The microRNA expression signature of pancreatic ductal adenocarcinoma by RNA sequencing: anti-tumour functions of the microRNA-216 cluster.

We analysed the RNA sequence-based microRNA (miRNA) signature of pancreatic ductal adenocarcinoma (PDAC). Aberrantly expressed miRNAs were successfully identified in this signature. Using the PDAC signature, we focused on 4 clustered miRNAs, miR-216a-5p, miR-216a-3p, miR-216b-5p and miR-216b-3p on human chromosome 2p16.1. All members of the miR-216 cluster were significantly reduced in PDAC specimens. Ectopic expression of these miRNAs suppressed cancer cell aggressiveness, suggesting miR-216 cluster as anti-tumour miRNAs in PDAC cells. The impact of miR-216b-3p (passenger strand of pre-miR-216b) on cancer cells is still ambiguous. Forkhead box Q1 (FOXQ1) was directly regulated by miR-216b-3p and overexpression of FOXQ1 was confirmed in clinical specimens. High expression of FOXQ1 predicted a shorter survival of patients with PDAC by Kaplan-Meier analysis. Loss-of-function assays showed that cancer cell migration and invasion activities were significantly reduced by siFOXQ1 transfectants. We investigated pathways downstream from FOXQ1 by using genome-wide gene expression analysis. Identification of the miR-216-3p/FOXQ1-mediated network in PDAC should enhance understanding of PDAC aggressiveness at the molecular level.

Regulation of actin-binding protein ANLN by antitumor miR-217 inhibits cancer cell aggressiveness in pancreatic ductal adenocarcinoma.

Analysis of our microRNA (miRNA) expression signature of pancreatic ductal adenocarcinoma (PDAC) revealed that microRNA-217 (miR-217) was significantly reduced in cancer tissues. The aim of this study was to investigate the antitumor roles of miR-217 in PDAC cells and to identify miR-217-mediated molecular pathways involved in PDAC aggressiveness. The expression levels of miR-217 were significantly reduced in PDAC clinical specimens. Ectopic expression of miR-217 significantly suppressed cancer cell migration and invasion. Transcription of actin-binding protein Anillin (coded by ANLN) was detected by our in silico and gene expression analyses. Moreover, luciferase reporter assays showed that ANLN was a direct target of miR-217 in PDAC cells. Overexpression of ANLN was detected in PDAC clinical specimens by real-time PCR methods and immunohistochemistry. Interestingly, Kaplan-Meier survival curves showed that high expression of ANLN predicted shorter survival in patients with PDAC by TCGA database analysis. Silencing ANLN expression markedly inhibited cancer cell migration and invasion capabilities of PDAC cell lines. We further investigated ANLN-mediated downstream pathways in PDAC cells. "Focal adhesion" and "Regulation of actin binding protein" were identified as ANLN-modulated downstream pathways in PDAC cells. Identification of antitumor miR-217/ANLN-mediated PDAC pathways will provide new insights into the potential mechanisms underlying the aggressive course of PDAC.

Impact of Snail and E-cadherin expression in pancreatic neuroendocrine tumors.

Pancreatic neuroendocrine tumors (PNETs) are a rare type of malignancy with a prognosis that is relatively good, compared with that of pancreatic adenocarcinoma. However, a number of patients with PNETs have distant metastasis and a less favorable prognosis. Epithelial-mesenchymal transition (EMT) is essential for tumor progression and metastasis. Snail and E-cadherin serve key roles in the process of EMT in numerous tumor types, including gastric and pancreatic adenocarcinoma. However, the role of EMT in PNETs remains unclear. The aim of the present study was to investigate the significance of Snail and E-cadherin expression in PNETs. Tissue samples were obtained from 40 resected PNETs. The expression of Snail and E-cadherin was evaluated in the primary tumors using immunohistochemical staining. The association between protein expression and patient clinicopathological features was then analyzed. High and low Snail expression levels were observed in 11 (27.5%) and 29 (72.5%) patients, respectively. Preserved and reduced E-cadherin expression was observed in 19 (47.5%) and 21 (52.5%) patients, respectively. Patients with low Snail expression and preserved E-cadherin expression had a significantly lower risk of vascular invasion, lymphatic invasion, lymph node metastasis and liver metastasis and a lower WHO classification, as compared with the group that included patients with high Snail and reduced E-cadherin, high Snail and preserved E-cadherin, and low Snail and reduced E-cadherin expression. In addition, the patients with low Snail expression levels and preserved E-cadherin expression had more a favorable prognosis compared with the other group. The present study indicates that EMT serves an important role in tumor progression in PNETs. Immunohistochemical evaluation of Snail and E-cadherin is useful for predicting the risk of vessel invasion and metastasis in PNETs.

Noncoding RNA and colorectal cancer: its epigenetic role.

The use of novel sequencing and high-throughput techniques has become widespread, and are now readily available to obtain the comprehensive transcription profile of the human genome. Noncoding RNAs (ncRNAs) are transcripts that have no apparent protein-coding capacity, but they have important roles in human physiology. Most research in this area has focused on micro-RNAs. However, the role of long ncRNAs (lncRNAs) as drivers of tumor suppression and oncogenic functions has recently been examined in numerous cancer types. Epigenetic alterations can reportedly deregulate the expression of any type of transcript. However, the exact mechanisms of epigenetic regulation of lncRNA are still unknown. In this review, the authors primarily focus on the epigenetic effects modulating ncRNA in colorectal cancer (CRC). The authors specifically discuss examples of oncogenic ncRNA in CRC pathobiology, as well as its extended diagnosis, prognosis and therapy.

