June-Sik Cho

Frequent silencing of popeye domain-containing genes, BVES and POPDC3 , is associated with promoter hypermethylation in gastric cancer

The Popeye domain-containing (POPDC) genes BVES, POPDC2 and POPDC3 encode proteins that regulate cell-cell adhesion and cell migration during development. Herein, we report the frequent downregulation of BVES and POPDC3 by promoter hypermethylation in gastric cancer. POPDC expression in 11 gastric cancer cell lines and 96 paired gastric tumor and normal adjacent tissues was analyzed with quantitative reverse transcription-polymerase chain reaction. The methylation status of BVES and POPDC3 was analyzed with methylated DNA immunoprecipitation sequencing, bisulfite sequencing and pyrosequencing. Expression of BVES and POPDC3 was downregulated in 73% of the gastric cancer cell lines and in 69% (BVES) and 87% (POPDC3) of the gastric cancer tissues. The BVES and POPDC3 promoter regions were hypermethylated in the gastric cancer cell lines in which they were silenced. Combined treatment with a DNA methylation inhibitor and a histone deacetylase inhibitor strongly induced BVES and POPDC3 expression. BVES and POPDC3 were hypermethylated in 69% (BVES) and 64% (POPDC3) of the gastric cancer tissues. We knocked down POPDC3 expression with short hairpin RNAs and examined the consequences on cell migration and invasion. Knockdown of POPDC3 in SNU-216 cells caused increased cell migration and invasion. Thus, epigenetic inactivation of BVES and POPDC3 occurs frequently in gastric tumors and may promote gastric cancer cell migration and invasion.

Epigenetic Down-Regulation and Suppressive Role of DCBLD2 in Gastric Cancer Cell Proliferation and Invasion

The promoter region of Discoidin, CUB and LCCL domain containing 2 (DCBLD2) was found to be aberrantly methylated in gastric cancer cell lines and in primary gastric cancers, as determined by restriction landmark genomic scanning. DCBLD2 expression was inversely correlated with DCBLD2 methylation in gastric cancer cell lines. Treatment with 5-aza-2′-deoxycytidine and trichostatin A partially reversed DCBLD2 methylation and restored gene expression in DCBLD2-silenced cell lines. In an independent series of 82 paired gastric cancers and adjacent normal tissues, DCBLD2 expression was down-regulated in 79% of gastric cancers as compared with normal tissues as measured by real-time reverse transcription-PCR. Pyrosequencing analysis of the DCBLD2 promoter region revealed abnormal hypermethylation in gastric cancers, and this hypermethylation was significantly correlated with down-regulation of DCBLD2 expression. Furthermore, ectopic expression of DCBLD2 in gastric cancer cell lines inhibited colony formation in both anchorage-dependent and anchorage-independent cultures and also inhibited invasion through the collagen matrix. These data suggest that down-regulation of DCBLD2, often associated with promoter hypermethylation, is a frequent event that may be related to the development of gastric cancer. (Mol Cancer Res 2008;6(2):222–30)

LRRC3B, Encoding a Leucine-Rich Repeat-Containing Protein, Is a Putative Tumor Suppressor Gene in Gastric Cancer

Leucine-rich repeat-containing 3B (LRRC3B) is an evolutionarily highly conserved leucine-rich repeat-containing protein, but its biological significance is unknown. Using restriction landmark genomic scanning and pyrosequencing, we found that the promoter region of LRRC3B was aberrantly methylated in gastric cancer. Gastric cancer cell lines displayed epigenetic silencing of LRRC3B, but treatment with the DNA methylation inhibitor 5-aza-2-deoxycytidine and/or the histone deacetylase inhibitor trichostatin A increased LRRC3B expression in gastric cancer cell lines. Real-time reverse transcription-PCR analysis of 96 paired primary gastric tumors and normal adjacent tissues showed that LRRC3B expression was reduced in 88.5% of gastric tumors compared with normal adjacent tissues. Pyrosequencing analysis of the promoter region revealed that LRRC3B was significantly hypermethylated in gastric tumors. Stable transfection of LRRC3B in SNU-601 cells, a gastric cancer cell line, inhibited anchorage-dependent and anchorage-independent colony formation, and LRRC3B expression suppressed tumorigenesis in nude mice. Microarray analysis of LRRC3B-expressing xenograft tumors showed induction of immune response-related genes and IFN signaling genes. H&E-stained sections of LRRC3B-expressing xenograft tumors showed lymphocyte infiltration in the region. We suggest that LRRC3B is a putative tumor suppressor gene that is silenced in gastric cancers by epigenetic mechanisms and that LRRC3B silencing in cancer may play an important role in tumor escape from immune surveillance.

