Phosphoprotein profiles of candidate markers for early cellular responses to low-dose γ-radiation in normal human fibroblast cells

Yim, Ji-Hye,Yun, Jung Mi,Kim, Ji Young,Lee, In Kyung,Nam, Seon Young,Kim, Cha Soon JAPAN RADIATION RESEACH SOCIETY 2017 JOURNAL OF RADIATION RESEARCH Vol.58 No.3

<P><B>Abstract</B></P><P>Ionizing radiation causes biological damage that leads to severe health effects. However, the effects and subsequent health implications caused by exposure to low-dose radiation are unclear. The objective of this study was to determine phosphoprotein profiles in normal human fibroblast cell lines in response to low-dose and high-dose γ-radiation. We examined the cellular response in MRC-5 cells 0.5 h after exposure to 0.05 or 2 Gy. Using 1318 antibodies by antibody array, we observed ≥1.3-fold increases in a number of identified phosphoproteins in cells subjected to low-dose (0.05 Gy) and high-dose (2 Gy) radiation, suggesting that both radiation levels stimulate distinct signaling pathways. Low-dose radiation induced nucleic acid–binding transcription factor activity, developmental processes, and multicellular organismal processes. By contrast, high-dose radiation stimulated apoptotic processes, cell adhesion and regulation, and cellular organization and biogenesis. We found that phospho-BTK (Tyr550) and phospho-Gab2 (Tyr643) protein levels at 0.5 h after treatment were higher in cells subjected to low-dose radiation than in cells treated with high-dose radiation. We also determined that the phosphorylation of BTK and Gab2 in response to ionizing radiation was regulated in a dose-dependent manner in MRC-5 and NHDF cells. Our study provides new insights into the biological responses to low-dose γ-radiation and identifies potential candidate markers for monitoring exposure to low-dose ionizing radiation.</P>

Low-dose-rate radiation exposure leads to testicular damage with decreases in DNMT1 and HDAC1 in the murine testis

Gong, Eun Ji,Shin, In Sik,Son, Tae Gen,Yang, Kwangmo,Heo, Kyu,KIM, Joong Sun JAPAN RADIATION RESEACH SOCIETY 2014 JOURNAL OF RADIATION RESEARCH Vol.55 No.1

<P>This study examined the effects of continuous low-dose-rate radiation exposure (3.49 mGy/h) of gamma rays on mice testicles. C57BL/6 mice were divided into sham and radiation groups (<I>n</I> = 8 each), and were exposed to either sham irradiation or 2 Gy for 21 days, 0.2 Gy for 2 days, or 0.02 Gy for 6 h of low-dose-rate irradiation. Testicular weight, seminiferous tubular diameter, and seminiferous epithelial depth were significantly decreased in the mice irradiated with 2 Gy at 1 and 9 days after exposure. Moreover, the low-dose-rate radiation exposure induced an increase in malondialdehyde levels, and a decrease in superoxide dismutase activity in the testis of mice irradiated with 2 Gy at 1 and 9 days after exposure. The sperm count and motility in the epididymis also decreased in mice irradiated with 2 Gy at 1 and 9 days after exposure, whereas there was no significant effect on the proportion of abnormal sperm. The expressions of DNA methlytransferases-1 and histone deacetylases 1 in testes irradiated with 2 Gy were significantly decreased compared with the sham group. In conclusion, the damage exerted on the testes and epididymis largely depended on the total dose of low-dose-rate radiation.</P>

Low-dose of Ionizing Radiation Enhances Cell Proliferation Via Transient ERK1/2 and p38 Activation in Normal Human Lung Fibroblasts

KIM, Cha Soon,KIM, Jin-Mo,NAM, Seon Young,YANG, Kwang Hee,JEONG, Meeseon,KIM, Hee Sun,LIM, Young-Khi,KIM, Chong Soon,JIN, Young-Woo,KIM, Joon JAPAN RADIATION RESEACH SOCIETY 2007 JOURNAL OF RADIATION RESEARCH Vol.48 No.5

