• 미생물학회지
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• 제12권2호
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• pp.67-76
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• 1974

This experiment was carried out to identify and to compare the radiosensitivities of bacteriz isolated from the sources of different radiation exposure histories. Among 10 strains isolated in this investigation, 4 strains of bacteria, Bacillus firmus, Bacillus brevis, Baciilus subtilis and Bacillus sphaericus were isolated from high and low radioactive sites simulaneously. Bacterial strains isolated from radioactive sources such as reactor and isotope production rooms were more resistant to irradiation than the microganisms from medical products and laboratories, however, there was no significance in radiosensitivity in the same species of bacteriz, even if they were isolated from different radiation exposure histories.

• Molecules and Cells
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• 제25권2호
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• pp.305-311
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• 2008

After successful clinical application, arginine deiminase (ADI) has been proposed to be a new cancer therapeutic. In the present study, we examined the effect of ADI in combination with ionizing radiation (IR) on MCF-7 cell growth and clonogenic cell death. Cell growth was inhibited by IR in a dose-dependent manner and ADI enhanced the radiosensitivity. ADI itself did not suppress the growth of MCF-7 cells due to the high level of expression of argininosuccinate synthetase (ASS), which convert citrulline, a product of arginine degradation by ADI, to arginine. Previously, it was suggested that ammonia, another product of arginine degradation by ADI, is the main cause of the growth inhibition of irradiated hepatoma cells contaminated with ADI-expressing mycoplasma [van Rijn et al. (2003)]. However, we found that ammonia is not the only factor that enhances radiosensitivity, as enhancement was also observed in the absence of ammonia. In order to identify the enhancing effect, levels of ASS and proteins related to the cell cycle were examined. ASS was unchanged by ADI plus IR, but p21 (a CDK inhibitor) was upregulated and c-Myc downregulated. These findings indicate that changes in the expressions of cell cycle proteins are involved in the enhancement of radiosensitivity by ADI. We suggest that ADI is a potential adjunct to cancer therapy.

• Asian Pacific Journal of Cancer Prevention
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• 제14권2호
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• pp.795-799
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• 2013

Ku70/80 heterodimer is a central element in the nonhomologous end joining (NHEJ) DNA repair pathway, Ku80 playing a key role in regulating the multiple functions of Ku proteins. It has been found that the Ku80 protein located at telomeres is a major contributor to radiosensitivity in some telomerase positive human cancer cells. However, in ALT human osteosarcoma cells, the precise function in radiosensitivity and telomere maintenance is still unknown. The aim of this study was to investigate the effects of Ku80 depletion in the U2OS ALT cell line cell line. Suppression of Ku80 expression was performed using a vector-based shRNA and stable Ku80 knockdown in cells was verified by Western blotting. U2OS cells treated with shRNA-Ku80 showed lower radiobiological parameters (D0, Dq and SF2) in clonogenic assays. Furthermore, shRNA-Ku80 vector transfected cells displayed shortening of the telomere length and showed less expression of TRF2 protein. These results demonstrated that down-regulation of Ku80 can sensitize ALT cells U2OS to radiation, and this radiosensitization is related to telomere length shortening.

• Radiation Oncology Journal
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• 제23권4호
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• pp.211-216
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• 2005

