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Primary Gastric Cancers (primary + gastric_cancers)

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Medical Sciences	100%

Selected Abstracts

Hypermethylation of the TSLC1 Gene Promoter in Primary Gastric Cancers and Gastric Cancer Cell Lines

CANCER SCIENCE, Issue 8 2002
Teiichiro Honda
The TSLC1 (tumor suppressor in lung cancer,1) gene is a novel tumor suppressor gene on chromosomal region 11q23.2, and is frequently inactivated by concordant promoter hypermethylation and loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). Because LOH on 11q has also been observed frequently in other human neoplasms including gastric cancer, we investigated the promoter methylation status of TSLC1 in 10 gastric cancer cell lines and 97 primary gastric cancers, as well as the corresponding non-cancerous gastric tissues, by bisulfite-SSCP analysis followed by direct sequencing. Allelic status of the TSLC1 gene was also investigated in these cell lines and primary gastric cancers. The TSLC1 promoter was methylated in two gastric cancer cell lines, KATO-III and ECC10, and in 15 out of 97 (16%) primary gastric cancers. It was not methylated in non-cancerous gastric tissues, suggesting that this hypermethylation is a cancer-specific alteration. KATO-III and ECC10 cells retained two alleles of TSLC1, both of which showed hypermethylation, associated with complete loss of gene expression. Most of the primary gastric cancers with promoter methylation also retained heterozygosity at the TSLC1 locus on 11q23.2. These data indicate that bi-allelic hypermethylation of the TSLC1 promoter and resulting gene silencing occur in a subset of primary gastric cancers. [source]

Expression of cyclooxygenase-2 in primary and remnant gastric carcinoma: Comparing it with p53 accumulation, Helicobacter pylori infection, and vascular endothelial growth factor expression

JOURNAL OF SURGICAL ONCOLOGY, Issue 2 2002
Atsushi Kawabe MD
Abstract Background and Objectives Cyclooxygenase-2 (COX-2) expression may contribute to the synthesis of prostanoids, which have been related to carcinogenesis and tumor progression. It is well known that the gastric remnant is at greater risk of the development of gastric cancer than is the whole stomach; incidence rates for gastric cardia adenocarcinoma are rising in the United States and Europe. Our objective was to determine the involvement of COX-2 in primary and remnant gastric cancer tissues as well as in adjacent noncancerous mucosa. Methods We investigated the expression of COX-2 in 91 human gastric cancer tissue and adjacent noncancerous mucosa samples (40 remnant gastric cancer, 37 gastric cardia cancer, and 14 gastric corpus and antrum cancer), using immunohistochemistry. In addition, p53 expression, Helicobacter pylori infection, and vascular endothelial growth factor in the tissues were evaluated by immunohistochemical staining and compared with COX-2 expression. Results There were no significant differences in clinicopathological data in the gastric cancer tissues. There was a significant relation between the expression of COX-2 and p53 in gastric cancer tissues (P,=,0.0048). However, vascular endothelial growth factor expression and Helicobacter pylori infection showed no correlation with the expression of COX-2. In the case of adjacent noncancerous mucosa, the positive rate of COX-2 expression was significantly higher in the remnant gastric cancers (75.0%) than in the primary gastric cancers (25.5%) (P,<,0.0001). Conclusions This information may help in the analysis of the carcinogenesis of gastric cancer; there is also a possibility that the COX-2 selective inhibitor to the remnant gastric cancer has a chemopreventive effect. J. Surg. Oncol. 2002;80:79,88. © 2002 Wiley-Liss, Inc. [source]

Quantitative assessment of RUNX3 methylation in neoplastic and non-neoplastic gastric epithelia using a DNA microarray

PATHOLOGY INTERNATIONAL, Issue 10 2006
Kanji So
Silencing of the RUNX3 gene by hypermethylation of its promoter CpG island plays a major role in gastric carcinogenesis. To quantitatively evaluate RUNX3 methylation, a fiber-type DNA microarray was used on which methylated and unmethylated sequence probes were mounted. After bisulfite modification, a part of the RUNX3 promoter CpG island, at which methylation is critical for gene silencing, was amplified by polymerase chain reaction using a Cy5 end-labeled primer. Methylation rates (MR) were calculated as the ratio of the fluorescence intensity of a methylated sequence probe to the total fluorescence intensity of methylated and unmethylated probes. Five gastric cancer cell lines were analyzed, as well as 26 primary gastric cancers and their corresponding non-neoplastic gastric epithelia. MR in four of the cancer cell lines that lost RUNX3 mRNA ranged from 99.0% to 99.7% (mean, 99.4%), whereas MR in the remaining cell line that expressed RUNX3 mRNA was 0.6%. In primary gastric cancers and their corresponding non-neoplastic gastric epithelia, MR ranged from 0.2% to 76.5% (mean, 22.7%) and from 0.7% to 25.1% (mean, 5.5%). Ten (38.5%) of the 26 gastric cancers and none of their corresponding non-neoplastic gastric epithelia had MR >30%. Most of the samples with MR >10% tested methylation-positive by conventional methylation-specific polymerase chain reaction (MSP). This microarray-based methylation assay is a promising method for the quantitative assessment of gene methylation. [source]

