Dagmar Führer

Brain activity in hunger and satiety: An exploratory visually stimulated fMRI study

Objective: To explore neuroanatomical sites of eating behavior, we have developed a simple functional magnetic resonance imaging (fMRI) paradigm to image hunger vs. satiety using visual stimulation.

Improved Survival in Patients with Stage II Adrenocortical Carcinoma Followed Up Prospectively by Specialized Centers

CONTEXT Median survival in stage II adrenocortical carcinoma (ACC) differs widely in published series ranging between 23 and more than 60 months. We hypothesized that these results may have been affected by a referral bias because many patients may contact specialized centers only after recurrence. OBJECTIVE The objective of the study was a comparison of outcome in patients with stage II ACC who were followed up prospectively early after surgery and were counseled by a specialized center (prospective group) with patients who registered with the German ACC registry later than 4 months after diagnosis (retrospective group). PATIENTS/METHODS The study was a cohort analysis in 149 adult patients with stage II ACC. RESULTS Patients who were followed up prospectively (n = 30) had a lower recurrence rate and a superior 5-yr survival compared with the 119 patients in the retrospective group (30 vs. 74%, P < 0.01 and 96 vs. 55%, P < 0.05, respectively). In the retrospective group, 67% of the patients had registered only after disease recurrence. In the remaining patients, the recurrence rate was low (21%), and the 5-yr survival was greater than 95%. More patients in the prospective group received adjuvant mitotane (53 vs. 16%, P < 0.001), and adjuvant mitotane was associated with improved survival [hazard risk 0.35 (95% confidence interval 0.13-0.97); P = 0.04]. However, the survival advantage was maintained when only patients without mitotane therapy were analyzed. CONCLUSIONS Patients who are followed up prospectively after surgery for stage II ACC and receive early specialized care have a much better prognosis than previously reported due to a major referral bias in previous series and use of adjuvant mitotane. These findings will impact on the perception of prognosis in newly diagnosed stage II ACC.

Detection of thyroid-stimulating hormone receptor and Gsα mutations: in 75 toxic thyroid nodules by denaturing gradient gel electrophoresis

The actual frequency of constitutively activating thyrotropin receptor or Gsα mutations in toxic thyroid nodules (TTNs) remains controversial as considerable variation in the prevalence of these mutations has been reported. We studied a series of 75 consecutive TTNs and performed mutation screening by the more sensitive method of denaturing gradient gel electrophoresis (DGGE) in addition to direct sequencing. Furthermore, the likelihood of somatic mutations occurring in genes other than that for the thyroid-stimulating hormone receptor (TSHR) and exons 7–9 of the Gsα protein gene was determined by clonality analysis of TTNs, which did not harbor mutations in the investigated genes. In 43 of 75 TTNs (57%) constitutively active TSHR mutations were identified. Six TSHR mutations were detected only by DGGE, underlining the importance of a sensitive screening method. Novel, constitutively activating mutations were identified at positions 425 (Ser→Leu) and 512 (Leu→Glu/Arg). Furthermore, a new base substitution was detected at position Pro639Ala (CCA→GCA). Ten of 20 TSHR or Gsα mutation negative cases (50%) showed nonrandom X-chromosome inactivation, indicating clonal origin. In conclusion, somatic, constitutively activating TSHR mutations appear to be a major cause of TTNs (57%), while mutations in Gsα play a minor role (3%). The mutation negative but clonal cases indicate a probable involvement of somatic mutations other than in the TSH receptor or Gsα genes as the molecular cause of these hot nodules.

Thyroid hormone, thyroid hormone receptors and cancer: a clinical perspective

Thyroid hormones (THs) may play a role in diseases other than hyper- and hypothyroidism. Several lines of evidence suggest tumor-promoting effects of TH and TH receptors. They are possibly mediated by phosphatidylinositol-3-kinase and MAPK and involve among others stimulation of angiogenesis via αvβ3. Thus, an increased risk for colon, lung, prostate, and breast cancer with lower TSH has been demonstrated in epidemiological studies, even suggesting a TH dose effect on cancer occurrence. Furthermore, higher TH levels were associated with an advanced clinical stage of breast and prostate cancer. In rodent models, TH stimulated growth and metastasis of tumor transplants, whereas hypothyroidism had opposite effects. In clinical studies of glioblastoma and head and neck cancer, hypothyroid patients showed longer survival than euthyroid patients. Also, patients with renal cell cancer that were treated with the tyrosine kinase inhibitor sunitinib and developed hypothyroidism in due course showed significantly longer survival than patients that remained euthyroid. Development of hypothyroidism was an independent predictor for survival in two studies. Yet, it is still possible that hypothyroidism is only a surrogate marker for treatment efficacy and does not positively influence treatment outcome by itself. Future cancer treatment studies, especially with substances that can induce hypothyroidism, should therefore be designed in a way that allows for an analysis of thyroid function status and its contribution on treatment outcome.

