Mitsuru Mori

Frequent epigenetic inactivation of Wnt antagonist genes in breast cancer.

Although mutation of APC or CTNNB1 (β-catenin) is rare in breast cancer, activation of Wnt signalling is nonetheless thought to play an important role in breast tumorigenesis, and epigenetic silencing of Wnt antagonist genes, including the secreted frizzled-related protein (SFRP) and Dickkopf (DKK) families, has been observed in various tumours. In breast cancer, frequent methylation and silencing of SFRP1 was recently documented; however, altered expression of other Wnt antagonist genes is largely unknown. In the present study, we found frequent methylation of SFRP family genes in breast cancer cell lines (SFRP1, 7 out of 11, 64%; SFRP2, 11 out of 11, 100%; SFRP5, 10 out of 11, 91%) and primary breast tumours (SFRP1, 31 out of 78, 40%; SFRP2, 60 out of 78, 77%; SFRP5, 55 out of 78, 71%). We also observed methylation of DKK1, although less frequently, in cell lines (3 out of 11, 27%) and primary tumours (15 out of 78, 19%). Breast cancer cell lines express various Wnt ligands, and overexpression of SFRPs inhibited cancer cell growth. In addition, overexpression of a β-catenin mutant and depletion of SFRP1 using small interfering RNA synergistically upregulated transcriptional activity of T-cell factor/lymphocyte enhancer factor. Our results confirm the frequent methylation and silencing of Wnt antagonist genes in breast cancer, and suggest that their loss of function contributes to activation of Wnt signalling in breast carcinogenesis.

Frequent epigenetic inactivation of SFRP genes and constitutive activation of Wnt signaling in gastric cancer

Activation of Wnt signaling has been implicated in gastric tumorigenesis, although mutations in APC (adenomatous polyposis coli), CTNNB1 (β-catenin) and AXIN are seen much less frequently in gastric cancer (GC) than in colorectal cancer. In the present study, we investigated the relationship between activation of Wnt signaling and changes in the expression of secreted frizzled-related protein (SFRP) family genes in GC. We frequently observed nuclear β-catenin accumulation (13/15; 87%) and detected the active form of β-catenin in most (12/16; 75%) GC cell lines. CpG methylation-dependent silencing of SFRP1, SFRP2 and SFRP5 was frequently seen among GC cell lines (SFRP1, 16/16, 100%; SFRP2, 16/16, 100%; SFRP5, 13/16, 81%) and primary GC specimens (SFRP1, 42/46, 91%; SFRP2, 44/46, 96%; SFRP5, 30/46, 65%), and treatment with the DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine rapidly restored SFRP expression. Ectopic expression of SFRPs downregulated T-cell factor/lymphocyte enhancer factor transcriptional activity, suppressed cell growth and induced apoptosis in GC cells. Analysis of global expression revealed that overexpression of SFRP2 repressed Wnt target genes and induced changes in the expression of numerous genes related to proliferation, growth and apoptosis in GC cells. It thus appears that aberrant SFRP methylation is one of the major mechanisms by which Wnt signaling is activated in GC.

A case-control study of diet and prostate cancer in Japan: possible protective effect of traditional Japanese diet.

The age‐adjusted incidence of prostate cancer is low in Japan, and it has been suggested that the traditional Japanese diet, which includes many soy products, plays a preventive role against prostate cancer. We performed a case‐control study on dietary factors and prostate cancer in order to assess the hypothesis that the traditional Japanese diet reduces the risk of prostate cancer. Four geographical areas (Ibaraki, Fukuoka, Nara, and Hokkaido) of Japan were selected for the survey. Average daily intake of food from 5 years before the diagnosis was measured by means of a semi‐quantitative food frequency questionnaire. We studied 140 cases and 140 individually age (±5 years)‐matched hospital controls for analysis. Estimates of age‐adjusted odds ratios (ORs) and linear trends were calculated by conditional logistic regression models with adjustment for cigarette smoking and total energy intake as confounding factors. Consumption of fish, all soybean products, tofu (bean curds), and natto (fermented soybeans) was associated with decreased risk. ORs of the fourth vs. first quartile and 95% confidence intervals (95%CIs) were 0.45 (0.20–1.02) for fish, 0.53 (0.24–1.14) for all soybean products, 0.47 (0.20–1.08) for tofu, and 0.25 (0.05–1.24) for natto. Consumption of fish and natto showed significantly decreasing linear trends for risk (P<0.05). Consumption of meat was significantly associated with increased risk (the OR of the second vs. first quartile was 2.19, 95%CI 1.00–4.81). Consumption of milk, fruits, all vegetables, green‐yellow vegetables, and tomatoes showed no association. Our results provide support to the hypothesis that the traditional Japanese diet, which is rich in soybean products and fish, might be protective against prostate cancer.

