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Hidetaka Eguchi

Publications and source records attributed to Hidetaka Eguchi.

15 recordsLinked to original sources
PubMed2007

The presence of BRAF point mutation in adult papillary thyroid carcinomas from atomic bomb survivors correlates with radiation dose.

In papillary thyroid carcinogenesis, the constitutively activated mitogen-activated protein (MAP) kinase signaling pathway caused by a genetic alteration such as RET/PTC rearrangement or mutation of RAS and BRAF genes, is thought to be a major early event. Among these, the recently identified BRAF(V600E) mutation has been found at high frequency in adult patients with papillary thyroid carcinoma (PTC). However, the association between this mutation and radiation exposure in adult PTC is still unknown. In this study, we examined the BRAF(V600E) mutation in 64 PTCs among adult atomic bomb survivors in Hiroshima, Japan, comprising 17 nonexposed (0 mGy) and 47 exposed patients who developed the carcinoma after the bombing, and assessed the association of BRAF(V600E) mutation with clinico-pathological and epidemiological variables. The median radiation dose in PTCs with the BRAF(V600E) mutation was significantly lower than that without the mutation (18.5 vs.156.9 mGy, Wilcoxon rank-sum test, P=0.022). A significant difference was found in the median latency period (years elapsed from atomic bombing to diagnosis) between exposed patients with and without BRAF(V600E) mutation (29 vs. 21 yr, Wilcoxon rank-sum test, P=0.014). These findings were further confirmed by logistic regression analysis with BRAF(V600E) mutation status as a dependent variable and taking into account possible interactions between the variables. We found that the log-transformed radiation dose and latency period were independently associated with the BRAF(V600E) mutation (P=0.039 and P=0.010, respectively). These results suggest that involvement of BRAF mutation in thyroid carcinogenesis in exposed people may differ from that in the nonexposed people.

Adult↗
PubMed2006

Mutation profile of EGFR gene detected by denaturing high-performance liquid chromatography in Japanese lung cancer patients.

PURPOSE: EGFR mutations in lung cancer increase sensitivity to an EGFR tyrosine kinase inhibitor, gefitinib. Mutation analysis of EGFR is essential for prediction of gefitinib response and avoidance of the coincidental severe side effects for the unresponsive population. The purpose of the present study is to apply DHPLC as a screening system of detection of EGFR mutations for large scaled population. METHODS: EGFR mutations were detected by both DHPLC procedure and direct sequencing using lung cancer tissue samples obtained from 97 patients (81 surgical specimens and 16 pleural effusions of non-resectable lung cancer patients). RESULTS: DHPLC analysis detected EGFR mutations in 5 h as opposed to 18 h by direct sequencing for ten samples, and it costs eightfold more expensive by direct sequencing than DHPLC. In addition, DHPLC analysis was sixfold more sensitive than sequencing analysis for detection of the point mutation of exon 21, L858R. Using this system, EGFR mutations in exons 18, 19 and 21 were found in 34 of 97 patients (36%). Thirteen of the 15 patients with exon 21 mutations (87%) were female non-smokers, who were diagnosed with adenocarcinomas with the feature of BAC. Eight of the 18 patients with exon 19 mutations (44%) were 7 male and 1 female current or former smokers, and BAC feature was observed in 61% (8/18). CONCLUSION: DHPLC analysis for screening followed by sequencing analysis appears to be more sensitive and accurate, as well as easier and faster. In addition, these results suggest different mutagenesis and carcinogenesis pathways for mutations.

Base Sequence↗
PubMed2006

Development of a novel method to detect Helicobacter pylori cagA genotype from paraffin-embedded materials: comparison between patients with duodenal ulcer and gastric cancer in young Japanese.

