Radiation-quality-dependent bystander cellular effects induced by heavy-ion microbeams through different pathways.

We investigated the radiation-quality-dependent bystander cellular effects using heavy-ion microbeams with different ion species. The heavy-ion microbeams were produced in Takasaki Ion Accelerators for Advanced Radiation Application, National Institutes for Quantum Science and Technology. Carbon (12C5+, 220 MeV), neon (20Ne7+, 260 MeV) and argon (40Ar13+, 460 MeV) ions were used as the microbeams, collimating the beam size with a diameter of 20 µm. After 0.5 and 3 h of irradiation, the surviving fractions (SFs) are significantly lower in cells irradiated with carbon ions without a gap-junction inhibitor than those irradiated with the inhibitor. However, the same SFs with no cell killing were found with and without the inhibitor at 24 h. Conversely, no cell-killing effect was observed in argon-ion-irradiated cells at 0.5 and 3 h; however, significantly low SFs were found at 24 h with and without the inhibitor, and the effect was suppressed using vitamin C and not dimethyl sulfoxide. The mutation frequency (MF) in cells irradiated with carbon ions was 8- to 6-fold higher than that in the unirradiated control at 0.5 and 3 h; however, no mutation was observed in cells treated with the gap-junction inhibitor. At 24 h, the MFs induced by each ion source were 3- to 5-fold higher and the same with and without the inhibitor. These findings suggest that the bystander cellular effects depend on the biological endpoints, ion species and time after microbeam irradiations with different pathways.

RNA sequencing data for gamma radiation response in the extremotolerant tardigrade Ramazzottius varieornatus.

Tardigrades are microscopic animals of which terrestrial species are capable of tolerating extreme environments by entering a desiccated ametabolic state known as anhydrobiosis. Intriguingly, they survive high dosage gamma rays (>4,000 Gy), possibly through a mechanism known as cross-tolerance. We hypothesized that anhydrobiosis genes are also regulated during cross-tolerance, thus we submitted Ramazzottius varieornatus to 500 Gy 60Co gamma-ray and conducted time-course low-input RNA-Seq. The gene expression was quantified with RSEM and differential expression was determined with DEseq2. Differentially expressed genes were submitted to gene ontology enrichment analysis with GOStat. The transcriptome dynamically shifted nine hours post-exposure.

Histone Deacetylase Inhibitors Sensitize Murine B16F10 Melanoma Cells to Carbon Ion Irradiation by Inducing G1 Phase Arrest.

Epigenetic processes, in addition to genetic abnormalities, play a critical role in refractory malignant diseases and cause the unresponsiveness to various chemotherapeutic regimens and radiotherapy. Herein we demonstrate that histone deacetylase inhibitors (HDACis) can be used to sensitize malignant melanoma B16F10 cells to carbon ion irradiation. The cells were first treated with HDACis (romidepsin [FK228, depsipeptide], trichostatin A [TSA], valproic acid [VPA], and suberanilohydroxamic acid [SAHA, vorinostat]) and were then exposed to two types of radiation (carbon ions and gamma-rays). We found that HDACis enhanced the radiation-induced apoptosis and suppression of clonogenicity that was induced by irradiation, having a greater effect with carbon ion irradiation than with gamma-rays. Carbon ion irradiation and the HDACi treatment induced G2/M and G0/G1 cell cycle arrest, respectively. Thus, it is considered that HDACi treatment enhanced the killing effects of carbon ion irradiation against melanoma cells by inducing the arrest of G1 phase cells, which are sensitive to radiation due to a lack of DNA homologous recombination repair. Based on these findings, we propose that pretreatment with HDACis as radiosensitizers to induce G1 arrest combined with carbon ion irradiation may have clinical efficacy against refractory cancer.

In vivo 3D analysis of systemic effects after local heavy-ion beam irradiation in an animal model.

