Aberrant expression of microRNAs (miRNA) is associated with phenotypes of various cancers, including pancreatic cancer. However, the mechanism of the aberrant expression is largely unknown. Activation of the mitogen-activated protein kinase (MAPK) signaling pathway plays a crucial role in gene expression related to the malignant phenotype of pancreatic cancer. Hence, we studied the role of MAPK in the aberrant expression of miRNAs in pancreatic cancer cells. The alterations in expression of 183 miRNAs induced by activation or inactivation of MAPK were assayed in cultured pancreatic cancer cells and HEK293 cells by means of the quantitative real-time PCR method. We found that four miRNAs, namely, miR-7-3, miR-34a, miR-181d, and miR-193b, were preferentially associated with MAPK activity. Among these miRNAs, miR-7-3 was upregulated by active MAPK, whereas the others were downregulated. Promoter assays indicated that the promoter activities of the host genes of miR-7-3 and miR-34a were both downregulated by alteration in MAPK activity. Exogenous overexpression of the MAPK-associated miRNAs had the effect of inhibition of the proliferation of cultured pancreatic cancer cells; miR-193b was found to exhibit the most remarkable inhibition. A search for target genes of miR-193b led to identification of CCND1, NT5E, PLAU, STARD7, STMN1, and YWHAZ as the targets. Translational suppression of these genes by miR-193b was confirmed by reporter assay. These results indicate that activation of MAPK may play a significant role in aberrant expression of miRNAs and their associated phenotypes in pancreatic cancer. Mol Cancer Res; 10(2); 259-69. Ó2011 AACR.

Supplemental digital content is available in the text.

Background: The incidence of pancreatic cancer is increasing year-by-year in Japan. Among the diseases that complicate pancreatic cancer, diabetes is the most common. Recently, it has become evident that patients suffering from diabetes and obesity show increased expression of osteopontin (OPN). The purpose of this study was to investigate the effect of high glucose and high insulin culture conditions on a human pancreatic duct epithelial cell line (HPDE-6), focusing particularly on OPN expression. Methods: HPDE-6 were cultured under various conditions, employing several combinations of glucose (normal, 6 mM high, 30 mM, and 60 mM) and insulin (0.1 nM, 1 nM) concentration. Results: HPDE-6 cell proliferation was significantly accelerated under high glucose culture conditions in comparison to samples in 6 mM glucose, and was more prominent under high insulin conditions. At the same time, the expression of OPN mRNA was also increased significantly. In comparison with 6 mM glucose, the expression of 8-OHdG DNA was increased in high glucose culture. Conclusion: HPDE-6 cells show accelerated proliferation and increased OPN expression when cultured under high glucose and high insulin conditions. Furthermore, the cells show increased oxidative stress in the presence of high glucose.

Undifferentiated carcinoma with OGCs usually exhibits an invasive tumor at diagnosis and is associated with a poor outcome, but the patient is alive without recurrence 22 months after surgery. To our knowledge, this is the first reported case of UC in situ without evident extraductal invasion in English literature.

Pancreatic ductal adenocarcinoma (PDAC) is difficult to distinguish from autoimmune pancreatitis (AIP) because of their clinical and radiological similarities, and therefore simple and minimally invasive surrogate markers for differential diagnosis would be useful. In our previous studies, we identified four microRNAs (miRNAs)–miR-7, miR-34a, miR-181d, and miR-193b –as MAPK-associated microRNAs whose expression was altered significantly with upregulation of the MAPK signaling pathway. Recently it has been reported that these miRNAs could be used as biomarkers in serum samples for accurate diagnosis of pancreatic lesions. The aim of the present study was to evaluate whether these MAPK-associated miRNAs in serum could be used as biomarkers for differentiating PDAC from AIP. We enrolled 69 patients with PDAC, 26 with intraductal papillary mucinous neoplasm (IPMN) and 15 with AIP. The expression of MAPK-associated miRNAs in serum was measured by quantitative real-time PCR. The 2-ΔCT method was used to quantify the expression of miRNAs, and the data were normalized using spiked-in synthetic cel-miR-39. Patients with PDAC or IPMN showed significantly higher amounts of serum MAPK-associated miRNAs than those with AIP (p<0.009 for miR-7, p<0.002 for miR-34a, p<0.001 for miR-181d, p<0.002 for miR-193b). ROC curve analysis demonstrated that these miRNAs had an area under the ROC curve (AUC) of 0.723–0.882 for differentiation between PDAC or IPMN from AIP. Furthermore, serum miR-181d was significantly associated with the presence of metastasis in patients with PDA (p = 0.014). Serum MAPK-associated miRNAs could be novel noninvasive biomarkers for differentiation between PDAC or IPMN and AIP.