Stan B. Sidhu

miR-195 and miR-483-5p Identified as Predictors of Poor Prognosis in Adrenocortical Cancer

Purpose: Adrenocortical adenomas are common, whereas adrenocortical carcinomas are rare. Discriminating between benign and malignant adrenocortical tumors using conventional histology can be difficult. In addition, adrenocortical carcinomas generally have poor prognosis and limited treatment options. MicroRNAs are short noncoding RNAs that are involved in regulation of gene transcription. Experimental Design: To identify microRNAs involved in the pathogenesis of adrenocortical tumors, expression profiling of microRNAs was done on a cohort of 22 adrenocortical carcinomas, 27 adrenocortical adenomas, and 6 normal adrenal cortices. Results: Twenty-three microRNAs were found to be significantly differentially expressed between adrenocortical carcinomas and adrenocortical adenomas. miR-335 and miR-195 were significantly downregulated in adrenocortical carcinomas compared with adrenocortical adenomas. This result was further validated in an external cohort of six adrenocortical carcinomas and four adrenocortical adenomas. Using Kaplan-Meier analysis, downregulation of miR-195 and upregulation of miR-483-5p in adrenocortical carcinomas were significantly associated with poorer disease-specific survival. Conclusions: These findings indicate that deregulation of microRNAs is a recurring event in human adrenocortical carcinomas and that aberrant expression of miR-195 and miR-483-5p identifies a subset of poorer prognosis adrenocortical carcinomas. (Clin Cancer Res 2009;15(24):7684–92)

Immunohistochemistry for SDHB triages genetic testing of SDHB, SDHC, and SDHD in paraganglioma-pheochromocytoma syndromes.

Up to 30% of pheochromocytomas and paragangliomas are associated with germline RET, Von Hippel-Lindau (VHL), neurofibromatosis type I (NF1), and succinate dehydrogenase subunits (SDHB, SDHC, and SDHD) mutations. Genetic testing allows familial counseling and identifies subjects at high risk of malignancy (SDHB mutations) or significant multiorgan disease (RET, VHL, or NF1). However, conventional genetic testing for all loci is burdensome and costly. We performed immunohistochemistry for SDHB on 58 tumors with known SDH mutation status. We defined positive as granular cytoplasmic staining (a mitochondrial pattern), weak diffuse as a cytoplasmic blush lacking definite granularity, and negative as completely absent staining in the presence of an internal positive control. All 12 SDH mutated tumors (6 SDHB, 5 SDHD, and 1 SDHC) showed weak diffuse or negative staining. Nine of 10 tumors with known mutations of VHL, RET, or NF1 showed positive staining. One VHL associated tumor showed weak diffuse staining. Of 36 tumors without germline mutations, 34 showed positive staining. One paraganglioma with no known SDH mutation but clinical features suggesting familial disease was negative, and one showed weak diffuse staining. We also performed immunohistochemistry for SDHB on 143 consecutive unselected tumors of which 21 were weak diffuse or negative. As SDH mutations are virtually always germline, we conclude that approximately 15% of all pheochromocytomas or paragangliomas are associated with germline SDH mutation and that immunohistochemistry can be used to triage genetic testing. Completely absent staining is more commonly found with SDHB mutation, whereas weak diffuse staining often occurs with SDHD mutation.

Pheochromocytoma: Current Approaches and Future Directions

Pheochromocytomas are rare catecholamine-secreting tumors that arise from chromaffin tissue within the adrenal medulla and extra-adrenal sites. Because of the excess secretion of hormones, these tumors often cause debilitating symptoms and a poor quality of life. While medical management plays a significant role in the treatment of pheochromocytoma patients, surgical excision remains the only cure. Improved medical management and surgical techniques and an increased understanding of hereditary disease have improved the outcome of pheochromocytoma patients with benign disease; however, the outcome of patients with malignant disease remains poor. In this review, we discuss the presentation, diagnosis, management, and future directions in the management of this disease.

Immunohistochemistry for SDHB divides gastrointestinal stromal tumors (GISTs) into 2 distinct types.