New Type of Reconstruction Method after Subtotal Gastrectomy (Noh’s Operation)

The aim of this study was to compare a new type of reconstruction method (Noh’s operation) with Roux-en-Y operation after subtotal gastrectomy. Noh’s operation described herein includes a jejunal occlusion, an end-to-side gastrojejunostomy, a side-to-end jejunoduodenostomy, and a side-to-side jejunojejunostomy after subtotal gastrectomy. A series of 43 patients who had the new operation were compared with 47 patients with the Roux-en-Y procedure. The postgastrectomy syndromes, and the mucosal change of the remnant stomach and esophagus were evaluated after surgery. In the new operation, the Roux stasis syndrome occurred in 34.9% at 3 months, in 23.3% at 6 months, in 14.0% at 12 months, and in 11.6% at 24 months. In patients undergoing the Roux-en-Y operation, the syndrome occurred in 42.6% at 3 months, in 34.0% at 6 months, in 31.9% at 12 months, and in 29.8% at 24 months. This study shows that the new type of operation (Noh’s operation) can be a good option for reconstruction after subtotal gastrectomy.

Non-invasive Assessment of Liver Fibrosis with ElastPQ: Comparison with Transient Elastography and Serologic Fibrosis Marker Tests, and Correlation with Liver Pathology Results

We investigated the feasibility of using ultrasound shear wave elastography point quantification (ElastPQ) for liver fibrosis staging and compared it with other non-invasive tools with respect to efficacy in liver stiffness measurement. A total of 106 patients who underwent liver stiffness measurements, using ElastPQ and biochemical investigations, before parenchymal liver biopsy or surgery were included. Among these, 51 also underwent transient elastography (TE). Correlations of ElastPQ, TE and aspartate aminotransferase-to-platelet ratio index (APRI) with histopathological findings (as the reference standard) were determined using Spearmans correlation coefficient. The diagnostic performance of ElastPQ, TE and APRI was evaluated using receiver operating characteristic (ROC) curve analysis. ElastPQ had good diagnostic accuracy in identifying each liver fibrosis stage, with an area under the ROC curve (AUC) of 0.810 to 0.864. Stiffness values obtained using ElastPQ, TE and APRI were significantly positively correlated (rxa0=xa00.686, rxa0=xa00.732 and rxa0=xa00.454, respectively) with histologic fibrosis staging (pxa0<xa00.001). According to the AUC for the diagnosis of significant fibrosis (≥F2) and cirrhosis (=F4), ElastPQ had better diagnostic accuracy (AUCxa0=xa00.929 and 0.834, respectively) than APRI (AUCxa0=xa00.656 and 0.618, respectively) (pxa0<xa00.05), and was similar to TE (AUCxa0=xa00.915 and 0.879, respectively). ElastPQ is a promising ultrasound-based imaging technique for evaluation of liver fibrosis, with a diagnostic accuracy comparable to that of TE.

Computer-aided diagnosis of splenic enlargement using wave pattern of spleen in abdominal CT images

It is known that the spleen accompanied by liver cirrhosis is hypertrophied or enlarged. We have examined a wave pattern at the left boundary of spleen on the abdominal CT images having liver cirrhosis, and found that they are different from those on the images having a normal liver. It is noticed that the abdominal CT images of patient with liver cirrhosis shows strong bending in the wave pattern. In the case of normal liver, the images may also have a wave pattern, but its bends are not strong. Therefore, the total waving area of the spleen with liver cirrhosis is found to be greater than that of the spleen with a normal liver. Moreover, we found that the waves of the spleen from the image with liver cirrhosis have the higher degree of circularity compared to the normal liver case. Based on the two observations above, we propose an automatic method to diagnose splenic enlargement by using the wave pattern of the spleen in abdominal CT images. The proposed automatic method improves the diagnostic performance compared with the conventional process based on the size of spleen.

Computerized detection of liver cirrhosis using wave pattern of spleen in abdominal CT images

We examined the wave pattern of the spleen by using abdominal CT images of a patient with liver cirrhosis, and found that they are different from those of a person with a normal liver. This paper suggests a method to diagnose liver cirrhosis by using the wave pattern of the spleen in abdominal CT images on the basis of the two principles. It tells us that we can judge if the liver has liver cirrhosis, without the test of the ratio of caudate lobe to right lobe, only with the spleen.