Effect Of Proton Beam Irradiation Research Articles

Effect of proton-beam irradiation on cell survival of MCF-7 and its chemo-resistant subgroups

Effect of proton-beam irradiation on cell survival of MCF-7 and its chemo-resistant subgroups

Reduced interface effect of proton beam irradiation on the electrical properties of WSe2/hBN field effect transistors

Two-dimensional transition metal dichalcogenide (TMDC) semiconductors are emerging as strong contenders for electronic devices that can be used in highly radioactive environments such as outer space where conventional silicon-based devices exhibit nonideal characteristics for such applications. To address the radiation-induced interface effects of TMDC-based electronic devices, we studied high-energy proton beam irradiation effects on the electrical properties of field-effect transistors (FETs) made with tungsten diselenide (WSe2) channels and hexagonal boron-nitride (hBN)/SiO2 gate dielectrics. The electrical characteristics of WSe2 FETs were measured before and after the irradiation at various proton beam doses of 1013, 1014, and 1015 cm−2. In particular, we demonstrated the dependence of proton irradiation-induced effects on hBN layer thickness in WSe2 FETs. We observed that the hBN layer reduces the WSe2/dielectric interface effect which would shift the transfer curve of the FET toward the positive direction of the gate voltage. Also, this interface effect was significantly suppressed when a thicker hBN layer was used. This phenomenon can be explained by the fact that the physical separation of the WSe2 channel and SiO2 dielectric by the hBN interlayer prevents the interface effects originating from the irradiation-induced positive trapped charges in SiO2 reaching the interface. This work will help improve our understanding of the interface effect of high-energy irradiation on TMDC-based nanoelectronic devices.

Effect of proton beam irradiation on the tracking efficiency of CMOS image sensors

A star tracker provides accurate space positioning and reference for satellites, intercontinental strategic missiles, and other spacecrafts. However, the main imaging unit of the star sensor – the image sensor – is affected by the space radiation environment and, in turn, affects the precision with which the star is located by the star tracker. In this study, the parameter degradation of a CMOS image sensor (CIS) after proton irradiation with different fluences was investigated. An outfield test platform for star map collection was built using the star sensor lens and image collection system. The influence of dark current, dark-current nonuniformity, and photo-response nonuniformity of the irradiated CIS on the star diagonal distance measurement error and star-point centroid position detection accuracy was studied. The results showed that with increasing proton fluences, the CIS noise increased, leading to an increase in the error in the measured diagonal distance of the star and a decrease in the star’s position detection accuracy. Among these parameters, the dark current plays the greatest role in influencing the measurement accuracy of the star tracker. Furthermore, when a tracker is exposed to space radiation with fluences that are same as those used in this experiment, it is beneficial to reduce the integration time. This reduction in the time will decrease the noise and improve the position measurement accuracy.

Electrochemical evaluation of proton beam radiation effect on the B16 cell culture

The interaction of radiation with matter takes place through energy transfer and is accomplished especially by ionized atoms or molecules. The effect of radiation on biological systems involves multiple physical, chemical and biological steps. Direct effects result in a large number of reactive oxygen species (ROS) within and outside and inside of the cells as well, which are responsible for oxidative stress. Indirect effects are defined as alteration of normal biological processes and cellular components (DNA, protein, lipids, etc.) caused by the reactive oxygen species directly induced by radiation. In this work, a classical design of an electrochemical (EC) three-electrodes system was employed for analyzing the effects of proton beam radiation on melanoma B16 cell line. In order to investigate the effect of proton radiation on the B16 cells, the cells were grown on the EC surface and irradiated. After optimization of the experimental set-up and dosimetry, the radiobiological experiments were performed at doses ranging between 0 and 2 Gy and the effect of proton beam irradiation on the cells was evaluated by the means of cyclic voltammetry and measuring the open circuit potential between working and reference electrodes.

