Jae Hwi Song’s research while affiliated with Catholic University of Korea and other places

SOX9 belongs to the SOX [sry-related high-mobility group (HMG) box] family and acts as a transcription factor that plays a central role in the development and differentiation of multiple cell lineages. The aim of this study was to determine whether the GKN1 gene is involved in the development of gastric cancer by regulating SOX9. The effect of GKN1 and β-catenin on SOX9 expression was examined in GKN1 and β-catenin-transfected AGS and MKN-1 gastric cancer cells. SOX9 expression was also determined in gastric cancer tissues and cell lines by Western blot analysis and immunohistochemistry. Ectopic expression of β-catenin induced increased expression of SOX9 in AGS cells, whereas GKN1 decreased expression of SOX9 in AGS and MKN-1 cells. In addition, we found an inverse correlation between expression of SOX9 and GKN1 in gastric cancer tissues and cell lines. In immunohistochemistry, nuclear SOX9 expression was detected in 64 (34.6 %) of 185 gastric carcinomas and its expression was closely associated with GKN1 immunonegativity. There was no significant relationship between altered expression of SOX9 protein and clinicopathological parameters including overall survival. These data suggest that aberrant SOX9 expression by GKN1 inactivation may be involved in the development of sporadic gastric cancers as an early event.

The specific aim of this study is to unravel a DNA copy number alterations, and to search for novel genes that are associated with the development of Korean gastric cancer. We investigated a DNA copy number changes in 23 gastric adenocarcinomas by array-comparative genomic hybridization and quantitative real-time polymerase chain reaction analyses. Besides, the expression of UQCRFS1, which shows amplification in array-CGH, was examined in 186 gastric cancer tissues by an immunohistochemistry, and in 9 gastric cancer cell lines, as well as 24 gastric cancer tissues by immunoblotting. We found common gains at 48 different loci, and a common loss at 19 different loci. Amplification of UQCRFS1 gene at 19q12 was found in 5 (21.7%) of the 23 gastric cancers in an array-comparative genomic hybridization and DNA copy number were increased in 5 (20.0%) out of the 25 gastric cancer in quantitative real-time polymerase chain reaction. In immunohistochemistry, the overexpression of the protein was detected in 105 (56.5%) out of the 186 gastric cancer tissues. Statistically, there was no significant relationship between the overexpression of UQCRFS1 and clinicopathologic parameters (P>0.05). In parallel, the overexpression of UQCRFS1 protein was confirmed in 6 (66.7%) of the 9 gastric cancer cell lines, and 12 (50.0%) of the 24 gastric cancer tissues by immunoblotting. These results suggest that the overexpression of UQCRFS1 gene may contribute to the development and/or progression of gastric cancer, and further supported that mitochondrial change may serve as a potential cancer biomarker.

Gastrokine 1 (GKN1) plays an important role in the gastric mucosal defense mechanism and also acts as a functional gastric tumor suppressor. The aim of this study is to determine whether inactivation of the GKN1 gene is involved in the development and/or progression of the gastric cancers. GKN1 expression was examined in gastric adenomas and cancer by immunohistochemistry and Western blot analysis. We also analyzed mutation and epigenetic alteration, DNA copy number change and mRNA transcript of GKN1 in gastric adenomas and carcinomas. The effect of GKN1 on cell proliferation and death was further examined in wild-type GKN1 transfected AGS gastric cancer cells. In immunohistochemistry, reduced or loss of GKN1 expression was detected in 36 (90%) and 170 (89.5%) of 40 adenomas and 190 gastric cancers, respectively. Statistically, there was no significant relationship between altered expression of GKN1 protein and clinicopathologic parameters, including depth of invasion, location, and lymph node metastasis (Chi-Square test, P>0.05). In Western blot analysis, absence or reduced expression was found in 21 (84.0%) of 25 gastric carcinomas. No mutation was detected in gastric tumors, and hypermethylation of GKN1 gene was found in 2 gastric cancers. Interestingly, DNA copy number and mRNA transcript of GKN1 were significantly decreased in gastric cancers. In functional analysis, AGS gastric cancer cells transfected with GKN1 wild-type showed marked inhibition of cell proliferation and induction of cell death. These data suggest that inactivation of the GKN1 gene may play an important role in the development of sporadic gastric cancers, as an early event. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2205. doi:10.1158/1538-7445.AM2011-2205

