Shogo Yamada

Age-associated increase of spontaneous mutant frequency and molecular nature of mutation in newborn and old lacZ-transgenic mouse

Accumulation of mutation has long been hypothesized to be a cause of aging and contribute to many of the degenerative diseases, which appear in the senescent phase of life. To test this hypothesis, age-associated changes in spontaneous mutation in different tissues of the body as well as the molecular nature of such changes should be examined. This kind of approach has become feasible only lately with a development of new transgenic mice suitable for mutation assay. Here, using one of these transgenic mice harboring lacZ gene, we have shown that the age-associated increase in spontaneous mutant frequency is common to all tissues examined; spleen, liver, heart, brain, skin and testis, while the rates of increase in mutant frequency differed among the tissues. DNA sequencing of the 496 lacZ mutants recovered from the tissues of newborn and old mice has revealed that spectra of mutations are similar at the two age points with G:C to A:T transition at CpG site being a predominant type of mutation. Furthermore, some mutations in old tissues are complex type and not found in tissues of newborn mice. These results suggest that similar mechanisms may be operating for mutation induction in fetal and postnatal aging process. In addition, the appearance of complex types of mutations in the old tissues suggests a unique cause for these mutations in aging tissues.

Intraoperative radiation therapy (IORT) for previously untreated malignant gliomas

BackgroundIntraoperative radiation therapy (IORT) is one of the methods used to deliver a large single dose to the tumor tissue while reducing the exposure of normal surrounding tissue. However, the usefulness of intraoperative electron therapy for malignant gliomas has not been established.MethodsDuring the period from 1987 to 1997, 32 patients with malignant gliomas were treated with IORT. The histological diagnoses were anaplastic astrocytoma in 11 patients and glioblastoma in 21 patients. Therapy consisted of surgical resection and intraoperative electron therapy using a dose of 12–15 Gy (median, 15 Gy). The patients later underwent postoperative external radiation therapy (EXRT) with a median total dose of 60 Gy. Each of the 32 patients treated with IORT was randomly matched with patients who had been treated with postoperative EXRT alone (control). Patients were matched according to histological grade, age, extent of tumor removal, and tumor location.ResultsIn the anaplastic astrocytoma group, the one-, two- and five-year survival rates were 81%, 51% and 15%, respectively in the IORT patients and 54%, 43% and 21%, respectively in the control patients. In the glioblastoma group, one-, two- and five-year survival rates were 63%, 26% and 0%, respectively in the IORT patients and 70%, 18% and 6%, respectively in the control patients. There was no significant difference between survival rates in the IORT patients and control patients in either the anaplastic astrocytoma group or glioblastoma group.ConclusionsIORT dose not improve survival of patients with malignant gliomas compared to that of patients who have received EXRT alone.

Radiation therapy for superficial esophageal cancer: a comparison of radiotherapy methods

PURPOSE A comparison of treatment outcomes in response to various methods of radiotherapy for superficial esophageal cancer (SEC) was carried out for a large series of patients. METHODS AND MATERIALS During the period from March 1987 to November 1998, 147 patients with superficial esophageal cancer received definitive radiation therapy at nine radiotherapy institutions in Japan. Fifty-five patients were treated with external radiation therapy alone, 69 with high-dose-rate intracavitary radiation therapy with or without external radiation therapy, and 23 with low-dose-rate intracavitary radiation therapy and external radiation therapy. RESULTS The 5-year survival rates for mucosal and submucosal cancer patients were 62% and 42%, respectively. The 5-year cause-specific survival rates for mucosal and submucosal cancer patients were 81% and 64%, respectively (p = 0.013). There was no statistically significant difference in the survival rates for either mucosal or submucosal cancer patients between treatment groups. Metastasis was observed only in submucosal cancer patients. Esophageal ulcers developed only in patients who received intracavitary radiation therapy, and were especially common in patients treated with a fraction size of 5 Gy or more. CONCLUSIONS The use of intracavitary radiation therapy does not influence the survival or local control rate of SEC. Optimal radiotherapy methods for SEC should be determined by a randomized clinical trial.

