A distinct expression pattern of the long 3'-untranslated region dicer mRNA and its implications for posttranscriptional regulation in colorectal cancer.

OBJECTIVES: Reduced expression of Dicer is associated with global downregulation of microRNAs. Primary Dicer transcripts can be processed at two alternative polyadenylation sites, generating two pools of messenger RNAs (mRNAs) that carry either a long or a short 3'-untranslated regions (3'UTRs), that both encode the same Dicer protein. The short 3'UTR Dicer mRNA is not regulated by miR-103/107. The aim of this study was to investigate the expression of total Dicer mRNA, long 3'UTR Dicer mRNA, and miR-103 in colorectal cancer (CRC). METHODS: Paired tumor and normal mucosal specimens were obtained from 66 patients with CRC. Real-time reverse transcription PCR of long 3'UTR Dicer mRNA, total Dicer mRNA and miR-103 was carried out using the TaqMan Expression assay and the TaqMan MicroRNA assay. RESULTS: The median expression level of coding Dicer mRNA in the tumors was significantly lower than that in normal mucosa (P<0.001). There was no significant difference in expression levels of long 3'UTR Dicer mRNA between the tumors and the normal mucosa (P=0.90). The median expression ratio of long 3'UTR Dicer mRNA to total Dicer mRNA in tumors was significantly higher than in normal mucosa (P<0.001). There was no significant difference in expression levels of miR-103 between the tumors and normal mucosa (P=0.17). There was no significant correlation between clinicopathological findings, such as stage, tumor location, and histological grade and expression levels of total Dicer mRNA, long 3'UTR Dicer mRNA, or expression ratio of long 3'UTR Dicer mRNA to total Dicer mRNA. CONCLUSIONS: These results suggest that both transcriptional and posttranscriptional dysregulation of Dicer expression may be involved in colon carcinogenesis.

[A case of hemorrhage from varices of an interposed jejunum after choledochojejunostomy treated successfully by endoscopic injection using α-cyanoacrylate monomer].

A 73-year-old woman was admitted with gastrointestinal bleeding. She had undergone pylorus-preserving pancreaticoduodenectomy, hepaticojejunostomy and pancreatojejunostomy for pancreatic cancer a year earlier. Gastrointestinal endoscopy revealed bleeding from varices in an interposed jejunum. Enhanced CT showed an extrahepatic portal venous obstruction and cavernous transformation of the portal vein, which were complications of these operations. We performed endoscopic injection using α-cyanoacrylate monomer for the varices. After 4 treatments, the bleeding stopped. We concluded that endoscopic injection using α-cyanoacrylate monomer was effective and useful treatment for bleeding from hepatopetal varices, including cavernous transformation of the portal vein. This method is also useful in emergency situations.

Fecal cyclooxygenase 2 plus matrix metalloproteinase 7 mRNA assays as a marker for colorectal cancer screening.

We previously reported that fecal cyclooxygenase 2 (COX-2) mRNA assay, detecting COX-2 mRNA in feces, is useful for identifying subjects with colorectal cancer (CRC). To further improve the sensitivity, we evaluated the usefulness of the combination of COX-2 mRNA and matrix metalloproteinase 7 (MMP-7) mRNA assays as a marker of CRC. The study cohort included 62 patients with CRC and 29 control patients without colorectal neoplasia. RNA was isolated from routinely collected fecal samples. The expression levels of COX-2 and MMP-7 mRNAs were determined by nested reverse transcription-PCR. PCR conditions were optimized where the specificity of fecal COX-2 and MMP-7 mRNA assay result in 100%. The sensitivity of each fecal assay was 87% [95% confidence interval (95% CI), 76-94%] and 65% (95% CI, 51-76%) for CRC, respectively. The sensitivity of fecal RNA test (either marker being positive) was high for CRC (90%; 95% CI, 80-96%). The sensitivity of the fecal RNA test was also high (93%; 95% CI, 80-98%) in patients with stage I or II who are often cured by surgical resection. The fecal RNA test using COX-2 and MMP-7 mRNAs improved the sensitivity to detect CRC without decreasing the specificity. These results suggest that the fecal RNA test would be a promising approach for CRC screening, although larger clinical investigations are indicated.

Cyclooxygenase-2 and tumor biology.

There is now substantial evidence for the role of cyclooxygenase (COX)-2 in causation and prevention of cancer. Selective COX-2 inhibitors (coxibs) were considered attractive candidate chemoprevention agents; however, concerns over the toxicity of systemic selective inhibition have cast some doubt on COX-2 inhibition as a safe chemoprevention strategy. COX-2 can serve as a potential biomarker of tumor evaluation including prognosis. This chapter describes proposed mechanisms for the role of COX-2 in carcinogenesis, proliferation, inhibition of apoptosis, promotion of angiogenesis, enhanced invasiveness, immune modulation, and increased mutagenesis. Critical discussions focus on the use of COX-2 as a biomarker in the evaluation of neoplasm. Our chapter demonstrates that "Fecal COX-2 Assay," a novel method to detect COX-2 messenger RNA (mRNA) in feces from subjects with colorectal neoplasms, is potentially useful for colorectal cancer screening.

EGF rapidly translocates tight junction proteins from the cytoplasm to the cell-cell contact via protein kinase C activation in TMK-1 gastric cancer cells.

Tight junctions are commonly disrupted in cancer cells, including gastric cancer. Various growth factors have been reported to affect the localization of tight junction-associated proteins such as ZO-1 and occludin. We investigated the effect of epidermal growth factor (EGF), a growth factor that is often overexpressed in gastric cancer, and fetal bovine serum (FBS) on the localization of ZO-1 and occludin in a gastric cancer cell line. In the poorly differentiated gastric cancer cell line TMK-1, immunohistochemistry demonstrated that ZO-1 and occludin were predominantly localized to the cytoplasm, although there was some weak expression at the cell-cell contact. When the medium was replaced with fresh medium containing 10% FBS, ZO-1 and occludin were rapidly translocated from the cytosol to the cell-cell contact. A similar effect was seen in EGF exposure. These effects induced by FBS or EGF were attenuated in the presence of protein kinase C (PKC) inhibitors calphostin C and bisindolylmaleimide I, but not another PKC inhibitor Gö6976, PD98059 (MAPK inhibitor), LY294002 (PI3 kinase inhibitor) or KT5720 (protein kinase A inhibitor). These results suggest that serum-derived factors, including EGF, can rapidly alter the localization of ZO-1 and occludin via a protein kinase C signaling pathway in TMK-1 gastric cancer cells.