ZFP36L2 promotes cancer cell aggressiveness and is regulated by antitumor microRNA-375 in pancreatic ductal adenocarcinoma.

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.

MicroRNA in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies. Patients with PDAC are often asymptomatic, and many have lymph node and distant metastases as well as vessel invasion upon diagnosis. Surgery and current chemotherapy have limited efficacy for improving prognosis, which accounts for overall median survival of 8.6 months and a 9.7% 5-year survival rate. MicroRNAs (miRNAs) are attracting increasing attention because of their association with tumour progression. At least 50% of miRNAs that are aberrantly expressed in tumours have important roles as post-transcriptional regulators and exhibit oncogenic or tumour suppressive activities by directly binding to their target messenger RNAs. Various techniques are available to identify miRNAs that are differentially expressed in cancerous vs normal tissues. In this review, we summarise the miRNA profiles of normal pancreatic tissue and cancer tissue of patients with PDACs and characterise the expression of miRNAs associated with tumour progression. Further, we highlight the target genes and signalling pathways of miRNAs that are aberrantly expressed in PDACs. This knowledge may lead to the development of preventive and therapeutic strategies for treating this deadly disease.

Expression of Maternal Embryonic Leucine Zipper Kinase (MELK) Correlates to Malignant Potentials in Hepatocellular Carcinoma.

BACKGROUND/AIM: Maternal embryonic leucine zipper kinase (MELK) is categorized as a member of AMP-activated protein kinase families. Various MELK-associated cellular and biological processes affect multiple stages of tumorigenesis. The aim of the present study was to clarify the relationship between MELK expression and hepatocellular carcinoma (HCC) clinicopathological features. MATERIALS AND METHODS: In thirty conserved frozen primary HCC and non-HCC samples MELK mRNA expression was examined by quantitative real-time polymerase chain reaction (PCR). RESULTS: HCC tissues exhibited significantly higher expression levels compared to non-cancerous tissues. MELK expression had a statistically parallel correlation between tumor diameter and protein induced by vitamin K absence or antagonist II (PIVKA-II). The overall survival (OS) and recurrence-free survival (RFS) of the low MELK mRNA expression group was significantly longer than that of the high MELK mRNA expression group. CONCLUSION: MELK expression in HCC is extremely intense compared to its expression reported in other types of cancer. MELK could be a promising effective tumor marker of HCC and further consideration is needed.

Regulation of MMP13 by antitumor microRNA-375 markedly inhibits cancer cell migration and invasion in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive malignancies. Recently developed molecular targeted therapies are not available for patients with ESCC. After curative surgical resection, patients frequently suffer distant metastasis and recurrence. Exploration of novel ESCC metastatic pathways may lead to the development of new treatment protocols for this disease. Accordingly, we have sequentially identified microRNA (miRNA)-mediated metastatic pathways in several cancers. Our past studies of miRNA expression signatures have shown that microRNA-375 (miR-375) is frequently reduced in several types of cancers, including ESCC. In the present study, we aimed to investigate novel miR-375-mediated metastatic pathways in ESCC cells. The expression of miR-375 was downregulated in ESCC tissues, and ectopic expression of this miRNA markedly inhibited cancer cell migration and invasion, suggesting that miR-375 acted as an antimetastatic miRNA in ESCC cells. Our strategies for miRNA target searching demonstrated that matrix metalloproteinase 13 (MMP13) was directly regulated by miR-375 in ESCC cells. Overexpression of MMP13 was observed in ESCC clinical tissues, and the expression of MMP13 promoted cancer cell aggressiveness. Moreover, oncogenic genes, including CENPF, KIF14 and TOP2A, were shown to be regulated downstream of MMP13. Taken together, these findings demonstrated that the antitumor miR-375/oncogenic MMP13 axis had a pivotal role in ESCC aggressiveness. These results provide novel insights into the potential mechanisms of ESCC pathogenesis.

[A case of rectal cancer which showed complete response to chemotherapy for para-aortic lymph node metastases remaining after surgery, for which resection of Virchow's lymph node recurrence led to long-term survival].

A 55-year-old man with a positive fecal occult blood test visited our department, and after a thorough medical evaluation, was diagnosed with Stage IV Rs rectal cancer with marked para-aortic lymph node metastasis. In December 2007, the patient underwent low anterior rectal resection with D3 lymph node dissection, but the para-aortic lymph nodes were left. The metastatic lymph nodes showed a complete response(CR)to post-operative chemotherapy with FOLFOX, FOLFIRI, IRIS, and irinotecan+cetuximab, and the complete response was sustained for 18 months after surgery. Later, he developed Virchow's lymph node metastasis, which was also resected. At present, 5 years after the first surgery, the patient, whose chemotherapy has been discontinued, is alive without recurrence. It appears that using key drugs, such as 5-fluorouracil, leukovorin, oxaliplatin, irinotecan, and cetuximab, and performing aggressive salvage surgery for Virchow's lymph node recurrence, led to long-term recurrence-free survival.