Manifestation of Pathological States of Numerous Diseases in the Largest Organ of the Human Body: (II) From Pancreatitis to Pancreatic Cancer Invasion, Formation of Stroma around the Primary Tumor in the Fascia, to Early Detection of Non-Coding microRNAs in Body Fluids and Development of Drugs to Treat Different Stages of Pancreatic Cancer

Patients suffering from pancreatic ductal adenocarcinoma (PDAC) have an average survival time of 4 - 6 months after confirmed diagnosis. The primary tumor is surrounded by a thick interstitial fluid with high pressure and dense distribution of collagen, forming a huge stroma, rendering the tumor resistant to chemo- and radiotherapy. From the genetic point of view, pancreatic carcinogenesis is driven by mutations, resulting in common activation of the oncogene KRAS, and/or inactivation of one or more of the tumor suppressor genes CDKN2A, TP53, SMAD4 [1]. The pancreas is a mixed exocrine and autocrine organ, with different cell types building up the organ. The pathogenesis involves more than 13 signaling pathways at different stages. Off-balance of the function of the proteins in these pathways due to the stated 4 plus other mutations could readily lead to carcinogenesis. We first present the basic mechanism of these 13 relevant pathways. We then provide a detailed analysis of the progression of this disease, from pancreatitis to tumor formation and metastasis, with special attention on the roles played by the newly discover calcium channel Piezo, stellate cells, stem-cell-like cells, and the concept invadopodium. Thirty potential drugs, based on in vitro and xenograft experiments from different groups, are discussed, including vitamins A, Tocotrienols-E, and D, chemical compounds, non-coding micro RNAs, circular RNA, piwi-interacting RNAs. The recent detection of exosomes enclosing many of these RNAs in body fluids gives us hope of developing early detection methodology because these RNAs carry messages for cell-cell communication at a distance. Delivery of potent drugs by nanoparticles gives us chance to send drugs through the stroma to target the tumor. Since body fluids form a circulating system, together with the connective tissues (where the tumor is associated) form the largest organ—the fascia, we conclude that manifestation of successive pathological states of pancreatic carcinogenesis can be found in compartments of the fascia. We present 17 figures, hoping to ease off the complexity of the pathogenesis of this most lethal cancer disease.