Differentiation potential of pancreatic fibroblastoid cells/stellate cells: effects of peroxisome proliferator-activated receptor gamma ligands

Emerging role of pancreatic stellate cell-derived extracellular vesicles in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive cancer that is characterised by a prominent collagenous stromal reaction/desmoplasia surrounding tumour cells. Pancreatic stellate cells (PSCs) are responsible for the production of this stroma and have been shown to facilitate PDAC progression. Recently, extracellular vesicles (EVs), in particular, small extracellular vesicles (exosomes) have been a topic of interest in the field of cancer research for their emerging roles in cancer progression and diagnosis. EVs act as a form of intercellular communication by carrying their molecular cargo from one cell to another, regulating functions of the recipient cells. Although the knowledge of the bi-directional interactions between the PSCs and cancer cells that promote disease progression has advanced significantly over the past decade, studies on PSC-derived EVs in PDAC are currently rather limited. This review provides an overview of PDAC, pancreatic stellate cells and their interactions with cancer cells, as well as the currently known role of extracellular vesicles derived from PSCs in PDAC progression.

Computed tomography findings for predicting the future occurrence of pancreatic cancer: value of pancreatic volumetry

BACKGROUND

The features of pancreatic parenchyma that tend to progress towards pancreatic cancer (PC) are unknown. We performed volumetry of the pancreas in PC patients using computed tomography (CT) scans acquired before detection of PC, and investigated whether CT findings of pancreatic parenchyma could predict the future occurrence of PC.

METHODS

Between April 2009 and March 2017, a total of 3769 patients underwent abdominal contrast-enhanced CT, the scans of which were archived as digital images. Among them, 15 PC patients underwent abdominal CT 6-120 months before diagnosis of PC. This retrospective study compared the 15 PC patients (PC group) with 15 propensity score-matched subjects without PC (non-PC group). Pancreatic volumetry and radiological findings were compared between the two groups.

RESULTS

There were significant differences between the PC and non-PC groups in the volume of the main pancreatic duct (MPD) plus any cystic lesion (P = 0.007), volume of the MPD plus any cystic lesion/body surface area (BSA; P = 0.009), MPD diameter (P = 0.011), and MPD diameter/BSA (P = 0.013). Univariate analysis revealed volume of MPD plus any cystic lesion/BSA ≥ 0.53 mL/m² (odds ratio [OR] 38.50, P = 0.002), volume of pancreatic parenchyma/BSA < 27.0 mL/m² (OR 12.25, P = 0.030), and MPD diameter/BSA ≥ 1.0 mm/m² (OR 13.00, P = 0.006) as significant risk factors for PC.

CONCLUSIONS

Quantification of the volume of MPD plus any cystic lesion/BSA, volume of pancreatic parenchyma/BSA, and MPD diameter/BSA on pre-diagnosis CT were useful for predicting the future occurrence of PC.

A Rising Star in Pancreatic Diseases: Pancreatic Stellate Cells

Pancreatic stellate cell (PSC) is a type of pluripotent cell located between pancreatic lobules and the surrounding area of acinars. When activated, PSC can be transformed into myofibroblast-like cell. A number of evidences suggest that activated PSC is the main source of the accumulation of extracellular matrix (ECM) protein under the pathological conditions, which lead to pancreatic fibrosis in chronic pancreatitis and pancreatic cancer. Recent studies have found that PSC also plays an important role in the endocrine cell function, islet fibrosis and diabetes. In order to provide new strategies for the treatment of pancreatic diseases, this paper systematically summarizes the recent researches about the biological behaviors of PSC, including its stem/progenitor cell characteristics, secreted exosomes, cellular senescence, epithelial mesenchymal transformation (EMT), energy metabolism and direct mechanical reprogramming.

Acute pancreatitis-onset carcinoma in situ of the pancreas with focal fat replacement diagnosed using serial pancreatic-juice aspiration cytologic examination (SPACE)

A 59-year-old woman was admitted for acute pancreatitis. Abdominal computed tomography and magnetic resonance imaging revealed a swollen pancreatic parenchyma with dilatation of the main pancreatic duct (MPD) of the pancreas tail, which was separated from the normal pancreas body side by a locally atrophic part of the pancreas. Magnetic resonance cholangiopancreatography showed MPD stricture in the pancreas tail with dilatation of the upstream MPD. Endoscopic ultrasonography revealed that the MPD stricture of the pancreas tail was surrounded by a blurred and hypoechoic area. Endoscopic retrograde cholangiopancreatography was performed for serial pancreatic-juice aspiration cytologic examination (SPACE). The result indicated adenocarcinoma. Distal pancreatectomy was performed, and the histopathological examination showed high-grade PanIN (carcinoma in situ of the pancreatic duct) of the pancreas tail with atrophy and fibrosis of the pancreatic parenchyma, and local fat replacement adjacent to the lesion. The final histopathological diagnosis was carcinoma in situ of the pancreatic duct of the pancreas tail. Acute pancreatitis and local fatty change of the pancreatic parenchyma with MPD stricture are important clinical manifestations of pancreatic carcinoma in situ (PCIS) and performing SPACE in cases of MPD stricture without a recognizable mass is preferable for a diagnosis of PCIS.

Peroxisome proliferator-activated receptor gamma and regulations by the ubiquitin-proteasome system in pancreatic cancer

Pancreatic cancer is one of the most lethal forms of human cancer. Although progress in oncology has improved outcomes in many forms of cancer, little progress has been made in pancreatic carcinoma and the prognosis of this malignancy remains grim. Several molecular abnormalities often present in pancreatic cancer have been defined and include mutations in K-ras, p53, p16, and DPC4 genes. Nuclear receptor Peroxisome Proliferator-Activated Receptor gamma (PPARγ) has a role in many carcinomas and has been found to be overexpressed in pancreatic cancer. It plays generally a tumor suppressor role antagonizing proteins promoting carcinogenesis such as NF-κB and TGFβ. Regulation of pathways involved in pancreatic carcinogenesis is effectuated by the Ubiquitin Proteasome System (UPS). This paper will examine PPARγ in pancreatic cancer, the regulation of this nuclear receptor by the UPS, and their relationship to other pathways important in pancreatic carcinogenesis.