| Budget Amount *help |
¥3,890,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥390,000)
Fiscal Year 2007: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Fiscal Year 2006: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
1) Objective: Angiogenesis, the formation of new capillary blood vessels, is essential for tumor progression. We had reported that Type 1 angiotensin receptor (AT1-R) antagonist reduced tumor-associated angiogenesis. Since anti-angio-genic agents were reported to enhance efficacy of radiation therapy, we tested here whether or not AT1-R blockade facilitates the effects of radiation. Methods: 1 X 10^6 LLC cells were injected into the subcutaneous tissue of male C57BL/6 mice, and when the average tumor volume reached around 0.1 cm3, radiation doses (3, 5, 10, and 15 Gy) were given on day 1. Results: The mean tumor volumes at day 22 were 6.39 (3 Gy), 6.15 (5 Gy), 5.15 (10 Gy), and 3.07 (15 Gy) cm3, respectively. Combination of 10 Gy radiation with AT1R antagonist TCV-116 (30 mg/kg) significantly inhibited tumor growth by 83% (1.47 + 0.11 cm^3, P < 0.01) in comparison with its inhibition of control tumors (8.81 + 0.45 cm^3). The same was true for mean vessel density, and the combination th
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erapy markedly reduced tumor-associated angio- genesis. This was confirmed by the reduced expression of CD31. LLC tumor growth was blocked by neutralizing antibody against vascular endothelial growth factor (VEGF). Real-time PCR analysis of VEGF disclosed a marked reduction in the mice under combination therapy, compared with control mice. Conclusions: These results suggest that combination of radiation with AT1-R blockade markedly reduced the LLC growth rate, and that this was due to reduction of neovascularization by reducing VEGF levels. Combination therapy consisting of radiation and AT1R blockade may become an effective novel strategy for cancer treatment.
2) We here analyzed EGFR mutations in matched pre- and post-therapeutic tumors of six gefitinib-responding lung cancers. With conventional PCR-based sequencing, classic mutations were detected in pretreatment samples of each case, and the same mutations could be readily confirmed in treated lesions of four cases, While the corresponding mutations were absent in those of cases 1 and 2. Subsequent mutant-enriched peptide-nucleic-acid-mediated, PCR clamping and subcloning assays detected the mutation in minor cells of treated lesions of case 1, but still failed top detect mutation in case 2. We thus performed a microdissection-based cell cluster mutation analysis of pretreatment and found that three, including the first two concurrently contained tumor cells with either mutant- or wild-EGFR, although the latter composed only a minor fraction. These findings suggest that some NSCLC are genetically heterogeneous with regard to EGFR mutations; the gefitinib-sensitive mutants decrease or vanish while the wild clones selectively survive with gefitinib treatment. In addition, secondary T790M was detected in a small fraction of treated lesions of three cases. Thus, selection on a background of EGFR genetic heterogeneity may also contribute to acquisition of gefitinib resistance in a proportion of non-small-cell lung carcinomas. Less
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