcripts in Sertoli cells of the roe deer testis.

Animals↗
PubMed2004

Expression, regulation and function of autotaxin in thyroid carcinomas.

Autotaxin (ATX/NPP2) is a tumor cell motility-stimulating factor that displays both a nucleotide pyrophosphatase/phosphodiesterase activity and a recently described lysophospholipase D (lysoPLD) activity. The precise function of ATX in tumor cells and the role of ATX in thyroid carcinoma remains unclear. We have quantified ATX mRNA expression in thyroid carcinoma cell lines and in tissues of patients with thyroid carcinomas. ATX gene activity was significantly higher in undifferentiated anaplastic thyroid carcinoma cell lines (UTC) and tumor tissues as compared to follicular thyroid carcinoma (FTC) cell lines, FTC tissues or goiter tissues that were used as a control. In the thyroid carcinoma cell line 1736, EGF and bFGF stimulated ATX mRNA expression, whereas the cytokines IL-4, IL-1beta and TGF-beta reduced ATX transcriptional levels. FTC-133 cells, stably transfected with an expression vector for ATX, showed a higher lysoPLD activity, a higher proliferation rate and an increased migratory behavior. In addition, ATX also displayed a paracrine stimulatory effect on the motility of different thyroid carcinoma cell lines. Overexpression of ATX in the stably transfected FTC-133 resulted in down-regulation of CD54/ intercellular adhesion molecule-1 (ICAM-1) gene expression and augmented gene activity of the pro-angiogenic chemokine IL-8. We conclude that ATX may be regarded as a new tissue marker for undifferentiated human thyroid carcinoma cells. ATX increases the proliferation and migration of thyroid carcinoma cell lines and may also affect the angiogenic potential of thyroid carcinoma cells. Further studies are needed to provide insight into the role of ATX in the normal and neoplastic thyroid gland.

Adenocarcinoma, Follicular↗
PubMed2004

Expression of CD97 and CD55 in human medullary thyroid carcinomas.

The heterodimeric CD97 protein is a member of the EGF-TM7 family of class II seven-transmembrane (7TM) receptors of 75-90 kDa and structurally related to the secretin receptor family. CD97 is expressed on leucocytes, lymphocytes and in cells of the hematopoietic system. The precise role for CD97 is still unknown. The ubiquitously expressed CD55 (also known as decay accelerating factor, DAF) protects host cells from complement attack. In addition, CD55 is a bacterial/viral receptor and was identified as a ligand for CD97. Employing computer aided UV-laser microdissection CD97 and CD55 were investigated in C-cells of non-neoplastic thyroid specimens (n=3) and in medullary thyroid carcinomas (n=54) by multiplex RT-PCR. Frozen sections of all tissues were investigated by immunohistochemistry. All non-malignant thyroid specimens expressed CD97 mRNA weakly and were devoid of immunoreactive CD97 protein. Transcripts for CD97 were detected in all 54 MTC tissue specimens and CD97 gene activity directly correlated with the histopathological stage of the MTC. CD97 transcriptional activity was high in advanced stages of MTC such as pT3/4. pT1/2 tumors with exclusive intrathyroidal growth revealed weak CD97 expression. CD55 gene expression was significantly lower in normal C-cells than in tumor tissues and all MTC displayed strong and specific CD55 immunostaining. We did not observe a correlation between the expression of CD55 mRNA or protein, respectively, and pTNM classification. In summary, in the present study we have identified CD97 as a novel marker expressed in dedifferentiated neoplastic human thyroid C-cells. CD97 and CD55 may facilitate adhesion of C-cell carcinoma to surrounding surfaces which would result in rapid tumor cell spread.

Adolescent↗
PubMed2004

CD82, and CD63 in thyroid cancer.

CD82 (KAI1) and CD63 (ME491) are highly glycosylated proteins which belong to the transmembrane 4 superfamily (TM4SF). CD82 has been implicated as a possible prostate cancer metastasis suppressor gene, whereas CD63 is involved in the progression of human melanoma cancer. Down-regulation of both CD82 and CD63 expression has been associated with the metastatic potential of several solid tumors. Currently, information is lacking on the role of CD82 and CD63 during thyroid carcinogenesis. The aim of this study was to determine whether the expression of CD82 and CD63 is a useful prognostic indicator in patients with thyroid carcinoma. The expression of CD82 and CD63 was analysed by reverse transcriptase-PCR (RT-PCR) and immunohistochemistry in benign goiter (n=12) and 75 primary thyroid carcinoma tissue specimens (PTC: 33, FTC: 24, UTC: 18) out of which 36 were non-metastasized primary tumors and 39 were metastasized tumors (regional lymph node and/or distant metastases). All of the benign goiter tissues showed CD82 expression. By contrast, a significant decrease in CD82 mRNA and protein levels was detected in carcinoma tissues as compared to benign goiter tissues (p<0.001). A similar down-regulation was observed in metastasized tumor tissues when compared with non-metastasized tumors (all p<0.05). CD82 expression was correlated with pTNM status of differentiated and undifferentiated thyroid tumor and the pathologic stage of differentiated thyroid tumor. In contrast to CD82, CD63 mRNA and protein expression was unchanged in all thyroid carcinomas. Benign goiter tissues showed weak expression of CD63. There were no significant correlation between CD63 mRNA/protein expression and any clinical/pathological parameters. Our results support the hypothesis that down-regulation of CD82 expression may reflect an increased in vivo metastatic potential of thyroid cancer cells. CD82 may serve as a prognostic marker of metastasis in thyroid cancer. Constitutive expression of CD63 may indicate that this factor does not play a direct role in thyroid carcinogenesis.