Radiotherapy is widely used in cancer treatment. In addition to inducing effects in the irradiated area, irradiation may induce effects on tissues close to and distant from the irradiated area. Japanese medaka, Oryzias latipes, is a small teleost fish and a model organism for evaluating the environmental effects of radiation. In this study, we applied low-energy carbon-ion (26.7 MeV/u) irradiation to adult medaka to a depth of approximately 2.2 mm from the body surface using an irradiation system at the National Institutes for Quantum and Radiological Science and Technology. We histologically evaluated the systemic alterations induced by irradiation using serial sections of the whole body, and conducted a heart rate analysis. Tissues from the irradiated side showed signs of serious injury that corresponded with the radiation dose. A 3D reconstruction analysis of the kidney sections showed reductions in the kidney volume and blood cell mass along the irradiated area, reflecting the precise localization of the injuries caused by carbon-beam irradiation. Capillary aneurysms were observed in the gill in both ventrally and dorsally irradiated fish, suggesting systemic irradiation effects. The present study provides an in vivo model for further investigation of the effects of irradiation beyond the locally irradiated area.

Nitric oxide-mediated bystander signal transduction induced by heavy-ion microbeam irradiation.

In general, a radiation-induced bystander response is known to be a cellular response induced in non-irradiated cells after receiving bystander signaling factors released from directly irradiated cells within a cell population. Bystander responses induced by high-linear energy transfer (LET) heavy ions at low fluence are an important health problem for astronauts in space. Bystander responses are mediated via physical cell-cell contact, such as gap-junction intercellular communication (GJIC) and/or diffusive factors released into the medium in cell culture conditions. Nitric oxide (NO) is a well-known major initiator/mediator of intercellular signaling within culture medium during bystander responses. In this study, we investigated the NO-mediated bystander signal transduction induced by high-LET argon (Ar)-ion microbeam irradiation of normal human fibroblasts. Foci formation by DNA double-strand break repair proteins was induced in non-irradiated cells, which were co-cultured with those irradiated by high-LET Ar-ion microbeams in the same culture plate. Foci formation was suppressed significantly by pretreatment with an NO scavenger. Furthermore, NO-mediated reproductive cell death was also induced in bystander cells. Phosphorylation of NF-κB and Akt were induced during NO-mediated bystander signaling in the irradiated and bystander cells. However, the activation of these proteins depended on the incubation time after irradiation. The accumulation of cyclooxygenase-2 (COX-2), a downstream target of NO and NF-κB, was observed in the bystander cells 6 h after irradiation but not in the directly irradiated cells. Our findings suggest that Akt- and NF-κB-dependent signaling pathways involving COX-2 play important roles in NO-mediated high-LET heavy-ion-induced bystander responses. In addition, COX-2 may be used as a molecular marker of high-LET heavy-ion-induced bystander cells to distinguish them from directly irradiated cells, although this may depend on the time after irradiation.

Dependence of the bystander effect for micronucleus formation on dose of heavy-ion radiation in normal human fibroblasts.

Ionising radiation-induced bystander effects are well recognised, but its dependence on dose or linear energy transfer (LET) is still a matter of debate. To test this, 49 sites in confluent cultures of AG01522D normal human fibroblasts were targeted with microbeams of carbon (103 keV µm(-1)), neon (375 keV µm(-1)) and argon ions (1260 keV µm(-1)) and evaluated for the bystander-induced formation of micronucleus that is a kind of a chromosome aberration. Targeted exposure to neon and argon ions significantly increased the micronucleus frequency in bystander cells to the similar extent irrespective of the particle numbers per site of 1-6. In contrast, the bystander micronucleus frequency increased with increasing the number of carbon-ion particles in a range between 1 and 3 particles per site and was similar in a range between 3 and 8 particles per site. These results suggest that the bystander effect of heavy ions for micronucleus formation depends on dose.

Endovascular repair with contralateral external-to-internal iliac artery bypass grafting: a case series.

BACKGROUND: To report a technique of keeping unilateral blood flow in the internal iliac artery in cases of an abdominal aortic aneurysm in achieving successful Endovascular abdominal aortic aneurysm repair using an external-to-internal artery bypass. CASE PRESENTATION: 6 japanese patients with infra-renal abdominal aortic aneurysms were treated using the retroperitoneal approach via a left (right) paramedian incision followed by an external-to-internal artery bypass. Endovascular abdominal aortic aneurysm repair was conducted on mean postoperative day 29 ± 18 and was performed because the contralateral internal iliac artery, which was not involved in the external-to-internal artery bypass, was treated with a coil embolization. No complications developed during the postoperative follow-up period (17 ± 1.5 months). In all 6 patients, patent grafts were evident on computed tomography angiography scans even after 1-3 months. CONCLUSIONS: Endovascular abdominal aortic aneurysm repair with unilateral internal iliac artery embolization and contralateral external-to-internal artery bypass is feasible with a relatively low risk. It is a safe procedure and reduces the incidence of postoperative complications.

