Abstract
BackgroundAltered expression of serum microRNAs (miRNAs) have been reported to correlate with carcinogenesis and progression of pancreatic adenocarcinoma (PC), but descriptions of serum exosomal miRNAs in PC are still lacking. This study was designed to evaluate serum exosomal miRNA levels in PC patients and to investigate their relationships with clinicopathologic features and prognosis.MethodsFour miRNAs (miR-17-5p, miR-21, miR-155 and miR-196a) related to PC were selected for examination in our research. Serum miRNA was examined by RT-PCR in a group of 49 patients, including 22 with PCs, 6 with benign pancreatic tumors, 7 with ampullary carcinomas, 6 with chronic pancreatitis and 8 healthy participants. The clinicopathologic data were also collected, and PC patients were classified according to the presence of metastasis, tumor differentiation and advanced stage.ResultsThere were low expressions of exosomal miR-155 and miR-196a in serum samples of PC patients when U-6 was used as a control. Serum exosomal miR-17-5p was higher in PC patients than in non–PC patients and healthy participants. High levels of miR-17-5p were significantly correlated with metastasis and advanced stage of PC. The serum exosomal miR-21 level in PC was higher than that in the normal and chronic pancreatitis groups, but was not significantly correlated with PC differentiation and tumor stage.ConclusionsThere were high expressions of serum exosomal miR-17-5p and miR-21 in PC patients. Examination of serum exosomal microRNA is a useful serum biomarker for PC diagnosis other than serum-free microRNA. It is postulated that exosomal miR-17-5p participates in the progression of PC.
Highlights
Altered expression of serum microRNAs have been reported to correlate with carcinogenesis and progression of pancreatic adenocarcinoma (PC), but descriptions of serum exosomal miRNAs in PC are still lacking
We found that miR-21, miR-17-5P and U6 were stably expressed in the serum exosome of PC patients (CT values = 29.7, 29.4 and 26.6, respectively), whereas there was low expression of miR-155 and miR-196a (Figures 1 and 2)
The mean levels of miR-17-5p and miR-21 were significantly higher in PC patients than in healthy participants (HP) and the non-PC group, with 3.16- and 4.05-fold changes compared with the non-PC group and with 3.2- and 5.86-fold changes compared with HPs (Figure 3)
Summary
Altered expression of serum microRNAs (miRNAs) have been reported to correlate with carcinogenesis and progression of pancreatic adenocarcinoma (PC), but descriptions of serum exosomal miRNAs in PC are still lacking. This study was designed to evaluate serum exosomal miRNA levels in PC patients and to investigate their relationships with clinicopathologic features and prognosis. Because of a lack of improvement in early detection and desirable treatment strategies, the prognosis of PC patients is MicroRNAs (miRNAs) are small, noncoding RNAs about 22 nt in length that regulate gene expression at the posttranscriptional level and play an important role in cell proliferation, apoptosis and differentiation [4]. The expression pattern of miRNAs seems to be a better way than that of mRNA to identify cancer type, because these are more informative during tumor carcinogenesis, differentiation and progression. Fifteen overexpressed and eight underexpressed miRNAs differentiated pancreatic cancer from chronic pancreatitis (CP). miR-21, which has been well-described in the literature, has been reported to be strongly overexpressed in PC and to significantly upregulate PDCD4 expression, contributing to cell proliferation and invasion, as well as chemoresistance, in patients with PC [8]
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