Circulating miR-483-3p and miR-21 is highly expressed in plasma of pancreatic cancer

Abstract

Several recent studies have revealed that microRNAs (miRNAs) have a role in carcinogenesis and cancer development, and that it is stably detectable in plasma/serum. The aim of this study was to test whether miR‑483-3p as well as miR‑21 could be plasma biomarkers for PDAC. The plasma samples were obtained from three groups including 32 pancreatic ductal adenocarcinoma (PDAC) patients, 12 patients with intraductal papillary mucinous neoplasm (IPMN) patients and 30 healthy controls (HC). We evaluated the plasma miR‑483-3p and miR‑21 expression level by quantitative RT-PCR. We compared the differences in the plasma level of these miRNAs among the three groups, and investigated the relevance of their plasma expression level to the clinical factors in PDAC. The expressions of miR‑483-3p and miR‑21 were detected in all examined plasma samples. The plasma expression levels of these miRNAs were significantly higher in PDAC compared to HC (P<0.01). The plasma miR‑483-3p expression was significantly higher in PDAC patients than IPMN patients (P<0.05). The plasma miR‑21 level was associated with advanced stage (P<0.05), metastasis to lymph node and liver (P<0.01), and shorter survival (P<0.01) of the PDAC patients. Together, these findings suggest that measurement of the plasma miR‑483-3p level is useful for discriminating PDAC from IPMN, and that the plasma miR‑21 level predicts outcome of PDAC patients.

Figure 1

The expression of miR-483-3p and miR-21 in microdissected lesions. MicroRNA extraction was carried out from the microdissected lesions. Neoplastic lesions stained with hematoxylin [left panels in (A) and (B)] were selectively dissected [right panels in (A) and (B)] using a Leica CIR MIC system and recovered in lysis buffer. (A) PDAC tissue; (B) IPMN tissue. (C) The miRNA-483-3p and (D) miR-21 expression levels were detected by quantitative RT-PCR. Boxes represent the interquartile range and the line indicates the median value. Whiskers indicate maximum and minimum values. RNU6B was used for normalization. The miR-483-3p and miR-21 expression levels are significantly higher in PDAC tissue than in non-cancer tissue and IPMN tissue. Mann-Whitney U test was used to evaluate statistical significance. N, non-cancer tissue. ^**P<0.01.

Figure 2

The expression of miR-483-3p and miR-21 in plasma samples. (A) The distribution of the plasma miR-483-3p expression level in all samples. (B) The miR-483-3p expression level in PDAC, IPMN and normal plasma samples. Boxes represent the interquartile range and the line indicates the median value. Whiskers indicate maximum and minimum values. miR-16 was used for normalization. The miR-483-3p expression level in plasma is significantly higher in PDAC than HC and IPMN group, while no significant difference is found between IPMN and the HC group. Mann-Whitney U test was used to evaluate statistical significance. (C) The plasma miR-21 expression level in PDAC, IPMN and HC. The plasma miR-21 level is significantly higher in PDAC than HC group, whereas no significant difference was observed between PDAC and IPMN. ^*P<0.05 and ^**P<0.01.

Figure 3

The ROC curve analysis of plasma miRNA and serum tumor marker levels for PDAC diagnosis. (A) The ROC curves for differentiating between PDAC and HC (left), PDAC and IPMN (center), PDAC, and HC and IPMN (right) based on the miR-483-3p plasma level. (B) The ROC curves for differentiating between PDAC and HC (left), PDAC and IPMN (center), PDAC, and HC and IPMN (right) based on the plasma miR-21 level. The ROC curves for differentiating PDAC from IPMN and HC based on the combination of the miR-483-3p and miR-21 plasma levels (C), serum CEA (D) and serum CA19-9 level (E).

Figure 4

The correlation between plasma miRNA expression and overall survival (OS) of PDAC patients. Kaplan-Meier overall survival curve in 24 PDAC patients who were excluded based on their plasma miRNA expression. (A) There was no significant relationship between the plasma miR-483-3p level and overall survival. (B) The prognosis for PDAC patients was worse in those with high expression of plasma miR-21. ^**P<0.01.

Figure 5

The plasma expression level of miR-483-3p and tumor markers before and after surgery. The plasma miR-483-3p level was drastically decreased after surgery in two PDAC patients: A, case 1 and B, case 2. Both cases were diagnosed as pancreatic adenocarcinoma and were classified as stage IIA (T3N0M0) using the UICC classification.