Radiation therapy for loco-regionally recurrent esophageal cancer after surgery

PURPOSE To evaluate the treatment outcome of radiation therapy for 33 loco-regionally recurrent esophageal cancer patients. METHODS Between 1988 and 1997, 33 patients with loco-regional recurrence of esophageal cancer after curative surgery received radiation therapy at an average total dose of 61 Gy. The site of recurrence was the supraclavicular region in 14 patients, the mediastinal region in 13 patients, and both the supraclavicular and mediastinal regions in six patients. If patients had ether distant metastasis or malignant pleural effusion, they were excluded from analysis. Patients who received prophylactic postoperative irradiation were also excluded from analysis. RESULTS The median survival period was 7 months. The survival rates at 1, 2, and 3 years were 33, 15, and 12%, respectively. In univariate analysis, patients with a short time interval between surgery and recurrence (P=0.0098) and patients with recurrence in both the supraclavicular and mediastinal regions (P=0.036) had a worse prognosis. In multivariate analysis, the time interval between surgery and recurrence (P<0.001) and age (worse prognosis in younger patients, P=0.019) were the significant prognostic factors. Complete or partial responses were observed in nine (27%) and 21 (64%) of the patients, respectively. Changes in clinical symptoms, such as dysphagia, chest pain and back pain, could be evaluated in 11 patients, and improvement in symptoms was obtained in eight (73%) patients. CONCLUSIONS The prognosis of patients who received radiation therapy for postoperative loco-regional recurrence of esophageal cancer is poor. However, there is symptomatic relief in a significant proportion of such patients, and long-term survival is possible in some patients.

Radiation therapy for limited-stage small-cell esophageal cancer

Between 1985 and 1999, 20 patients with limited-stage small-cell carcinoma of the esophagus (SCEC) received radiation therapy at Tohoku University Hospital and Miyagi Cancer Center Hospital. Twelve patients received definitive radiation therapy and eight patients received postoperative prophylactic irradiation after surgery. The 1-, 2-, and 5-year survival rates of all cases were 44%, 37%, and 19%, respectively. Distant metastasis was the most frequent pattern of recurrence. Survival rates differed significantly between the 6 patients who were not treated with chemotherapy (median survival time, 5 months) and the 14 patients who were (24 months) (p = 0.0061). Good local control rates can be obtained by definite or postoperative radiation therapy for SCEC. However, SCEC should be regarded as a systemic disease, and chemotherapy should be given. Multiinstitutional studies are needed to obtain sufficiently large populations for investigation and optimization of local therapy for this disease.

Neurophilin-1 is a downstream target of transcription factor Ets-1 in human umbilical vein endothelial cells

Transcription factor Ets‐1 expressed in endothelial cells promotes angiogenesis. Here, we transiently overexpressed Ets‐1 in human umbilical vein endothelial cells (HUVECs) and comprehensively searched for potential downstream targets of Ets‐1 by cDNA microarray analysis. The expression of several angiogenesis‐related genes including neuropilin‐1 was augmented by the overexpression of Ets‐1. Quantitative real‐time RT‐PCR and Western blotting confirmed the increase in the levels of neuropilin‐1 mRNA and protein. In contrast, dominant negative ets‐1 decreased the levels of neuropilin‐1 mRNA and protein. These results indicate that neuropilin‐1 is a downstream target of Ets‐1 in HUVECs.

Results of radiation therapy combined with nedaplatin (cis-diammine-glycoplatinum) and 5-Fluorouracil for postoperative locoregional recurrent esophageal cancer

BackgroundAlthough the effectiveness of radiotherapy with concurrent administration of several anti-tumor drugs for postoperative recurrent esophageal cancer has been demonstrated, the results are not satisfactory. The purpose of the present study was to evaluate the effectiveness and safety of radiotherapy combined with nedaplatin and 5-FU for postoperative locoregional (excluding hematogenous metastasis) recurrent esophageal cancer.MethodsIn June 2000, we started a phase II study on treatment of postoperative locoregional recurrent esophageal cancer with radiotherapy (60 Gy/30 fr/6 weeks) combined with chemotherapy consisting of two cycles of nedaplatin (70 mg/m2/2 h) and 5-FU (500 mg/m2/24 h for 5 days).The primary endpoint of the present study was overall survival rate, and the second endpoints were irradiated-field control rate, tumor response and toxicity.ResultsA total of 30 patients were included in this study. The 1-year and 3-year overall survival rates were 60.6% and 56.3%, respectively, with a median survival period of 39.0 months, and the 1-year and 3-year irradiated-field control rates were 86.4% and 72%, respectively. Complete response and partial response were observed in 13.3% and 60.0% of the patients, respectively. Grade 3 or higher leukocytopenia and thrombocytopenia were observed in 30% and 3.3% of the patients, respectively, but renal toxicity of grade 3 or higher was not observed. The regimen was completed in 76.7% of the patients.In univariate analysis, the difference between survival rate in preradiotherapy performance status, recurrent pattern (worse for patients with anastomotic recurrence) and age (worse for younger patients) were statistically significant.ConclusionRadiotherapy combined with nedaplatin and 5-FU is a safe and effective salvage treatment for postoperative locoregional recurrent esophageal cancer.

