Microbiota is just beginning to be recognized as an important player in carcinogenesis and the interplay among microbes is greater than expected. Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease for which mortality closely parallels incidence. Early detection would provide the best opportunity to increase survival rates. Specific well-studied oral, gastrointestinal, and intrapancreatic microbes and some kinds of hepatotropic viruses and bactibilia may have potential etiological roles in pancreatic carcinogenesis, or modulating individual responses to oncotherapy. Concrete mechanisms mainly involve perpetuating inflammation, regulating the immune system-microbe-tumor axis, affecting metabolism, and altering the tumor microenvironment. The revolutionary technology of omics has generated insight into cancer microbiomes. A better understanding of the microbiota in PDAC might lead to the establishment of screening or early-stage diagnosis methods, implementation of cancer bacteriotherapy, adjustment of therapeutic efficacy even alleviating the adverse effects, creating new opportunities and fostering hope for desperate PDAC patients.

Pancreatic ductal adenocarcinoma (PDAC) constitutes one of the most challenging lethal tumors and has a very poor prognosis. In addition to cancer cells, the tumor microenvironment created by a repertoire of resident and recruited cells and the extracellular matrix also contribute to the acquisition of hallmarks of cancer. Among these factors, cancer-associated fibroblasts (CAFs) are critical components of the tumor microenvironment. CAFs originate from the activation of resident fibroblasts and pancreatic stellate cells, the differentiation of bone marrow-derived mesenchymal stem cells and epithelial-to-mesenchymal transition. CAFs acquire an activated phenotype via various cytokines and promote tumor proliferation and growth, accelerate invasion and metastasis, induce angiogenesis, promote inflammation and immune destruction, regulate tumor metabolism, and induce chemoresistance; these factors contribute to the acquisition of major hallmarks of PDAC. Therefore, an improved understanding of the impact of CAFs on the major hallmarks of PDAC will highlight the diagnostic and therapeutic values of these targeted cells.

Diagnostic and prognostic value of carcinoembryonic antigen in pancreatic cancer: a systematic review and meta-analysis Qingcai Meng,1–3,* Si Shi,1–3,* Chen Liang,1–3,* Dingkong Liang,1–3 Wenyan Xu,1–3 Shunrong Ji,1–3 Bo Zhang,1–3 Quanxing Ni,1–3 Jin Xu,1–3 Xianjun Yu1–3 1Department of Pancreatic Surgery, Fudan University Shanghai Cancer Center, 2Department of Oncology, Shanghai Medical College, 3Pancreatic Cancer Institute, Fudan University, Shanghai, People’s Republic of China *These authors contributed equally to this work Background: Carcinoembryonic antigen (CEA) is one of the most widely used tumor markers and is increased in 30%–60% of patients with pancreatic cancer. Although carbohydrate antigen 19-9 (CA19-9) is the most important serum biomarker in pancreatic cancer, the diagnostic and prognostic value of CEA is gradually being recognized.Materials and methods: The MEDLINE, EMBASE, and Web of Science databases were searched for related literature published until January 2017. Diagnostic accuracy variables were pooled using the Meta-Disc software. The pooled hazard ratios (HRs) for prognostic data were calculated and analyzed using Stata software.Results: A total of 3,650 participants enrolled in 19 studies met our inclusion criteria. The pooled sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio of a CEA-based panel were 0.45 (95% confidence interval [CI], 0.41–0.50), 0.89 (95% CI, 0.86–0.91), 5.39 (95% CI, 3.16–9.18), and 0.55 (95% CI, 0.41–0.72), respectively. The area under the curve (AUC, 0.90) and Q-value (0.84) of the CEA-based panel indicated a significantly higher diagnostic accuracy compared with CEA or CA19-9 alone. Moreover, there was also a significant association between high levels of CEA and worse overall survival (HR, 1.43; 95% CI, 1.31–1.56).Conclusion: Our meta-analysis indicated that elevated serum CEA level, as a vital supplementary to CA19-9, can play an important role in the clinical diagnosis of pancreatic cancer patients and predict poor prognosis. Keywords: carcinoembryonic antigen, pancreatic cancer, diagnosis, prognosis, meta-analysis

Background: Dysregulated microRNA (miRNA) expression in cancer can act as a key factor that modifies biological processes, including chemoresistance. Our study aimed to identify the miRNAs associated with gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC) and to explore the potential mechanisms.