Effects of proton beam irradiation on the physical and chemical properties of IGTO thin films with different thicknesses for thin-film transistor applications

In this study, we investigated the effects of film thickness (tch) on the radiation damage of indium-gallium-tin oxide (IGTO) thin films and radiation tolerance of high-mobility IGTO thin-film transistors (TFTs). The radiation tolerance of the TFTs was evaluated using a 5-MeV proton beam at a fixed dose of 1013 cm−2. Using tch values of 12, 27, and 42 nm, the IGTO TFT with the 12-nm-thick channel layer exhibited the best electrical performance and radiation tolerance. The radiation tolerance significantly decreased as tch increased. To elucidate the mechanism responsible for the observed phenomena, the physical and chemical properties of the IGTO thin films with different values of tch were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy before and after the proton beam irradiation. The characterization results revealed that the decreased radiation tolerance of the thicker-channel IGTO TFTs were mainly attributed to the further enhanced oxygen vacancy generation due to the atomic displacement cascades within the IGTO channel layer after the proton irradiation. To the best of our knowledge, this is the first report studying the tch effects on the radiation hardness of oxide TFTs. The results of this study demonstrate that tch is a key parameter determining the radiation tolerance of oxide TFTs and a thin channel layer is advantageous in improving the radiation tolerance of oxide TFTs.

Evaluation of proton beam radiation-induced skin injury in a murine model using a clinical SOBP.

The purpose of this paper is to characterize the skin deterministic damage due to the effect of proton beam irradiation in mice occurred during a long-term observational experiment. This study was initially defined to evaluate the insurgence of myelopathy irradiating spinal cords with the distal part of a Spread-out Bragg peak (SOBP). To the best of our knowledge, no study has been conducted highlighting high grades of skin injury at the dose used in this paper. Nevertheless these effects occurred. In this regard, the experimental evidence of significant insurgence of skin injury induced by protons using a SOBP configuration will be shown. Skin damages were classified into six scores (from 0 to 5) according to the severity of the injuries and correlated to ED50 (i.e. the radiation dose at which 50% of animals show a specific score) at 40 days post-irradiation (d.p.i.). The effects of radiation on the overall animal wellbeing have been also monitored and the severity of radiation-induced skin injuries was observed and quantified up to 40 d.p.i.

Effect of 5-fluorouracil on cellular response to proton beam in esophageal cancer cell lines according to the position of spread-out Bragg peak

Introduction: To investigate enhancement by 5-fluorouracil (5-FU) of the sensitivity of cancer cells to proton beam irradiation and clarify the differences in the responses of the 5-FU-treated cells to proton beam irradiation according to the position of the cells on the spread-out Bragg peak (SOBP).Methods: OE21 human esophageal squamous cells were irradiated with a 235-MeV proton beam at four different positions on the SOBP. The effects of the irradiation plus 5-FU treatment on the cell survival were assessed by clonogenic assays and determination of the sensitizer enhancement ratio (SER). In addition, DNA double-strand breaks were estimated by measuring phospho-histone H2AX (γH2AX) foci formation in the cells at 0.5 and 24 h after irradiation.Results: The relative biological effectiveness (RBE) of proton beam irradiation against vehicle-control cells tended to increase with an increase in the depth of the cells on the SOBP. On the other hand, the degree of enhancement of the cellular sensitivity to proton beam irradiation by 5-FU was similar across all the positions on the SOBP. Furthermore, a marked increase in the number of residual γH2AX foci at 24 h post-irradiation was observed in the cells at the distal end of the SOBP.Conclusions: Our data indicated that the degree of enhancement by 5-FU of the sensitivity of OE21 cells to 235-MeV proton beam irradiation did not differ significantly depending on the position of the cells on the SOBP. Furthermore, the degree of increase in the number of γH2AX foci at 24 h after proton beam irradiation with or without 5-FU exposure did not differ significantly according to the position on the SOBP. The effect of 5-FU in enhancing the effect of proton beam irradiation on cancer cells may be constant for all positions on the SOBP.

Dose-dependent effect of proton irradiation on electrical properties of WSe2 ambipolar field effect transistors.

The irradiation effect of high energy proton beams on tungsten diselenide (WSe2) ambipolar field-effect transistors was investigated. We measured the electrical characteristics of the fabricated WSe2 FETs before and after the 10 MeV proton beam irradiation with different doses of 1012, 1013, 1014, and 1015 cm-2. For low dose conditions (1012, 1013, and 1014 cm-2), the threshold voltages shifted to the negative gate voltage direction, and the current in the hole and electron accumulation regimes decreased and increased, respectively. However, the trends were opposite for the high dose condition (1015 cm-2); the threshold voltages shifted to the positive gate voltage direction, and the current in the hole and electron accumulation regimes increased and decreased, respectively. These phenomena can be explained by the combined effect of proton irradiation-induced traps and the applied gate bias condition. Specifically, irradiation-induced positive oxide traps in SiO2 dielectrics play a role in enhancing electron accumulation and reducing hole accumulation in the WSe2 channel, whereas the irradiation-induced holes near the WSe2/SiO2 interface act as electron trapping sites, with enhancing hole accumulation and reducing electron accumulation in the WSe2 channel. This work will help improve the understanding of the effect of high energy irradiation on WSe2-based and other ambipolar nanoelectronic devices. In addition, this work shows the possibility of tuning the electrical properties of WSe2-based devices.

