Takahiro Shimamura

EPHA2/EFNA1 expression in human gastric cancer

The erythropoietin‐producing hepatocellular (EPH)A2 receptor, tyrosine kinase, is overexpressed and phosphorylated in several types of human tumors and has been associated with malignant transformation. A recent report, however, indicated that stimulation of the EPHA2 receptor ligand, ephrinA1 (EFNA1), inhibits the growth of EPHA2‐expressing breast cancer. The authors examined the expression of EPHA2 and EFNA1 using semiquantitative reverse transcription‐polymerase chain reaction (RT‐PCR) in four gastric cancer cell lines and 49 primary gastric cancer samples, as well as in normal gastric tissue. EPHA2 was more highly expressed in tumor tissue than in normal tissue in 27 cases (55%). EFNA1 was overexpressed in tumor tissue in 28 cases (57%). No significant correlation was detected between the expression levels and histologic features such as tumor size, age, vessel invasion, or lymph node involvement. However, EPHA2 overexpression was more prominent in macroscopic type 3 and 4 tumors than in type 1 or 2 advanced gastric cancer. The authors observed EPHA2 expression in three of the four gastric cancer cell lines (AGS, KATO3, and MKN74) that were examined. In one cell line, TMK1, EPHA2 expression was barely detectable using northern blotting, RT‐PCR, and western blotting. In contrast, EFNA1 was detected in all cell lines. In the gastric cancer cell lines that endogenously expressed EPHA2, stimulation with ephrinA1‐Fc led to decreased EPHA2 protein expression and increased EPHA2 phosphorylation. Finally, the growth of EPHA2‐expressing cells was inhibited by repetitive stimulation with soluble ephrinA1‐Fc. Taken together, these findings suggest that EPHA2 and EFNA1 expression may influence the behavior of human gastric cancer. (Cancer Sci 2005; 96: 42–48)

Correlation of EPHA2 overexpression with high microvessel count in human primary colorectal cancer

Evidence suggests that the erythropoietin‐producing hepatocellular (EPH) receptor tyrosine kinases (RTKs) and their ephrin (EFN) ligands are involved in human carcinogenesis. Expression of two of them, EFNA1 ligand and its receptor, EPHA2, has been proposed to contribute to tumor‐induced neovascularization. Colorectal cancers were examined for expressions of EPHA2 and its ligand EFNA1 by semi‐quantitative RT‐PCR, and double‐immunostained for EPHA2 and CD34. Microvessels in the tumors were counted. Double‐staining was also performed in 25 cases of adenoma with focal cancer for comparison. Trends of overexpression of both EPHA2 and EFNA1 was found in tumor tissue compared to the corresponding normal tissue in the same specimen [22/37 (59.5%) and 25/37 (67.5%), respectively; P=0.100 for EPHA2 and P=0.009 for EFNA1]. Overexpression of EPHA2 and EFNA1 was noted more frequently in the early stage than in the late stage [EPHA2, 15/21 (71.4%) vs. 7/16 (43.8%), P=0.007; EFNA1, 15/21 (71.4%) vs. 10/16 (62.5%), P=0.007]. Both EPHA2 and EFNA1 were more frequently overexpressed in smaller tumors (less than 5 cm) than in larger tumors [EPHA2, 15/21 (71.4%) vs. 7/16 (43.8%), P=0.017; EFNA1, 16/21 (76.2%) vs. 8/16 (50%), P=0.001]. Tumors less than 5 cm in diameter and in stages I and II were significantly more likely to overexpress EPHA2 and EFNA1 (P=0.001 for EPHA2, P=0.001 for EFNA1). Microvessel counts (MVCs) after immuno‐staining for CD34 were significantly correlated (r=0.343, P=0.037) with overexpression of EPHA2. EPHA2‐expressing focal cancer also surrounded microvessels in adenomas with focal cancers. These findings suggest an involvement of EPHA2 in colon carcinogenesis, mainly in stages I and II, and probably through their effect on microvessel induction.