BACKGROUND/AIM: cagA gene polymorphism of Helicobacter pylori contributes to clinical outcome of patients. We investigated the implication of the cagA polymorphism in young Japanese patients using paraffin-embedded sections. METHODS: We studied 71 young patients with gastric cancer or with duodenal ulcer. H. pylori infection was confirmed by sections with Giemsa staining and immunohistochemical staining and the degree of gastritis was evaluated. DNA was extracted from paraffin-embedded sections of 20 patients both from the gastric corpus and the antrum. A portion of cagA gene was amplified with polymerase chain reaction, followed by direct sequencing of the fragment. RESULTS: We established a novel method to determine the cagA subtype using paraffin-embedded sections. We found that all the samples possessed East-Asian type cagA both in the corpus and the antrum, not only in patients with gastric cancer but also with duodenal ulcer. Although the cagA gene sequence was completely identical between the gastric corpus and the antrum in all patients, the corpus gastritis was more prominent in patients with gastric cancer than those with duodenal ulcer. CONCLUSIONS: cagA polymorphism can be evaluated with the use of paraffin-embedded sections. The degree of corpus gastritis may not be regulated by cagA diversity only.

Adult↗
PubMed2006

Improved RT-PCR amplification for molecular analyses with long-term preserved formalin-fixed, paraffin-embedded tissue specimens.

Recently, in addition to DNA, RNA extracted from archival tissue specimens has become an invaluable source of material for molecular biological analysis. Successful amplification with PCR/RT-PCR is problematic when using amplicons of short size due to degradation of DNA or RNA. We established an improved method for efficient RT-PCR amplification of RNA extracted from archival formalin-fixed, paraffin-embedded tissue by the elimination of RNA modification and the restoration of RNA template activity. Namely, the preheating in citrate buffer (pH 4.0) of RNA extracted from long-term preserved tissue specimens resulted in significantly increased efficiency of RT-PCR.

Buffers↗
PubMed2005

A single nucleotide polymorphism in the extracellular domain of TRAIL receptor DR4 at nucleotide 626 in gastric cancer patients in Japan.

Death receptor 4 (DR4) is a member of the tumor necrosis factor-related apoptosis-inducing ligand receptor genes. A single nucleotide polymorphism (Thr or Arg, C or G) in the extracellular domain was reported to be associated with a risk of lung cancer, head and neck cancer, and bladder cancer. In this study, we examined the association between the DR4 polymorphism and gastric cancer. The Thr/Thr, Thr/Arg and Arg/Arg genotypes were found in 250 (91.2%), 23 (8.4%) and 1 (0.4%) of 274 gastric cancer patients and in 317 (92.2%), 21 (6.1%) and 6 (1.7%) of 344 control subjects, respectively. The OR of Thr/Arg or Arg/Arg genotype did not reveal a significantly enhanced risk of 1.13 (95% CI, 0.63-2.00) compared to Thr/Thr genotype, suggesting that the DR4 polymorphism did not modify the risk of gastric cancer. In patients, no association between the genotype and clinicopathological characteristics (depth of invasion, lymph node metastasis, distant metastasis, stage and grade of differentiation) of gastric carcinoma was found. DR4 was constantly expressed in gastric carcinoma, but not in non-neoplastic gastric epithelium in immunohistochemistry. In conclusion, a Thr to Arg single nucleotide polymorphism in the extracellular domain of DR4 could not be associated with the development and progression of gastric cancer.

Adenocarcinoma↗
PubMed2004

Prediction of prognosis of estrogen receptor-positive breast cancer with combination of selected estrogen-regulated genes.

Estrogen receptor (ER)-positive breast cancer is a distinct subpopulation of breast cancer exhibiting a high response rate to endocrine therapy. However, not all ER-positive patients respond to the therapy, and a subgrouping of ER-positive patients based on the physiology of estrogen signaling is expected to be useful for predicting the prognosis. This study has revealed that selected estrogen-regulated genes (ERGs) are useful in identification of a poor-prognosis population among ER-positive breast cancer patients. First, the expression levels of 11 ERGs, selected based on our earlier microarray study in cultured cells, were analyzed by means of real-time reverse transcription-PCR in 14 ER-positive human breast cancer tissues. The patients were clearly divided into two groups in cluster analysis. Then, we examined the expression levels of two representative ERGs, histone deacetylase 6 (HDAC6) and insulin-like growth factor binding protein 4 (IGFBP-4), in 62 ER-positive patients with immunohistochemistry to assess the impact of ERG expression on prognosis (median follow-up 4409 days). Positive HDAC6 staining was significantly correlated with a lower disease-free survival rate. Moreover, when the expression level of HDAC6 was assessed in combination with IGFBP-4 expression in the nucleus, the poor-prognosis patients were more accurately identified. This study has identified new candidate ERGs for prediction of prognosis, and we suggest that combined assessment of the expression levels of these ERGs will contribute to the clinically useful stratification of ER-positive breast cancer patients.

