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e15266 Background: The preoperative identification of pancreatic cystic neoplasms (PCNs) is crucial to the surgical decision-making. Besides pursuing better imaging and laboratory techniques, this ...

e14651 Background: Early lymph node metastasis is one of the most important characteristic features of pancreatic ductal adenocarcinoma (PDAC) with a dismal prognosis. MicroRNAs (miRNAs) have been shown to have a role in oncogenesis, invasion, and metastasis via epigenetic posttranscriptional gene regulation. However lymphatic metastasis related miRNAs of pancreatic cancer (PC) has not been well documented. Methods: Through microarray analysis aberrantly expressing miRNAs potentially regulating lymphatic metastasis in PC were gained from PDAC tissue specimens and cell lines. Candidate miRNAs were confirmed in total 40 resected PDAC cases and cell lines by quantitative reverse transcription-PCR (qRT-PCR). In situ hybridization was performed to elucidate the expression features of miRNA-218 in PDAC, precursor lesions, metastatic lymph nodes and cell lines. Results: MiRNA-218 and other five miRNAs were found aberrantly expressing both in PDAC and BxPC-3-LN5 (cell line with high-metastasis characteristics) by microarray analysis. Down-regulated expression of miRNA-218 was validated in PDAC tissue samples (4 fold decrease) compared to adjacent benign tissue (p=0.006) and cell line BxPC-3-LN5 (3 fold decrease) compared to BxPC-3 (p=0.01). Clinicopathological data demonstrated inverse correlation of miRNA-218 expression with lymph node metastasis (p=0.045). Expression of miRNA-218 was down-regulated in IPMN and even decreased in PDAC in a grade-dependent manner. Almost negative expression of miRNA-218 was revealed in metastatic lymph nodes. Conclusions: Down-regulated expression of miRNA-218 in PDAC and its expression features in precursor lesions suggests a tumor suppressor action of miRNA-218 in PDAC. Decreased expression of miRNA-218 may be associated with lymphatic metastasis of PDAC and interpret the high-metastasis ability of BxPC-3-LN5 cell line.