The association of changes in RAD51 and survivin expression levels with the proton beam sensitivity of Capan‑1 and Panc‑1 human pancreatic cancer cells.

Fewer than 20% of patients diagnosed with pancreatic cancer can be treated with surgical resection. The effects of proton beam irradiation were evaluated on the cell viabilities in Panc‑1 and Capan‑1 pancreatic cancer cells. The cells were irradiated with proton beams at the center of Bragg peaks with a 6‑cm width using a proton accelerator. Cell proliferation was assessed with the MTT assay, gene expression was analyzed with semi‑quantitative or quantitative reverse transcription‑polymerase chain reaction analyses and protein expression was evaluated by western blotting. The results demonstrated that Capan‑1 cells had lower cell viability than Panc‑1 cells at 72h after proton beam irradiation. Furthermore, the cleaved poly (ADP‑ribose) polymerase protein level was increased by irradiation in Capan‑1 cells, but not in Panc‑1 cells. Additionally, it was determined that histone H2AX phosphorylation in the two cell lines was increased by irradiation. Although a 16 Gy proton beam was only slightly up‑regulated cyclin‑dependent kinase inhibitor1 (p21) protein expression in Capan‑1 cells, p21 expression levels in Capan‑1 and Panc‑1 cells were significantly increased at 72h after irradiation. Furthermore, it was observed that the expression of DNA repair protein RAD51 homolog1 (RAD51), a homogenous repair enzyme, was decreased in what appeared to be a dose‑dependent manner by irradiation in Capan‑1 cells. Contrastingly, the transcription of survivin in Panc‑1 was significantly enhanced. The results suggest that RAD51 and survivin are potent markers that determine the therapeutic efficacy of proton beam therapy in patients with pancreatic cancer.

Molecular characterization of proton beam-induced mutations in soybean using genotyping-by-sequencing.

Proton beam irradiation is a next-generation technique to develop mutant crop varieties. The mutagenic effects and molecular mechanisms of radiation are important multi-disciplinary research subjects. This study was conducted to investigate the types of mutations induced in the soybean genome by proton beam irradiation. In total, 22 plants, including 10 M2 plants treated with proton beam irradiation at 118 and 239Gy, each, and two wild-type plants (Daepung) were sequenced by genotyping-by-sequencing (GBS). In total, 7453 single nucleotide polymorphisms (SNPs) were detected in the 20 M2 plants, compared with the two wild-type controls. The SNP frequency was 1/36,976bp with proton beam irradiation at 118Gy, and 1/32,945bp at 239Gy. Of these, 3569 SNPs were detected in genic regions. We observed that proton beam irradiation induced more substitutions than small insertion-deletions (INDELs). Based on the mutagenic effect of proton beam irradiation, the frequency of transition mutations was shown to be higher than that of transversions. The proton beam-induced SNPs were distributed uniformly in most of the chromosomes. Gene ontology (GO) analysis showed that there were many genes involved in protein metabolic process under biological process, intracellular membrane-bounded organelle under cellular component, and nucleic acid binding under molecular function. This study could provide valuable information for investigating the potential mechanisms of mutation, and guidance for developing soybeans cultivars using mutation breeding.

Effects of proton beam irradiation on seed germination and growth of soybean (Glycine max L. Merr.)

The present study aimed to evaluate the morphological effects of proton beam irradiation on the seed germination, seedling survival, and plant growth of soybean. Seeds of three Korean elite cultivars (Kwangankong, Daepungkong, and Pungsannamulkong) were irradiated with a 57-MeV proton beam in the range of 50 - 400 Gy. The germination rates of all the varieties increased to > 95%; however, the survival rates were significantly reduced. At doses of > 300 Gy irradiation, the Daepungkong, Kwangankong, and Pungsannamulkong cultivars exhibited 39, 75, and 71% survival rates, respectively. In addition, plant height and the fresh weight of shoots and roots were significantly decreased by doses of > 100 Gy irradiation, as were the dry weights of the shoots and roots. However, SPAD values increased with increasing doses of irradiation. Abnormal plants with atypically branched stems, modified leaves, and chlorophyll mutations were observed. Based on the survival rate, plant growth inhibition, and mutation frequency, it appears that the optimum dosage of proton beam irradiation for soybean mutation breeding is between 250 and 300 Gy.

