Pancreatic cancer is associated with aberrant monocyte function and successive differentiation into macrophages with inferior anti-tumour characteristics

Differential Effects of Pancreatic Cancer-Derived Extracellular Vesicles Driving a Suppressive Environment

Pancreatic ductal adenocarcinoma (PDAC) cells display extensive crosstalk with their surrounding environment to regulate tumor growth, immune evasion, and metastasis. Recent advances have attributed many of these interactions to intercellular communication mediated by small extracellular vesicles (sEVs), involving cancer-associated fibroblasts (CAF). To explore the impact of sEVs on monocyte lineage transition as well as the expression of checkpoint receptors and activation markers, peripheral blood monocytes from healthy subjects were exposed to PDAC-derived sEVs. Additionally, to analyze the role of sEV-associated HA in immune regulation and tissue-resident fibroblasts, monocytes and pancreatic stellate cells were cultured in the presence of PDAC sEVs with or depleted of HA. Exposure of monocytes to sEVs resulted in unique phenotypic changes in HLA-DR, PD-L1, CD86 and CD64 expression, and cytokine secretion that was HA-independent except for IL-1β and MIP1β. In contrast, monocyte suppression of autologous T cell proliferation was reduced following exposure to HA-low sEVs. In addition, exposure of stellate cells to sEVs upregulated the secretion of various cytokines, including MMP-9, while removal of HA from PDAC-derived sEVs attenuated the secretion of MMP-9, demonstrating the role of sEV-associated HA in regulating expression of this pro-tumorigenic cytokine from stellate cells. This observation lends credence to the findings from the TCGA database that PDAC patients with high levels of enzymes in the HA synthesis pathway had worse survival rates compared with patients having low expression of these enzymes. PDAC-derived sEVs have an immune modulatory role affecting the activation state of monocyte subtypes. However, sEV-associated HA does not affect monocyte phenotype but alters cytokine secretion and suppression of autologous T cell proliferation and induces secretion of pro-tumorigenic factors by pancreatic stellate cells (PSC), as has been seen following the conversion of PSCs to cancer-associated fibroblasts (CAFs). Interruption of the hexosamine biosynthetic pathway, activated in PDAC producing the key substrate (UDP-GlcNAc) for HA synthesis, thus, represents a potential clinical interception strategy for PDAC patients. Findings warrant further investigations of underlying mechanisms involving larger sample cohorts.

Exploring the key genetic association between chronic pancreatitis and pancreatic ductal adenocarcinoma through integrated bioinformatics

Background: Pancreatic ductal adenocarcinoma (PDAC) develops rapidly and has a poor prognosis. It has been demonstrated that pancreatic ductal adenocarcinoma and chronic pancreatitis (CP) have a close connection. However, the underlying mechanisms for chronic pancreatitis transforming into pancreatic ductal adenocarcinoma are still unclear. The purpose of this study was to identify real hub genes in the development of chronic pancreatitis and pancreatic ductal adenocarcinoma. Methods: RNA-seq data of chronic pancreatitis and pancreatic ductal adenocarcinoma were downloaded from the Gene Expression Omnibus (GEO) database. Weighted gene co-expression network analysis (WGCNA) was performed to construct a gene co-expression network between chronic pancreatitis and pancreatic ductal adenocarcinoma. GEO2R and a Venn diagram were used to identify differentially expressed genes. Then visualized networks were constructed with ClueGO, and modules of PPI network were calculated by MCODE plugin. Further validation of the results was carried out in two additional cohorts. Analyses of CEL-coexpressed genes and regulators including miRNAs and transcription factors were performed by using the corresponding online web tool. Finally, the influence of CEL in the tumor immune microenvironment (TIME) was assessed by immune contextual analysis. Results: With the help of WGCNA and GEO2R, four co-expression modules and six hub genes were identified, respectively. ClueGO enrichment analysis and MCODE cluster analysis revealed that the dysfunctional transport of nutrients and trace elements might contribute to chronic pancreatitis and pancreatic ductal adenocarcinoma development. The real hub gene CEL was identified with a markedly low expression in pancreatic ductal adenocarcinoma in external validation sets. According to the miRNA-gene network construction, hsa-miR-198 may be the key miRNA. A strong correlation exists between CEL and TIME after an evaluation of the influence of CEL in TIME. Conclusion: Our study revealed the dysfunctional transport of nutrients and trace elements may be common pathogenesis of pancreatic ductal adenocarcinoma and chronic pancreatitis. Examination on these common pathways and real hub genes may shed light on the underlying mechanism.