Gastrokine 1 (GKN1) plays a role in the gastric mucosal defence mechanism and may be a gastric tumour suppressor. We have investigated whether inactivation of the GKN1 gene is involved in the development and/or progression of gastric cancers. GKN1 protein expression was examined in gastric adenomas and cancer and we also analysed GKN1 mutation and epigenetic alteration, DNA copy number change and mRNA transcript expression. The effect of GKN1 on cell proliferation and death was examined in wild-type GKN1-transfected AGS gastric cancer cells. Reduced or loss of GKN1 expression was detected in 36 (90%) and 170 (89.5%) of 40 adenomas and 190 gastric cancers, respectively. Statistically, there was no significant relationship between altered expression of GKN1 protein and clinicopathological parameters, including depth of invasion, location and lymph node metastasis (χ(2) test, p > 0.05). In western blot analysis, absence or reduced expression was found in 21 (84.0%) of 25 gastric carcinomas. No mutation was detected in gastric tumours, and hypermethylation of GKN1 gene was found in two tumours. DNA copy number and mRNA transcript of GKN1 were significantly decreased in gastric cancers. In functional analysis, AGS gastric cancer cells transfected with GKN1 wild-type showed marked inhibition of cell proliferation and induction of cell death. These data suggest that inactivation of the GKN1 gene may play an important role in the development of sporadic gastric cancers, as an early event.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is expressed on epithelial cells throughout the intestinal tract and is a negative regulator of tumor cell growth, suggesting that it may function as a tumor suppressor. In this study, to determine whether the CEACAM1 is involved in colorectal tumorigenesis, we have investigated the genetic alterations, including mutations and allelic loss, of the CEACAM1 gene in 17 colonic adenomas and 123 sporadic colorectal cancers. In addition, the expression pattern of the CEACAM1 protein was examined in 60 colonic adenomas and 123 sporadic colorectal adenocarcinomas. No mutation was found in colonic adenomas, but four somatic missense mutations, L36F, T312I, V398I and A445V, were detected in colorectal cancers. Interestingly, all of the mutations were found in left-side colon cancers of the patients with clinical stage III. In LOH analysis, nine adenomas were informative for at least one of the markers and five (55.6%) showed allelic loss. Thirty-eight cancers were informative at D19S211 and D19S872 markers and 21 (56.3%) showed LOH at these markers. Statistically, the frequency of allelic loss at the CEACAM1 locus was not associated with clinicopathologic parameters (P > 0.05). In immunohistochemical analysis, loss of expression of CEACAM1 protein was detected in nine (15.0%) and 30 (24.4%) of 60 colorectal adenomas and 123 colorectal cancers. Statistically, there was no significant relationship between loss of CEACAM1 expression and clinicopathologic parameters, including clinical stage, tumor location, tumor size, lymph node metastasis and 5-year survival (P > 0.05). These data suggest that genetic alteration and loss of expression of the CEACAM1 may contribute to the development of colorectal cancers, as an early event.

CHOP, a member of the C/EBP family of the transcriptional factor, showed a tumor suppressor activity by binding to TCF and inhibiting the Wnt signaling pathway. In this study, to determine whether genetic alterations of CHOP gene are involved in the development and/or progression of the gastric cancers, we have screened a set of 47 gastric adenoma and 81 sporadic gastric cancers for mutations and allelic loss. In mutation analysis, we found one and five somatic missense mutations, P41T, E69K, S79N, P80S, P80L and G36S, in gastric adenoma and cancer, respectively. All of the mutations were detected in transactivation domain of the CHOP gene. An allelic loss was found in 19 (38.8%) of forty-nine informative cases at one or both microsatellite markers, D12S305 and D12S1691. Clinically, five cancer cases with mutations were of intestinal-type gastric cancers and three mutations were found in the cases with surrounding lymph node metastasis. These data suggest that genetic alterations of the CHOP gene may play an important role in the development of sporadic gastric cancers. KeywordsCHOP–Wnt–Gastric cancer–Mutation–Deletion

Microsatellite instability (MSI) is a form of genetic instability present in virtually all tumors from patients with hereditary nonpolyposis colon cancer and a subset of various sporadic tumors, including colorectal and gastric cancers. Transforming growth factor-beta receptor 2 (TGFBR2) mutations in MSI-positive cancer cell lines may partially inactivate TGF-β-induced growth inhibition. The aim of this study was to investigate whether MSI and TGFBR2 gene mutations contribute to the progression from gastric adenoma to cancer in multistep gastric carcinogenesis. MSIs were analyzed using 5 microsatellite markers and a frameshift mutation in poly(A)10 within the TGFBR2 gene in 50 gastric adenomas and 88 gastric cancer specimens. One (2.0%) of 50 gastric adenomas and 22 (25.0%) of 88 gastric cancers were MSI-positive. TGFBR2 frameshift mutations were found in 9 gastric cancers, but not in adenoma. All cases with the TGFBR2 frameshift mutation showed high-frequency MSIs. These results suggest that MSIs may occur in the development of gastric cancers, but not in adenomas less than 2 cm, and the TGFBR2 gene may be a target of genomic instability in MSI gastric carcinogenesis. Keywords TGFBR2 -Microsatellite instability-Mutation-Gastric cancers

