Felix Haglund

Genetic characterization of large parathyroid adenomas

In this study, we genetically characterized parathyroid adenomas with large glandular weights, for which independent observations suggest pronounced clinical manifestations. Large parathyroid adenomas (LPTAs) were defined as the 5% largest sporadic parathyroid adenomas identified among the 590 cases operated in our institution during 2005–2009. The LPTA group showed a higher relative number of male cases and significantly higher levels of total plasma and ionized serum calcium (P<0.001). Further analysis of 21 LPTAs revealed low MIB1 proliferation index (0.1–1.5%), MEN1 mutations in five cases, and one HRPT2 (CDC73) mutation. Total or partial loss of parafibromin expression was observed in ten tumors, two of which also showed loss of APC expression. Using array CGH, we demonstrated recurrent copy number alterations most frequently involving loss in 1p (29%), gain in 5 (38%), and loss in 11q (33%). Totally, 21 minimal overlapping regions were defined for losses in 1p, 7q, 9p, 11, and 15q and gains in 3q, 5, 7p, 8p, 16q, 17p, and 19q. In addition, 12 tumors showed gross alterations of entire or almost entire chromosomes most frequently gain of 5 and loss of chromosome 11. While gain of 5 was the most frequent alteration observed in LPTAs, it was only detected in a small proportion (4/58 cases, 7%) of parathyroid adenomas. A significant positive correlation was observed between parathyroid hormone level and total copy number gain (r=0.48, P=0.031). These results support that LPTAs represent a group of patients with pronounced parathyroid hyperfunction and associated with specific genomic features.

Evidence of a functional estrogen receptor in parathyroid adenomas.

CONTEXT Primary hyperparathyroidism (PHPT) is most frequently present in postmenopausal women. Although the involvement of estrogen has been suggested, current literature indicates that parathyroid tumors are estrogen receptor (ER) α negative. OBJECTIVE The aim of the study was to evaluate the expression of ERs and their putative function in parathyroid tumors. DESIGN A panel of 37 parathyroid tumors was analyzed for expression and promoter methylation of the ESR1 and ESR2 genes as well as expression of the ERα and ERβ1/ERβ2 proteins. Transcriptome changes in primary cultures of parathyroid adenoma cells after treatment with the selective ERβ1 agonist diarylpropionitrile (DPN) and 4-hydroxytamoxifen were identified using next-generation RNA sequencing. RESULTS Immunohistochemistry revealed very low expression of ERα, whereas all informative tumors expressed ERβ1 (n = 35) and ERβ2 (n = 34). Decreased nuclear staining intensity and mosaic pattern of positive and negative nuclei of ERβ1 were significantly associated with larger tumor size. Tumor ESR2 levels were significantly higher in female vs. male cases. In cultured cells, significantly increased numbers of genes with modified expression were detected after 48 h, compared to 24-h treatments with DPN or 4-hydroxytamoxifen, including the parathyroid-related genes CASR, VDR, JUN, CALR, and ORAI2. Bioinformatic analysis of transcriptome changes after DPN treatment revealed significant enrichment in gene sets coupled to ER activation, and a highly significant similarity to tumor cells undergoing apoptosis. CONCLUSIONS Parathyroid tumors express ERβ1 and ERβ2. Transcriptional changes after ERβ1 activation and correlation to clinical features point to a role of estrogen signaling in parathyroid function and disease.

Estrogen Receptor β as a Therapeutic Target in Breast Cancer Stem Cells

Abstract Background: Breast cancer cells with tumor-initiating capabilities (BSCs) are considered to maintain tumor growth and govern metastasis. Hence, targeting BSCs will be crucial to achieve successful treatment of breast cancer. Methods: We characterized mammospheres derived from more than 40 cancer patients and two breast cancer cell lines for the expression of estrogen receptors (ERs) and stem cell markers. Mammosphere formation and proliferation assays were performed on cells from 19 cancer patients and five healthy individuals after incubation with ER-subtype selective ligands. Transcriptional analysis was performed to identify pathways activated in ERβ-stimulated mammospheres and verified using in vitro experiments. Xenograft models (n = 4 or 5 per group) were used to study the role of ERs during tumorigenesis. Results: We identified an absence of ERα but upregulation of ERβ in BSCs associated with phenotypic stem cell markers and responsible for the proliferative role of estrogens. Knockdown of ERβ caused a reduction of mammosphere formation in cell lines and in patient-derived cancer cells (40.7%, 26.8%, and 39.1%, respectively). Gene set enrichment analysis identified glycolysis-related pathways (false discovery rate < 0.001) upregulated in ERβ-activated mammospheres. We observed that tamoxifen or fulvestrant alone was insufficient to block proliferation of patient-derived BSCs while this could be accomplished by a selective inhibitor of ERβ (PHTPP; 53.7% in luminal and 45.5% in triple-negative breast cancers). Furthermore, PHTPP reduced tumor initiation in two patient-derived xenografts (75.9% and 59.1% reduction in tumor volume, respectively) and potentiated tamoxifen-mediated inhibition of tumor growth in MCF7 xenografts. Conclusion: We identify ERβ as a mediator of estrogen action in BSCs and a novel target for endocrine therapy.