Serum phytoestrogens and prostate cancer risk in a nested case‐control study among Japanese men

The purpose of this study was to examine whether a high serum concentration of phytoestrogens reduces the risk of prostate cancer in a case‐control study nested in a community‐based cohort in Japan (Japan Collaborative Cohort (JACC) Study). Information on lifestyles and sera of the subjects were collected in 1988–90, and they were followed up to 1999. Incident and dead cases of prostate cancer and controls were matched for study area and age. Phytoestrogens and sex hormones in sera stored at −80°C were measured in 2002. Of 14,105 male subjects of the cohort who donated their sera, 52 cases and 151 controls were identified. Three datasets were analyzed; 1) all subjects, 2) 40 cases and 101 controls after excluding subjects with low testosterone levels who were suspected of having had medical intervention, and 3) 28 cases and 69 controls with prostate specific antigen level of ∼10.0 ng/ml. The odds ratio (OR) for the highest level to the lowest was 0.38 (95% confidence interval (CI); 0.13, 1.13) for genistein, 0.41 (0.15, 1.11) for daidzein, and 0.34 (0.11, 1.10) for equol for the second dataset. Genistein and daidzein showed similar findings in the third one. Equol and equol/daidzein ratio showed consistent findings in all three datasets (OR=0.39, 95% CI; 0.13, 0.89, trend P=0.02 for the first dataset). Their effects seemed to be independent of serum sex hormones. In conclusion, serum genistein, daidzein, and equol seemed to dose‐dependently reduce prostate cancer risk. (Cancer Sci 2004; 95: 65–71)

Overexpression of metastasis-associated MTA1 mRNA in invasive oesophageal carcinomas

SummaryThe MTA1 gene is a recently identified novel candidate breast cancer metastasis-associated gene which has been implicated in the signal transduction or regulation of gene expression. We examined the mRNA expression levels of the MTA1, the human homologue of the rat mta1 gene in 47 surgically resected oesophageal squamous cell carcinomas by quantitative reverse transcription polymerase chain reaction. The relative overexpression of MTA1 mRNA (tumour/normal ratio ≥ 2) was observed in 16 out of 47 (34.0%) oesophageal carcinomas. Oesophageal tumours overexpressing MTA1 mRNA (T/N ratio ≥ 2) showed significantly higher frequencies of adventitial invasion (P < 0.05) and lymph node metastasis (P < 0.05), and tended to have a higher rate of lymphatic involvement than the remaining tumours. Thus, the data suggest that the MTA1 gene might play an important role in invasion and metastasis of oesophageal carcinomas.

Clinical symptoms in endoscopic reflux esophagitis: evaluation in 8031 adult subjects.

This study aimed to evaluate the correlation between symptoms and endoscopic findings in reflux esophagitis. Subjects, 8031 persons without medication for gastrointestinal disease, were briefly asked about the presence of heartburn, dysphagia, odynophagia, and acid regurgitation by associated medical staff before endoscopy for assessment of esophagitis utilizing the Los Angeles Classification. Endoscopically, 1199 (14.9%) were classified as positive reflux esophagitis, and 2223 (27.7%) had heartburn, 1522 (19.0%) had dysphagia, 493 (6.1%) had odynophagia, and 1466 (18.3%) had acid regurgitation. Multivariate analysis indicated that the symptom most related to esophagitis was heartburn (odds ratio: 2.46), although ∼40% of subjects with grade C or D did not complain of heartburn. Regarding the other symptoms, less than 30% subjects with severe esophagitis complained of the symptoms and the odds ratio was ∼1. These results indicate that endoscopic esophagitis was not equivalent to any reflux symptoms from which subjects suffered in their daily lives.

Epidemiologic Survey of Japanese Patients with Idiopathic Pulmonary Fibrosis and Investigation of Ethnic Differences