A mathematical model of radiation-induced responses in a cellular population including cell-to-cell communications.

Cell-to-cell communication is an important factor for understanding the mechanisms of radiation-induced responses such as bystander effects. In this study, a new mathematical model of intercellular signalling between individual cells in a cellular population is proposed. The authors considered two types of transmission of signals: via culture medium and via gap junction. They focus on the effects that radiation and intercellular signalling have on cell-cycle modification. The cell cycle is represented as a virtual clock that includes several checkpoint pathways within a cyclic process. They also develop a grid model and set up diffusion equations to model the propagation of signals to and from spatially located cells. The authors have also considered the role that DNA damage plays in the cycle of cells which can progress through the cell cycle or stop at the G1, S, G2 or M-phase checkpoints. Results of testing show that the proposed model can simulate intercellular signalling and cell-cycle progression in individual cells during and after irradiation.

The bystander cell-killing effect mediated by nitric oxide in normal human fibroblasts varies with irradiation dose but not with radiation quality.

PURPOSE: To investigate the dependence of the bystander cell-killing effect on radiation dose and quality, and to elucidate related molecular mechanisms. MATERIALS AND METHODS: Normal human fibroblast WI-38 cells were irradiated with 0.125 - 2 Gy of γ-rays or carbon ions and were co-cultured with non-irradiated cells. Survival rates of bystander cells were investigated using the colony formation assays, and nitrite concentrations in the medium were measured using the modified Saltzman method. RESULTS: Survival rates of bystander cells decreased with doses of γ-rays and carbon ions of ≤ 0.5 Gy. Treatment of the specific nitric oxide (NO) radical scavenger prevented reductions in survival rates of bystander cells. Moreover, nitrite concentrations increased with doses of less than 0.25 Gy (γ-rays) and 1 Gy (carbon ions). The dose responses of increased nitrite concentrations as well as survival reduction were similar between γ-rays and carbon ions. In addition, negative relationships were observed between survival rates and nitrite concentrations. CONCLUSION: The bystander cell-killing effect mediated by NO radicals in normal human fibroblasts depends on irradiation doses of up to 0.5 Gy, but not on radiation quality. NO radical production appears to be an important determinant of γ-ray- and carbon-ion-induced bystander effects.

Early detection of vulnerable atherosclerotic plaque for risk reduction of acute aortic rupture and thromboemboli and atheroemboli using non-obstructive angioscopy.

The mortality rate due to rupture of aortic dissection and aortic aneurysm is approximately 90%. Acute aortic rupture can be fatal prior to hospitalization and has proven difficult to diagnose correctly or predict. The in-hospital mortality rate of ruptured aortic aneurysm ranges from 53 to 66%. Emergency surgical and endovascular treatments are the only options for ruptured aortic dissection and aortic aneurysm. No method of systematic early detection or inspection of vessel injury is available at the prevention stage. Regardless of the improvement in many imaging modalities, aortic diameter has remained a major criterion for recommending surgery in diagnosed patients. Previous reports have suggested a relationship between vulnerable plaque and atherosclerotic aortic aneurysm. Non-obstructive angioscopy is a new method for evaluating intimal injury over the whole aorta. It has been used to identify many advanced atherosclerotic plaques that were missed on traditional imaging modalities before aneurysm formation. Non-obstructive angioscopy has shown that atherosclerosis of the aorta begins before that of the coronary artery, which had been noted on autopsy "in vivo". Strong or repetitive aortic injuries might cause sudden aortic disruption. Aortic atheroma is also a risk factor of stroke and perivascular embolism. Detecting aortic vulnerable atherosclerotic plaque on non-obstructive angioscopy may not only clarify the pathogenesis of acute aortic rupture and "aortogenic" thromboemboli and atheroemboli but also play a role in the pre-emptive medicine.

Nonhomologous end-joining repair plays a more important role than homologous recombination repair in defining radiosensitivity after exposure to high-LET radiation.

