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Biomedical subjects

Yong Shin

Publications and source records attributed to Yong Shin.

14 recordsLinked to original sources
PubMed2006

Analysis of microsatellite instability in stool DNA of patients with colorectal cancer using denaturing high performance liquid chromatography.

AIM: To evaluate the usefulness of denaturing high performance liquid chromatography (DHPLC) for analyzing microsatellite instability (MSI) status in stool DNA of patients with colorectal cancer. METHODS: A total of 80 cancer tissues from patients with primary sporadic colorectal tumor (proximal cancer: 27, distal cancer: 53) and matched stool (which were employed for comparison with the tissues) were analyzed for MSI status in BAT 26. DNA samples extracted from stool were evaluated by nested polymerase chain reaction (PCR) and DHPLC for MSI analysis. RESULTS: Six cases (7.5%) of MSI were identified in BAT 26 from 80 cancer tissues. All the stool DNA samples from patients whose cancer tissue showed MSI also displayed MSI in BAT 26. CONCLUSION: As MSI is one of the established fecal DNA markers to screen colorectal cancer, we propose to use DHPLC for the MSI analysis in fecal DNA.

Biomarkers, Tumor↗
PubMed2005

Mutation spectrum of the APC gene in 83 Korean FAP families.

Familial adenomatous polyposis (FAP) is a clinically well-defined hereditary disease caused by germline mutations in the adenomatous polyposis coli (APC) gene. FAP is characterized by polyposis in the large bowel and variable extracolonic manifestations. With an increase of reported APC germline mutations, many reports have investigated genotype-phenotype correlations in FAP patients. Here, we analyzed the APC gene for germline mutations in 83 unrelated Korean FAP patients and investigated genotype-phenotype correlations. We identified germline APC mutations in 59 (71%) of the cases, including 34 frameshift mutations, 19 nonsense mutations, and six splice site mutations. Among 59 patients with the identified germline mutation of the APC gene, 37 had been reported previously and were included in the genotype-phenotype analysis. In the other 22 patients, we identified seven novel mutations: c.1438C>T, c.2232_2233dupCT, c.3426delT, c.3739_3769del31, c.3931_3935delATTGG, c.4332dupA, and c.4722_4725delACTA. Desmoid tumors were identified in six of the examined FAP patients, five of whom had APC germline mutations; these mutations involved codons 849, 864, 1309, 1444 and 1464, respectively (c.2547_2548delTA, c.2592_2593insCT, c.3927_3931delAAAGA, c.4332dupA and c.4391-4394delAGAG). Four of the included FAP patients had papillary thyroid cancers; all were female and had germline APC mutations (c.1863_1865delTTAincCT, c.2805C>A, c.3183_3187delACAAA and c.3927_3931delAAAGA).

Adenomatous Polyposis Coli↗
PubMed2005

Three novel VHL germline mutations in Korean patients with von Hippel-Lindau disease and pheochromocytomas.

Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited tumor syndrome associated with germline mutations in the VHL gene. VHL disease, as well as several other cancer syndromes, has been associated with an increased risk of pheochromocytomas, which are catecholamine-secreting tumors of the adrenal gland. VHL disease genotype-phenotype correlations have been well established based on the type of mutations in the VHL gene. However, although many groups have reported VHL germline mutations in different countries, no previous report has described VHL gene mutations in VHL disease and/or pheochromocytoma patients in Korea. In this study, we used direct sequencing to investigate VHL germline mutations in Korean patients with VHL disease or pheochromocytomas (11 VHL patients and 3 additional members from 7 families, 2 patients from 1 family with familial pheochromocytoma, and 2 cases of isolated pheochromocytoma). We found a total of 7 VHL germline mutations (6 missense and 1 frameshift), 3 of which were novel (323_324delGC, 355T>C and 361G>A). No VHL germline mutation was found in the 2 patients with isolated pheochromocytomas and paragangliomas. This study provides informative data for VHL germline mutations and VHL-related phenotypes in Korea.

Adrenal Gland Neoplasms↗
PubMed2004

A TP53-truncating germline mutation (E287X) in a family with characteristics of both hereditary diffuse gastric cancer and Li-Fraumeni syndrome.