<P>This study shows the human cellular responses and the mechanism of low-dose ionizing radiation in CCD 18 Lu cells, which are derived from normal human lung fibroblasts. Cell proliferation and viability assay were measured for the cells following γ-irradiation using trypan blue, BrdU incorporation, and Wst-1 assay. We also examined genotoxicity using a micronuclei formation assay. The activation of the MAPKs pathway was determined by Western blot analysis, and the siRNA system was used to inhibit the expression of ERK1/2 and p38. We found that 0.05 Gy of ionizing radiation stimulated cell proliferation and did not change Micronuclei frequencies. In addition, 0.05 Gy of ionizing radiation activated ERK1/2 and p38, but did not activate JNK1/2 in cells. A specific ERK1/2 inhibitor, U0126, decreased the phosphorylation of ERK1/2 proteins induced by 0.05 Gy of ionizing radiation, and a similar suppressive effect was observed with a p38 inhibitor, PD169316. Suppression of ERK1/2 and p38 phosphorylation with these inhibitors decreased cell proliferation, which was stimulated by 0.05 Gy of ionizing radiation. Furthermore, downregulation of ERK1/2 and p38 expression using siRNA blocked the cell proliferation that had been increased by 0.05 Gy of ionizing radiation. These results suggest that 0.05 Gy of ionizing radiation enhances cell proliferation through the activation of ERK1/2 and p38 in normal human lung fibroblasts.</P>

Sam68 is cleaved by caspases under apoptotic cell death induced by ionizing radiation

Cho, Seong-Jun,Choi, Moo Hyun,Nam, Seon Young,Kim, Ji Young,Kim, Cha Soon,Pyo, Suhkneung,Yang, Kwang Hee JAPAN RADIATION RESEACH SOCIETY 2015 JOURNAL OF RADIATION RESEARCH Vol.56 No.2

<P><B>Abstract</B></P><P>The RNA-binding protein Sam68, a mitotic substrate of tyrosine kinases, has been reported to participate in the cell cycle, apoptosis, and signaling. In particular, overexpression of Sam68 protein is known to suppress cell growth and cell cycle progression in NIH3T3 cells. Although Sam68 is involved in many cellular activities, the function of Sam68, especially in response to apoptotic stimulation, is not well understood. In this study, we found that Sam68 protein is cleaved in immune cells undergoing apoptosis induced by γ-radiation. Moreover, we found that Sam68 cleavage was induced by apoptotic stimuli containing γ-radiation in a caspase-dependent manner. In particular, we showed that activated casepase-3, 7, 8 and 9 can directly cleave Sam68 protein through <I>in vitro</I> protease cleavage assay. Finally, we found that the knockdown of Sam68 attenuated γ-radiation–induced cell death and growth suppression. Conclusively, the cleavage of Sam68 is a new indicator for the cell damaging effects of ionizing radiation.</P>

Protective activity of a novel resveratrol analogue, HS-1793, against DNA damage in ¹³⁷ Cs-irradiated CHO-K1 cells

Jeong, Min Ho,Yang, Kwang Mo,Jeong, Dong Hyeok,Lee, Chang Geun,Oh, Su Jung,Jeong, Soo Kyung,Lee, Ki Won,Jo, Young Rae,Jo, Wol Soon JAPAN RADIATION RESEACH SOCIETY 2014 JOURNAL OF RADIATION RESEARCH Vol.55 No.3

<P>Resveratrol has received considerable attention as a polyphenol with anti-oxidant, anti-carcinogenic, and anti-inflammatory effects. Radiation is an important component of therapy for a wide range of malignant conditions. However, it causes damage to normal cells and, hence, can result in adverse side effects. This study was conducted to examine whether HS-1793, a novel resveratrol analogue free from the restriction of metabolic instability and the high dose requirement of resveratrol, induces a protective effect against radiation-induced DNA damage. HS-1793 effectively scavenged free radicals and inhibited radiation-induced plasmid DNA strand breaks in an <I>in vitro</I> assay. HS-1793 significantly decreased reactive oxygen species and cellular DNA damage in 2 Gy-irradiated Chinese hamster ovary (CHO)-K1 cells. In addition, HS-1793 dose-dependently reduced the levels of phosphorylated H2AX in irradiated CHO-K1 cells. These results indicate that HS-1793 has chemical radioprotective activity. Glutathione levels and superoxide dismutase activity in irradiated CHO-K1 cells increased significantly following HS-1793 treatment. The enhanced biological anti-oxidant activity and chemical radioprotective activity of HS-1793 maintained survival of irradiated CHO-K1 cells in a clonogenic assay. Therefore, HS-1793 may be of value as a radioprotector to protect healthy tissue surrounding tumor cells during radiotherapy to obtain better tumor control with a higher dose.</P>