Monocytes in Tumorigenesis and Tumor Immunotherapy

Monocytes are highly plastic innate immune cells that display significant heterogeneity during homeostasis, inflammation, and tumorigenesis. Tumor-induced systemic and local microenvironmental changes influence the phenotype, differentiation, and distribution of monocytes. Meanwhile, monocytes and their related cell subsets perform an important regulatory role in the development of many cancers by affecting tumor growth or metastasis. Thanks to recent advances in single-cell technologies, the nature of monocyte heterogeneity and subset-specific functions have become increasingly clear, making it possible to systematically analyze subset-specific roles of monocytes in tumorigenesis. In this review, we discuss recent discoveries related to monocytes and tumorigenesis, and new strategies for tumor biomarker identification and anti-tumor immunotherapy.

Comprehensive Investigation Illustrates the Role of M2 Macrophages and Its Related Genes in Pancreatic Cancer

Background and Objectives: M2 macrophages play an important role in cancers. Our study aimed to illustrate the effect of M2 macrophages in pancreatic cancer (PC). Materials and Methods: The open-access data used for analysis were downloaded from The Cancer Genome Atlas Program database, as well as some online databases. R software was mainly used for data analysis based on the specific packages. Results: Here, we comprehensively investigated the role of M2 macrophages and their related genes in PC. We performed the biological enrichment of M2 macrophages in PC. Meanwhile, we identified adenosine A3 receptor (TMIGD3) as the interest gene for further analysis. The single-cell analysis showed that was mainly expressed in the Mono/Macro cells based on the data from multiple data cohorts. Biological investigation showed that TMIGD3 was primarily enriched in angiogenesis, pancreas-beta cells and TGF-beta signaling. Tumor microenvironment analysis indicated that TMIGD3 was positively correlated with monocyte_MCPCOUNTER, NK cell_MCPCOUNTER, macrophages M2_CIBERSORT, macrophage_EPIC, neutrophil_TIMER and endothelial cell_MCPCOUNTER. Interestingly, we determined that all the immune functions quantified by single sample gene set enrichment analysis algorithms were activated in the patients with high TMIGD3 expression. Conclusions: Our results provide a novel direction for the research focused on the M2 macrophages in PC. Meanwhile, TMIGD3 was identified as an M2 macrophage-related biomarker for PC.

Influences of calorie restriction and lipopolysaccharide therapy on inflammation, cytokine response, and cell proliferation in pancreatic adenocarcinoma mouse model

The study aimed to investigate the effects of lipopolysaccharide (LPS) alone and in combination with calorie restriction (CR) on the pancreatic tissues in C57BL/6 mice modeled with pancreatic ductal adenocarcinoma (PDAC). Forty male C57BL/6 mice (10-13 weeks old) were divided into five groups; LPS, LPS + CR, PDAC, PDAC + LPS, and PDAC + LPS + CR. Nuclear factor kappa B (NF-κβ), interleukin-6 (IL-6), and c-Jun N-terminal kinases (JNK) mRNA expression levels were measured in pancreatic tissues. NF-κβ, IL-6, JNK, and proliferating cell nuclear antigen (PCNA) peptide levels were determined by immunohistochemistry. Oxidative stress markers and antioxidant enzyme activities were determined spectrophotometrically. TH1/TH2 cytokine measurements were determined by a flow cytometer. It was detected that the number of PCNA immune + cells in the PDAC + LPS + CR group was significantly lower than in the PDAC and PDAC + LPS groups (p < 0.01, p < 0.05 respectively). PDAC + LPS + CR group's plasma interferon-gamma (IFN-γ), IL-6, IL-2, tumor necrosis factor-alpha, IL-3, and IL-4 levels were found to be significantly lower than the PDAC group (p < 0.01, p < 0.001, p < 0.01, p < 0.05, p < 0.01, and p < 0.05 respectively). According to our findings, the combination of low-dose LPS and 40% CR was found to be more effective in PDAC model mice.

Replication stress identifies novel molecular classification associated with treatment outcomes in pancreatic cancer

BACKGROUND

Replication stress is a prominent hallmark of tumor cells, which is crucial for maintaining genomic integrity. However, it remains poorly understood whether replication stress can serve as a surrogate biomarker to indicate prognosis and treatment response of pancreatic cancer.

