Implications of noncoding regulatory functions in the development of insulinomas

Pancreatic neuroendocrine neoplasms (pNENs): Genetic and environmental biomarkers for risk of occurrence and prognosis

Pancreatic neuroendocrine neoplasms (pNENs) are rare and heterogeneous tumors arising from neuroendocrine cells, representing approximately 10 % of all Gastro-Entero-Pancreatic neuroendocrine neoplasms. While most pNENs are sporadic, a subset is associated with genetic syndromes such as multiple endocrine neoplasia type 1 (MEN1) or von Hippel-Lindau disease (VHL). pNENs are further classified into functioning and non-functioning tumors, with distinct clinical behaviors, prognoses, and treatment approaches. This review explores genetic and environmental biomarkers that influence the risk, prognosis, and therapeutic responses in pNENs. The epidemiology of pNENs reveals an increasing incidence, primarily due to advancements in imaging techniques. Genetic factors play a pivotal role, with germline mutations in MEN1, VHL, and other genes contributing to familial pNENs. Somatic mutations, including alterations in the mTOR pathway and DNA maintenance genes such as DAXX and ATRX, are critical in sporadic pNENs. These mutations, along with epigenetic dysregulation and transcriptomic alterations, underpin the diverse clinical and molecular phenotypes of pNENs. Emerging evidence suggests that epigenetic changes, including DNA methylation profiles, can stratify pNEN subtypes and predict disease progression. Environmental and lifestyle factors, such as diabetes, smoking, and chronic pancreatitis, have been linked to an increased risk of sporadic pNENs. While the association between these factors and tumor progression is still under investigation, their potential role in influencing therapeutic outcomes warrants further study. Advances in systemic therapies, including somatostatin analogs, mTOR inhibitors, and tyrosine kinase inhibitors, have improved disease management. Biomarkers such as Ki-67, somatostatin receptor expression, and O6-methylguanine-DNA methyltransferase (MGMT) status are being evaluated for their predictive value. Novel approaches, including the use of circulating biomarkers (NETest, circulating tumor cells, and ctDNA) and polygenic risk scores, offer promising avenues for non-invasive diagnosis and monitoring. Despite these advancements, challenges remain, including the need for large, well-annotated datasets and validated biomarkers. Future research should integrate multi-omics approaches and leverage liquid biopsy technologies to refine diagnostic, prognostic, and therapeutic strategies. Interdisciplinary collaborations and global consortia are crucial for overcoming current limitations and translating research findings into clinical practice. These insights hold promise for improving prevention, early detection, and tailored treatments, ultimately enhancing patient outcomes.

Single-cell transcriptomic analysis of canine insulinoma reveals distinct sub-populations of insulin-expressing cancer cells

Canine malignant insulinoma is a rare, highly metastatic and life-threatening neuroendocrine tumour of pancreatic beta cells. To map the single-cell transcriptomic landscape of canine insulinoma for the first time, transcriptomic profiles of 5,532 cells were captured from two spontaneous insulinomas (Patient 1 and 2) and one associated metastasis (Patient 2) in two Boxer dogs. Distinct cancer, endocrine, and immune cell populations were identified. Notably, all three tumour samples contained two transcriptionally distinct insulin-expressing tumour cell populations (INS+ and INS+FOS low ), characterised here for the first time. These two cancer cell populations significantly differed by ~ 8,000 differentially expressed genes (DEGs), particularly tumour suppressor genes (e.g. TP53, EGR1) and cancer-related pathways (e.g., MAPK, p53). In contrast, COX7A2L was one of a few genes ubiquitously expressed and significantly upregulated (> 20-fold) in both insulin-expressing tumour populations compared to other captured populations. Both populations were also characterised by expression of chromogranin/secretogranin neuroendocrine tumour marker genes (e.g. CHGA, SCGN). There were far fewer gene expression differences observed between insulin-expressing tumour cells from the two patients (~ 600 DEGs) than between the two cancer cell populations within each patient. These DEGs included CLTRN, TMSB4X, CSRP2, LGALS2, and C15orf48. Unexpectedly for a tumour of endocrine origin, the metastasis in Patient 2 exhibited > 20-70 fold upregulation of exocrine pancreatic genes including CLPS, PRSS2, PRSS and CTRC. Immune cell analyses identified distinct infiltrating immune populations, including memory T cells and macrophages and revealed likely tumour-immune interactions, including the CD40-CD40L interaction. This study provides the first single-cell RNA sequencing (scRNA-seq) analysis of naturally occurring insulinoma in any species, revealing tumour cell heterogeneity, novel immune microenvironment features, and potential therapeutic targets. Despite its small scale, the findings highlight the utility of scRNA-seq in veterinary oncology and its translational potential for pancreatic neuroendocrine tumours across species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s44356-025-00026-3.