FOXO3a: a novel player in thyroid carcinogenesis?

The forkhead box transcription factor FOXO3a has recently been identified as central mediator of the cellular response to oxidative stress inducing cell cycle arrest or apoptosis. The aim of our study was to investigate the regulation of FOXO3a in the thyroid and to determine whether alterations in FOXO3a activity occur in thyroid carcinogenesis. In vitro, we demonstrate that FOXO3a activity is negatively regulated by the PI3K/Akt cascade promoting increased phosphorylation and cytoplasmatic accumulation of FOXO3a with decreased transcription of the target genes p27kip (CDKN1B) and Bim (BCL2L11), but increased expression of GADD45A. By contrast, we show that H(2)O(2) exposure activates FOXO3a in thyrocytes with JNK (MAPK8)-mediated nuclear accumulation of FOXO3a and increased expression of the cell cycle arrest genes p27kip and GADD45A. In vivo, we observed a marked cytoplasmatic accumulation of FOXO3a in differentiated thyroid cancers versus an exclusive nuclear accumulation in follicular adenoma and normal thyroid tissue. Moreover, this cytosolic accumulation of FOXO3a correlated with an increased phospho-Akt expression in thyroid malignancies and was accompanied by decreased expression of the FOXO targets p27kip and Bim and an increase in GADD45A mRNA expression in the thyroid cancers. Our data suggest FOXO3a as a novel player of cellular stress response in the thyroid, mediating the thyrocytes fate either to survive or to undergo apoptosis. Furthermore, PI3K-dependent FOXO3a inactivation may be a novel pathomechanism for the escape from apoptosis in thyroid cancer cells, in particular in follicular thyroid carcinoma.

Forkhead box-O transcription factor: critical conductors of cancer's fate

Cells have evolved elaborated mechanisms to coordinate the cellular answer of either survival or apoptosis. Recent concepts of human carcinogenesis have suggested disturbances in these cellular relays as a potential link to cellular dedifferentiation and uncontrolled proliferation. Forkhead box-O transcription factors (FOXOs) play an important role in tumour suppression by regulating the expression of genes involved in stress resistance, DNA damage repair, cell cycle arrest and apoptosis. The specific regulation of FOXO function is tightly controlled by posttranslational modifications such as phosphorylation, acetylation and ubiquitination. Loss of FOXO function has recently been identified in several human cancers. In this review, we will give an overview about recent progress in the understanding of function and regulation of FOXOs, as well as their role in carcinogenesis. Furthermore, we will discuss a potential clinical use of FOXOs by therapeutically restoring their tumour suppressive properties.

Does tumor heterogeneity limit the use of the Weiss criteria in the evaluation of adrenocortical tumors

Adrenal incidentalomas are detected more frequently with high-resolution imaging modalities. It is difficult to distinguish between benign and malignant lesions despite the so-called histologic Weiss criteria, imaging features, and molecular studies. We here present a 52 yr-old man who was found to have an adrenal incidentaloma during an annual check-up at his urologist. An 8 cm large adrenal lesion was detected on ultrasound, computed tomography, and magnetic resonance imaging with imaging features suggestive of malignancy. The lesion was hormonally inactive. A left-sided adrenalectomy was performed and histologic grading revealed a Weiss score of 2, suggesting a benign tumor. However, on further follow-up, the patient developed a local recurrence and pulmonary metastases diagnosed 6 yr after initial presentation. After repeat surgery in the left adrenal bed adrenocortical tumor tissue had a Weiss score of 8, clearly suggesting histologic malignancy. The patient received adjuvant mitotane therapy. Under this therapy, he developed a right-sided adrenal mass (contralateral from the primary tumor) of 2 cm size which disappeared during the following 9 months, whereas the pulmonary metastases remained unchanged, suggesting tumor clones with a variable response to treatment or spontaneous apoptosis. This case suggests that adrenal inciden-talomas larger than 6 cm with imaging features such as intratumoral necrosis suggestive of malignancy, should be managed as potential cancers independent of the so-called Weiss criteria. In such patients, close follow-up examinations including high-resolution imaging (preferably 3 monthly) are needed and should be carried out by a physician familiar/specialized in endocrine oncology.

