Masaya Toda

Roles of calcitonin gene-related peptide in facilitation of wound healing and angiogenesis.

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide produced by tissue-specific alternative splicing of the primary transcript of the calcitonin/CGRP gene. CGRP is widely distributed in the central and peripheral neuronal systems and exhibits numerous biological activities in mammals. We examined in the present study whether or not endogenous CGRP released from neuronal systems facilitates neovascularization indispensable to wound healing. In CGRP knockout mice (CGRP-/-), wound-induced angiogenesis and wound closure were significantly suppressed compared with those in wild-type mice. The suppressed healing in CGRP-/- was accompanied by reduction in expressions of vascular endothelial growth factor (VEGF) in the wound granulation tissues. A CGRP antagonist, CGRP8-37 when infused with mini-osmotic pumps subcutaneously blocked the wound healing processes and reduced the expressions of CD31 and VEGF expression in the wound granulation tissues. Wound healing process was significantly delayed in neuropeptide-depleted mice pretreated with capsaicin, compared with vehicle-treated mice. These results indicate that CGRP derived from neuronal systems may facilitate wound healing and angiogenesis. Targeting of CGRP may be promising in controlling angiogenesis related to pathophysiological conditions.

Neuronal system-dependent facilitation of tumor angiogenesis and tumor growth by calcitonin gene-related peptide

A neuropeptide, calcitonin gene-related peptide (CGRP), is widely distributed in neuronal systems and exhibits numerous biological activities. Using CGRP-knockout mice (CGRP−/−), we examined whether or not endogenous CGRP facilitates angiogenesis indispensable to tumor growth. CGRP increased tube formation by endothelial cells in vitro and enhanced sponge-induced angiogenesis in vivo. Tumor growth and tumor-associated angiogenesis in CGRP−/− implanted with Lewis lung carcinoma (LLC) cells were significantly reduced compared with those in wild-type (WT) mice. A CGRP antagonist, CGRP8-37 or denervation of sciatic nerves (L1–5) suppressed LLC growth in the sites of denervation compared with vehicle infusion or sham operation. CGRP precursor mRNA levels in the dorsal root ganglion in LLC-bearing WT were increased compared with those in non-LLC-bearing mice. This increase was abolished by denervation. The expression of VEGF in tumor stroma was down-regulated in CGRP−/−. These results indicate that endogenous CGRP facilitates tumor-associated angiogenesis and tumor growth and suggest that relevant CGRP may be derived from neuronal systems including primary sensory neurons and may become a therapeutic target for cancers.

Blockade of an angiotensin type I receptor enhances effects of radiation on tumor growth and tumor-associated angiogenesis by reducing vascular endothelial growth factor expression

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 antiangiogenic 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 cm(3), 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) cm(3), 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 therapy markedly reduced tumor-associated angiogenesis. 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.

0597. The relation between intestinal intramucosal ph and stress hormones in pig hemorrhagic shock model

Measurements: Jejunal pHi was calculated by the luminal PCO2, obtained with a balloon tonometer, and arterial bicarbonate concentration. Arterial blood samples were taken for analysis of adrenaline (ADR), noradrenaline (NA), angiotensin II (Ang II) and arterial blood gas. SMV blood samples were taken for analysis of lactate/ pylvate acid (sma L/P), and blood gas (PsmvCO2). Results At shock phase, SMA flow decreased to 40% from the baseline (p < 0.01) and pHi decreased from 7.4 ± 0.2 to