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.

Congenital absence of the portal vein complicating hepatic tumors.

Congenital absence of the portal vein (CAPV) is a rare malformation that is often accompanied by other anomalies such as cardiac and skeletal malformations and/or hepatic tumors. We describe here a case of CAPV complicating hepatic tumors in a 16-year-old Japanese girl. Abdominal ultrasonography revealed a hyperechoic tumor in the liver and dilatation of the portal vein that appeared to be connected directly with the inferior vena cava. Subsequent abdominal computed tomography (CT) revealed tumors and magnetic resonance angiography confirmed that the portal vein entered directly into the inferior vena cava just above the liver. In addition, there was absence of the right portal vein and the left intrahepatic branch except for the presence of left portal vein only within the porta hepatis. These findings led to a diagnosis of CAPV complicated hepatic tumors. Careful monitoring of these hepatic tumors is ongoing due to the possibility of malignant transformation.