Adolescent↗
PubMed2003

Biological significance of aminopeptidase N/CD13 in thyroid carcinomas.

Aminopeptidase N (APN)/CD13 is a transmembrane ectopeptidase expressed on a wide variety of cells. However, the precise function of APN/CD13 in tumor cells and the relationship of APN/CD13 to thyroid cancer remain unclear. In our study, we quantified the expression of APN/CD13 and additionally dipeptidyl peptidase IV (DPIV)/CD26 in thyroid carcinoma cell lines and in tissues of patients with thyroid carcinomas. Undifferentiated anaplastic thyroid carcinomas expressed more APN/CD13 than differentiated thyroid carcinomas. DPIV/CD26 showed an opposite expression pattern. We detected higher levels of DPIV/CD26 in follicular thyroid carcinomas (FTCs) and papillary thyroid carcinomas than in undifferentiated anaplastic thyroid carcinomas. In the undifferentiated thyroid carcinoma cell line 1736, APN/CD13 mRNA expression could be increased by epidermal growth factor, basic fibroblast growth factor, interleukin-6, and tumor necrosis factor alpha. FTC-133 cells stably transfected with an expression vector for APN-enhanced green fluorescent protein showed a higher migration rate than FTC-133 cells transfected with the enhanced green fluorescent protein-control plasmid. Overexpression of APN/CD13 in stably transfected cells is associated with down-regulation of N-myc down-regulated gene (NDRG)-1, melanoma-associated antigen ME491/CD63, and DPIV/CD26 gene expression. Inhibition of APN/CD13 mRNA expression by small interfering RNA induced NDRG-1, ME491/CD63, and DPIV/CD26 mRNA expression in cells of the undifferentiated thyroid carcinoma cell line C643. We conclude that APN/CD13-associated down-regulation of NDRG-1, ME491/CD63, and DPIV/CD26 in thyroid carcinoma cells is an important step of tumor progression to more malignant phenotypes, and we underline the important role of APN/CD13 as mediator in a multimolecular process regulating cell migration.

Adult↗
PubMed2003

INSL3 ligand-receptor system in the equine testis.

We employed molecular and immunological techniques to investigate the expression of INSL3, a member of the insulin-like superfamily, in prepubertal testis, postpubertal testes exhibiting normal and disturbed spermatogenesis, and cryptorchid testes of male horses. In addition, the partial cDNA coding sequences of the equine homologue of the human relaxin/INSL3-receptor Lgr8 were determined. Nonradioactive in-situ hybridization with a cRNA probe for equine Insl3 and immunohistochemistry with a specific rabbit INSL3 antiserum localized Insl3 transcripts and immunoreactive INSL3 ligand to Leydig cells in all types of testes investigated. Quantitative polymerase chain reaction analysis revealed a down-regulation of Insl3 and an up-regulation of the relaxin/INSL3-receptor expression in unilateral cryptorchid versus descended testes. Western blot analysis of protein extracts from adult normal and cryptorchid testes and prepubertal testes showed a single immunoreactive band at 14.5 kDa, which correlates with the predicted size of equine proINSL3. Densitometric analysis of Western blot data of adult normal testes revealed significantly stronger expression of immunoreactive proINSL3 as compared to extracts derived from cryptorchid or prepubertal testes. Thus, decreased expression of immunoreactive INSL3 in cryptorchid and prepubertal equine testis is transcriptionally regulated. The detection of transcripts for equine Lgr8 in the testis has identified the testis as a potential target of INSL3.

Animals↗
PubMed2003

INSL-3 is expressed in human hyperplastic and neoplastic thyrocytes.

The insulin-like hormone INSL-3, also named relaxin-like factor (RLF) or Leydig-derived insulin-like peptide (LEY-IL), is expressed in various reproductive tissues and is regarded a marker of differentiation in human testicular Leydig cells. Recently, we have identified differential expression of human INSL-3 in neoplastic Leydig cells and mammary epithelial cells suggesting an involvement of INSL-3 in tumor biology. Here we have investigated the expression of INSL-3 in human thyroid carcinoma cell lines and in the human thyroid gland which has been shown to express transcripts for the G protein coupled INSL-3 receptor LGR8. When we determined the expression of INSL-3 in eight human thyroid carcinoma cell lines, a novel INSL-3 splice variant containing a 95 bp out-of-frame insertion at the beginning of exon II of the INSL-3 gene was discovered. Treatment of the human anaplastic thyroid carcinoma cell line 8505C with diethylstilbestrol (DES) caused a significant dose-dependent transcriptional down-regulation of INSL-3 and a marked up-regulation of LGR8. Employing in situ hybridization to detect INSL-3 transcripts and specific rabbit antisera against the INSL-3 proteins, both INSL-3 isoforms were detected in patients with Graves' disease (n=10), follicular carcinomas (FTC; n=12), papillary carcinomas (PTC; n=9) and undifferentiated anaplastic carcinomas (UTC; n=15). By contrast, thyrocytes of all 15 benign goiter tissues studied were devoid of both INSL-3 isoforms, mRNA and protein. Our data indicate that INSL-3 hormone is up-regulated in hyperplastic and neoplastic human thyrocytes suggesting that the INSL-3 isoforms may serve as additional markers for hyperplastic and neoplastic human thyrocytes. In the anaplastic thyroid carcinoma cell line 8505C, the regulation of both INSL-3 and LGR8 by estrogen may be the first indication of a novel hormonally responsive, auto-/paracrine INSL-3 LGR8 ligand receptor system active in human thyroid carcinoma cells.

Alternative Splicing↗