Mutations in CDH1, which encodes E-cadherin, have been associated with hereditary diffuse gastric cancer (HDGC) in Western populations but have not been shown to play a major role in Asians. Recently, a patient with familial gastric cancer (FGC) was shown to harbor a germline mutation in the TP53 gene, which encodes p53 and has been previously associated with Li-Fraumeni Syndrome (LFS). To determine whether mutations in TP53 are associated with FGC in Asians, we screened the entire coding region of TP53 in probands from 23 Korean FGC families. We identified a nonsense (E287X) TP53 germline mutation in a family whose history is compatible with both HDGC and LFS. Two members of this family (SNU-G2) were afflicted with brain tumors, seven with gastric cancers, two with sarcomas, and one with both gastric cancer and a sarcoma. The E287X TP53 mutation segregated with the cancer phenotype in the family members from whom DNA samples were available. To our knowledge, this is the first report of a large family with both HDGC and LFS. Our results suggest that TP53 mutational screening in FGC families should be interpreted with caution because additional TP53 mutation-carrying HDGC families may also show LFS-related phenotypes.

Base Sequence↗
PubMed2004

A functional polymorphism (-347 G-->GA) in the E-cadherin gene is associated with colorectal cancer.

E-cadherin, the main adhesion molecule of epithelial cells, has been implicated in carcinogenesis because its expression is frequently lost in human epithelial cancers. E-cadherin protein expression is significantly reduced in sporadic colorectal cancers (CRC), but apparently not as a consequence of allele loss or somatic mutation. We reported recently that a single nucleotide polymorphism (-347 G-->GA) in the E-cadherin promoter suppressed E-cadherin expression and was associated with familial gastric cancer. Here we sought to investigate whether the functional polymorphisms of E-cadherin might affect CRC. We genotyped 407 individuals (260 CRC patients and 147 normal controls) for the -347 G-->GA promoter polymorphism of E-cadherin using denaturing high-performance liquid chromatography and direct sequencing. We also measured the activity of promoters harboring the polymorphism by dual luciferase reporter assay in several CRC cell lines. We found that the E-cadherin GA genotype (G/GA heterozygous and GA homozygous) was more common in CRC patients than in normal controls (P = 0.011). Subjects with the E-cadherin GA genotype had an overall 1.75-fold increased risk of CRC. We also observed an increased risk association between the E-cadherin GA genotype and both proximal colon (P = 0.019) and distal CRC (P = 0.036). Interestingly, the GA allele decreased transcriptional efficiency by 12-, 9- and 10-fold compared with the G allele in SNU-C4, SNU-C5 and SNU-1033 cell lines, respectively. Additionally, we examined whether there was a correlation between the E-cadherin promoter polymorphism and microsatellite instability status, and found no such correlation. Taken together, our results suggest that the E-cadherin -347 G-->GA polymorphism may be associated with CRC.

Adenine↗
PubMed2004

The E-cadherin -347G->GA promoter polymorphism and its effect on transcriptional regulation.

E-cadherin plays a critical role in epithelial cell-cell adhesion and maintenance of tissue architecture. Loss of E-cadherin expression in humans has been associated with cancer, and a number of cancer-related mutations have been identified. Here, we sought to investigate whether the -347G-->GA single nucleotide polymorphism affects the transcriptional activity of the E-cadherin gene. First, we measured the promoter activity of the -347G-->GA polymorphism using a dual luciferase reporter assay and electrophoretic mobility shift assay (EMSA). The dual luciferase reporter assay showed that the GA allele decreased the transcriptional efficiency by 10-fold (P < 0.001) compared with the G allele. Similarly, EMSA revealed that the GA allele had a weak transcription factor binding strength compared with the G allele. We then examined the frequency of this polymorphism in familial gastric cancer (FGC) patients by denaturing high-performance liquid chromatography. We found that the E-cadherin genotype (-347G/GA heterozygous or GA homozygous) was associated with FGC patients (P < 0.05) compared with the G homozygous genotype. Taken together, these results suggest that the GA allele may cause weak transcription factor binding affinity and low transcriptional activity in E-cadherin expression.

Alleles↗
PubMed2004

Identification of genes with differential expression in acquired drug-resistant gastric cancer cells using high-density oligonucleotide microarrays.