목적: all-trans retinoic acid (ATRA)는 뇌종양 세포의 증식억제효과가 있으며, ATRA와 방사선의 병용은 악성 뇌종양의 치료 효과를 증진시키는 방법이 될 수 있다. 그러나 ATRA에 의해 항산화효소가 증가되며 이로 인해 방사선에 의해 생성된 reactive oxygen species (ROS)가 제거된다면 방사선의 효과는 낮아질 수 있다. 본 연구에서는 ATRA에 의해 유도되는 카탈라제(catalase)에 의한 방사선감수성의 변화를 보고자하였다. 대상 및 방법: 백서 교종세포(36B10)을 대상으로 ATRA 및 ATRA의 화학적 억제제인 3-amino-1, 2, 4-triazole (ATZ) 와 병용하여 카탈라제 활성도, 방사선감수성 및 ROS의 변화를 측정하였다. 카탈라제 활성도는 $H_2O_2$의 소멸을 자외선 분광광도계로 측정하는 방법을 이용해 정량하였으며, 방사선감수성은 단일집락군형성능력으로, ROS 는 2, 7-dichlorofluorescein diacetate 를 분광광도계로 측정하였다. 결과: 카탈라제 활성도는 ATRA의 농도(10, 25, $50{\mu}M$)에 따라 증가하였다. ATRA ($10{\mu}M$)와 방사선(4 Gy)의 병용에 의해 생존분획은 상승적(supra-auditive)으로 감소하였으며, 이 감소된 생존분획은 ATZ 동시 투여에 의해 증가하였다. ATRA $10{\mu}M$ 또는 $25{\mu}M$을 48시간 처리 후 ROS는 대조군에 비해 각각 1.5배, 2배 증가하였고, 4 Gy와 ATRA의 병용군에서는 2.5배 증가하였다. ATRA와 방사선의 병용에 의해 증가된 ROS는 ATZ에 의해 감소되었다. 결론: ATRA에 의해 유도되는 카탈라제는 방사선감수성을 감소시키지 않으며, 오히려 ROS의 증가에 의해 방사선감수성을 상승시켰다. 따라서 ATRA와 방사선의 병용은 뇌종양의 치료에 유용한 방법이 될 수 있을 것으로 보인다.

• 대한의생명과학회지
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• 제19권2호
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• pp.98-104
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• 2013

Radiation is one of the major therapy for the removal of cancer cells. The results of the radiation therapy depend on the radio-resistance of cancer cells. For the effective treatment in these radio-resistant cancers, the use of chemicals that act on cancer cells is known to enhance the cytotoxic effects of radiation therapy. In this study, I investigated the effect of potassium cyanate (KCN) on the irradiated-colorectal cancer cell line, HCT 116 cells. KCN induces the carbamylation of proteins and can change the biological activity of various human cells. To understand the effect of KCN on the radiosensitivity of HCT 116 cells, I examined alteration of the cell cycle, generation of reactive oxygen species (ROS), cell viability, apoptosis and intracellular signaling proteins in the irradiated cells with/without KCN treatment. Combination treatment caused significant increase in sub $G_0/G_1$ and ROS generation in HCT 116 cells. KCN inhibited the proliferation and cell viability in irradiated HCT 116 cells. KCN-induced apoptosis of irradiated cells was processed via the activation of caspase 3 and caspase 9. Apoptosis-associated signal proteins, including Bax and Bcl-2 were regulated by irradiation with KCN treatment. Taken together, these results may indicate that KCN enhances the radiosensitivity of radio-resistant cell and then has a synergistic effect on radiation therapy in colorectal cancer.

• Molecules and Cells
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• 제25권2호
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• pp.224-230
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• 2008

Ceramides are well-known second messengers that induce apoptosis in various kinds of cancer cells, and their effects are closely related to radiation sensitivity. Phytoceramides, the yeast counterparts of the mammalian ceramides, are also reported to induce apoptosis. We investigated the effect of a novel ceramide derivative, N-acetylphytosphingosine (NAPS), on the radiosensitivity of NCI-H460 human lung carcinoma cells and its differential cytotoxicity in tumor and normal cells. The combination of NAPS with radiation significantly increased clonogenic cell death and caspase-dependent apoptosis. The combined treatment greatly increased Bax expression and Bid cleavage, but not Bcl-2 expression. However, there was no effect on radiosensitivity and apoptosis in BEAS2B cells, which derive from normal human bronchial epithelium. Cell proliferation and DNA synthesis were significantly inhibited by NAPS in both NCI-H460 and BEAS2B cells, but only the BEAS2B cells recovered by 48h after removal of the NAPS. Furthermore, the NCI-H460 cells underwent more DNA fragmentation than the BEAS2B cells in response to NAPS. Our results indicate that NAPS may be a potential radiosensitizing agent with differential effects on tumor vs. normal cells.