The Carney triad (CT) is gastrointestinal stromal tumor (GIST), paraganglioma, and pulmonary chondroma. The GISTs of CT show different clinical, molecular, and morphologic features to usual adult GISTs but are similar to the majority of pediatric GISTs. We postulated that these GISTs would show negative staining for succinate dehydrogenase B (SDHB). We performed SDHB immunohistochemistry on GISTs arising in 5 individuals with CT, 1 child, 7 individuals with GIST in young adulthood including 2 with germline KIT mutations, 3 individuals with neurofibromatosis 1, one 63-year-old female with multifocal gastric epithelioid GIST with lymph node metastases, and 104 consecutive unselected individuals with apparently sporadic GIST. The GISTs and paragangliomas arising in CT, the pediatric GIST, and the multifocal gastric GIST from the 63-year-old showed negative SDHB staining. GISTs from the 7 young adults and 3 with neurofibromatosis were SDHB positive. Of the unselected GISTs, 101 (97%) were positive. One of the negative GISTs arose in a 48-year-old female with previous recurrent multifocal gastric GISTs and the other 2 arose in females also in their 40s with gastric GISTs with epithelioid morphology. We conclude that negative staining for SDHB is characteristic of the GISTs of CT and the subgroup of pediatric GISTs which it resembles. Furthermore, when negative staining occurs in apparently sporadic GISTs in adults, the GISTs show morphologic and clinical features similar to pediatric and CT type GISTs. GISTs may therefore be divided into type 1 (SDHB positive) and type 2 (SDHB negative) subtypes.

Comprehensive Pan-Genomic Characterization of Adrenocortical Carcinoma

We describe a comprehensive genomic characterization of adrenocortical carcinoma (ACC). Using this dataset, we expand the catalogue of known ACC driver genes to include PRKAR1A, RPL22, TERF2, CCNE1, and NF1. Genome wide DNA copy-number analysis revealed frequent occurrence of massive DNA loss followed by whole-genome doubling (WGD), which was associated with aggressive clinical course, suggesting WGD is a hallmark of disease progression. Corroborating this hypothesis were increased TERT expression, decreased telomere length, and activation of cell-cycle programs. Integrated subtype analysis identified three ACC subtypes with distinct clinical outcome and molecular alterations which could be captured by a 68-CpG probe DNA-methylation signature, proposing a strategy for clinical stratification of patients based on molecular markers.

Increasing incidence of thyroid cancer is due to increased pathologic detection

BACKGROUND There has been a marked increase in the incidence of thyroid cancer worldwide over recent decades. Patients with retrosternal goiter (RSG) are not picked up generally by common surveillance techniques such as ultrasound. The aim of this project was to study the incidence of thyroid cancer in patients with RSG. METHODS This is a retrospective cohort study. Documented were patient demographics as well as the size, type, and numbers of thyroid cancers. The number of routine histologic blocks examined for multinodular goiter in the different time periods was also examined. RESULTS Within a cohort of 13,793 thyroidectomies performed over 40 years, there were 2,260 patients (14%) who underwent surgery for RSG. The percentage of patients with RSG containing thyroid cancer increased from 3.6 to 7.5% (P < .05); however, once papillary microcarcinomas (PMC) (</=10 mm) were excluded there was no increase in cancer incidence (3.4-3.5%, P = .9). The increase in the number of PMCs diagnosed is associated with the increase in the routine number of blocks sampled over the 40-year time period (P < .01). CONCLUSION This study has confirmed an increase in the incidence of thyroid cancer over 4 decades. However, that increase appears to be due to an increase in the diagnosis of PMC associated with increased sampling of resected specimens by pathologists, raising the possibility that the current epidemic of thyroid cancer may be largely manmade.

Comprehensive Re-Sequencing of Adrenal Aldosterone Producing Lesions Reveal Three Somatic Mutations near the KCNJ5 Potassium Channel Selectivity Filter

Background Aldosterone producing lesions are a common cause of hypertension, but genetic alterations for tumorigenesis have been unclear. Recently, either of two recurrent somatic missense mutations (G151R or L168R) was found in the potassium channel KCNJ5 gene in aldosterone producing adenomas. These mutations alter the channel selectivity filter and result in Na+ conductance and cell depolarization, stimulating aldosterone production and cell proliferation. Because a similar mutation occurs in a Mendelian form of primary aldosteronism, these mutations appear to be sufficient for cell proliferation and aldosterone production. The prevalence and spectrum of KCNJ5 mutations in different entities of adrenocortical lesions remain to be defined. Materials and Methods The coding region and flanking intronic segments of KCNJ5 were subjected to Sanger DNA sequencing in 351 aldosterone producing lesions, from patients with primary aldosteronism and 130 other adrenocortical lesions. The specimens had been collected from 10 different worldwide referral centers. Results G151R or L168R somatic mutations were identified in 47% of aldosterone producing adenomas, each with similar frequency. A previously unreported somatic mutation near the selectivity filter, E145Q, was observed twice. Somatic G151R or L168R mutations were also found in 40% of aldosterone producing adenomas associated with marked hyperplasia, but not in specimens with merely unilateral hyperplasia. Mutations were absent in 130 non-aldosterone secreting lesions. KCNJ5 mutations were overrepresented in aldosterone producing adenomas from female compared to male patients (63 vs. 24%). Males with KCNJ5 mutations were significantly younger than those without (45 vs. 54, respectively; p<0.005) and their APAs with KCNJ5 mutations were larger than those without (27.1 mm vs. 17.1 mm; p<0.005). Discussion Either of two somatic KCNJ5 mutations are highly prevalent and specific for aldosterone producing lesions. These findings provide new insight into the pathogenesis of primary aldosteronism.