RATIONALE Idiopathic pulmonary fibrosis (IPF) has an unknown etiology and poor prognosis. Several large-scale epidemiologic studies have been conducted predominantly in Western countries. There are few studies reported from Asian countries. It remains unclear whether ethnic difference exists in IPF. It is important to determine the current IPF status in Asian populations and compare it with that of Western populations. OBJECTIVES To provide the epidemiologic status of IPF in Japan and to investigate ethnic differences. METHODS We selected Hokkaido prefecture (population, 5.6 million) as the epidemiologic cohort of IPF among Japanese. On the basis of the clinical records of 553 patients with IPF who were accepted based on the application of the Certificate of Medical Benefit between 2003 and 2007, we conducted a retrospective epidemiologic and prognostic analysis. MEASUREMENTS AND MAIN RESULTS The prevalence and cumulative incidence of IPF was 10.0 and 2.23 per 100,000 population, respectively, with 72.7% predominance of males and an increase in frequency with age. The median survival time was 35 months, and the most common (40%) cause of death was acute exacerbation. The most important factor influencing IPF prognosis was the percent vital capacity. CONCLUSIONS The status of IPF in the Japanese population was clarified for the first time through our study. Our results showed that in men, the incidence of death caused by acute exacerbation was higher and that caused by cardiovascular disease was lower in Japan than in Western countries. These results may suggest ethnic differences in IPF.

Clinical significance of tissue inhibitor of metalloproteinase expression in gastric carcinoma.

Tissue inhibitor of metalloproteinase (TIMP) has been reported to inhibit tumour invasion through an inactivation of matrix metalloproteinase (MMP) both in vitro and in vivo. Among the TIMP family, TIMP-1 possesses not only proteinase inhibitory activity but also a growth-promoting function. However, the significance of the expression of TIMP-1 in human gastric carcinoma tissue has yet to be clarified. In 50 examined cases of gastric carcinoma, 44 (88%) cases showed a higher expression of TIMP-1 mRNA in the biopsy samples from the tumour tissue (T) than in the biopsy samples from the corresponding normal tissue (N), as determined by semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). In a multivariate analysis, the T/N ratio of TIMP-1 mRNA was found to be an independent factor influencing the depth of tumour invasion and was the second most important factor in determining the prognosis of patients. As RT-PCR assay can be performed on biopsy specimens obtained before surgery, an evaluation of the TIMP-1 expression in biopsy specimens by RT-PCR may thus provide useful preoperative information on tumour aggressiveness.

Preoperative Diagnosis and Treatment Results in 106 Patients with Uterine Sarcoma in Hokkaido, Japan

Objective: The aim of this study was to evaluate the clinicopathological features of uterine sarcoma in Hokkaido, Japan, between 1990 and 1999, and to identify prognostic factors of patients with such malignancies in this area and period. Methods: One hundred and six patients with histologically proven uterine sarcoma were evaluated retrospectively. Results: 93.5% of the patients with carcinosarcoma (CS) were diagnosed as having malignant disease preoperatively, while 65% of those with leiomyosarcoma (LMS) and 75% of those with endometrial stromal sarcoma (ESS) were preoperatively diagnosed as benign leiomyoma. When patients had no residual disease postoperatively, 5-year survival rates in patients with CS and LMS were 78.8 and 73.0%, respectively. ESS cases had a better prognosis (94.7% for stage I cases). In patients with early-stage sarcoma, pelvic lymphadenectomy and adjuvant chemotherapy, with or without cis-diamminedichloroplatinum, failed to show a survival benefit in both CS and LMS cases. Distant metastasis, myometrial invasion, and no residual disease at surgery were significantly associated with risk of death or recurrence in CS and LMS cases. Conclusion: Accurate preoperative diagnosis of uterine sarcoma was difficult, and no residual disease at surgery was the most important prognostic factor in patients with this disease. Postoperative adjuvant therapy had little effect on survival , especially in early-stage disease.

LINE-1 Hypomethylation Is Associated with Increased CpG Island Methylation in Helicobacter pylori–Related Enlarged-Fold Gastritis

Background: The molecular mechanism by which Helicobacter pylori infection leads to gastric cancer is not fully understood. Similarly, patients with enlarged-fold (EF+) gastritis, one cause of which is H. pylori infection, have an increased risk for gastric cancer, although again molecular mechanism is unclear. In the present study, we analyzed the methylation status of long interspersed nucleotide elements (LINE-1) and three cancer-related genes in a panel of gastric mucosae, with or without EF+ gastritis. Methods: We used bisulfite pyrosequencing to assess the levels of LINE-1, CDH1, CDH13, and PGP9.5 methylation in 78 gastric mucosa specimens from 48 patients. Results: Levels of LINE-1 methylation were significantly reduced in mucosae from patients with EF+ gastritis. This hypomethylation of LINE-1 was associated with increased methylation of the 5′ CpG islands of the genes, which suggests that, in EF+ gastritis, the methylation of the promoter regions of certain genes is accompanied by global demethylation of repetitive sequences. Conclusions: Our results indicate that genomewide hypomethylation and regional hypermethylation occur in EF+ gastritis and may contribute to the tumorigenesis of diffuse-type gastric cancers. (Cancer Epidemiol Biomarkers Prev 2008;17(10):2555–64)