Adult↗
PubMed2003

Hypoxia-inducible factor-1alpha polymorphisms associated with enhanced transactivation capacity, implying clinical significance.

Hypoxia-inducible factor-1 (HIF-1) is a pivotal factor that regulates cellular responses to hypoxia and is presumably linked to regulation of angiogenesis and tumor growth. We assessed the difference in transcription activity of two HIF-1alpha polymorphic variants (P582S and A588T), along with molecular epidemiological study among head and neck squamous cell carcinoma (HNSCC) patients. Both HIF-1alpha variants revealed significantly higher transcription activity than wild-type (WT) did, under normoxic and hypoxic conditions (P < 0.02). Furthermore, tumors from HNSCC patients with heterozygous alleles having P582S or A588T had significantly increased numbers of microvessels compared with those with homozygous WT (P = 0.02). In addition, all patients with tumors of T1 (below 2 cm diameter) were WT, while 14 of 47 patients with tumors of > or =T2 were heterozygous. The elevated transactivation capacity of variant forms of HIF-1alpha implies a role of HIF-1alpha polymorphisms in generating individually different tumor progression.

Amino Acid Sequence↗
PubMed2003

Estrogen receptor (ER) beta1 and ERbetacx/beta2 inhibit ERalpha function differently in breast cancer cell line MCF7.

Estrogen receptor (ER) alpha plays an important role in the proliferation and progression of breast cancer. In order to explore the function of wild-type ERbeta (ERbeta1) and its variant form, ERbetacx/beta2, stable transformants of ERalpha-positive breast cancer MCF7 cells with ERbeta1 or ERbetacx/beta2 expression vector were established. Constitutive expression of ERbeta1 or ERbetacx/beta2 reduced the S phase population of the cell cycle in dish culture and the number of colonies in an anchorage-independent assay. DNA-protein complexes of ERE with nuclear extracts from ERbeta1 transformants were observed in the electrophoretic mobility shift assay, while no complex was observed for ERbetacx/beta2 transformants. Reporter gene assay using estrogen-responsive element (ERE)-luciferase showed less responsiveness to estrogen in these transformants compared with parental cells. Endogenous mRNA expression of two known estrogen-responsive genes, cathepsin D and IGFBP4, was weakly induced by estrogen in ERbeta1 and ERbetacx/beta2 transformants compared with parental cells. A comprehensive gene expression analysis using our custom-made cDNA microarray showed that MCF7 and ERbeta1 transformants had a similar gene expression profile, whereas ERbetacx/beta2 showed a distinct profile from others. These results indicate that ERbeta1 and ERbetacx/beta2 inhibit ERalpha function differently in MCF7 cells.

Breast Neoplasms↗
PubMed2003

Can teatime increase one's lifetime?

Lifestyle-related diseases, including cancer and cardiovascular disease, are also characterized as aging-related diseases, where aging may be the most potent causal factor. In light of this, prevention of lifestyle-related diseases will depend on slowing the aging process and avoiding the clinical appearance of the diseases. Green tea is now accepted as a cancer preventive on the basis of numerous in vitro, in vivo and epidemiological studies. In addition, green tea has also been reported to reduce the risk of cardiovascular disease. We found an apparent delay of cancer onset/death and all cause deaths associated with increased consumption of green tea, specifically in ages before 79 in a prospective cohort study of a Japanese population with 13-year follow-up data. This is consistent with analyses of age-specific cancer death rate and cumulative survival, indicating a significant slowing of the increase in cancer death and all cause death with aging. These results indicate that daily consumption of green tea in sufficient amounts will help to prolong life by avoiding pre-mature death, particularly death caused by cancer.