Protective Effect of Triphlorethol-A from <i>Ecklonia cava </i>against Ionizing Radiation <i>in vitro</i>

KANG, Kyoung Ah,ZHANG, Rui,LEE, Kyoung Hwa,CHAE, Sungwook,KIM, Bum Joon,KWAK, Young Sook,PARK, Jae Woo,LEE, Nam Ho,HYUN, Jin Won JAPAN RADIATION RESEACH SOCIETY 2006 JOURNAL OF RADIATION RESEARCH Vol.47 No.1

<P>We studied the cytoprotective effect of triphlorethol-A against γ-ray radiation- induced oxidative stress. In this study, hydrogen peroxide, which is a reactive oxygen species (ROS), was detected using 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA) assay. Triphlorethol-A reduced intracellular hydrogen peroxide generated by γ-ray radiation. This compound provided protection against radiation-induced membrane lipid peroxidation and cellular DNA damage which are the main targets of radiation-induced damage. Triphlorethol-A protected the cell viability damaged by the radiation through inhibition of apoptosis. Triphlorethol-A reduced the expression of bax and activated caspase 3 induced by radiation, but recovered the expression of bcl-2 decreased by radiation. Taken together, the results suggest that triphlorethol-A protects cells against oxidative damage induced by radiation through reducing ROS.</P>

Development of a minipig physical phantom from CT data

Park, Sooyeun,Lee, Pilsoo,Ha, Wi-Ho,Kim, Han Sung,Park, Byeong Ryong,Kim, Jae ,Seok,Shim, Sehwan,Park, Sunhoo,Kim, Young-su,Kim, Chan Hyeong,Jin, Young-Woo JAPAN RADIATION RESEACH SOCIETY 2017 JOURNAL OF RADIATION RESEARCH Vol.58 No.5

<P><B>ABSTRACT</B></P><P>Quantification of pathological progression of radiation-induced injury is essential in development of treatment methods, and a proper animal model is necessary for relevant radiological and medical studies. A minipig is a current animal model selected because of its similarities to humans in anatomy and pathology. In the present study, a minipig physical phantom was developed using computed tomography (CT) data. For dosimetry purposes, the minipig physical phantom was constructed on a slice-by-slice basis, with an array of holes to accommodate dosimeters. The phantom is constituted of three major organs, i.e. bone, lung, and remaining soft tissue, and the organs are clearly distinguishable on each 20-mm-thick axial slice. The quality of the tissue-equivalent (TE) substitutes was analyzed in terms of the atomic compositions and Hounsfield units (HUs). The density (in g/cm<SUP>3</SUP>) and effective atomic number of TE substitutes for the bone, lung, and soft tissue are 1.4 and 7.9, 0.5 and 10.0, and 1.0 and 5.9, respectively. Although the TE substitutes have slightly different physical properties, we think the phantom is acceptable because the HU values of the TE substitutes lie in the HU range of real tissues.</P>

Chronic low-dose γ-irradiation of <i>Drosophila melanogaster</i> larvae induces gene expression changes and enhances locomotive behavior

Kim, Cha Soon,Seong, Ki Moon,Lee, Byung Sub,Lee, In Kyung,Yang, Kwang Hee,Kim, Ji-Young,Nam, Seon Young JAPAN RADIATION RESEACH SOCIETY 2015 JOURNAL OF RADIATION RESEARCH Vol.56 No.3

<P>Although radiation effects have been extensively studied, the biological effects of low-dose radiation (LDR) are controversial. This study investigates LDR-induced alterations in locomotive behavior and gene expression profiles of <I>Drosophila melanogaster</I>. We measured locomotive behavior using larval pupation height and the rapid iterative negative geotaxis (RING) assay after exposure to 0.1 Gy γ-radiation (dose rate of 16.7 mGy/h). We also observed chronic LDR effects on development (pupation and eclosion rates) and longevity (life span). To identify chronic LDR effects on gene expression, we performed whole-genome expression analysis using gene-expression microarrays, and confirmed the results using quantitative real-time PCR. The pupation height of the LDR-treated group at the first larval instar was significantly higher (∼2-fold increase in PHI value, <I>P</I> < 0.05). The locomotive behavior of LDR-treated male flies (∼3 − 5 weeks of age) was significantly increased by 7.7%, 29% and 138%, respectively (<I>P</I> < 0.01), but pupation and eclosion rates and life spans were not significantly altered. Genome-wide expression analysis identified 344 genes that were differentially expressed in irradiated larvae compared with in control larvae. We identified several genes belonging to larval behavior functional groups such as locomotion (1.1%), oxidation reduction (8.0%), and genes involved in conventional functional groups modulated by irradiation such as defense response (4.9%), and sensory and perception (2.5%). Four candidate genes were confirmed as differentially expressed genes in irradiated larvae using qRT-PCR (>2-fold change). These data suggest that LDR stimulates locomotion-related genes, and these genes can be used as potential markers for LDR.</P>