DNA double-strand breaks (DSBs) induced by ionizing radiation pose a major threat to cell survival. The cell can respond to the presence of DSBs through two major repair pathways: homologous recombination (HR) and nonhomologous end joining (NHEJ). Higher levels of cell death are induced by high-linear energy transfer (LET) radiation when compared to low-LET radiation, even at the same physical doses, due to less effective and efficient DNA repair. To clarify whether high-LET radiation inhibits all repair pathways or specifically one repair pathway, studies were designed to examine the effects of radiation with different LET values on DNA DSB repair and radiosensitivity. Embryonic fibroblasts bearing repair gene (NHEJ-related Lig4 and/or HR-related Rad54) knockouts (KO) were used and their responses were compared to wild-type cells. The cells were exposed to X rays, spread-out Bragg peak (SOBP) carbon ion beams as well as with carbon, iron, neon and argon ions. Cell survival was measured with colony-forming assays. The sensitization enhancement ratio (SER) values were calculated using the 10% survival dose of wild-type cells and repair-deficient cells. Cellular radiosensitivity was listed in descending order: double-KO cells > Lig4-KO cells > Rad54-KO cells > wild-type cells. Although Rad54-KO cells had an almost constant SER value, Lig4-KO cells showed a high-SER value when compared to Rad54-KO cells, even with increasing LET values. These results suggest that with carbon-ion therapy, targeting NHEJ repair yields higher radiosensitivity than targeting homologous recombination repair.

Increase in cell motility by carbon ion irradiation via the Rho signaling pathway and its inhibition by the ROCK inhibitor Y-27632 in lung adenocarcinoma A549 cells.

This study aimed to investigate the effect of carbon ion (C-ion) irradiation on cell motility through the ras homolog gene family member (Rho) signaling pathway in the human lung adenocarcinoma cell line A549. Cell motility was assessed by a wound-healing assay, and the formation of cell protrusions was evaluated by F-actin staining. Cell viability was examined by the WST-1 assay. The expression of myosin light chain 2 (MLC2) and the phosphorylation of MLC2 at Ser19 (P-MLC2-S19) were analyzed by Western blot. At 48 h after irradiation, the wound-healing assay demonstrated that migration was significantly greater in cells irradiated with C-ion (2 or 8 Gy) than in unirradiated cells. Similarly, F-actin staining showed that the formation of protrusions was significantly increased in cells irradiated with C-ion (2 or 8 Gy) compared with unirradiated cells. The observed increase in cell motility due to C-ion irradiation was similar to that observed due to X-ray irradiation. Western-blot analysis showed that C-ion irradiation (8 Gy) increased P-MLC2-S19 expression compared with in unirradiated controls, while total MLC2 expression was unchanged. Exposure to a non-toxic concentration of Y-27632, a specific inhibitor of Rho-associated coiled-coil-forming protein kinase (ROCK), reduced the expression of P-MLC2-S19 after C-ion irradiation (8 Gy), resulting in a significant reduction in migration. These data suggest that C-ion irradiation increases cell motility in A549 cells via the Rho signaling pathway and that ROCK inhibition reduces that effect.

Quadricuspid aortic valve complicated with infective endocarditis: report of a case.

Congenital quadricuspid aortic valve is a rare cardiac malformation with an unknown risk of infective endocarditis. We report a case of quadricuspid aortic valve complicated with infective endocarditis. A 53-year-old Japanese woman was hospitalized with leg edema and a fever of unknown origin. Corynebacterium striatum was detected in the blood culture. Echocardiography demonstrated a quadricuspid aortic valve with vegetation and severe functional regurgitation. The condition was diagnosed as a quadricuspid aortic valve with infective endocarditis, for which surgery was performed. The quadricuspid aortic valve had three equal-sized cusps and one smaller cusp (type B according to Hurwitz classification). We dissected the vegetation and infectious focus and implanted a mechanical valve. Following the case report, we review the literature.

Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures: the impact of radiation quality.

Understanding the mechanisms underlying the bystander effects of low doses/low fluences of low- or high-linear energy transfer (LET) radiation is relevant to radiotherapy and radiation protection. Here, we investigated the role of gap-junction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from monochromatic 5.35 keV X ray (LET ~6 keV/µm), 18.3 MeV/u carbon ion (LET ~103 keV/µm), 13 MeV/u neon ion (LET ~380 keV/µm) or 11.5 MeV/u argon ion (LET ~1,260 keV/µm) microbeams in the presence or absence of 18-α-glycyrrhetinic acid (AGA), an inhibitor of GJIC. After 4 h incubation at 37°C, the cells were subcultured and assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, MN formation for the heavy-ion microbeam irradiation in the absence of AGA was higher than in its presence at high mean absorbed doses. In contrast, there were no significant differences in cell cultures exposed to X-ray microbeam irradiation in presence or absence of AGA. This showed that the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. Bystander cells recipient of growth medium harvested from 5.35 keV X-irradiated cultures experienced stress manifested in the form of excess micronucleus formation. Together, the results support the involvement of both junctional communication and secreted factor(s) in the propagation of radiation-induced stress to bystander cells. They highlight the important role of radiation quality and dose in the observed effects.

