Recombinant Human Epidermal Growth Factor (rhEGF) Protects Radiation-Induced Intestine Injury in Murine System

OH, Haejin,SEONG, Jinsil,KIM, Wonwoo,PARK, Sooyeon,KOOM, Woong Sub,CHO, Nam Hoon,SONG, Mihee Journal of Radiation Research Editorial Committee 2010 JOURNAL OF RADIATION RESEARCH Vol.51 No.5

<P>This study was to investigate whether rhEGF protects radiation induced intestine injury without compromising antitumor effect of radiation in murine system. A radiation induced intestinal injury model was established in mice by whole body irradiation. Using this model, 4 groups were set; control, rhEGF (100 μg/kg intraperitoneally), radiation (10 Gy), and a combination (rhEGF and radiation). The level of apoptosis and proliferation were analyzed by TUNEL assay and proliferation cell nuclear antigen (PCNA) immunohistochemical staining, respectively, as well as observation of survival and body weight change. A tumor growth delay assay was performed using murine syngeneic tumors; one radioresistant tumor, HCa-I and one radiosensitive tumor, MCa-K. In the radiation induced intestinal injury model, the 10 Gy group had significantly more weight loss with less number of crypt cells and higher apoptosis than the 8 Gy group. Using 10 Gy model, radioprotective effect of rhEGF was tested. Addition of rhEGF improved not only the body weight loss but also survival following radiation. It also induced suppression of apoptosis as well as increase of PCNA expression and recovery of villi. rhEGF did not enhance the tumor growth after radiation exposure in the tested tumors. These findings suggest that combination of exogenous rhEGF and radiation can be a new anticancer strategy by protecting radiation-induced intestinal injury without alleviating antitumor effect of radiation.</P>

Two-Dimensional Electrophoretic Analysis of Radio Frequency Radiation-Exposed MCF7 Breast Cancer Cells

KIM, Ki-Bum,BYUN, Hae-Ok,HAN, Na-Kyung,KO, Young-Gyu,CHOI, Hyung-Do,KIM, Nam,PACK, Jeong-Ki,LEE, Jae-Seon Journal of Radiation Research Editorial Committee 2010 JOURNAL OF RADIATION RESEARCH Vol.51 No.2

<P>Although many <I>in vitro </I>studies have previously been conducted to elucidate the biological effects of radio frequency (RF) radiation over the past decades, the existence and nature of any effects is still inconclusive. In an effort to further elucidate this question, we have monitored changes in protein expression profiles in RF-exposed MCF7 human breast cancer cells using two-dimensional gel electrophoresis. MCF7 cells were exposed to 849 MHz RF radiation for 1 h per day for three consecutive days at specific absorption rates (SARs) of either 2 W/Kg or 10 W/kg. During exposure, the temperature in the exposure chamber was kept in an isothermal condition. Twenty-four hours after the final RF exposure, the protein lysates from MCF cells were prepared and two-dimensional electrophoretic analyses were conducted. The protein expression profiles of the MCF cells were not significantly altered as the result of RF exposure. None of the protein spots on the two-dimensional electrophoretic gels showed reproducible changes in three independent experiments. To determine effect of RF radiation on protein expression profiles more clearly, three spots showing altered expression without reproducibility were identified using electrospray ionization tandem mass spectrometry analysis and their expressions were examined with RT-PCR and Western blot assays. There was no alteration in their mRNA and protein levels. As we were unable to observe any significant and reproducible changes in the protein expression profiles of the RF radiation-exposed MCF7 cells using high throughput and non-high throughput techniques, it seems unlikely that RF exposure modulates the protein expression profile.</P>

The Preventive Effect of Recombinant Human Growth Factor (rhEGF) on the Recurrence of Radiodermatitis

RYU, Seung-Hee,KIM, Yeun Hwa,LEE, Sang-wook,HONG, Joon Pio Journal of Radiation Research Editorial Committee 2010 JOURNAL OF RADIATION RESEARCH Vol.51 No.5

