Exosomal glypican-1 is elevated in pancreatic cancer precursors and can signal genetic predisposition in the absence of endoscopic ultrasound abnormalities

BACKGROUND Individuals within specific risk groups for pancreatic ductal adenocarcinoma(PDAC)[mucinous cystic lesions(MCLs),hereditary risk(HR),and new-late onset diabetes mellitus(NLOD)]represent an opportunity for early cancer detection.Endoscopic ultrasound(EUS)is a premium image modality for PDAC screening and precursor lesion characterization.While no specific biomarker is currently clinically available for this purpose,glypican-1(GPC1)is overexpressed in the circulating exosomes(crExos)of patients with PDAC compared with healthy subjects or those harboring benign pancreatic diseases.AIM To evaluate the capacity of GPC1+crExos to identify individuals at higher risk within these specific groups,all characterized by EUS.METHODS This cross-sectional study with a prospective unicentric cohort included 88 subjects:40 patients with MCL,20 individuals with HR,and 20 patients with NLOD.A control group(CG)was submitted to EUS for other reasons than pancreatic pathology,with normal pancreas and absence of hereditary risk factors(n=8).The inclusion period was between October 2016 and January 2019,and the study was approved by the Ethics Committee of Centro Hospitalar Universitário de São João,Porto,Portugal.All patients provided written informed consent.EUS and blood tests for quantification of GPC1+crExos by flow cytometry and carbohydrate antigen 19-9(CA 19-9)levels by ELISA were performed in all subjects.EUS-guided tissue acquisition was done whenever necessary.For statistical analysis,SPSS®27.0(IBM Corp.,Armonk,NY,United States)version was used.All graphs were created using GraphPad Prism 7.00(GraphPad Software,San Diego,CA,United States).RESULTS Half of MCLs harbored worrisome features(WF)or high-risk stigmata(HRS).Pancreatic abnormalities were detected by EUS in 10.0%and 35.0%in HR and NLOD individuals,respectively,all considered non-malignant and“harmless.”Median levels of GPC1+crExos were statistically different:MCL[99.4%,interquartile range(IQR):94.9%-99.8%],HR(82.0%,IQR:28.9%-98.2%),NLOD(12.6%,IQR:5.2%-63.4%),and CG(16.2%,IQR:6.6%-20.1%)(P<0.0001).Median levels of CA 19-9 were within the normal range in all groups(standard clinical cut-off of 37 U/mL).Within HR,individuals with a positive history of cancer had higher median levels of GPC1+crExos(97.9%;IQR:61.7%-99.5%),compared to those without(59.7%;IQR:26.3%-96.4%),despite no statistical significance(P=0.21).Pancreatic cysts with WF/HRS were statistically associated with higher median levels of GPC1+crExos(99.6%;IQR:97.6%-99.8%)compared to those without(96.5%;IQR:81.3%-99.5%)(P=0.011),presenting an area under the receiver operating characteristic curve value of 0.723(sensitivity 75.0%and specificity 67.7%,using a cutoff of 98.5%;P=0.012).CONCLUSION GPC1+crExos may act as biomarker to support the diagnosis and stratification of PDAC precursor lesions,and in signaling individuals with genetic predisposition in the absence of EUS abnormalities.

Exosome and Exosomal MicroRNA: Trafficking, Sorting, and Function

Exosomes are 40–100 nm nano-sized vesicles that are released from many cell types into the extracellular space. Such vesicles are widely distributed in various body fluids. Recently,m RNAs and micro RNAs（mi RNAs） have been identified in exosomes, which can be taken up by neighboring or distant cells and subsequently modulate recipient cells. This suggests an active sorting mechanism of exosomal mi RNAs, since the mi RNA profiles of exosomes may differ from those of the parent cells. Exosomal mi RNAs play an important role in disease progression, and can stimulate angiogenesis and facilitate metastasis in cancers. In this review, we will introduce the origin and the trafficking of exosomes between cells, display current research on the sorting mechanism of exosomal mi RNAs, and briefly describe how exosomes and their mi RNAs function in recipient cells.Finally, we will discuss the potential applications of these mi RNA-containing vesicles in clinical settings.