Chemical genomic screening for methylation-silenced genes in gastric cancer cell lines using 5-aza-2,-deoxycytidine treatment and oligonucleotide microarray

CANCER SCIENCE, Issue 1 2006
Satoshi Yamashita
To identify novel methylation-silenced genes in gastric cancers, we carried out a chemical genomic screening, a genome-wide search for genes upregulated by treatment with a demethylating agent, 5-aza-2,-deoxycytidine (5-aza-dC). After 5-aza-dC treatment of a gastric cancer cell line (AGS) 579 genes were upregulated 16-fold or more, using an oligonucleotide microarray with 39 000 genes. From these genes, we selected 44 known genes on autosomes whose silencing in gastric cancer has not been reported. Thirty-two of these had CpG islands (CGI) in their putative promoter regions, and all of the CGI were methylated in AGS, giving an estimated number of 421 ± 75 (95% confidence interval) methylation-silenced genes. Additionally, we analyzed the methylation status of 16 potential tumor-related genes with promoter CGI that were upregulated four-fold or more, and 14 of these were methylated in AGS. Methylation status of the 32 randomly selected and 16 potential tumor-related genes was analyzed in 10 primary gastric cancers, and 42 genes (ABHD9, ADFP, ALDH1A3, ANXA5, AREG, BDNF, BMP7, CAV1, CDH2, CLDN3, CTSL, EEF1A2, F2R, FADS1, FSD1, FST, FYN, GPR54, GREM1, IGFBP3, IGFBP7, IRS2, KISS1, MARK1, MLF1, MSX1, MTSS1, NT5E, PAX6, PLAGL1, PLAU, PPIC, RBP4, RORA, SCRN1, TBX3, TFAP2C, TNFSF9, ULBP2, WIF1, ZNF177 and ZNF559) were methylated in at least one primary gastric cancer. A metastasis suppressor gene, MTSS1, was located in a genomic region with frequent loss of heterozygosity (8q22), and was expressed abundantly in the normal gastric mucosa, suggesting its role in gastric carcinogenesis. (Cancer Sci 2006; 97: 64 ,71) [source]

Frequent hypomethylation in multiple promoter CpG islands is associated with global hypomethylation, but not with frequent promoter hypermethylation

CANCER SCIENCE, Issue 1 2004
Atsushi Kaneda
Hypomethylation of the global genome, considered to be composed mainly of repetitive sequences, is consistently observed in cancers, and aberrant hypo- and hypermethylation of CpG islands (CGIs) in promoter regions are also observed. Since methylation alterations in unique promoter sequences and in other genomic regions have distinct consequences, we analyzed the relationship between the global hypomethylation and the hypomethylation of unique promoter CGIs using human gastric cancers. Seven of ten gastric cancer cell lines showed marked decreases in 5-methylcytosine content, which correlated with hypomethylation of the LINE1 repetitive sequence. Six of the seven cell lines showed hypomethylation in five or all of the six normally methylated CGIs in promoter regions of six genes, and this was associated with induction of aberrant expression. The remaining three cell lines without global hypomethylation showed promoter hypomethylation in one or none of the six CGIs. Frequent promoter hypomethylation, however, did not correlate with frequent promoter hypermethylation. In primary gastric cancers too, global hypomethylation was associated with hypomethylation of LINE1 repetitive sequence and promoter hypomethylation. Of 93 gastric cancers, 33 cancers with frequent promoter hypomethylation and 27 cancers with frequent promoter hypermethylation constituted different groups. These findings represent experimental evidence that frequent hypomethylation of normally methylated promoter CGIs is associated with global hypomethylation, and that these hypomethylations occur independently of frequent promoter CGI hypermethylation. (Cancer Sci 2004; 95: 58,64) [source]