<P>The effects of topical application of recombinant human epidermal growth factor (rhEGF) on wound healing and the recurrence of radiodermatitis were assessed in the irradiated skin of BALB/c Nu/Nu mice. Mice irradiated with 45 Gy of radiation were divided into 5 groups and treated with 10, 50, and 100 μg/g rhEGF ointment, vehicle alone, or no treatment (control) for 6 months. Wounds were observed initially in all groups and complete healing time (HT<SUB>100</SUB>) for initial wound repair did not differ significantly among groups. However, the rate of recurrence over 6 months was significantly lower in the EGF-treated groups than in the control group (<I>p</I> < 0.05). Histological examination showed that treatment with the optimum dose of EGF (50 μg/g) accelerated normal wound healing when compared with the higher dose of EGF (100 μg/g), vehicle alone, or no treatment, with the latter group showing irregular epidermal thickness, poor definition of epidermis and dermis, and unstable dermal structure. Collagen distribution was also significantly increased in mice treated with 50 μg/g rhEGF (<I>p</I> < 0.05) compared with the control or vehicle-treated group. Taken together, these results indicate that treatment with exogenous EGF (50 μg/g dose) can enhance radiation-induced wound repair while preserving structural tissue stability and preventing the recurrence of radiodermatitis.</P>

Recombinant Human Epidermal Growth Factor Accelerates the Proliferation of Irradiated Human Fibroblasts and Keratinocytes <i>in vitro</i> and <i>in vivo</i>

RYU, Seung-Hee,MOON, Soo Young,YANG, Youn-Joo,MOON, Sun Rock,HONG, Joon Pio,CHOI, Jene,LEE, Sang-wook Journal of Radiation Research Editorial Committee 2009 JOURNAL OF RADIATION RESEARCH Vol.50 No.6

<P>Irradiation causes the impaired proliferation of cells lining mucosal membranes. Epidermal growth factor (EGF) facilitates proliferation of various skin cells; however, the wound healing effects of EGF on radiation-damaged cells is less well known. To evaluate the effects of recombinant human EGF (rhEGF) on the proliferation of cells following irradiation, we tested two types of fibroblast cell lines and one keratinocyte cell line. The viable cell numbers were significantly increased by rhEGF treatment for 24 h immediately after 8 Gy of irradiation. The most effective dose of rhEGF was 10 nM in all cell lines used in this study. The percentage of BrdU-labeled cells was also significantly increased by rhEGF treatment. To evaluate the effects of rhEGF on radiation-induced oral mucosal damage in BALB/c mice, we systematically injected 1 mg/kg/day EGF for three days after 17 Gy of irradiation. Administered rhEGF ameliorated radiation-induced mucosal damage <I>in vivo</I>. rhEGF significantly increased the epithelial cell layer thickness and the proliferation of basal layer cells as detected by Ki-67 staining. Our results suggest that rhEGF can be a therapeutic treatment for radiation-induced wounds by stimulating the proliferation of fibroblasts and keratinocytes following irradiation.</P>

Acute Exposure to UV-B Sensitizes Cucumber, Tomato, and Arabidopsis Plants to Photooxidative Stress by Inhibiting Thermal Energy Dissipation and Antioxidant Defense

MOON, Yu Ran,LEE, Min Hee,TOVUU, Altanzaya,LEE, Choon-Hwan,CHUNG, Byung Yeoup,PARK, Youn-Il,KIM, Jin-Hong Journal of Radiation Research Editorial Committee 2011 Journal of radiation research Vol.52 No.2

<P>To characterize a change in NPQ upon exposure to ultraviolet-B (UV-B), the xanthophyll cycle-dependent and -independent NPQs were compared in <I>Cucumis sativus</I>, <I>Lycopersicum esculentum</I>, and <I>Arabidopsis thaliana</I> leaves. The xanthophyll cycle-dependent NPQ was dramatically but reversibly suppressed by UV-B radiation. This suppression was correlated more strongly with a marked decrease in photosynthetic electron transport rather than changes in xanthophyll cycle enzymes such as violaxanthin de-epoxidase and zeaxanthin epoxidase. Accordingly, the UV-B-induced suppression of NPQ cannot be attributed to changes in expressions of VDE and ZEP. However, suppression of the xanthophyll cycle-dependent NPQ could only account for the 77 K fluorescence emission spectra of thylakoid membranes and the increased level of <SUP>1</SUP>O<SUB>2</SUB> production, but not for the decreased levels of •O<SUB>2</SUB><SUP>–</SUP> production and H<SUB>2</SUB>O<SUB>2</SUB> scavenging. These results suggest that a gradual reduction of H<SUB>2</SUB>O<SUB>2</SUB> scavenging activity as well as a transient and reversible suppression of thermal energy dissipation may contribute differentially to increased photooxidative damages in cucumber, tomato, and Arabidopsis plants after acute exposure to UV-B radiation.</P>

HDAC Inhibitor-Mediated Radiosensitization in Human Carcinoma Cells: A General Phenomenon?

