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Wataru Yasui

Publications and source records attributed to Wataru Yasui.

83 records · Page 5Linked to original sources
PubMed2002

Increased expression of CHK2 in human gastric carcinomas harboring p53 mutations.

Human Chk1 and Chk2 are DNA damage-activated protein kinases that function as downstream mediators of ataxia-telangiectasia mutated (ATM), which is involved in G(2)/M cell cycle arrest. To clarify the relation between the expression of Chk1/Chk2 and p53 gene status in human gastric carcinomas, we examined expression of Chk1, Chk2 and p53 proteins in 87 gastric carcinomas by Western blotting and immunohistochemistry. We found a significant correlation between the expression levels of Chk1 and p53 proteins in gastric carcinomas (p = 0.016). Significant statistical association was also observed between levels of Chk2 and p53 proteins (p = 0.00024). To clarify the genetic alterations of p53 in gastric carcinomas, we performed PCR-SSCP analysis on 47 gastric carcinomas. Although we found that 5 of 7 (71%) gastric cancers expressed elevated levels of Chk1 had p53 mutation, there was not a statistically significant correlation between expression of Chk1 and genetic status of p53. We also found that 7 of 11 (78%) gastric carcinomas expressed elevated levels of Chk2 had p53 mutation, and this correlation was significant (p = 0.0157). We used a highly quantitative 5' nuclease fluorogenic RT-PCR method (TaqMan) to analyze the expression of Chk2 mRNA in 22 gastric carcinomas. Chk2 mRNA expression was higher in gastric carcinomas with p53 mutations compared to those harboring wild-type p53. A significant association was recognized between the expression of Chk2 mRNA and p53 mutational status (p = 0.031). Our findings support the hypothesis that expression of Chk2 protein is increased in gastric carcinomas with mutant p53. Chk1 and Chk2 may play important roles in the checkpoint function in human gastric carcinomas harboring p53 mutation when their functions are preserved to prevent cell cycle progression.

Adenocarcinoma, Papillary↗
PubMed2002

Expression of receptors for advanced glycation end-products (RAGE) is closely associated with the invasive and metastatic activity of gastric cancer.

The receptor for advanced glycation end-products (RAGE) is a newly recognized factor regulating cancer cell invasion and metastasis. This study investigated the expression of RAGE in gastric carcinomas and its association with invasion and metastasis. Of eight gastric cancer cell lines examined, seven constitutively expressed RAGE messenger ribonucleic acid (mRNA), MKN45 being the exception. RAGE protein expression of MKN28 cells treated with RAGE antisense S-oligodeoxynucleotide was nine times less than that of sense S-oligodeoxynucleotide-treated cells. Growth of cells under RAGE antisense S-oligodeoxynucleotide treatment was not different from that seen under sense S-oligodeoxynucleotide treatment in MKN28 (a cell line producing high levels of RAGE) and MKN45 (a non-RAGE-expressing cell line). RAGE antisense S-oligodeoxynucleotide treatment suppressed the invasive activity of RAGE-positive MKN28 cells, as estimated by in vitro invasion assay. The number of MKN28 cells invading the type IV collagen-coated membrane under RAGE antisense S-oligodeoxynucleotide treatment was significantly lower than under RAGE sense S-oligodeoxynucleotide treatment (p<0.0001). In contrast, antisense and sense S-oligodeoxynucleotide-treated RAGE-negative MKN45 cells showed no difference. A wound-healing assay showed that no RAGE antisense S-oligodeoxynucleotide-treated MKN28 cells migrated into the scraped area, whereas sense S-oligodeoxynucleotide-treated cells showed many budding nests in the scraped area. Immunohistochemistry of gastric carcinoma tissue showed that 62 (65%) of the 96 cases examined were RAGE-positive and that poorly differentiated adenocarcinomas preferentially expressed RAGE protein (38/42, 90%) (p<0.0001). Strong RAGE immunoreactivity was also correlated with depth of invasion and lymph node metastasis (p<0.0001). RAGE-positive cancer cells tended to be distributed at the invasive front of primary tumours and were detected in all metastatic foci in lymph nodes. In contrast, a major RAGE ligand, amphoterin, was expressed in 82 (85%) of the 96 cases, regardless of histological type and disease progression. RAGE expression appears to be closely associated with invasion and metastasis in gastric cancer.

Adenocarcinoma↗
PubMed2002

Distinct promoter hypermethylation of p16INK4a, CDH1, and RAR-beta in intestinal, diffuse-adherent, and diffuse-scattered type gastric carcinomas.

