Ling‐Ye Tao

Background and aims Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related death worldwide. Neurotransmitter-initiated signalling pathway is profoundly implicated in tumour initiation and progression. Here, we investigated whether dysregulated neurotransmitter receptors play a role during pancreatic tumourigenesis. Methods The Cancer Genome Atlas and Gene Expression Omnibus datasets were used to identify differentially expressed neurotransmitter receptors. The expression pattern of gamma-aminobutyric acid type A receptor pi subunit (GABRP) in human and mouse PDAC tissues and cells was studied by immunohistochemistry and western blot analysis. The in vivo implications of GABRP in PDAC were tested by subcutaneous xenograft model and lung metastasis model. Bioinformatics analysis, transwell experiment and orthotopic xenograft model were used to identify the in vitro and in vivo effects of GABRP on macrophages in PDAC. ELISA, co-immunoprecipitation, proximity ligation assay, electrophysiology, promoter luciferase activity and quantitative real-time PCR analyses were used to identify molecular mechanism. Results GABRP expression was remarkably increased in PDAC tissues and associated with poor prognosis, contributed to tumour growth and metastasis. GABRP was correlated with macrophage infiltration in PDAC and pharmacological deletion of macrophages largely abrogated the oncogenic functions of GABRP in PDAC. Mechanistically, GABRP interacted with KCNN4 to induce Ca 2+ entry, which leads to activation of nuclear factor κB signalling and ultimately facilitates macrophage infiltration by inducing CXCL5 and CCL20 expression. Conclusions Overexpressed GABRP exhibits an immunomodulatory role in PDAC in a neurotransmitter-independent manner. Targeting GABRP or its interaction partner KCNN4 may be an effective therapeutic strategy for PDAC.

Abstract Perineural invasion is a common feature of pancreatic ductal adenocarcinoma (PDAC). Here, we investigated the effect of perineural invasion on the microenvironment and how this affects PDAC progression. Transcriptome expression profiles of PDAC tissues with different perineural invasion status were compared, and the intratumoral T-cell density and levels of neurotransmitters in these tissues were assessed. Perineural invasion was associated with impaired immune responses characterized by decreased CD8+ T and Th1 cells, and increased Th2 cells. Acetylcholine levels were elevated in severe perineural invasion. Acetylcholine impaired the ability of PDAC cells to recruit CD8+ T cells via HDAC1-mediated suppression of CCL5. Moreover, acetylcholine directly inhibited IFNγ production by CD8+ T cells in a dose-dependent manner and favored Th2 over Th1 differentiation. Furthermore, hyperactivation of cholinergic signaling enhanced tumor growth by suppressing the intratumoral T-cell response in an orthotopic PDAC model. Conversely, blocking perineural invasion with bilateral subdiaphragmatic vagotomy in tumor-bearing mice was associated with an increase in CD8+ T cells, an elevated Th1/Th2 ratio, and improved survival. In conclusion, perineural invasion–triggered cholinergic signaling favors tumor growth by promoting an immune-suppressive microenvironment characterized by impaired CD8+ T-cell infiltration and a reduced Th1/Th2 ratio. Significance: These findings provide a promising therapeutic strategy to modulate the immunosuppressive microenvironment of pancreatic ductal adenocarcinoma with severe perineural invasion.

Hypoxia and the hypovascular tumor microenvironment are major hallmarks of pancreatic ductal adenocarcinoma (PDAC), in which glycolysis is of great importance to tumor survival and proliferation. There is little research regarding the role of Nuclear Factor of Activated T Cells 5 (NFAT5) in relation to carcinoma. Here, we explored the impact of NFAT5 on the biological behavior of PDAC and the underlying mechanism. We demonstrated that NFAT5 was highly expressed in PDAC and was related to poorer prognosis. Knockdown of NFAT5 lead to impaired proliferation of tumor cells caused by an aberrant Warburg effect. Mechanically, phosphoglycerate kinase 1 (PGK-1), which is the first enzyme generating ATP in glycolysis, was verified as a target gene of NFAT5. Over-expression of PGK1 compromised the aberrant oncological behavior caused by knockdown of NFAT5 both in vitro and in vivo. Clinical samples underwent positron emission tomography-computed tomography (PET-CT) examination and KrasG12D/+/Trp53R172H/+/Pdx1-Cre (KPC) mice were collected to support our conclusion.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers due to its high metastasis rate in the liver. However, little is known about the molecular features of hepatic metastases due to difficulty in obtaining fresh tissues and low tumor cellularity. RESULTS: We conduct exome sequencing and RNA sequencing for synchronous surgically resected primary tumors and the paired hepatic metastases from 17 hepatic oligometastatic pancreatic ductal adenocarcinoma and validate our findings in specimens from 35 of such cases. The comprehensive analysis of somatic mutations, copy number alterations, and gene expressions show high similarity between primary tumors and hepatic metastases. However, hepatic metastases also show unique characteristics, such as a higher degree of 3p21.1 loss, stronger abilities of proliferation, downregulation of epithelial to mesenchymal transition activity, and metabolic rewiring. More interesting, altered tumor microenvironments are observed in hepatic metastases, especially a higher proportion of tumor infiltrating M2 macrophage and upregulation of complement cascade. Further experiments demonstrate that expression of C1q increases in primary tumors and hepatic metastases, C1q is mainly produced by M2 macrophage, and C1q promotes migration and invasion of PDAC cells. CONCLUSION: Taken together, we find potential factors that contribute to different stages of PDAC metastasis. Our study broadens the understanding of molecular mechanisms driving PDAC metastasis.