KIM, In Ah,KIM, Il Han,KIM, Hak Jae,CHIE, Eui Kyu,KIM, Jae-Sung Journal of Radiation Research Editorial Committee 2010 JOURNAL OF RADIATION RESEARCH Vol.51 No.3

<P>Histone deacetylase inhibitors (HDIs) have attracted considerable attention for anticancer therapy strategy, including radiosensitization. Regarding a potential application of HDI as a radiosensitizer in the treatment of solid tumors, an important question is whether treatment efficacy would be influenced by intrinsic differences between cancer cells, such as different histologic origin and status of ATM or p53. First we have observed the in vitro radiosensitization by Trichostatin A (TSA) on the broad spectrum of human tumor cell lines having different histologic origin such as HCT116 adenocarcinoma of colon, A549 adenocarcinoma of lung, HN-3 squamous cell carcinoma of head/neck, and HeLa squamous cacinoma of uterine cervix, using clonogenic assay. Next, we have systematically assessed the radiosensitization on the cell lines having different ATM or p53 status. We found that pretreatment of HDI consistently resulted in radiosensitization of all cell lines tested, though the sensitizer enhancement ratio of individual cell lines was variable. We also observed that TSA-mediated radiosensitization was clearly influenced by p53 and ATM status of cells tested. The data presented here indicate that HDI enhances the radiation induced cell killing in the various cancer cells having intrinsic differences and may serve as a general strategy for enhancing tumor cell radiosensitivity. These results have potential implications for the clinical utility of HDI in increasing the anticancer efficacy of radiation.</P>

Analysis of the Cellular Stress Response in MCF10A Cells Exposed to Combined Radio Frequency Radiation

KIM, Han-Na,HAN, Na-Kyung,HONG, Mi-Na,CHI, Sung-Gil,LEE, Yun-Sil,KIM, Taehong,PACK, Jeong-Ki,CHOI, Hyung-Do,KIM, Nam,LEE, Jae-Seon Journal of Radiation Research Editorial Committee 2012 JOURNAL OF RADIATION RESEARCH Vol.53 No.2

<P>Exposure to environmental stressors can be measured by monitoring the cellular stress response in target cells. Here, we used the cellular stress response to investigate whether single or combined radio frequency (RF) radiation could induce stress response in human cells. Cellular stress responses in MCF10A human breast epithelial cells were characterized after exposure to 4 h of RF radiation [code division multiple access (CDMA) or CDMA plus wideband CDMA (WCDMA)] or 2 h RF radiation on 3 consecutive days. Specific absorption rate (SAR) was 4.0 W/kg for CDMA signal alone exposure and 2.0 W/kg each, 4.0 W/kg in total for combined CDMA plus WCDMA signals. Expression levels and phosphorylation states of specific heat shock proteins (HSPs) and mitogen-activated protein kinases (MAPKs) were analyzed by Western blot. It was found that HSP27 and ERK1/2 phosphorylations are the most sensitive markers of the stress response in MCF10A cells exposed to heat shock or ionizing radiation. Using these markers, we demonstrated that neither one-time nor repeated single (CDMA alone) or combined (CDMA plus WCDMA) RF radiation exposure significantly altered HSP27 and ERK1/2 phosphorylations in MCF10A cells (<I>p</I> > 0.05). The lack of a statistically significant alteration in HSP27 and ERK1/2 phosphorylations suggests that single or combined RF radiation exposure did not elicit activation of HSP27 and ERK1/2 in MCF10A cells.</P>

Identification of Proteins that Regulate Radiation-induced Apoptosis in Murine Tumors with Wild Type p53

SEONG, Jinsil,OH, Hae Jin,KIM, Jiyoung,AN, Jeung Hee,KIM, Wonwoo Journal of Radiation Research Editorial Committee 2007 JOURNAL OF RADIATION RESEARCH Vol.48 No.5

