miRNA Expression Profiling in G1 and G2 Pancreatic Neuroendocrine Tumors.

Pancreatic neuroendocrine neoplasms pose a growing clinical challenge due to their rising incidence and variable prognosis. The current study aims to investigate microRNAs (miRNA; miR) as potential biomarkers for distinguishing between grade 1 (G1) and grade 2 (G2) pancreatic neuroendocrine tumors (PanNET). A total of 33 formalin-fixed, paraffin-embedded samples were analyzed, comprising 17 G1 and 16 G2 tumors. Initially, literature-based miRNAs were validated via real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR), confirming significant downregulation of miR-130b-3p and miR-106b in G2 samples. Through next-generation sequencing, we have identified and selected the top six miRNAs showing the highest difference between G1 and G2 tumors, which were further validated. RT-qPCR validation confirmed the downregulation of miR-30d-5p in G2 tumors. miRNA combinations were created to distinguish between the two PanNET grades. The highest diagnostic performance in distinguishing between G1 and G2 PanNETs by a machine learning algorithm was achieved when using the combination miR-106b + miR-130b-3p + miR-127-3p + miR-129-5p + miR-30d-5p. The ROC analysis resulted in a sensitivity of 83.33% and a specificity of 87.5%. The findings underscore the potential use of miRNAs as biomarkers for stratifying PanNET grades, though further research is warranted to enhance diagnostic accuracy and clinical utility.

Circulating non-coding RNA biomarkers of endocrine tumours.

Circulating non-coding RNA (ncRNA) molecules are being investigated as biomarkers of malignancy, prognosis and follow-up in several neoplasms, including endocrine tumours of the pituitary, parathyroid, pancreas and adrenal glands. Most of these tumours are classified as neuroendocrine neoplasms (comprised of neuroendocrine tumours and neuroendocrine carcinomas) and include tumours of variable aggressivity. We consider them together here in this Review owing to similarities in their clinical presentation, pathomechanism and genetic background. No preoperative biomarkers of malignancy are available for several forms of these endocrine tumours. Moreover, biomarkers are also needed for the follow-up of tumour progression (especially in hormonally inactive tumours), prognosis and treatment efficacy monitoring. Circulating blood-borne ncRNAs show promising utility as biomarkers. These ncRNAs, including microRNAs, long non-coding RNAs and circular RNAs, are involved in several aspects of gene expression regulation, and their stability and tissue-specific expression could make them ideal biomarkers. However, no circulating ncRNA biomarkers have yet been introduced into routine clinical practice, which is mostly owing to methodological and standardization problems. In this Review, following a brief synopsis of these endocrine tumours and the biology of ncRNAs, the major research findings, pathomechanisms and methodological questions are discussed along with an outlook for future studies.

Over-representation of the G12S polymorphism of the SDHD gene in patients with MEN2A syndrome

OBJECTIVE: To evaluate whether germline variants of the succinate dehydrogenase genes might be phenotypic modifiers in patients with multiple endocrine neoplasia type 2. Mutations of genes encoding subunits of the succinate dehydrogenase are associated with hereditary paraganglioma/pheochromocytoma syndrome. Pheochromocytoma is one of the main manifestations of multiple endocrine neoplasia type 2 caused by germline mutation of the rearranged during transfection proto-oncogene. METHODS: Polymorphisms of the succinate dehydrogenase genes were analyzed in 77 rearranged during transfection mutation carriers, 47 patients with sporadic medullary thyroid cancer, 48 patients with sporadic Pheo, and 100 healthy individuals. Exons 10-16 of the rearranged during transfection proto-oncogene were analyzed by direct DNA sequencing, and all exons of the von Hippel-Lindau, succinate dehydrogenase B, and succinate dehydrogenase subunit D genes were tested by direct DNA sequencing and multiple ligation probe analysis. The G12S polymorphism of the succinate dehydrogenase subunit D gene was determined by restriction fragment length polymorphism. RESULTS: Of the 77 rearranged during transfection mutation carriers, 55 from 16 families had multiple endocrine neoplasia type 2A, three from three families had multiple endocrine neoplasia type 2B, and 19 from two families had familial medullary thyroid carcinoma. Eight of 55 (14.5%) patients with multiple endocrine neoplasia type 2A had this variant whereas it was absent in multiple endocrine neoplasia type 2B, familial medullary thyroid carcinoma, sporadic medullary thyroid carcinoma, and sporadic pheochromocytoma groups, and its prevalence in controls was 1% (p<0.002 multiple endocrine neoplasia type 2A versus controls). No associations between G12S and age of manifestation, incidence of pheochromocytoma or hyperparathyroidism, or level of serum calcitonin were observed. CONCLUSION: The high prevalence of the G12S variant in patients with multiple endocrine neoplasia type 2A raises questions about its role as a genetic modifier, but this proposal remains to be established.