Inappropriate activation of the Wnt signaling pathway has been repeatedly implicated in the tumorigenesis of colon, liver, and gastric cancers. There is accumulating evidences that transcriptional factor 7 (TCF7; also called T cell factor 1) might also be one of the tumor suppressor genes in the Wnt pathway. We performed PCR-based sequencing analysis of the TCF7 gene in 234 alimentary tract cancers. The TCF7 mutants detected in this study were functionally analyzed after they were generated by a QuickChange site-directed mutagenesis kit. We detected 7 somatic mutations in the TCF7 gene, including 4 missense, 2 frameshift, and one 28-bp deletion. In a yeast two-hybrid assay, most of the mutants showed varying degrees of decreased binding to an amino-terminal enhancer of split (AES), a truncated form of Groucho-related protein lacking WD40 repeats. To determine whether mutant TCF7 proteins had decreased DNA binding, we performed electrophoretic mobility shift assays, and the 2 frameshift mutants were shown to have no DNA binding activity. Furthermore, luciferase reporter assays revealed that TCF7 mutants in the presence of AES failed in the AES-dependent transcriptional repression of the reporter gene. In addition, human embryonic kidney 293 cells transfected with TCF7 mutants expressed high levels of cyclin D1, up to 6 times more than cells transfected with wild-type TCF7. Therefore, the TCF7 mutations detected in this study seem to be “loss-of-function mutations“ caused by loss of TCF7 repressor activity through decreased binding to Groucho-related protein and/or DNA, thereby contributing to neoplastic transformation by causing accumulation of cylin D1. Keywords TCF7 -Wnt signaling pathway-Somatic mutations-Loss of heterozygosity-Alimentary tract cancers

Background: Osteoarthritis (OA) is a common disease characterized by degenerating joint cartilage in the knee, hip, and hand. A functional single nucleotide polymorphism (SNP) +104-T/C; rs143383 in the 5′untranslated region of the growth differentiation factor 5 (GDF5) gene was recently associated with susceptibility to OA in the Japanese and Chinese populations. Methods: To investigate whether this association is present in the Korean population, the frequency of the polymorphism was investigated in 276 patients with knee OA and 298 healthy subjects as controls. Polymorphism analysis was performed by amplifying the core promoter region of the GDF5 gene and digesting it with the BsiEI restriction enzyme. Results: The frequency of the TT, CT, and CC genotypes was 54.3% (150/276), 41.7% (115/276), and 4.0% (11/276), respectively, in patients with OA, and 53.4% (159/298), 37.9% (113/298), and 8.7% (26/298), respectively, in healthy controls. No significant differences in genotypic or allelic frequencies of the +104T/C SNP of the GDF5 gene were observed between patients with OA and controls. Also, no significant differences in allelic and genotypic frequencies were found when the individuals were stratified by age and gender. Conclusions: The results suggest that the +104T/C; rs143383 GDF5 core promoter polymorphism is not a risk factor for OA in the Korean population.

Recently, the succinate dehydrogenase subunit B gene, SDHB, has emerged as a novel tumor suppressor. In this study, we have examined the genetic and epigenetic alterations of the SDHB gene in sporadic gastric adenocarcinomas in order to investigate if the SDHB gene is involved in gastric carcinogenesis. The expression of SDHB proteins was also examined with immunohistochemistry and Western blot in 184 and eight gastric cancers, respectively. There was loss or reduced expression of SDHB in 45 (24.5%) of the 184 gastric cancers. Statistically, altered expression of SDHB was not associated with clinicopathological parameters, including tumor differentiation, location, depth of invasion, and lymph node metastasis (P > 0.05). Western blot analysis showed a reduced expression of SDHB in four (50.0%) of the eight paired gastric cancer tissues. Genetic analysis showed one missense mutation, GCC --> ACC (Ala --> Thr) at codon 29. In addition, promoter hypermethylation was not detected in the gastric cancer samples. This is the first investigation of the genetic and protein expression analysis of the SDHB gene in gastric cancers. Our results suggest that genetic, epigenetic, and protein expression pattern alterations of the SDHB gene might play a minor role in the development or progression of gastric cancers.