Overexpression of MUC13 is associated with intestinal-type gastric cancer

Mucins are secreted or transmembrane glycoproteins that are expressed mainly in the digestive tract. This family of proteins has been the focus of much gastric cancer research as some transmembrane mucins are implicated in tumorigenesis and make attractive targets for cancer diagnosis and therapeutics. Mucins have also been utilized to classify gastric cancer by differentiating between gastric and intestinal phenotypes. Here we show that transmembrane mucin MUC13 is upregulated in gastric cancer. By quantitative real‐time reverse transcription‐polymerase chain reaction and immunoblot analysis, overexpression of MUC13 was verified in more than half of the samples examined. In immunohistochemical analysis, MUC13 staining was observed in 74 of 114 cases of gastric cancer (64.9%), predominantly in intestinal type (P < 0.001), and in 9 of 10 cases of intestinal metaplasia, precancerous lesions of intestinal‐type gastric cancer, but not observed in normal gastric mucosa. Moreover, MUC13 staining patterns characteristic of histological type were identified: staining was on the apical side of tubular glands in intestinal type and on the cytoplasm in diffuse type. These results suggest that MUC13 is a good differentiation marker for gastrointestinal mucosa and that it may have a causal role that correlates with two distinct gastric tumorigenesis pathways. (Cancer Sci 2005; 96: 265 –274)

Human homolog of NOTUM, overexpressed in hepatocellular carcinoma, is regulated transcriptionally by β-catenin/TCF

The Drosophila Notum gene, which is regulated by the Wingless pathway, encodes a secreted hydrolase that modifies heparan sulfate proteoglycans. In comparative analysis of the gene expression profiles in primary human hepatocellular carcinomas (HCC) and normal organs, we observed that the human ortholog of Drosophila Notum was overexpressed markedly in a subset of HCC, but expressed rarely in adult normal tissues. Immunoblotting confirmed the overexpression of NOTUM protein in 12 of 40 primary HCC cases (30%). High levels of NOTUM protein were significantly associated with intracellular (nuclear or cytoplasmic) accumulation of β‐catenin protein: all 10 HCC with high intracellular β‐catenin also had high NOTUM expression, whereas only 2 of 30 cases (6.7%) without intracellular β‐catenin had high NOTUM expression (P < 0.00001). NOTUM expression in HepG2 cells was downregulated significantly by induction of a dominant‐negative mutant of TCF4, a β‐catenin partner. In vivo binding of the β‐catenin/TCF complex to the NOTUM promoter was demonstrated by chromatin immunoprecipitation in HepG2 and SW480 cells, where canonical Wnt signaling is activated constitutively. These findings provide evidence that NOTUM is a novel target of β‐catenin/TCF4 and is upregulated in Wnt/β‐catenin signaling‐activated HCC. (Cancer Sci 2008; 99: 1139–1146)

Laparoscopic resection of adult colon duplication causing intussusception

Gastrointestinal duplications are uncommon congenital malformations that can occur anywhere along the gastrointestinal tract. Most cases are recognized before the age of 2 years, and those encountered in adults are rare. We describe here a case of ascending colon duplication in a 20-year-old male that caused intussusception and was treated laparoscopically. Although computed tomography revealed a cystic mass filled with stool-like material, the preoperative diagnosis was a submucosal tumor of the ascending colon. We performed a laparoscopic right colectomy, and the postoperative pathological diagnosis was duplication of the ascending colon, both cystic and tubular components. We conclude that gastrointestinal duplications, although rare, should be considered in the differential diagnosis of all abdominal and submucosal cystic lesions and that laparoscopy is a preferred approach for the surgical treatment of gastrointestinal duplications.

Transabdominal approach assisted by thoracoscopic drainage for lower esophageal perforation

The effectiveness of use of thoracoscopy for esophageal perforation has not been fully evaluated. We herein report a case of esophageal perforation for which a transabdominal approach assisted by thoracoscopic drainage was performed.