PURPOSE: A major obstacle in chemotherapy is treatment failure due to anticancer drug resistance. The emergence of acquired resistance results from host factors and genetic or epigenetic changes in the cancer cells. The purpose of this study was to identify differentially expressed genes associated with acquisition of resistance in human gastric cancer cells. EXPERIMENTAL DESIGN: We performed global gene expression analysis in the acquired drug-resistant gastric cancer cell lines to the commonly used drugs 5-fluorouracil, doxorubicin, and cisplatin using Affymetrix HG-U133A microarray. The gene expression patterns of 10 chemoresistant gastric cancer cell lines were compared with those of four parent cell lines using fold-change and Wilcoxon's test for data analysis. RESULTS: We identified over 250 genes differentially expressed in 5-fluorouracil-, cisplatin-, or doxorubicin-resistant gastric cancer cell lines. Our expression analysis also identified eight multidrug resistance candidate genes that were associated with resistance to two or more of the tested chemotherapeutic agents. Among these, midkine (MDK), a heparin-binding growth factor, was overexpressed in all drug-resistant cell lines, strongly suggesting that MDK might contribute to multidrug resistance in gastric cancer cells. CONCLUSIONS: Our investigation provides comprehensive gene information associated with acquired resistance to anticancer drugs in gastric cancer cells and a basis for additional functional studies.

Antineoplastic Agents↗
PubMed2004

Promoter hypermethylation and silencing of CHFR mitotic stress checkpoint gene in human gastric cancers.

CHFR is a recently identified mitotic stress check-point gene. CHFR is ubiquitously expressed in normal human tissues, whereas loss of CHFR expression has been observed in human tumors. Silencing of CHFR has been associated with aberrant promoter methylation and histone deacetylation in several cancer types. In this study, we investigated epigenetic CHFR inactivation in human gastric cancers by examining CHFR expression and methylation status in gastric cancer cell lines with RT-PCR analysis, bisulfite PCR and sequencing. A series of primary gastric tumors were also analyzed for CHFR methylation. Eight of 12 (66.7%) gastric cancer cell lines and 19/43 (44.2%) primary gastric tumors showed CHFR methylation. In addition, CpG methylation status correlated well with CHFR expression in the human gastric cancer cell lines, in which treatment with 5-aza-dC resulted in de novo or enhanced expression of CHFR. Combination treatment of 5-aza-dC with trichostatin A showed a synergistic effect on CHFR expression in some cases. Our results indicate that aberrant promoter methylation of the CHFR gene was observed in a significant proportion of human gastric cancers and was responsible for the inactivation of the CHFR gene in gastric cancers.

Base Sequence↗
PubMed2003

Mutational analysis of BRAF and K-ras in gastric cancers: absence of BRAF mutations in gastric cancers.

Recently, BRAF mutations were found in a variety of human cancers. Interestingly, the most common of BRAF mutation (V599E) has not been identified in tumors with K-ras mutations. Whereas the majority of human cancer types has been screened for BRAF mutations, no detailed studies on gastric cancers have been investigated. Thus, we decided to investigate the incidence of BRAF mutations in gastric cancers, and the relationship between BRAF and K-ras mutations in such cancers. Three non-pathogenic BRAF polymorphisms and seven K-ras missense mutations were found in 66 gastric cancers and 16 gastric cancer cell lines. Although only 9% of our gastric cancer panels had K-ras mutations, the incidence of BRAF mutations was not high. Thus, BRAF mutations, which are present in a variety of other human cancers, do not seem to be involved in gastric cancer development.

Base Sequence↗
PubMed2003

Robust microsatellite instability (MSI) analysis by denaturing high-performance liquid chromatography (DHPLC).

