Pancreatic ductal adenocarcinoma (PDAC) is one of the most common malignant tumors with poor prognosis due to extremely high malignancy, low rate of eligibility for surgical resection and chemoradiation resistance. Increasing evidence indicate that the interaction between activated pancreatic stellate cells (PSCs) and PDAC cells plays an important role in the development of PDAC. By producing high levels of cytokines, chemotactic factors, growth factors and excessive extracellular matrix (ECM), PSCs create desmoplasia and a hypoxic microenvironment that promote the initiation, development, evasion of immune surveillance, invasion, metastasis and resistance to chemoradiation of PDAC. Therefore, targeting the interaction between PSCs and PDAC cells may represent a novel therapeutic approach to advanced PDAC, especially therapies that target PSCs of the pancreatic tumor microenvironment.Pancreatic ductal adenocarcinoma (PDAC) is the most common and lethal malignant tumors in humans with very poor prognosis, due to a variety of causes including the insidious onset, absence of efficient screening methods for early detection, low rate of surgical resection at the time of clinical presentation and chemoradiation resistance. 1 Although scholars have been committed during the last three decades to studying genetic and/or epigenetic molecular changes of PDAC cells and chemotherapy with a combination of cytotoxic drugs have been implemented, the survival of patients with PDAC has not yet significantly improved.2,3 Until recently, an encouraging FOLFIRINOX scheme was reported to provide a statistically and clinically significant benefit over single-agent gemcitabine in patients with advanced PDAC but Key words: pancreatic ductal adenocarcinoma, pancreatic stellate cells, tumor microenvironment Abbreviations: ADMR: adrenomedullin receptor; AM: adrenomedullin; ATRA: all-trans retinoic acid; CTGF: connective tissue growth factor; DCs: dendritic cells; ECM: extracellular matrix; EGF: epidermal growth factor; EMMPRIN: extracellular matrix metalloproteinase inducer; EMT: epithelial-mesenchymal transition; ET-1: endothelin-1; FGF: fibroblast-growth-factor; GFAP: glial-fibrillary-acidic protein; HGF: hepatocyte growth factor; HPDE: human pancreatic duct epithelial; HSCs: hepatic stellate cells; HUVEC: endothelial cells; IGF-1: insulin-like growth factor-1; IL: interleukin; MMPs: matrix metalloproteinases; NADPH: nicotinamide adenine dinucleotide phosphate; NO: nitric oxide; PAEE: palmitic acid ethyl ester; PCLMs: pancreatic cancer liver metastases; PDAC: pancreatic ductal adenocarcinoma; PDGF: platelet-derived growth factor; PEDF: pigment epithelium-derived factor; PK: prokineticin; PKR: prokineticin receptor; PSCs: pancreatic stellate cells; ROS: oxygen species; Runx-2: Runt-related transcription factor-2; SDF-1: stromal cell-derived factor-1; sFRP4: secreted frizzled-related protein 4; SMO: smoothened; a-SMA: a-smooth muscle actin; SPARC: secreted protein acidic and rich in cysteine; TFF1: trefoil factor 1; TGF-b: transforming gr...