Proton beam irradiation inhibits the migration of melanoma cells.

PurposeIn recent years experimental data have indicated that low-energy proton beam radiation might induce a difference in cellular migration in comparison to photons. We therefore set out to compare the effect of proton beam irradiation and X-rays on the survival and long-term migratory properties of two cell lines: uveal melanoma Mel270 and skin melanoma BLM.Materials and methodsCells treated with either proton beam or X-rays were analyzed for their survival using clonogenic assay and MTT test. Long-term migratory properties were assessed with time-lapse monitoring of individual cell movements, wound test and transpore migration, while the expression of the related proteins was measured with western blot.ResultsExposure to proton beam and X-rays led to similar survival but the quality of the cell colonies was markedly different. More paraclones with a low proliferative activity and fewer highly-proliferative holoclones were found after proton beam irradiation in comparison to X-rays. At 20 or 40 days post-irradiation, migratory capacity was decreased more by proton beam than by X-rays. The beta-1-integrin level was decreased in Mel270 cells after both types of radiation, while vimentin, a marker of EMT, was increased in BLM cells only.ConclusionsWe conclude that proton beam irradiation induced long-term inhibition of cellular motility, as well as changes in the level of beta-1 integrin and vimentin. If confirmed, the change in the quality, but not in the number of colonies after proton beam irradiation might favor tumor growth inhibition after fractionated proton therapy.

Motile activity and cytoskeleton changes in uveal melanoma after proton beam radiation

PurposeProton beam irradiation is known to invoke different biological response than photons.We compared the effect of proton beam irradiation and X‐rays on the survival and migratory properties of melanoma cells.MethodsMel270, human uveal melanoma cell line was treated with physical doses of 1‐5 Gy of proton beam (58 MeV) from Proteus C‐235 cyclotron or X‐rays (300 kV Phillips) at the dose rate of 1 Gy/min were given to suspended cells.ResultsInvasive potential of cells was slightly diminished after both types of radiation at 20 days post‐radiation and then returned to normal at 40 days. Wound healing ability was decreased after X‐rays. The beta‐1‐integrin level was decreased after both types of radiation in Mel270 cells, and vimentin, a marker of EMT was not changed. Less stress fibers were seen in cytoskeleton of Mel270 cells after radiation.ConclusionsLow doses of both types of radiation influenced the motile activity and cytoskeleton in Mel270 cells.

Effects of proton beam irradiation on mitochondrial biogenesis in a human colorectal adenocarcinoma cell line.

Proton beam therapy has recently been used to improve local control of tumor growth and reduce side-effects by decreasing the global dose to normal tissue. However, the regulatory mechanisms underlying the physiological role of proton beam radiation are not well understood, and many studies are still being conducted regarding these mechanisms. To determine the effects of proton beams on mitochondrial biogenesis, we investigated: mitochondrial DNA (mtDNA) mass; the gene expression of mitochondrial transcription factors, functional regulators, and dynamic-related regulators; and the phosphorylation of the signaling molecules that participate in mitochondrial biogenesis. Both the mtDNA/nuclear DNA (nDNA) ratio and the mitochondria staining assays showed that proton beam irradiation increases mitochondrial biogenesis in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced aggressive HT-29 cells. Simultaneously, proton beam irradiation increases the gene expression of the mitochondrial transcription factors PGC-1α, NRF1, ERRα, and mtTFA, the dynamic regulators DRP1, OPA1, TIMM44, and TOM40, and the functional regulators CytC, ATP5B and CPT1-α. Furthermore, proton beam irradiation increases the phosphorylation of AMPK, an important molecule involved in mitochondrial biogenesis that is an energy sensor and is regulated by the AMP/ATP ratio. Based on these findings, we suggest that proton beam irradiation inhibits metastatic potential by increasing mitochondrial biogenesis and function in TPA-induced aggressive HT-29 cells.

Transgenerational effects of proton beam irradiation on Caenorhabditis elegans germline apoptosis

When treating cancer using radiation therapy, it is critical to increase patient survival rates and to reduce side effects. In this respect, proton beam radiation treatment performs better than other radiation treatments because of its high target specificity. However, complications still remain after proton beam radiation treatment. Among them, the risk to progeny after irradiation of their parents is a major concern. In this study, we analyzed the transgenerational effects of proton beam irradiation using the model organism Caenorhabditis. elegans. We found that germline apoptosis increased after proton beam irradiation and its effects were sustained transgenerationally. Moreover, we identified that a germline-specific histone methyltransferase component, SET-2, has a critical role in transmitting the transgenerational effect on germline apoptosis to the next generation after proton beam irradiation.