Innate immune genes including a mucin-like gene, mul-1, induced by ionizing radiation in Caenorhabditis elegans.

The effect of radiation on the intestine has been studied for more than one hundred years. It remains unclear, however, whether this organ uses specific defensive mechanisms against ionizing radiation. The infection with Pseudomonas aeruginosa (PA14) in Caenorhabditis elegans induces up-regulation of innate immune response genes. Here, we found that exposure to ionizing radiation also induces certain innate immune response genes such as F49F1.6 (termed mul-1), clec-4, clec-67, lys-1 and lys-2 in the intestine. Moreover, pre-treatment with ionizing radiation before seeding on PA14 lawn plate significantly increased survival rate in the nematode. We also studied transcription pathway of the mul-1 in response to ionizing radiation. Induction of mul-1 gene was highly dependent on the ELT-2 transcription factor and p38 MAPK. Moreover, the insulin/IGF-1 signal pathway works to enhance induction of this gene. The mul-1 gene showed a different induction pattern from the DNA damage response gene, ced-13, which implies that the expression of this gene might be triggered as an indirect effect of radiation. Silencing of the mul-1 gene led to growth retardation after treatment with ionizing radiation. We describe the cross-tolerance between the response to radiation exposure and the innate immune system.

Synergistic effect of heat shock protein 90 inhibitor, 17-allylamino-17-demethoxygeldanamycin and X-rays, but not carbon-ion beams, on lethality in human oral squamous cell carcinoma cells.

The purpose of this study is to clarify the effect of a heat shock protein 90 inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), in combination with X-rays or carbon-ion beams on cell killing in human oral squamous cell carcinoma LMF4 cells. Cell survival was measured by colony formation assay. Cell-cycle distribution was analyzed by flow cytometry. Expression of DNA repair-related proteins was investigated by western blotting. The results showed 17-AAG to have synergistic effects on cell lethality with X-rays, but not with carbon-ion beams. The 17-AAG decreased G(2)/M arrest induced by X-rays, but not by carbon-ion beams. Both X-ray and carbon-ion irradiation up-regulated expression of non-homologous end-joining-associated proteins, Ku70 and Ku80, but 17-AAG inhibited only X-ray-induced up-regulation of these proteins. These results show that 17-AAG with X-rays releases G(2)/M phase arrest; cells carrying misrepaired DNA damage then move on to the G(1) phase. We demonstrate, for the first time, that the radiosensitization effect of 17-AAG is not seen with carbon-ion beams because 17-AAG does not affect these changes.

Ionising irradiation alters the dynamics of human long interspersed nuclear elements 1 (LINE1) retrotransposon.

It is important to identify the mechanism by which ionising irradiation induces various genomic alterations in the progeny of surviving cells. Ionising irradiation activates mobile elements like retrotransposons, although the mechanism of its phenomena consisting of transcriptions and insertions of the products into new sites of the genome remains unclear. In this study, we analysed the effects of sparsely ionising X-rays and densely ionising carbon-ion beams on the activities of a family of active retrotransposons, long interspersed nuclear elements 1 (L1). We used the L1/reporter knock-in human glioma cell line, NP-2/L1RP-enhanced GFP (EGFP), that harbours full-length L1 tagged with EGFP retrotransposition detection cassette (L1RP-EGFP) in the chromosomal DNA. X-rays and carbon-ion beams similarly increased frequencies the transcription from L1RP-EGFP and its retrotransposition. Short-sized de novo L1RP-EGFP insertions with 5'-truncation were induced by X-rays, while full-length or long-sized insertions (>5 kb, containing ORF1 and ORF2) were found only in cell clones irradiated by the carbon-ion beams. These data suggest that X-rays and carbon-ion beams induce different length of de novo L1 insertions, respectively. Our findings thus highlight the necessity to investigate the mechanisms of mutations caused by transposable elements by ionising irradiation.