METHODS

Transcriptomic and clinical data were obtained from The Cancer Genome Atlas and literature. An integrated signature of 18 replication-stress associated genes (termed as REST18) was established using the cox proportional hazards regression analysis. Tumors were sorted into REST18-low and REST18-high groups. Survival analysis, gene set enrichment analysis and composition of immune cells were compared between these tumors.

RESULTS

Patients with REST18-high tumors showed worse prognoses than those with REST18-low tumors in the TCGA database and the finding is validated in an independent cohort of pancreatic cancer. Comparison of REST18 model and other molecular classifications showed that REST18-high tumors are positively correlated to basal-like or squamous phenotypes, which have higher metastasis potential. DNA repair pathway is enriched in the REST18-high tumors. Analysis of tumor immune microenvironment found that REST18-high tumors are characterized with "immune-cold" features. Univariate and multivariate analysis show that REST18 is an independent risk factor for overall survival and predicts outcomes of chemotherapy in pancreatic cancer.

CONCLUSION

REST18 is a novel biomarker to indicate prognosis and treatment response of chemotherapy in pancreatic cancer.

Mass cytometry-based peripheral blood analysis as a novel tool for early detection of solid tumours: a multicentre study

OBJECTIVE

Early detection of a tumour remains an unmet medical need, and approaches with high sensitivity and specificity are urgently required. Mass cytometry time-of-flight (CyTOF) is a powerful technique to profile immune cells and could be applied to tumour detection. We attempted to establish diagnostic models for hepatocellular carcinoma (HCC) and pancreatic ductal adenocarcinoma (PDAC).

DESIGN

We performed CyTOF analysis for 2348 participants from 15 centres, including 1131 participants with hepatic diseases, 584 participants with pancreatic diseases and 633 healthy volunteers. Diagnostic models were constructed through random forest algorithm and validated in subgroups.

RESULTS

We determined the disturbance of systemic immunity caused by HCC and PDAC, and calculated a peripheral blood immune score (PBIScore) based on the constructed model. The PBIScore exhibited good performance in detecting HCC and PDAC, with both sensitivity and specificity being around 80% in the validation cohorts. We further established an integrated PBIScore (iPBIScore) by combining PBIScore and alpha-fetoprotein or carbohydrate antigen 19-9. The iPBIScore for HCC had an area under the curve (AUC) of 0.99, 0.97 and 0.96 in training, internal validation and external validation cohorts, respectively. Similarly, the iPBIScore for PDAC showed an AUC of 0.99, 0.98 and 0.97 in the training, internal validation and external validation cohorts, respectively. In early-stage and tumour-marker-negative patients, our iPBIScore-based models also showed an AUC of 0.95-0.96 and 0.81-0.92, respectively.

CONCLUSION

Our study proved that the alterations of peripheral immune cell subsets could assist tumour detection, and provide a ready-to-use detection model for HCC and PDAC.

Peripheral blood monocytes predict clinical prognosis and support tumor invasiveness through NF-κB-dependent upregulation of Snail in pancreatic cancer

Background

The tumor inflammatory microenvironment plays a vital role in the initiation and progression of pancreatic cancer (PC). Both the lymphocyte-to-monocyte ratio (LMR) and preoperative peripheral blood monocytes are related to the prognosis of PC patients. However, the direct effect of monocytes on PC cells is not fully understood. The current study aimed to assess the effect of monocytes on PC and explore its potential mechanism.

Methods

The cutoff value of peripheral blood monocytes was evaluated by the receiver operating characteristic (ROC) curve. Transwell migration and invasion assays were used to detect the mobility of PC cells. The cytokines derived from monocytes were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Western blotting was utilized to assess the expression of epithelial-mesenchymal transition (EMT) related markers. The expression level of Snail in PC tissue was determined by immunohistochemical (IHC) staining.

Results

A high monocyte count was inversely correlated with lymph node status and 5-year overall survival in PC. The PC cells underwent a cellular morphology change and increased cell motility after coculture with THP-1 monocytes. The THP-1 monocytes secreted various proinflammatory cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-1α (IL-1α), which activated the nuclear factor-κB (NF-κB) signaling pathway leading to the upregulation of Snail and thereby promoting the EMT of PC cells. The expression level of Snail correlated significantly with the density of peripheral blood monocytes, and their level status was significantly associated with 5-year overall survival.

Conclusions

These findings indicated that elevated monocytes counts were a poor prognostic marker in PC, and monocytes could directly induce the EMT process of PC cells by upregulating Snail expression through the NF-κB signaling pathway.