Background: Pancreatic cancer exhibits limited clinical responses to immunotherapy, highlighting the need for new strategies to counteract its immunosuppressive microenvironment. Although metabolic reprogramming and epigenetic changes contribute to malignancy, the impact of lactate-driven histone lactylation on the tumour microenvironment (TME) has not been fully explored. Objective: This study aims to investigate the role of histone lactylation in pancreatic cancer, focusing on its effects on cholesterol metabolism and antitumour immunity. Designs: Global lactylome profiling was conducted to identify novel epigenetic mechanisms driven by lactate-induced histone lactylation. Mechanisms were investigated via RNA sequencing, CUT&Tag, immunoprecipitation-mass spectrometry and GST-pull down. Mass cytometry by time-of-flight, in vitro co-culture system, orthotopic pancreatic cancer models and flow cytometry were used to explore Acetyl-CoA acetyltransferase (ACAT2) functions. A proteolysis-targeting chimaera (PROTAC) was developed to degrade ACAT2. Results: Global lactylome profiling revealed that lactate-driven histone lactylation, particularly H3K18la, promotes the transcriptional activation of ACAT2. ACAT2 acetylates mitochondrial carrier homolog 2 (MTCH2), stabilising it and disrupting oxidative phosphorylation, which increases lactate production and fuels a positive feedback loop in pancreatic cancer. This loop facilitates the delivery of cholesterol via small extracellular vesicles (sEVs), polarising tumour-associated macrophages toward an immunosuppressive M2 phenotype. Additionally, the PROTAC targeting ACAT2 enhanced the efficacy of immune checkpoint blockade therapy in vivo . Conclusions: Our findings highlight the critical role of the H3K18la/ACAT2/sEV-cholesterol axis in TME reprogramming. Targeting this pathway may improve anti-PD-1 therapy response in pancreatic cancer, providing a novel therapeutic strategy by linking histone lactylation, cholesterol metabolic reprogramming and immune modulation.

The epigenetic factor protein arginine methyltransferase 5 (PRMT5) has been reported to play vital roles in a wide range of cellular processes, such as gene transcription, genomic organization, differentiation and cell cycle control. However, its role in pancreatic cancer remains unclear. Our study aimed to investigate the roles of PRMT5 in pancreatic cancer prognosis and progression and to explore the underlying molecular mechanism. Real-time PCR, immunohistochemistry and analysis of a dataset from The Cancer Genome Atlas (TCGA) were performed to study the expression of PRMT5 at the mRNA and protein levels in pancreatic cancer. Cell proliferation assays, including cell viability, colony formation ability and subcutaneous mouse model assays, were utilized to confirm the role of PRMT5 in cell proliferation and tumorigenesis. A Seahorse extracellular flux analyzer, a glucose uptake kit, a lactate level measurement kit and the measurement of 18F-FDG (fluorodeoxyglucose) uptake by PET/CT (positron emission tomography/computed tomography) imaging were used to verify the role of PRMT5 in aerobic glycolysis, which sustains cell proliferation. The regulatory effect of PRMT5 on cMyc, a master regulator of oncogenesis and aerobic glycolysis, was explored by quantitative PCR and protein stability measurements. PRMT5 expression was significantly upregulated in pancreatic cancer tissues compared with that in adjacent normal tissues. Clinically, elevated expression of PRMT5 was positively correlated with worse overall survival in pancreatic cancer patients. Silencing PRMT5 expression inhibited the proliferation of pancreatic cancer cells both in vitro and in vivo. Moreover, PRMT5 regulated aerobic glycolysis in vitro in cell lines, in vivo in pancreatic cancer patients and in a xenograft mouse model used to measure 18F-FDG uptake. We found that mechanistically, PRMT5 posttranslationally regulated cMyc stability via F-box/WD repeat-containing protein 7 (FBW7), an E3 ubiquitin ligase that controls cMyc degradation. Moreover, PRMT5 epigenetically regulated the expression of FBW7 in pancreatic cancer cells. The present study demonstrated that PRMT5 epigenetically silenced the expression of the tumor suppressor FBW7, leading to increased cMyc levels and the subsequent enhancement of the proliferation of and aerobic glycolysis in pancreatic cancer cells. The PRMT5/FBW7/cMyc axis could be a potential therapeutic target for the treatment of pancreatic cancer.