Phase Ia study of a hypoxic cell sensitizer doranidazole (PR-350) in combination with conventional radiotherapy.

A phase Ia study of a 2-nitroimidazole nucleoside analog radiosensitizer doranidazole was conducted to evaluate its toxicity and pharmacokinetics in patients undergoing conventional external beam radiotherapy. Twenty-nine patients, aged 40-74 years, with a WHO performance status of 0-2 and with adequate organ functions, were entered in the study. Single administration of doranidazole was investigated first with 13 patients and then a course of five consecutive daily administrations was tested in 16 patients. Doranidazole was given i.v. 25 min before irradiation. Doranidazole doses of 400, 800, 1300 and 2000 mg/m2 were evaluated in the former study, and daily doses of 800, 1300 and 2000 mg/m2 were investigated in the latter study. All patients tolerated doranidazole administration. Although a transient decrease in the 24-h creatinine clearance rate was observed in five patients (one in the single administration study and four in the repeat administration study), this was not considered to be the dose-limiting toxicity. Other toxicities (hematological and gastrointestinal), which may not be related to doranidazole administration, were also mild and were not dose limiting. No neurotoxicity was observed. The average maximum concentration, area under the time-concentration curve and half-life of doranidazole in serum were 172-194 μg/ml, 502-582 μg·h/l and 4.2-4.6 h, respectively, at 2000 mg/m2. At the tested doses, administration of doranidaozle was tolerable and achieved serum concentrations at which reasonable radiosensitization could be expected. A phase Ib/II study to evaluate the feasibility and efficacy of up to 30 repeat administrations seems to be warranted.

Treatment of superficial esophageal cancer by external radiation therapy alone: results of a multi-institutional experience

PURPOSE To assess the effectiveness and toxicity of external radiation therapy for superficial esophageal cancer. METHODS AND MATERIALS During the period from March 1979 to November 1996, 78 patients with superficial esophageal cancer received radiation therapy without intracavitary irradiation at nine radiotherapy institutions in Japan. All patients had histologically-proven squamous cell carcinoma. Endoscopic ultrasonography was performed in 34 patients to discriminate mucosal from submucosal cancer. Most of the patients had received radiation therapy using conventional fractionation at an average dose of 65.5 Gy. RESULTS The survival rates at 1, 2, and 5 years were 88%, 73%, and 45%, respectively. The local control rates at 1, 2, and 5 years were 85%, 79%, and 66%, respectively. Although the difference was not significant, the survival rate of cancer patients with a tumor invading the submucosa was lower than that of the other patients. In 6 mucosal cancer patients, local recurrence was observed in 1 patient with extensive cancer. Regional lymph node recurrence and distant failure were not observed in mucosal cancer patients, while in 28 submucosal cancer patients, the 5-year survival rate and relapse free rate were only 49% and 43%, respectively. Univariate and multivariate analysis identified age as the only significant prognostic factor. Severe late injury, such as esophageal ulcer, perforation, and bleeding, was not observed. CONCLUSION External radiation therapy is effective for mucosal cancer. However, further investigation is needed to establish a better standard treatment protocol for submucosal cancer.

Radiation therapy combined with cis-diammine-glycolatoplatinum (Nedaplatin) and 5-fluorouracil for untreated and recurrent esophageal cancer.

From January 1999 to November 2000, a total of 24 esophageal cancer patients (17 untreated and 7 recurrent cases) were treated with radiation therapy (60–70 Gy) combined with cis-diammine-glycolatoplatinum (Nedaplatin) (80–120 mg/body) and 5-fluorouracil (5-FU) (500–1,000 mg/body/24 h, continuous infusion for 5 days). Grade III leukocytopenia was observed in 6 (25%) of the patients. Grade III and IV thrombocytopenia was observed in one patient each. The 1-year and 2-year survival rates for definitively irradiated patients were 59% and 39%, respectively, and for patients with postoperative recurrence 69% and 69%, respectively. High-dose radiation combined with Nedaplatin and 5-FU is a safe and effective method for treating esophageal cancer.