Molecular Markers and the Pathogenesis of Adrenocortical Cancer

Adrenal tumors are common, with an estimated incidence of 7.3% in autopsy cases, while adrenocortical carcinomas (ACCs) are rare, with an estimated prevalence of 4-12 per million population. Because the prognoses for adrenocortical adenomas (ACAs) and ACCs are vastly different, it is important to be able to accurately differentiate the two tumor types. Advancement in the understanding of the pathophysiology of ACCs is essential for the development of more sensitive means of diagnosis and treatment, resulting in better clinical outcome. Adrenocortical tumors (ACTs) occur as a component of several hereditary tumor syndromes, which include the Li-Fraumeni syndrome, Beckwith-Wiedemann syndrome, multiple endocrine neoplasia 1, Carney complex, and congenital adrenal hyperplasia. The genes involved in these syndromes have also been shown to play a role in the pathogenesis of sporadic ACTs. The adrenocorticotropic hormone-cAMP-protein kinase A and Wnt pathways are also implicated in adrenocortical tumorigenesis. The aim of this review is to summarize the current knowledge on the molecular mechanisms involved in adrenocortical tumorigenesis, including results of comparative genomic hybridization, loss of heterozygosity, and microarray gene-expression profiling studies.

MicroRNA Profiling of Sporadic and Hereditary Medullary Thyroid Cancer Identifies Predictors of Nodal Metastasis, Prognosis, and Potential Therapeutic Targets

Purpose: While the molecular basis of hereditary medullary thyroid cancer (HMTC) has been well defined, little is known about the molecular pathogenesis of sporadic medullary thyroid cancer (SMTC). In addition, microRNAs (miRNAs) have been shown to be important diagnostic and prognostic markers in cancer but have not been defined in MTC. Our aim was to study the miRNA profile of MTC to identify prognostic biomarkers and potential therapeutic targets. Experimental Design: MiRNA microarray profiling was carried out in fresh frozen tissues from patients with SMTC (n = 12) and HMTC (n = 7). Differential expression of three miRNAs was confirmed in a validation cohort of SMTC and HMTC samples (n = 45) using quantitative reverse transcriptase-PCR and correlated with clinical outcomes. The functional role of a selected miRNA was investigated in vitro in the human medullary thyroid carcinoma cell line (TT cells) using cell proliferation assays and Western blotting analysis. Results: MiRs-183 and 375 were overexpressed (P = 0.001; 0.031) and miR-9* was under-expressed (P = 0.011) in SMTC versus HMTC. Overexpression of miRs-183 and 375 in MTC predicted lateral lymph node metastases (P < 0.001; P = 0.001) and was associated with residual disease (P = 0.001; 0.003), distant metastases (P = 0.003; 0.001), and mortality (P = 0.01; 0.011). Knock down of miR-183 expression in the TT cell line induced a significant decrease in the viable cell count and upregulation of the protein LC3B, which is associated with autophagy. Conclusions: Our data indicate that miRNAs play a pivotal role in the biology of MTC and represent an important class of prognostic biomarkers and therapeutic targets warranting further investigation. Clin Cancer Res; 17(14); 4772–81. ©2011 AACR.

AUSTRALIAN ENDOCRINE SURGEONS GUIDELINES AES06/01. POSTOPERATIVE PARATHYROID HORMONE MEASUREMENT AND EARLY DISCHARGE AFTER TOTAL THYROIDECTOMY: ANALYSIS OF AUSTRALIAN DATA AND MANAGEMENT RECOMMENDATIONS

Background:  The risk of hypocalcaemia after thyroidectomy has traditionally mandated inpatient monitoring for signs and symptoms as well as frequent measurement of serum calcium levels. In recent years there has been much interest in the published work about the use of intact parathyroid hormone (PTH) to better predict hypocalcaemia after thyroidectomy. Although generally accurate, the use of intact parathyroid hormone in Australia has not become widespread. On behalf of the Australian Endocrine Surgeons an analysis of Australian data on the use of PTH levels to predict hypocalcaemia after thyroidectomy was carried out. The data were analysed with a view to making recommendations about the use of this test in clinical practice and the feasibility of achieving safe early discharge for patients.