• Journal of Radiation Protection and Research
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• 제28권3호
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• pp.233-237
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• 2003

It has been known that ATM plays a central role in response of cells to ionizing radiation by enhancing DNA repair. We have investigated the feasibility of increasing radiosensitivity of tumor cells with the use of ATM inhibitors such as caffeine, pentoxifylline and wortmannin. Human colorectal cancer RKO.C cells and RKO-ATM cells (RKO cells overexpressing ATM) were used in the present study. The clonogenic cell survival in vitro indicated that RKO-ATM cells were markdely radioresistant than RKO.C cells. Treatment with 3 mM of caffeine significantly increased the radiosensitivity of cells, particulary the RKO-ATM cells, so that the radiosensitivity of RKO.C cells and RKO-ATM cells were almost similar. The radiation induced G2/M arrest in RKO-ATM cells was noticeably longer than that in RKO.C cells and caffeine treatment significantly reduced the length of the radiation induced G2/M arrest in both RKO.C and RKO-ATM cells. Pentoxifylline and wortmannin were also less effective than caffeine to radiosensitize RKO.C or RKO-ATM cells. However, wortmannin was more effective than caffeine against human lung adenocarcinoma A549 cells indicating the efficacy of ATM inhibitor to increase radiosensitivity is cell line dependent. For in vivo study, RKO.C cells were injected s.c. into the hind-leg of BALB/C-nuslc nude mice, and allowed to grow to 130mm3 tumor. The mice were i.p. injected with caffeine solution or saline and the tumors irradiated with 10 Gy of X-rays. The radiation induced growth delay was markedly increased by 1-2 mg/g of caffeine. It was concluded that caffeine increases radiosensitivity of tumor cells by inhibiting ATM kinase function, thereby inhibiting DNA repair, that occurs during the G2/M arrest after radiation.

• Radiation Oncology Journal
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• 제12권2호
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• pp.129-141
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• 1994

Intracellular ions which have a major role in cellular function have been reported to affect repair of radiation damage. Recently it has been reported that ouabain sensitizes A549 tumor cellls but not CCL-120 normal cells to radiation. Ouabain inhibits the $Na^+-K^+$-pump rapidly thus it increases intracellular Na concentration, Vanadate which is distributed extensively in almost all living organisms is known to be a $Na^+-K^+$-ATPase inhibitors, This study was performed to see any change in radiosensitivity of tumor cell by vanadate and any role of $Na^+-K^+$ATPase in radiosensitization. Experiments have been carried out by pretreatment with vanadate in human cell line(A549, JMG) and mouse cell line(L1210, spleen). For the cell survival MTT assay was performed for A549 and JMC cells and frypan blue dye exclusion test for L120, and spleen cells. Measurements of $Na^+-K^+$-ATPase activity in control, vanadate treated cell, radiation treated cell (9 Gy for A549 and JMG, 2 Gy for L1201, spleen), and combined $10^{-6}M$ vanadate and radiation treated cells were done. The results were summerized as fellows. 1. L1210 cell was most radiosensitive, and spleen cell and JMG cell were intermediate, and A549 cell was least radiosensitive. 2. Mininum or no cytotoxicity was seen with vanadate below concentration of $10^{-6}M$. 3. In A549 cells there was a little change in radiosensitivity with treatment of vanadate. However radiation sensitization was shown in low dose level of radiation i. e. 2- Gy. In JMG cells no change in radiosensitivity was noted. Both L1210 and spleen cell had radiosensitization but change was greater in tumor cell. 4. $Na^+-K^+$-ATPase activity was inhibited significantly in tumor cell by treatment of vanadate. 5. Radiaiton itself inhibited $Na^+-K^+$-ATPase activity of tumor cell with high $Na^+-K^+$-ATPase concention. Increase in radiosensitivity by vanadate was closely associated with orginal $Na^+-K^+$-ATPase contents. From the above results vanadate had little cytotoxicity and it sensitized tumor cells to radiation. Inhibitory effect of vanadate on $Na^+-K^+$-ATPase activity might be one of the contributing factors for radiosensitization to tumor cells which has greater enzyme activity than that of normal cell. It was suggested vanadate could be used as a potential radiosensitizer for tumor cells.