Hypermethylation of CpG islands in gene promoters is associated with silencing of various tumour suppressor genes. Recent studies of colorectal and gastric carcinomas have defined a CpG island methylator phenotype (CIMP), which involves the targeting of multiple genes by promoter hypermethylation. In this study, methylation-specific polymerase chain reaction (PCR) was performed to study methylation of CpG islands in the promoters of the p16(INK4a), cadherin 1 (CDH1), and retinoic acid receptor-beta (RAR-beta) genes in 45 gastric carcinomas and to investigate whether CDH1 and RAR-beta promoter hypermethylation is associated with CIMP-positive gastric carcinoma. CpG island hypermethylation of the p16(INK4a), CDH1, and RAR-beta promoters was detected in 12 (27%), 26 (58%), and 24 (53%) of the 45 gastric carcinomas, respectively. Hypermethylation of the p16(INK4a) promoter was more common in intestinal type than in diffuse type gastric carcinomas (p = 0.0023; Fisher's exact test) and was inversely associated with p53 mutations (p = 0.0225; Fisher's exact test). However, CDH1 and RAR-beta promoter hypermethylation was observed more frequently in diffuse-scattered type gastric carcinoma than in other types (intestinal and diffuse-adherent types) (p = 0.0175 and p = 0.0335, respectively; Fisher's exact test) and was not associated with p53 mutation status. Moreover, hypermethylation of the CDH1 and RAR-beta promoters occurred concordantly (p < 0.0001; Fisher's exact test). These results suggest that at least two types of promoter methylation status are involved in the development of the intestinal (p16(INK4a) promoter hypermethylation) and diffuse-scattered types (CDH1 and RAR-beta promoter hypermethylation) of gastric carcinoma.

Antigens, CD↗
PubMed2002

Induction of hRAD9 is required for G2/M checkpoint signal transduction in gastric cancer cells.

DNA damage triggers the activation of checkpoints that delay cell cycle progression to allow for DNA repair. Loss of G2 checkpoints provides a growth advantage for tumor cells undergoing aberrant mitosis. However, the precise mechanisms of G2 checkpoints acting in gastric cancer are unknown. Here, we analyzed the G2 checkpoint function in two gastric cancer cells, MKN-28 cells containing a mutant p53 gene and MKN-45 cells which have wild-type p53. Two agents damaging DNA, camptothecin (CPT) or ultraviolet light (UV), were utilized to trigger a G2 phase cell cycle checkpoint response in these tumor cells. Both CPT and UV inhibited the growth of MKN-45 cells, whereas they did not affect the growth of MKN-28 cells. CPT induced cell cycle arrest at the G2/M phase and enhanced the expression of human RAD9 (hRAD9) in MKN-45 cells. In addition, hRAD9 showed perinuclear staining and similar localization with Bcl-2 in MKN-45 cells but not in MKN-28 cells after having applied CPT or UV light. These results suggest that besides p53 activity, the induction of hRAD9 is required for G2/M checkpoint signal transduction in gastric cancer cells.

Adenocarcinoma↗
PubMed2002

[Molecular diagnosis of gastric cancer].

Based on the genetic and epigenetic abnormalities of cancer-related genes during the development and progression of gastric cancer, we have established a system of molecular-pathological diagnosis as a routine service in Hiroshima. Approximately 5,000 lesions of the stomach have been diagnosed and useful information on differential diagnosis, grade of malignancy, and tumor multiplicity has been obtained using this system. Further research on systemic gene expression profiles, epigenetic alterations, and genetic polymorphisms will improve the quality and efficiency of diagnosis. With the application of novel knowledge on molecular carcinogenesis and microarray techniques, molecular diagnosis will identify the characteristics of individual cancers and persons, which will lead to the development of personalized medicine.

Apoptosis↗
PubMedDate not supplied

No mutations of the Bub1 gene in human gastric and oral cancer cell lines.

Chromosomal instability is one of the most important characteristics underlying tumorigenesis. Certain colorectal cancers with chromosomal instability have been shown to have inactivation of a spindle assembly checkpoint party due to mutation of Bub1, a mitotic checkpoint gene. We performed sequencing analysis on reverse transcriptase-polymerase chain reaction (RT-PCR) product of the Bub1 cDNA (entire coding sequence) from 8 human gastric cancer cell lines. In addition, genomic PCR products of Bub1 exon 8, 10, 12, 15 and kinase domain from 9 oral cancer cell lines were analyzed by polymerase chain reaction-single-stand conformation polymorphism (PCR-SSCP). Although sequencing analysis of the Bub1 cDNA revealed several point mutations in 8 gastric cancer cell lines, we could not confirm the mutations by analyzing genomic DNA. Furthermore, genomic PCR-SSCP analysis revealed no mutations in exon 8, 10, 12, 15 and kinase domain of the Bub1 gene in any oral cancer cell lines examined. These results suggest that mutation of the Bub1 gene might not play a role in human stomach and oral carcinogenesis.

Codon↗
PubMedDate not supplied

Expression and distribution of human telomerase catalytic component, hTERT, in human breast tissues.