The combination of ionizing radiation and proteasomal inhibition by bortezomib enhances the expression of NKG2D ligands in multiple myeloma cells

Lee, Young Shin,Heo, Woong,Nam, Jiho,Jeung, Young Hwa,Bae, Jaeho JAPAN RADIATION RESEACH SOCIETY 2018 JOURNAL OF RADIATION RESEARCH Vol.59 No.3

<P><B>Abstract</B></P><P>Bortezomib, which is a potent proteasome inhibitor, has been used as a first-line drugs to treat multiple myeloma for a few decades, and radiotherapy has frequently been applied to manage acute bone lesions in the patients. Therefore, it was necessary to investigate what the benefits might be if the two therapies were applied simultaneously in the treatment of multiple myeloma. Since it was known that radiotherapy and proteasome inhibitors could increase the expression of NKG2D ligands through induction of protein synthesis and suppression of protein degradation of NKG2D ligands, respectively, we supposed that the combined treatment might further enhance the expression of NKG2D ligands. In this study, we analyzed the expression level of NKG2D ligands using multiplex PCR and flow cytometry after treatment of IM-9 and RPMI-8226 myeloma cells with bortezomib and ionizing radiation; we then assayed the susceptibility to NK-92 cells. Although the expression of only some kinds of NKG2D ligands were increased by treatment with bortezomib alone, five kinds of NKG2D ligands that we assayed were further induced at the surface protein level after combined treatment with ionizing radiation and bortezomib. Furthermore, combined treatment made myeloma cells more susceptible to NK-92 cells, compared with treatment with bortezomib alone. In conclusion, the combination therapy of ionizing radiation plus the proteasome inhibitor bortezomib is a promising therapeutical strategy for enhancing NK cell–mediated anticancer immune responses.</P>

Pancreatic radiation effect in apoptosis-related rectal radiation toxicity

You, Sei Hwan,Cho, Mee Yon,Sohn, Joon Hyung,Lee, Chang Geol JAPAN RADIATION RESEACH SOCIETY 2018 JOURNAL OF RADIATION RESEARCH Vol.59 No.5

<P><B>Abstract</B></P><P>Pancreatic radiation effect (PRE) can be a component of gastrointestinal tract (GIT) radiotoxicity. This inter-organ correlation between the GIT and the pancreas was assessed through a rat model. Separate local irradiation to the abdomen and the pelvis was applied concurrently for 8-week-old male Sprague Dawley rats. Abdominal irradiation was categorized into pancreatic shield (PS) and non-pancreatic shield (NPS) irradiation. After 5 Gy and 15 Gy irradiation, the rectal mucosa was analyzed at the first week (early phase, Ep) and the 14th week (late phase, Lp). A slow gain in body weight was observed initially, particularly in the NPS group receiving a 15 Gy dose (<I>P</I> < 0.001). The large number of apoptotic bodies after 15 Gy at Ep decreased at Lp. At Ep for the 5-Gy group, the NPS group revealed more fibrotic change than the PS group (<I>P</I> = 0.002). Cleaved caspase-3 (CCP3) expression was greater at Lp, and the Ep–Lp increase was prominent in the NPS-15-Gy group (<I>P</I> = 0.010). At Lp, for 15 Gy irradiation, CCP3 was expressed more in the NPS group than in the PS group (<I>P</I> = 0.032). Despite no direct toxicity difference between the PS and NPS groups, small changes in parameters such as fibrosis or CCP3 expression suggest that pancreatic shielding does have an effect on the radiation response in the rectal mucosa, which suggests a need for a multi-organ effect-based approach in GIT radiotoxicity assessment.</P>