Takuya Ando

RNASEN Regulates Cell Proliferation and Affects Survival in Esophageal Cancer Patients

Purpose: MicroRNAs (miRNA) are small noncoding RNAs thought to be involved in physiologic and developmental processes by negatively regulating the expression of target genes. Little is known about the role of miRNAs in normal and cancer cells. It is possible that deregulation of miRNA may contribute to the oncogenesis of some cancers. We studied the expression level of the miRNA processing enzyme (DICER1, DGCR8, and RNASEN) in esophageal squamous cell carcinoma (ESCC). Experimental Design: The expression levels of DICER1, DGCR8, and RNASEN mRNA in 73 ESCC tissues were compared with that in corresponding normal esophageal epithelium by Taqman real-time reverse-transcription PCR. We also examined RNASEN protein expression in 27 cell lines. The role of RNASEN in cell proliferation in ESCC cells was assessed by small interfering RNA. Paraffin sections of ESCC patients were immunohistochemically investigated. Results: We found that RNASEN expression levels were enhanced in a fraction of esophageal cancers. Multivariate Cox regression analysis showed that the prognostic effect of RNASEN (P = 0.0036) seems to be independent of disease stage (P = 0.0060). Knockdown of RNASEN in esophageal cancer cell lines resulted in a 46% to 85% reduction in cell number. In an immunohistochemical study, the intensity of RNASEN expression was often increased in the tumor compared with that in normal epithelium. Conclusions: The relationship between the RNASEN expression and the prognosis of the ESCC patients warrants a further study on the role of miRNA and tumor progression.

Relationship between expression of 5-fluorouracil metabolic enzymes and 5-fluorouracil sensitivity in esophageal carcinoma cell lines

5-Fluorouracil (5-FU) is a key drug in the treatment of esophageal squamous cell carcinoma (ESCC). Gene expression of 5-FU metabolic enzymes such as thymidylate synthase (TS), thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD) and orotate phosphoribosyl transferase (OPRT), has recently been investigated in order to predict the 5-FU sensitivity of several cancers. We examined the relationship between such gene expression and 5-FU sensitivity in 25 ESCC cell lines. TS, DPD, TP and OPRT mRNA levels were assessed by real-time polymerase chain reaction. The 50% inhibitory concentrations (IC50) of 5-FU in 25 ESCC cell lines were determined by cell proliferation assay. IC50 values for 5-FU ranged from 1.00 to 39.81 micromol/L. There were significant positive correlations between IC50 and TS mRNA expression (R(2) = 0.5781, P < 0.0001) and DPD mRNA expression (R(2) = 0.3573, P = 0.0016). There were no correlations between IC50 and TP or OPRT mRNA expression. TS and DPD mRNA expression levels may be useful indicators in predicting the anti-tumor activity of 5-FU in ESCC.

A New Technique for Shaping the Gastric Tube, Using Both Radial and Linear Staplers

One factor influencing surgery for esophageal cancer is the reconstruction technique, which may involve constructing a tube from the stomach or the intestines. Good blood flow and adequate length are necessary. Gastric tube formation became easier with the availability of improved surgical staplers, but gastric tube necrosis and leakage may still occur. Therefore, a simple technique providing good blood flow to the end of the gastric tube is needed. One method is called the whole stomach technique: the surgeon excises the small part of the gastric wall supplied by the left gastric artery. Another is called the gastric tube technique: the surgeon divides the stomach from the lesser curvature along the axis of the greater curvature. But the gastric tube method is so difficult that different devices are used in each institution. We use the gastric tube method, except in patients with gastric cancer or patients with a history of gastrectomy. One reason for choosing this method is that it provides sufficient length. Length is never a problem, even in the case of laryngo-esophagotomy. With a linear cutting stapler, shaping the gastric tube is comparatively easy and time-saving. Since 2012, we have used the EndoGIA60 with Tri-Staple (Covidien Japan). To shape a long, slender tube, we usually use 6 or 7 linear staplers. The first problem is an irregular section of a knot, which causes no trouble if the serial stapling is in the same direction (Fig. 1). But once the direction shifts, inserting a linear stapler becomes difficult, and the knot becomes more notched. To shape a long tube, the first 2 staplers must be at a nearly right angle. If the area below is the remaining side, the section is more notched. These sides are vulnerable, with limited blood flow. Therefore, we developed a new technique using 2 types of staplers.