BACKGROUND: Activation of telomerase is essential in a variety of malignant tumors. However, the regulation of its activation and the expression of human telomerase reverse transcriptase (hTERT) are not fully understood in breast tissues. MATERIALS AND METHODS: In order to clarify this point, the telomerase activity was examined by telomeric repeat amplification protocol (TRAP) assay and quantified by hybridization protection assay (HPA) and, moreover, the expressions of hTERT mRNA and protein were examined by RT-PCR and immunohistochemistry, respectively. RESULTS: Telomerase activity and the expression of hTERT mRNA were detected in 41(75%) and 37(67%) cases among 55 breast carcinomas, respectively. However, the telomerase ZV activity was detected in only 14(40%) among 35 benign breast tumors. Strong correlation was observed between telomerase activity and hTERT mRNA expression, as described previously. Moreover, the strong expression of hTERT protein in the nucleus of the cell was detected in 30 (57%) cases among 53 breast carcinomas and weak expression of the protein was also detected in 11 (35%) cases among 31 benign breast tumors by immunohistochemistry. There were 12 breast carcinomas which had no telomerase activity. Three of them had hTERT mRNA and protein and in 3 other cases, only hTERT protein was detected. Five cases had the expression of mRNA but not the protein and it was only one case which had no activity and expression of hTERT mRNA and protein. However, in benign tumors, 14 (87.5%) cases among 16 TRAP-negative tumors had no mRNA and protein expression. CONCLUSION: These results indicate that complicated regulation might be involved in the regulation of telomerase activity and also the activation of the gene may be important in the carcinogenesis of human breast carcinomas.

Breast Neoplasms↗
PubMedDate not supplied

Induction mechanism of apoptosis by troglitazone through peroxisome proliferator-activated receptor-gamma in gastric carcinoma cells.

BACKGROUND: It has been reported recently that the antidiabetic thiazolidinediones not only induce fibroblast differentiation but also inhibit the growth of carcinoma cells. MATERIALS AND METHODS: In the present study, in order to elucidate the further mechanism of growth inhibition by troglitazone, the expression of cell cycle regulators and apoptotic regulators were examined by cDNA microarrays and Western blot analysis by gastric carcinoma cells. RESULTS: Six gastric carcinoma cell lines (TMK-1, MKN-1,7,28,45,74) were treated with 0.1, 1, 10, 100 microM of troglitazone in vitro. The growth of 5 cell lines were inhibited by troglitazone in a time- and dose-dependent manner. Interestingly, the expression of cyclin D mRNA and protein was decreased and that of p27 was increased in TMK-1 cells at 12 hours after troglitazone treatment, suggesting the induction of cell cycle arrest of the cells. On the other hand, DNA ladder formation was observed at 12 hours after treatment. Moreover, the expression of cytochrome C, caspases 3 and 8 and PARP genes was increased after treatment and the gradual reduction of Bcl-XL protein was observed, which indicate that the apoptotic signals were induced after treatment by troglitazone. CONCLUSION: These results suggest that the thiazolidinediones can be a new therapeutic tool for gastric carcinoma via cell cycle regulation and apoptosis.

Antineoplastic Agents↗
PubMedDate not supplied

DNA methylation of CHFR is not a predictor of the response to docetaxel and paclitaxel in advanced and recurrent gastric cancer.

BACKGROUND: Cell cycle checkpoint dysfunction is often associated with sensitivity to chemotherapeutic agents. In this study, the question of whether DNA methylation of CHFR, a mitotic checkpoint gene, can predict the response of advanced and recurrent gastric cancers (GCs) to docetaxel or paclitaxel was examined. MATERIALS AND METHODS: In a retrospective study, 41 patients with GC treated with paclitaxel alone (n=12) or a combination of docetaxel and S-1 (tegafur, 5-chloro-2,4-dihydroxypyridine, potassium oxonate) (n=29) were studied. The DNA methylation status of the CHFR gene was examined by combined bisulfite restriction analysis of DNAs from 41 GC tissues and the methylation status was compared to their sensitivity to chemotherapy. The levels of CHFR mRNA were measured by quantitative reverse transcription-PCR. RESULTS: DNA methylation of CHFR was found in 15 (36.6%) out of the 41 GC samples and the levels of CHFR mRNA were associated with the methylation status of CHFR (p = 0.034). In 41 samples of corresponding non-neoplastic mucosae, no DNA methylation of CHFR was detected. Among 12 patients treated with paclitaxel alone, only 1 (20.0%) of the 5 patients with CHFR methylation had a partial response (PR) to paclitaxel, whereas 3 (42.9%) of the 7 patients without CHFR methylation had a PR to paclitaxel (p = 0.836). In 29 patients treated with a combination of S-1 and docetaxel, there was no clear association between the CHFR methylation status and response to chemotherapy (p = 0.092). CONCLUSION: We conclude that the DNA methylation of CHFR alone cannot predict the response of advanced and recurrent GC to docetaxel or paclitaxel. Both paclitaxel and docetaxel may be effective for treatment of GC even if CHFR is expressed.

Adult↗