Somatostatin receptor subtype expression in human thyroid tumours.

Somatostatin receptors (SSTR) are expressed in various endocrine tumours. The expression of SSTR at the tumour cell surface confers the possibility for diagnostic imaging and therapy of tumours using radiolabeled somatostatin analogues. The majority of currently available somatostatin analogues show a higher binding affinity for the SSTR2 subtype. To date, the precise expression pattern of the SSTR subtypes 1-5 in thyroid epithelial tumours remains to be determined. We investigated the mRNA expression of SSTR1-5 in benign and malignant epithelial thyroid tumours [20 cold thyroid nodules (CTNs), 20 toxic thyroid nodules (TTNs), 20 papillary, 20 follicular, and 5 anaplastic carcinomas (PTCs, FTCs, ATCs, respectively)] and compared them to normal surrounding thyroid tissues. Four out of five SSTR subtypes were detected in malignant thyroid tumours, benign neoplasia, and normal surrounding tissue with a predominant expression of SSTR2 and SSTR5, and a weak expression of SSTR1 and SSTR3. Weak SSTR4 mRNA expression was detected in some PTCs. Compared to normal thyroid tissue, SSTR2 was significantly upregulated in PTC and ATC. In addition significant upregulation of SSTR3 was found in PTC. SSTR5 mRNA expression was increased in PTC and FTC and significantly decreased in CTN and TTN compared to normal thyroid tissue. SSTR2 is the predominant subtype in thyroid epithelial tumours with a high expression pattern, in particular, in PTC . Perspectively, the expression of distinct SSTR in thyroid epithelial tumours might represent a promising avenue for diagnostics and therapy of advanced thyroid cancer with somatostatin analogues.

TFF3-Based Candidate Gene Discrimination of Benign and Malignant Thyroid Tumors in a Region with Borderline Iodine Deficiency

BACKGROUND With the advent of microarray technology, increasing numbers of marker genes are proposed to distinguish benign and malignant thyroid lesions. However, most markers await confirmation through independent studies. In this paper, we re-evaluate the diagnostic potential of 10 proposed candidate genes in benign and malignant thyroid pathologies in a region with borderline iodine deficiency. METHODS Quantitative real-time PCR was performed for CCND2, PLAB, PCSK2, HGD1, TFF3, B4GALT, LGALS3, ETS1, ADM3, and TG in 150 thyroid specimens, including 52 benign thyroid nodules (28 follicular adenoma and 24 adenomatous nodules), 52 corresponding normal thyroid tissues, 20 follicular carcinomas, 20 papillary carcinomas, and six undifferentiated carcinomas. RESULTS On a single-gene basis, significant differences in mRNA expression were found for TFF3, PLAB, and ADM3 in benign thyroid nodules and thyroid malignancy. Using two-marker gene sets, we identified 11 combinations, which allowed both a distinction of benign and malignant thyroid nodules and a discrimination of follicular adenoma and carcinoma. However, for cancer prediction, analysis of a minimum of six genes per sample was necessary and allowed correct prediction of a benign thyroid lesion and thyroid cancer with 94% accuracy in the most discriminative set (TFF3/PLAB/TG/ADM3/HGD1/LGALS3). CONCLUSION We confirm the applicability of a number of recently proposed marker genes for the distinction of benign and malignant thyroid tumor and suggest that their diagnostic usefulness is independent of the iodide supply. We propose that the most discriminative marker set identified in our validation study together with marker combinations proposed by other investigators should now be evaluated in multicenter trials.

Functional characterization of five constitutively activating thyrotrophin receptor mutations

Gain of function mutations of the thyrotrophin receptor (TSHR) affect several functional characteristics, such as cAMP and inositol phosphate (IP) accumulation, cell surface expression and TSH affinity. In this study we compared five constitutively activating TSHR mutations, four receptors with a point mutation (S505N, L629F, I630L, V656F) and a nine amino acid (aa) deletion mutant (aa positions 613–621) for these functional parameters in parallel transfection experiments.