Lack of S37A CTNNB1/β-catenin mutations in a Swedish cohort of 98 parathyroid adenomas

adrenal venous sampling (AVS) in patients with primary aldosteronism? Clinical Endocrinology, 70, 14–17. 7 Mulatero, P., Bertello, C., Sukor, N. et al. (2010) Impact of different diagnostic criteria during adrenal vein sampling on reproducibility of subtype diagnosis in patients with primary aldosteronism. Hypertension, 55, 667–673. 8 Kempers, M.J.E., Lenders, J.W.M., Van Outheusden, L. et al. (2009) Systematic review: diagnostic procedures to differentiate unilateral from bilateral adrenal abnormality in primary aldosteronism. Annals of Internal Medicine, 151, 329–337.

SUMO-modified Insulin-Like Growth Factor 1 Receptor (IGF-1R) Increases Cell Cycle Progression and Cell Proliferation.

Increasing number of studies have shown nuclear localization of the insulin‐like growth factor 1 receptor (nIGF‐1R) in tumor cells and its links to adverse clinical outcome in various cancers. Any obvious cell physiological roles of nIGF‐1R have, however, still not been disclosed. Previously, we reported that IGF‐1R translocates to cell nucleus and modulates gene expression by binding to enhancers, provided that the receptor is SUMOylated. In this study, we constructed stable transfectants of wild type IGF1R (WT) and triple‐SUMO‐site‐mutated IGF1R (TSM) using igf1r knockout mouse fibroblasts (R‐). Cell clones (R‐WT and R‐TSM) expressing equal amounts of IGF‐1R were selected for experiments. Phosphorylation of IGF‐1R, Akt, and Erk upon IGF‐1 stimulation was equal in R‐WT and R‐TSM. WT was confirmed to enter nuclei. TSM did also undergo nuclear translocation, although to a lesser extent. This may be explained by that TSM heterodimerizes with insulin receptor, which is known to translocate to cell nuclei. R‐WT proliferated substantially faster than R‐TSM, which did not differ significantly from the empty vector control. Upon IGF‐1 stimulation G1‐S‐phase progression of R‐WT increased from 12 to 38%, compared to 13 to 20% of R‐TSM. The G1‐S progression of R‐WT correlated with increased expression of cyclin D1, A, and CDK2, as well as downregulation of p27. This suggests that SUMO‐IGF‐1R affects upstream mechanisms that control and coordinate expression of cell cycle regulators. Further studies to identify such SUMO‐IGF‐1R dependent mechanisms seem important.

Molecular characterization of parathyroid tumors from two patients with hereditary colorectal cancer syndromes

The tumor suppressor adenomatous polyposis coli (APC) has recently been implicated in parathyroid development. We here report clinical, histopathological and molecular investigations in parathyroid tumors arising in two patients; one familial adenomatous polyposis (FAP) syndrome patient carrying a constitutional APC mutation, and one Lynch syndrome patient demonstrating a germline MLH1 mutation as well as a non-classified, missense alteration of the APC gene. We sequenced the entire APC gene in tumor and constitutional DNA from both cases, assessed the levels of APC promoter 1A and 1B methylation by bisulfite Pyrosequencing analysis and performed immunohistochemistry for APC and parafibromin. In addition, copy number analysis regarding the APC gene on chromosome 5q21-22 was performed using qRT-PCR. Histopathological workup confirmed both tumors as parathyroid adenomas without signs of malignancy or atypia. No somatic mutations or copy number changes for the APC gene were discovered in the tumors; however, in both cases, the APC promoter 1A was hypermethylated while the APC promoter 1B was unmethylated. APC promoter 1B-specific mRNA and total APC mRNA levels were higher than in normal parathyroid samples. Immunohistochemical analyses revealed strong APC protein immunoreactivity and positive parafibromin expression in both parathyroid tumors. Absence of additional somatic APC mutations and copy number changes in addition to the positive APC immunoreactivity obtained suggest that the tumors arose without biallelic inactivation of the APC tumor suppressor gene. The finding of an unmethylated APC promoter 1B and high APC 1B mRNA levels could explain the maintained APC protein expression. Moreover, the findings of positive parafibromin and APC immunoreactivity as well as a low MIB-1 proliferation index and absence of histopathological features of malignancy/atypical adenoma indicate that the parathyroid adenomas arising in these patients did not harbor malignant potential.

