Purpose: Pancreatic cancer remains a disease of high mortality despite advanced diagnostic techniques. Mucins (MUC) play crucial roles in carcinogenesis and tumor invasion in pancreatic cancers. MUC1 and MUC4 expression are related to the aggressive behavior of human neoplasms and a poor patient outcome. In contrast, MUC2 is a tumor suppressor, and we have previously reported that MUC2 is a favorable prognostic factor in pancreatic neoplasia. This study investigates whether the methylation status of three mucin genes from postoperative tissue specimens from patients with pancreatic neoplasms could serve as a predictive biomarker for outcome after surgery. Experimental Design: We evaluated the methylation status of MUC1, MUC2, and MUC4 promoter regions in pancreatic tissue samples from 191 patients with various pancreatic lesions using methylation-specific electrophoresis. Then, integrating these results and clinicopathological features, we used support vector machine-, neural network-, and multinomial-based methods to develop a prognostic classifier. Results: Significant differences were identified between the positive- and negative-prediction classifiers of patients in 5-year overall survival (OS) in the cross-validation test. Multivariate analysis revealed that these prognostic classifiers were independent prognostic factors analyzed by not only neoplastic tissues but also non-neoplastic tissues. These classifiers had higher predictive accuracy for OS than tumor size, lymph node metastasis, distant metastasis, and age and can complement the prognostic value of the TNM staging system. Conclusions: Analysis of epigenetic changes in mucin genes may be of diagnostic utility and one of the prognostic predictors for patients with pancreatic ductal adenocarcinoma.

Objective Tumor-associated macrophages (TAMs) are reportedly involved in lymphangiogenesis in primary tumors, playing a crucial role in lymphatic metastasis. Furthermore, nodal lymphangiogenesis precedes and promotes regional lymph node (RLN) metastasis. We investigated the relationship of M2-polarized TAM infiltration of the RLNs, nodal lymphangiogenesis, and occult nodal involvement in pN0 pancreatic cancer. Methods Hematoxylin-eosin–stained primary tumor and regional LN specimens from 40 patients diagnosed with pN0 pancreatic cancer according to the pathological TNM classification were assessed. To evaluate lymphangiogenesis, lymphatic vessel density was measured by using D2-40 antibody. CD163 and cytokeratin AE1/AE3 antibodies were used to detect M2-polarized TAMs and isolated tumor cells in the RLNs, respectively. Results The nodal lymphatic vessel density had a strong association with the M2-polarized TAM density in the RLNs (P < 0.0001). Most of these TAMs expressed vascular endothelial growth factor C. Furthermore, in the RLNs, the M2-polarized TAM density was significantly associated with the incidence of isolated tumor cells (P = 0.0477). Conclusions M2-polarized TAM infiltration of RLNs is significantly associated with nodal lymphangiogenesis and occult nodal involvement in pN0 pancreatic cancer. Node-infiltrating M2-polarized TAMs may facilitate nodal lymphangiogenesis via the production of vascular endothelial growth factor C and thus promote RLN metastasis.

Due to its aggressive nature, pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal and hard‐to‐treat malignancies. Recently developed targeted molecular strategies have contributed to remarkable improvements in the treatment of several cancers. However, such therapies have not been applied to PDAC. Therefore, new treatment options are needed for PDAC based on current genomic approaches. Expression of microRNA‐375 (miR‐375) was significantly reduced in miRNA expression signatures of several types of cancers, including PDAC. The aim of the present study was to investigate the functional roles of miR‐375 in PDAC cells and to identify miR‐375‐regulated molecular networks involved in PDAC aggressiveness. The expression levels of miR‐375 were markedly downregulated in PDAC clinical specimens and cell lines (PANC‐1 and SW1990). Ectopic expression of miR‐375 significantly suppressed cancer cell proliferation, migration and invasion. Our in silico and gene expression analyses and luciferase reporter assay showed that zinc finger protein 36 ring finger protein‐like 2 (ZFP36L2) was a direct target of miR‐375 in PDAC cells. Silencing ZFP36L2 inhibited cancer cell aggressiveness in PDAC cell lines, and overexpression of ZFP36L2 was confirmed in PDAC clinical specimens. Interestingly, Kaplan–Meier survival curves showed that high expression of ZFP36L2 predicted shorter survival in patients with PDAC. Moreover, we investigated the downstream molecular networks of the miR‐375/ZFP36L2 axis in PDAC cells. Elucidation of tumor‐suppressive miR‐375‐mediated PDAC molecular networks may provide new insights into the potential mechanisms of PDAC pathogenesis.