Biochemical Responses of Soybean (Glycine max L. Merr.) to Proton Beam Irradiation

The present study evaluated the biochemical effects of proton beam irradiation in soybean. Seeds of two Korean elite cultivars (Kwangan and Pungsannamul) were irradiated by a 57-MeV proton beam in the range of 50-400 Gy. We measured the contents of malondialdehyde (MDA), antioxidant enzymes, and chlorophyll. MDA contents in proton beam-irradiated plants were higher than those in control plants. The activity of antioxidant enzymes differed between the two cultivars. In Kwangan, ascorbate peroxidase (APX) activity increased by 29% relative to the control at 55 Gy and decreased by 58% at 308 Gy. Superoxide dismutase (SOD) and peroxidase (POD) activities decreased by 47 and 25% relative to the control at 55 Gy and recovered to 87 and 56% of that at 55 Gy with 172 Gy and 117 Gy, respectively. In Pungsannamul, APX and SOD decreased by 32 and 35% relative to the control at 62 Gy, with the highest value observed at 243 Gy. In terms of the chlorophyll content, the two varieties responded similarly to proton beam irradiation, whereas in Kwangan, no significant reduction was observed above 100 Gy when compared with the control. Proton beam irradiation affected chlorophyll b more than chlorophyll a. These results show that the activity of antioxidant enzymes decreased in response to irradiation with approximately 50 Gy proton beams, then increased gradually with increasing doses, followed by a moderate decrease at higher doses. According to correlation with MDA contents and antioxidant enzyme activities, defense system of Pungsannamul was less activated by proton-beam irradiation than that of Kwangan.

Damage effects of proton beam irradiation on single layer graphene

Graphene was first discovered in 2004 (Novoselov K S, et al. 2004 Science 306 666), it is a single atomic layer of sp2-bonded carbon atoms arranged in a honeycomb-like lattice. According to its extraordinary electronic, mechanical, thermal and optical properties, one can expect it to have a variety of applications in nanoscale electronics, composite materials, energy storage, and biomedicine fields. Although many experimental and theoretical studies on graphene have been carried, there still exist many obstacles to its applications. A representative example is nanoscale electronics (e.g., field-effect transistors and optoelectronic devices) that requires non-zero band-gap. Therefore, introducing defects into graphene and leading to band-gap opening are key steps for its technique applications.Recently, ion beam irradiation as a defects introducing technique was performed by Lee et al. (2015 Appl. Surf. Sci. 344 52) and Zeng et al. (2016 Carbon 100 16) through 5, 10, and 15 MeV protons and highly charged ions (HCIs) irradiating the graphene separately. Considering the advantages of simplity for preparing samples and feasibility in atmospheric condition of Raman spectroscopy compared with common characterization techniques (high resolution transmission electron microscopy, scanning electron microscopy, atomic force microscopy) for nano-materials, in both studies, Raman spectroscopy is used to obtain the evolution of ID/IG (ID is the peak intensity excited by defects, IG is the peak intensity origining from lateral vibration of carbon atoms) with different energies and fluences, respectively. In this work, considered are the following points:1) the absence of quantitive characterization for defects in the above two studies; 2) the low displacement energy of 25 eV required for a carbon atom to be knocked out (Zhao S J, et al. 2012 Nanotechnology 23 285703); 3) the complex interaction between HCIs and material. The irradiation effects of single layer graphene on silicon substrate are investigated by 750 keV and 1 MeV proton bombarding. This introduces the defects into graphene and thus leads to band-gap opening. By comparing Raman spectra of the samples before and after irradiation, a quantitive characterization about defects in graphene is achieved. Detailed analysis shows that 1) the value of ID/IG increases with the energy loss of incident proton, which is consistent with the result of SRIM simulation; 2) the average distance of defects LD increases with the incident proton energy; 3) the defect density nD decreases with the incident proton energy. These indicate that the damage effect for MeV protons in single layer graphene with substrate is similar to those in three-dimensional materials. The method presented here may facilitate the understanding of the physical mechanism of MeV proton interaction with two-dimensional materials, and provide a potential way of controlling the electronic structure and band-gap.