Aged↗
PubMed2002

Estrogen receptor-mediated effects of tamoxifen on human endometrial cancer cells.

Tamoxifen is an estrogen receptor (ER)-antagonist that is widely used for the treatment of breast cancer, although it increases the risk of endometrial cancer. The mechanism mediating the stimulatory effect of tamoxifen on endometrial cancer is presently unknown. In this study we examined the effects of tamoxifen on Ishikawa 3H-12 endometrial cancer cells and MCF-7 breast cancer cells. Ishikawa cell growth was stimulated by 4-hydroxytamoxifen and accompanied by increased transcriptional activity of the endogenous ER. These stimulatory effects did not occur in MCF-7 cells. The relative transcriptional activity of the activation function (AF) 1 domain of ERalpha compared with that of the AF2 domain was 4-fold higher in Ishikawa cells than in MCF-7 cells. Mitogen-activated protein (MAP) kinase, which stimulates the transcriptional activity of AF1, was constitutively activated in Ishikawa cells, but not in MCF-7 cells. These observations suggest that the constitutively activated MAP kinase-signaling pathway in Ishikawa cells enhances the transcriptional activity of ERalpha via the AF1 domain. This ERalpha activation pathway may be involved in the stimulatory effect of tamoxifen on the development and/or progression of endometrial cancer.

Adenocarcinoma↗
PubMed2002

Estrogen receptor beta is expressed in human stomach adenocarcinoma.

PURPOSE: In stomach adenocarcinoma, the role of the hormonal receptor, estrogen receptor (ER), has been controversial. Recently, a new estrogen receptor, called estrogen receptor beta (ER beta), was found to be expressed in various tissues including normal gastrointestinal tract. In this paper, the expression of ER beta in stomach adenocarcinomas has been investigated for the first time, specifically in signet ring cell adenocarcinomas, together with surrounding non-cancerous tissues. METHODS: By immunohistochemistry the expression of ER alpha and beta was studied in 29 stomach adenocarcinomas, ten signet ring cell adenocarcinomas, and 19 other adenocarcinomas. Western blotting was performed to examine the immunohistochemical result. Statistical studies (Student's t test and chi(2)-test) explored the relation between the immunohistochemical result and clinicopathological characteristics. RESULTS: All 29 adenocarcinomas, including the signet ring cell ones, demonstrated clear ER beta nucleus staining. Lymphocytes, venous endothelial cells, smooth muscle, and non-cancerous stomach glands also showed strong ER beta staining, while no staining was observed in the immunohistochemistry of ER alpha. Western blotting showed equivalent ER beta protein levels in cancerous and non-cancerous tissues, which was consistent with the results of immunohistochemical staining. Among signet ring cell adenocarcinomas of the stomach, cytoplasm were stained in addition to nuclei, specifically in patients under the age of 40 years. CONCLUSIONS: Our results imply that the effects of estrogen in stomach cancer, as well as those in normal stomach, may be mediated by ER beta, and that the role of ER beta may differ by the subtype of stomach adenocarcinoma - specifically signet ring cell adenocarcinomas and other ones - although large scale samples are needed to confirm these findings.

Adenocarcinoma↗
PubMed2002

Estradiol stabilizes p53 protein in breast cancer cell line, MCF-7.

Overexpression of the oncoprotein MDM2, an important regulator of the p53 tumor suppressor protein, is often observed in breast cancer tissues and cell lines, particularly in those which express estrogen receptor alpha (ERalpha). In MCF-7 breast cancer cell line possessing wild-type p53, ERalpha, and overexpressing MDM2, p53 accumulation was stimulated by 17beta-estradiol (E2) in a concentration-dependent manner. On the other hand, E2 caused no change of the expression of p53 mRNA, indicating that E2 affects p53 at the post-transcriptional level. To analyze the mechanism of p53 accumulation by E2, the stability of p53, ERalpha and MDM2 proteins was analyzed in the presence of cycloheximide under an E2-supplemented or -depleted condition. E2 significantly extended the half-life of p53 protein, but shortened that of ERalpha in MCF-7 cells. E2 significantly decreased the stability of p90(MDM2) and p60(MDM2) in MCF-7. Interestingly, E2 increased the ratio p60(MDM2)/p90(MDM2) inversely proportionally to the degradation of p53. These results suggest that the ratio of the two MDM2 proteins, p90(MDM2) and p60(MDM2), may affect the accumulation of wild-type p53 protein in response to E2.