<P>In this study, we investigated the molecular factors determining the induction of apoptosis by radiation. Two murine tumors syngeneic to C3H/HeJ mice were used: an ovarian carcinoma OCa-I, and a hepatocarcinoma HCa-I. Both have wild type p53, but display distinctly different radiosensitivity in terms of specific growth delay (12.7 d in OCa-I and 0.3 d in HCa-I) and tumor cure dose 50% (52.6 Gy in OCa-I and > 80 Gy in HCa-I). Eight-mm tumors on the thighs of mice were irradiated with 25 Gy and tumor samples were collected at regular time intervals after irradiation. The peak levels of apoptosis were 16.1 ± 0.6% in OCa-I and 0.2 ± 0.0% in HCa-I at 4 h after radiation, and this time point was used for subsequent proteomics analysis. Protein spots were identified by peptide mass fingerprinting with a focus on those related to apoptosis. In OCa-I tumors, radiation increased the expression of cytochrome c oxidase and Bcl2/adenovirus E1B-interacting 2 (Nip 2) protein higher than 3-fold. However in HCa-I, these two proteins showed no significant change. The results suggest that radiosensitivity in tumors with wild type p53 is regulated by a complex mechanism. Furthermore, these proteins could be molecular targets for a novel therapeutic strategy involving the regulation of radiosensitivity.</P>

p27Cip/Kip Is Involved in Hsp25 or Inducible Hsp70 Mediated Adaptive Response by Low Dose Radiation

SEO, Hang-Rhan,CHUNG, Hee-Yong,LEE, Yoon-Jin,BAE, Sangwoo,LEE, Su-Jae,LEE, Yun-Sil Journal of Radiation Research Editorial Committee 2006 Journal of radiation research Vol.47 No.1

<P>Thermoresistant (TR) clone of radiation-induced fibrosarcoma (RIF) cells have been reported to show adaptive response to 1cGy of low dose radiation, and hsp25 and inducible hsp70 are involved in this process. In the present study, to further elucidate the mechanism of how hsp25 and inducible hsp70 regulate the adaptive response, hsp25 or inducible hsp70 overexpressed RIF cells were irradiated with 1cGy and cell cycle was analyzed. Hsp25 or inducible hsp70 overexpressed cells as well as TR cells showed increase of G1 phase population after γ-irradiation at 1cGy, while the parent RIF cells did not. [<SUP>3</SUP>H]-Thymidine and BrdU incorporation also indicated that both hsp25 and inducible hsp70 were involved in G1 arrest after 1cGy irradiation. Molecular analysis revealed upregulation of p27Cip/Kip protein in hsp25 and inducible hsp70 overexpressed cells, and cotransfection of p27Cip/Kip antisense abolished the induction of adaptive response and 1cGy-mediated G1 arrest. The above results indicate that induction of adaptive response by hsp25 and inducible hsp70 is mediated by upregulation of p27Cip/Kip protein, resulting in low dose radiation-induced G1 arrest.</P>

Combination of Radiotherapy and Adenovirus-Mediated <i>p53</i> Gene Therapy for MDM2-Overexpressing Hepatocellular Carcinoma

KOOM, Woong Sub,PARK, Soo-Yeon,KIM, Wonwoo,KIM, Minjung,KIM, Ji-Seong,KIM, Hyunki,CHOI, Il-Kyu,YUN, Chae-Ok,SEONG, Jinsil Journal of Radiation Research Editorial Committee 2012 JOURNAL OF RADIATION RESEARCH Vol.53 No.2

<P>The <I>p53</I> gene plays a determinant role in radiation-induced cell death and its protein product is negatively regulated by MDM2. We investigated whether adenovirus-mediated modified <I>p53</I> gene transfer, which blocks p53-MDM2 binding, is effective for radiation-induced cell death in hepatocellular carcinoma (HCC) at different MDM2 cellular levels. Human hepatocellular carcinoma cell lines expressing MDM2 at low levels (Huh7) and high levels (SK-Hep1) were used. Ad-p53 and Ad-p53vp are replication-deficient adenoviral vectors containing human wild-type or modified p53, respectively. The anti-tumor effect was highest for Ad-p53 + radiotherapy (RT) in the low-level MDM2 cells, whereas this effect was highest for Ad-p53vp + RT in the MDM2-overexpressing cells. In Huh-7 cells, Ad-p53 + RT decreased cell viability (32%) <I>in vitro</I> and inhibited tumor growth (enhancement factor, 1.86) <I>in vivo</I>. Additionally, p21 expression and apoptosis were increased. In contrast, in SK-Hep1 cells, Ad-p53vp + RT showed decreased cell viability (51%) <I>in vitro</I> and inhibition of tumor growth (enhancement factor, 3.07) <I>in vivo</I>. Caspase-3 expression and apoptosis were also increased. Adenovirus-expressing modified p53, which blocks p53-MDM2 binding, was effective in killing tumor cells overexpressing MDM2. Furthermore, the combination strategy for disruption of the p53-MDM2 interaction with RT demonstrated enhanced anti-tumor effects both <I>in vitro</I> and <I>in vivo</I>.</P>