Effect of Proton Beam Irradiation on M1 Seeds and Seedling Growth in Rice

This study was carried out to evaluate effect of proton beam irradiation on M1 seed germination and seedling growth. For dosage effect, mature and healthy Supersami2 seeds were irradiated with 0, 204, 395, 502, and 700Gy. The traits for germination were not affected by dosage effect of proton beam irradiation. Germination rate evaluated at 7 days after imbibition ranged from 93.3% to 98.7%; germination vigor ranged from 59.3% to 68.7% where in the dose of 700Gy showed the lowest value of 59.3%. The average days of germination ranged from 1.36 to 1.48. The seedling growth was affected by the dosage. Withered rate (withered plants after germination) was increased as the dose increased. The withered rate of 53.9% was detected in 395Gy and no plant survived in 700Gy. In the ~400Gy treatment, the sensitivity of the traits of germination among Dianxi4, Jeogjinju, MS11(Maligaya Special 11), and Superjami2 was not different while the withered rate was different: 9.7% in MS11, 32.1% in Dianxi4, 53.9% in Superjami2, and 59.7% in Jeogjinju. Based on the germination rate and withered rate, it can be suggested that 350Gy to 450Gy is a starting point for applying proton beam irradiation to rice seed for mutation breeding.

Inhibitory effects of proton beam irradiation on integrin expression and signaling pathway in human colon carcinoma HT29 cells.

Proton radiotherapy has been established as a highly effective modality used in the local control of tumor growth. Although proton radiotherapy is used worldwide to treat several types of cancer clinically with great success due to superior targeting and energy deposition, the detailed regulatory mechanisms underlying the functions of proton radiation are not yet well understood. Accordingly, in the present study, to assess the effects of proton beam on integrin-mediated signaling pathways, we investigated the expression of integrins related to tumor progression and integrin trafficking, and key molecules related to cell adhesion, as well as examining phosphorylation of signaling molecules involved in integrin-mediated signaling pathways. Proton beam irradiation inhibited the increase in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced integrin β1 protein expression and the gene expression of members of the integrin family, such as α5β1, α6β4, αvβ3, and αvβ6 in human colorectal adenocarcinoma HT-29 cells. Simultaneously, the gene expression of cell adhesion molecules, such as FAK and CDH1, and integrin trafficking regulators, such as RAB4, RAB11, and HAX1, was decreased by proton beam irradiation. Moreover, proton beam irradiation decreased the phosphorylation of key molecules involved in integrin signaling, such as FAK, Src, and p130Cas, as well as PKC and MAPK, which are known as promoters of cell migration, while increased the phosphorylation of AMPK and the gene expression of Rab IP4 involved in the inhibition of cell adhesion and cell spreading. Taken together, our findings suggest that proton beam irradiation can inhibit metastatic potential, including cell adhesion and migration, by modulating the gene expression of molecules involved in integrin trafficking and integrin-mediated signaling, which are necessary for tumor progression.

Metastatic potential in MDA-MB-231 human breast cancer cells is inhibited by proton beam irradiation via the Akt/nuclear factor-κB signaling pathway.

A previous study has revealed that proton beam irradiation affects cell migration in MDA-MB-231 human breast cancer cells. Cyclooxygenase-2 (COX-2) and matrix metalloproteinase‑9 (MMP-9) are highly expressed in various cancers, such as colon, lung and breast cancer, and enhance cell migration and metastasis invitro and invivo. In the present study, the effects of proton beam irradiation on COX-2 and MMP-9 expression levels in MDA-MB‑231 human breast cancer cells were investigated, along with the signaling pathway involved in the proton beam irradiation‑mediated antimetastatic effect. The results revealed that 12-O-tetradecanoylphorbol-13‑acetate‑induced increases in COX-2 and MMP-9 expression levels were reversed by proton beam irradiation in a dose-dependent manner. In addition, proton beam irradiation inhibited phosphorylation of protein kinaseB (also known as Akt) and nuclear factor-κB (NF-κB), which are activated by phosphoinositide 3-kinase (PI3K) stimulation. MMP-9 and COX-2 expression levels are regulated by PI3K/Akt and/or protein kinaseC/mitogen-activated protein kinase signaling pathways that enhance NF-κB and activator protein-1 transcriptional activities. Therefore, the results suggest that proton beam irradiation inhibited the cancer cell growth and metastasis associated with COX-2 and MMP-9 expression in MDA-MB‑231 human breast cancer cells, and that the antimetastatic effect of proton beam irradiation is achieved by the suppression of NF-κB phosphorylation via inhibition of Akt activation.