Blotting, Northern↗
PubMedDate not supplied

Distinct promoter usage of mdm2 gene in human breast cancer.

Human breast cancers, especially estrogen receptor alpha (ER(alpha))-positive ones, often overexpress the oncoprotein MDM2 without mdm2 gene amplification. The mdm2 gene is transcribed into two different mRNAs, namely L-mdm2 and S-mdm2, which are generated from promoters P1 (constitutive) and P2 (regulated by tumor suppressor p53), respectively. To cast light on the mechanisms of MDM2 overexpression, we measured the expression levels of these mdm2 mRNAs using RT-PCR analysis in three human breast cancer cell lines and 15 breast cancer samples obtained from surgery. ER(alpha)-positive MCF-7 cells, which possess wild-type p53, displayed dominant expression of S-mdm2. In contrast, two other cell lines with mutant p53, T47-D (ER(alpha)-positive) and MDA-MB-231 (ER(alpha)-negative), showed almost equivalent expression of L-mdm2 and S-mdm2. Treatment of 17beta-estradiol (E2) significantly enhanced the expression of S-mdm2 but not that of L-mdm2 in MCF-7. Among 6 breast cancer samples regarded as ER(alpha)-positive with wild-type p53, 5 samples showed increased expression of S-mdm2. Expression of S-mdm2 was stimulated in 2 ER(alpha)-positive samples with mutant p53. In contrast, 4 of 5 samples which express mutant p53 without ER(alpha) showed poor expression of S-mdm2. There is a tendency that ER(alpha)-positive breast cancers with wild-type p53 preferably use P2 promoter for the expression of mdm2, possibly through E2-induced accumulation of p53. However, wild-type p53 and ER(alpha) are not necessarily enough for the utilization of S-mdm2. Tumors with mutant p53 also showed expression of S-mdm2 in some cases. These results strongly suggest that other factor(s) is also implicated in the promoter usage of mdm2 gene in human breast cancer tissues.

Adult↗
PubMedDate not supplied

Minimal sizes of cases with a susceptible genotype and minimal odds ratios among susceptible individuals in case-control studies.

OBJECTIVE: Disease risk elevation due to an environmental factor only for individuals with a susceptible genotype is a typical example of gene-environment interaction. In order to identify risk factors interacting with susceptible genotypes in case-control studies, presumptions on minimal size of cases with the susceptible genotype (S (min)) and odds ratio (OR) among the susceptible individuals (OR(susceptible)) are useful. MODEL: Proportion of exposed cases (P(1)) and OR for whole cases (OR(whole)) statistically detectable in a case-control study can be calculated in a conventional method. P(1) was assumed to be a weighted sum of the exposed among cases with the genotype (P(x)) and cases without the genotype (equal to proportion of the exposed among controls, P(0)), i.e., S P(x) + (1 - S) P0, where S is the size (proportion) of cases with the genotype. For each calculated P(1), S became the minimum (S(min)) in case of P(x) = 1. OR(susceptible) was calculated by {P(x) (1 - P(0))} / {(1 - P(x)) P(0)}. RESULTS: S(min) and OR(susceptible) were listed for the combinations of the above components. For example, a detectable P(1) was 0.638 for P(0)=0.5 in a case-control study with 200 cases (N(1)) and 200 controls (N(0)), when a error of a two-sided test was 0.05 with an 80% of power. In case of P(1)=0.638, OR(whole) was 1.77, producing S(min) = 0.277 for infinite OR(susceptible). It indicates that an environmental factor cannot be detected in case that a high-risk genotype frequency is less than 0.277. INTERPRETATION: If the size of cases with a susceptible genotype is expected to be less than S(min), case-control studies are unlikely to detect a significant OR of the environmental factor.

Case-Control Studies↗