Diffuse PTH expression in parathyroid tumors argues against important functional tumor subclones

Abstract Objective Primary hyperparathyroidism is usually characterized by a monoclonal parathyroid tumor secreting excess parathyroid hormone (PTH). The main regulator of PTH secretion is calcium and the calcium–PTH set point is shifted in parathyroid tumor cells. We sought to investigate the relationship between tumor PTH and PTH mRNA expression and clinical presentation as well as the regulatory factors including phosphate, vitamin D, and fibroblast growth factor 23. Design A total of 154 parathyroid tumors were analyzed by PTH immunohistochemistry and chromogenic in situ hybridization of PTH mRNA. A subset of samples (n = 34) was analyzed using quantitative real-time PCR. Results Low tumor PTH mRNA level was significantly associated with low tumor PTH immunoreactivity (P = 0.026), but the two did not correlate with regard to histological distribution within individual tumors. Tumors displaying reduced PTH mRNA levels as compared with normal rim were significantly larger (P = 0.013) and showed higher expression of the calcium-sensing receptor (CASR) (P = 0.046). Weaker tumor PTH mRNA level was significantly associated with higher concentration of circulating 25-hydroxyvitamin D (P = 0.005). No significant correlation was seen between PTH immunoreactivity and patient biochemistry. Tumor weight was strongly associated with circulatory concentrations of calcium and PTH. Conclusions No areas with apparently higher PTH expression were identified, perhaps suggesting that hyper functioning parathyroid tumor subclones should be rare. Circulating 25-hydroxyvitamin D levels may influence tumor PTH expression in vivo. If PTH immunoreactivity reflects the tumor calcium–PTH set point, our data imply that the main determinant of disease severity should be tumor weight.

Prolactin receptor in primary hyperparathyroidism--expression, functionality and clinical correlations.

Background Primary hyperparathyroidism (PHPT) is an endocrine disorder most commonly affecting women, suggesting a role for female hormones and/or their receptors in parathyroid adenomas. We here investigated the prolactin receptor (PRLr) which is associated with tumours of the breast and other organs. Methodology/Principal Findings PRLr expression was investigated in a panel of 37 patients with sporadic parathyroid tumours and its functionality in cultured parathyroid tumour cells. In comparison with other tissues and breast cancer cells, high levels of prolactin receptor gene (PRLR) transcripts were demonstrated in parathyroid tissues. PRLr products of 60/70 kDa were highly expressed in all parathyroid tumours. In addition varying levels of the 80 kDa PRLr isoform, with known proliferative activity, were demonstrated. In parathyroid tumours, PRLr immunoreactivity was observed in the cytoplasm (in all cases, n = 36), cytoplasmic granulae (n = 16), the plasma membrane (n = 12) or enlarged lysosomes (n = 4). In normal parathyroid rim (n = 28), PRLr was uniformly expressed in the cytoplasm and granulae. In in vitro studies of short-term cultured human parathyroid tumour cells, prolactin stimulation was associated with significant transcriptional changes in JAK/STAT, RIG-I like receptor and type II interferon signalling pathways as documented by gene expression profiling. Moreover, PRLR gene expression in parathyroid tumours was inversely correlated with the patients’ plasma calcium levels. Conclusions We demonstrate that the prolactin receptor is highly abundant in human parathyroid tissues and that PRLr isoforms expression and PRLr subcellular localisation are altered in parathyroid tumours. Responsiveness of PRLr to physiological levels of prolactin was observed in the form of increased PTH secretion and altered gene transcription with significant increase of RIG-I like receptor, JAK-STAT and Type II interferon signalling pathways. These data suggest a role of the prolactin receptor in parathyroid adenomas.

Nuclear insulin-like growth factor 1 receptor phosphorylates proliferating cell nuclear antigen and rescues stalled replication forks after DNA damage

We have previously shown that the insulin-like growth factor 1 receptor (IGF-1R) translocates to the cell nucleus, where it binds to enhancer-like regions and increases gene transcription. Further studies have demonstrated that nuclear IGF-1R (nIGF-1R) physically and functionally interacts with some nuclear proteins, i.e. the lymphoid enhancer-binding factor 1 (Lef1), histone H3, and Brahma-related gene-1 proteins. In this study, we identified the proliferating cell nuclear antigen (PCNA) as a nIGF-1R-binding partner. PCNA is a pivotal component of the replication fork machinery and a main regulator of the DNA damage tolerance (DDT) pathway. We found that IGF-1R interacts with and phosphorylates PCNA in human embryonic stem cells and other cell lines. In vitro MS analysis of PCNA co-incubated with the IGF-1R kinase indicated tyrosine residues 60, 133, and 250 in PCNA as IGF-1R targets, and PCNA phosphorylation was followed by mono- and polyubiquitination. Co-immunoprecipitation experiments suggested that these ubiquitination events may be mediated by DDT-dependent E2/E3 ligases (e.g. RAD18 and SHPRH/HLTF). Absence of IGF-1R or mutation of Tyr-60, Tyr-133, or Tyr-250 in PCNA abrogated its ubiquitination. Unlike in cells expressing IGF-1R, externally induced DNA damage in IGF-1R-negative cells caused G1 cell cycle arrest and S phase fork stalling. Taken together, our results suggest a role of IGF-1R in DDT.

FNA cytology of solitary fibrous tumors and the diagnostic value of STAT6 immunocytochemistry

Solitary fibrous tumors (SFTs) are rare mesenchymal tumors commonly located in the pleura, soft tissues, or meninges and are characterized by the NGFI‐A‐binding protein 2 (NAB2)–signal transducer and activator of transcription 6 (STAT6) fusion gene. Recent studies have indicated that nuclear STAT6 immunohistochemistry is a specific marker for SFTs.