Involvement of bystander effect in suppression of the cytokine production induced by heavy-ion broad beams.

PURPOSE: Immune cells accumulate in and around cancers and cooperate with each other using specific cytokines to attack the cancer cells. The heavy-ion beams for cancer therapy may stimulate immune cells and affect on the immune system. However, it is still poorly understood how the immune cells are stimulated by ion-beams. Here, we irradiated immune cells using heavy-ion beams and analyzed changes in production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) that are important cytokine for the cancer treatment. MATERIALS AND METHODS: The human THP-1 monocytes were differentiated into macrophages and then irradiated using carbon-ion broad-beams (108 keV µm(-1)). To examine the bystander response after heavy-ion irradiation, a very small fraction (approx. 0.45%) of the cell population was irradiated using heavy-ion microbeams. After irradiation, we examined the cytokine productions. RESULTS: When cells were irradiated with 5 Gy, cytokine levels were reduced after both microbeam irradiation and broad-beam irradiation. TNF-α production of macrophages with the nitric oxide (NO) inhibitor-treatment increased after carbon-ion broad-beam. NO was involved in the radiation-induced suppression of TNF-α production. CONCLUSIONS: The suppression of cytokine production arose after irradiation with heavy-ions, and may also be induced in the surrounding non-irradiated cells via the bystander effect.

Off-pump coronary artery bypass grafting as re-do surgery in two cases in which the right gastroepiploic artery was grafted to the right coronary artery.

Transdiaphragmatic off-pump coronary artery bypass grafting (OPCAB) to the right coronary artery, is an effective way to reduce the risks of second bypass surgery as well as the risk of graft injury after coronary artery bypass grafting (CABG). We report two cases of successful OPCAB as re-do surgery in which the right gastroepiploic artery (RGEA) was grafted to the right coronary artery. The first case was a 58-year-old woman, who underwent CABG 10 years ago. OPCAB (RGEA to right coronary artery) was performed since myocardial perfusion scintigraphy revealed ischemia in the inferior wall. The second case was a 67-year-old man who had hypertension, hyperlipidemia, peripheral arterial disease, and was undergoing dialysis (for 6 years). Six years previously, he developed a mycotic aneurysm of the right coronary artery and underwent open-heart surgery. He often had episodes of angina at night or during dialysis, and then developed congestive heart failure and was hospitalized. Since ischemia was considered to be in the inferior wall, the RGEA was grafted to the right coronary artery.

Radiation-induced ICAM-1 expression via TGF-ß1 pathway on human umbilical vein endothelial cells; comparison between X-ray and carbon-ion beam irradiation.

Adhesion of inflammatory cells to endothelial cells is considered to be involved in the process of radiation-induced damage and fibrosis. Intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-beta1 (TGF-ß1) are thought to play important roles in this process. In this study, radiation-induced ICAM-1 expression on endothelial cells was investigated with the use of an inhibitor of TGF-ß1 receptor kinase (SB431542) and the effects of X-ray and carbon-ion beam were compared. Cell cultures of human umbilical vein endothelial cells (HUVE cells) were incubated with TGF-ß1 and irradiated with 140 KV X-ray. Next, HUVE cells were irradiated with X-ray and 220 MeV carbon-ion beam with or without SB431542. Immunofluorescence analysis was used to quantify ICAM-1 expression. The expression of ICAM-1 on HUVE cells was significantly increased by the stimulation with TGF-ß1. Expression of ICAM-1 was increased by X-ray and carbon-ion beam irradiation and decreased significantly with SB431542 after both irradiations. The expression of ICAM-1 by 2 Gy of carbon-ion beam irradiation was 6.7 fold higher than that of non-irradiated cells, while 5 Gy of X-ray irradiation increased the expression of ICAM-1 by 2.5 fold. According to ICAM-1 expression, the effect of carbon-ion beam irradiation was about 2.2, 4.4 and 5.0 times greater than that of the same doses of X-ray irradiation (1, 2 and 5 Gy, respectively). The present results suggested that radiation-induced ICAM-1 expression on HUVE cells was, at least partially, regulated by TGF-ß1. Carbon-ion beam induced significantly higher ICAM-1 expression than X-ray.