Microsatellite instability (MSI) plays an important biological role in various types of cancers, and especially in colorectal cancers. This study aimed to develop a simple, efficient, new method for robust MSI analysis. DNA was extracted from 175 (105 proximal colon and 70 distal colorectal) cancer samples and matched normal tissues, and five Bethesda microsatellite markers (BAT-25, BAT-26, D5S346, D2S123, and D17S250) were examined for MSI by denaturing high-performance liquid chromatography (DHPLC) analysis at a temperature of 50 degrees C and a flow rate of 0.9 ml/min. It took just 9 min per PCR product to determine MSI or microsatellite stability (MSS) using the new protocol. The DHPLC results were confirmed with conventional gel-based electrophoresis and capillary-based sequencing method. Of 175 samples, 45 (26%) showed high microsatellite instability (MSI-H), 12 (7%) showed low microsatellite instability (MSI-L), and 118 (67%) showed MSS. All MSI samples were deletion mutants and all 12 MSI-L cases had MSI in dinucleotide markers (D5S346, D2S123, and D17S250). MSI was significantly associated with proximal colon cancers ( p<0.0001), as previously reported. The MSI-H tumors were also associated with tumor node metastasis (TNM) I/II stages ( p=0.05) and high-grade tumors ( p<0.01). Here, we propose a DHPLC-based method as an alternative for MSI analysis.

Chemistry Techniques, Analytical↗
PubMed2003

Development and applications of a beta-catenin oligonucleotide microarray: beta-catenin mutations are dominantly found in the proximal colon cancers with microsatellite instability.

beta-catenin mutations have been identified in a variety of human malignancies; most of these are missense mutations restricted at hot-spot areas in exon 3. beta-catenin mutations are known to be highly associated with colorectal cancers with microsatellite instability (MSI). More than 70 beta-catenin mutations have been reported in colorectal cancers, and approximately 90% of beta-catenin mutations have been found in 11 codons (codons 29, 31, 32, 33, 34, 35, 37, 38, 41, 45, and 48) as missense mutations or in-frame deletions. We have developed an oligonucleotide microarray for detecting beta-catenin mutations at these 11 codons. The developed oligonucleotide microarray can detect a total of 110 types of beta-catenin mutations, including the 60 mutations reported previously. Nine beta-catenin mutations were identified in this study by five different methods, i.e., PCR- single-strand conformational polymorphism, denaturing high performance liquid chromatography, direct sequencing, cloning-sequencing, and with an oligonucleotide microarray. All nine of the mutations were identified by denaturing high performance liquid chromatography, cloning-sequencing, and by the oligonucleotide microarray. However, PCR-single-strand conformational polymorphism missed 1 beta-catenin mutation and direct sequencing missed 2. Five beta-catenin mutations from 74 colorectal carcinomas (34 proximal colon cancers and 40 distal colorectal cancers) and 4 beta-catenin mutations from 31 colorectal cancer cell lines (7 from the proximal colon, 6 from the distal colorectum, and 18 unknown) were identified. In colorectal carcinomas, all 5 of the beta-catenin mutations were found in proximal colon tumors. In colorectal cancer cell lines, 2 of 4 cell lines with beta-catenin mutations originated from the proximal colon, and the remaining 2 cell lines were simply described as having originated from the colon. Considering the relationships among beta-catenin mutations, MSI, and tumor location, the frequency of beta-catenin mutations was found to be meaningfully higher in colorectal carcinomas with MSI than in those with microsatellite stability (P < 0.001); moreover, MSI was found to be more frequent in proximal colon tumors (P < 0.01). In addition, beta-catenin mutations were also found to be associated with proximal colon cancer (P = 0.017).

Adult↗
PubMed2002

Germline mutations of BRCA1 and BRCA2 in Korean breast and/or ovarian cancer families.

Germline mutations in the BRCA1 and BRCA2 genes are responsible for the predisposition and development of familial breast and/or ovarian cancer. Most mutations of BRCA1 and BRCA2 associated with breast and/or ovarian cancer result in truncated proteins. To investigate the presence of BRCA1 and BRCA2 germline mutations in Korean breast and/or ovarian cancer families, we screened a total of 27 cases from 21 families including two or more affected first- or second-degree relatives with breast and/or ovarian cancer. PTT, PCR-SSCP, and DHPLC analysis, followed by sequencing were used in the screening process. In nine families, we found BRCA1 and BRCA2 germline mutations that comprised four frameshift mutations and five nonsense mutations. All nine mutations led to premature termination producing shortened proteins. Among the nine mutations, three novel BRCA1 mutations (E1114X, Q1299X, 4159delGA) and two novel BRCA2 mutations (K467X, 8945delAA) were identified in this work.

BRCA1 Protein↗