• Imaging Science in Dentistry
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• 제33권2호
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• pp.97-105
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• 2003

Purpose : To evaluate the effect of all-trans-retinoic acid (ATRA) on the radiosensitivity of normal human oral keratinocyte (NHOK). Materials and methods: Relative cell survival fraction including SF2 (survival fraction at 2 Gy) was calculated on the basis of colony formation assay. Data were fitted to the linear-quadratic model to establish the survival curve and calculate α and β values. Using flow cytometry at 1, 2, 3, 4, and 5 days after exposure to 2 and 10 Gy irradiation, cell cycle arrest and apoptosis were analysed. To understand the molecular mechanism of the radiosensitization of ATRA on NHOK, proteins related with apoptosis and cell cycle arrest were investigated by Western blot analysis. Results: Treatment with ATRA resulted in a significant decrease of SF2 value for NHOK from 0.63 to 0.27, and increased α and β value, indicating that ATRA increased radiosensitivity of NHOK. ATRA increased LDH significantly, but increasing irradiation dose decreased LDH, suggesting that the radiosensitizing effect of ATRA is not directly related with increasing cell necrosis by ATRA. ATRA did not induce appotosis but increased G2 arrest after 10 Gy irradiation, implying that the increased radiosensitivity of NHOK may be due to a decrease in mitosis casued by increasing G2 arrest. ATRA inhibited the reduction of p53 at 3 days after l0Gy irradiation and increased p21 at 1 day after 10 Gy irradiation. Further study is required to determine the precise relationship between this effect and the radiosensitizing effect of A TRA. Conclusion: These results suggested that ATRA increase radiosensitivity by inhibiting mitosis caused by increasing G2 arrest.

• Radiation Oncology Journal
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• 제22권4호
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• pp.298-306
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• 2004

목적:. 방사선 감수성이 다른 마우스 조직에서 apoptosis 유도 수준을 확인하고 방사선 감수성에 관여 된 인자를 Proteomics를 통해서 확인한다. 대상 및 방법: C3H/HeJ 마우스에 10 Gy 방사선을 조사하고 8시간 후 비장과 간을 채취하여 apoptosis 유도 수준을 비교 분석하였다. 조직에서 단백질을 추출하여 2-dimension electrophoresis (2-DE)를 실시하였다. 2-DE에서 방사선에 의해 발현의 변화를 보이는 gel의 spot를 trypsin 처리하여 MALDI-TOF 측정한 후 Swiss-prot database를 통하여 단백질 을 동정하였다. 결과: Apoptosls index는 방사선 조사 후 비장 조직에서 $35.3{\pm}1.7{\%}$, 간조직은 $0.6{\pm}0.2{\%}$로 비장에 비해 간 조직이 낮게 나타났다. Proteomoics 결과에서 방사선 내성 조직인 간은 ROS대사에 관여되는 단백질인 glutathione Stransferase Pi, carbonic anhydrase, NADH dehydrogenase, peroxiredoxin VI, riken cDNA 등이 방사선 조사 후 증가되었고 apoptosis 관련된 단백질인 cytochrome c는 간과 비장 조직에서 확인되었다. 그러나 방사선 민감 조직인 비장에서는 방사선 조사 후 산화적 Stress에 관련된 단백질, apoptosis 관련 단백질, 신호 전달에 관련된 단백질, 면역반응, cell cycle, Ca 신호 전달, 대사 cycle에 관련된 단백질 등이 방사선에 관련하여 발현의 변화를 보여 주었다. 결론 : Apoptosis유도 수준이 다른 조직에서 apoptosis에 관련된 단백질과 redox에 관련된 단백질은 방사성 감수성 조절에 관련된 것으로 보인다.