Background: Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress response protein that plays an important role in pancreatic functions. As both alcohol and ER stress response proteins are involved in the pathogenesis of pancreatitis, we sought to investigate the expression of MANF in chronic alcoholic pancreatitis (CAP) and chronic non-alcoholic pancreatitis (CNP). Methods: A cohort of chronic pancreatitis tissues was gathered from routine surgical pathology (n = 77) and autopsy (n = 10) cases and tissue microarrays were created. Sampled tissues were reviewed and designated as representing CAP (n = 15), CNP (n = 58), or normal pancreatic tissue (NPT) (n = 27). MANF immunohistochemistry (IHC) and digital image analysis were performed to obtain an estimation of tissue fibrosis and an optical density (OD) of MANF IHC in ducts and acini for each case. The averaged values for these variables among histologic designations were compared. Results: The amount of fibrous tissue of the combined CAP and CNP group (chronic alcoholic and non-alcoholic pancreatitis, CANP) exceeded that of the NPT group (70% vs. 34%, p < 0.0001). The MANF OD in ducts of CANP was significantly higher than that of NPT (0.19 vs. 0.10, p < 0.05). The MANF OD in ducts of CAP was significantly higher than that of CNP (0.27 vs. 0.17, p < 0.05). The MANF OD in acini of CAP was significantly lower than that in CNP (0.81 vs. 1.05, p < 0.05). Finally, there was a statistically significant positive relationship between the amount of fibrosis and MANF OD in ducts (p < 0.001). Conclusions: MANF expression was higher in ducts of CAP than CNP. In contrast, MANF expression in acini was lower in CAP than CNP and NPT. There was a positive correlation between fibrosis and MANF levels in the ducts.

Purpose: Pancreatic neuroendocrine tumors (PNET) are rare malignancies of the endocrine pancreas with diverse clinical outcomes. Whereas some PNETs are indolent, others are aggressive and metastasize quickly. However, clinically relevant molecular stratification for PNET to predict outcomes and guide therapeutic decision-making is limited. Thus, there is an urgent need to understand the molecular heterogeneity of PNETs to refine prognostication and discover novel therapeutic vulnerabilities. Experimental Design: We performed single-nucleus RNA sequencing on untreated, resected primary, and metastatic PNETs (n = 18). We inferred gene expression programs (GEP) of malignant and nonmalignant cells and investigated associations with clinical outcomes. Next, we inferred interactions in the tumor microenvironment (TME) and performed transwell migration assays for functional validation. Finally, we explored genomic and transcriptomic evolution in a unique case study of an untreated primary PNET with two asynchronous hepatic metastases. Results: A malignant GEP enriched for neural/synaptic signaling genes was associated with worse overall survival, broad chromosomal loss of heterozygosity, and alternative lengthening of telomeres. Another malignant GEP enriched for VEGF signaling increased throughout metastatic progression in our case study. We found that macrophage-derived glutamate drives polarization toward an immunosuppressive phenotype and activates the MAPK/ERK pathway in malignant cells to increase migratory capacity. Conclusions: This study provides a detailed single-nucleus transcriptomic classification of malignant, stromal, and immune cell types and states in PNETs, their interactions in the TME, and associations with clinical outcomes. The refined molecular taxonomy of PNET may guide the development of more efficacious biomarkers and therapeutic strategies.

Rare subtypes of gastroesophageal malignancies represent a small but biologically meaningful fraction of upper gastrointestinal cancers. Although most therapeutic algorithms are derived from conventional squamous cell carcinoma and adenocarcinoma, uncommon entities such as variants of squamous cell carcinoma, lymphoepithelioma-like carcinoma, adenosquamous carcinoma, neuroendocrine carcinoma, and others display distinct clinicopathologic, immunologic, and molecular features that may influence prognosis and therapeutic decision-making. This review synthesizes current evidence regarding the epidemiology, histopathology, molecular alterations, and emerging therapeutic vulnerabilities across these rare subtypes. Importantly, these tumors frequently exhibit aggressive clinical behavior and are often managed by extrapolation from more common histologies due to the absence of prospective data. Increasing integration of genomic profiling, immune characterization, and biomarker-driven stratification is essential to refine diagnoses, expand precision therapeutic strategies, and improve outcomes. Recognition of these rare subtypes in routine practice is critical, as even small molecularly defined populations may carry disproportionate biological and translational significance within oncology.

Purpose:Pancreatic neuroendocrine tumors (PNET) are rare malignancies of the endocrine pancreas with diverse clinical outcomes. Whereas some PNETs are indolent, others are aggressive and metastasize quickly. However, clinically relevant molecular stratification for PNET to predict outcomes and guide therapeutic decision-making is limited. Thus, there is an urgent need to understand the molecular heterogeneity of PNETs to refine prognostication and discover novel therapeutic vulnerabilities.Experimental Design:We performed single-nucleus RNA sequencing on untreated, resected primary, and metastatic PNETs (n = 18). We inferred gene expression programs (GEP) of malignant and nonmalignant cells and investigated associations with clinical outcomes. Next, we inferred interactions in the tumor microenvironment (TME) and performed transwell migration assays for functional validation. Finally, we explored genomic and transcriptomic evolution in a unique case study of an untreated primary PNET with two asynchronous hepatic metastases.Results:A malignant GEP enriched for neural/synaptic signaling genes was associated with worse overall survival, broad chromosomal loss of heterozygosity, and alternative lengthening of telomeres. Another malignant GEP enriched for VEGF signaling increased throughout metastatic progression in our case study. We found that macrophage-derived glutamate drives polarization toward an immunosuppressive phenotype and activates the MAPK/ERK pathway in malignant cells to increase migratory capacity.Conclusions:This study provides a detailed single-nucleus transcriptomic classification of malignant, stromal, and immune cell types and states in PNETs, their interactions in the TME, and associations with clinical outcomes. The refined molecular taxonomy of PNET may guide the development of more efficacious biomarkers and therapeutic strategies.