The hyper-radiosensitivity effect of human hepatoma SMMC-7721 cells exposed to low dose gamma-rays and C-12 ions

Hypersensitive response of mammalian cells in cell killing to X- and gamma-rays has been reported at doses below 1 Gy. The purpose of this study was to examine the low dose sensitivity of human hepatoma SMMC-7721 cells irradiated with Co-60 gamma-rays and 50 MeV/u C-12 ions. Experiments using gamma-rays and charged particle irradiation were performed, particularly in the low dose range from 0 to 2 Gy. The survival effect of SMMC-7721 cells was measured by means of standard clonogenic assay in conjunction with a cell sorter. The result indicates SMMC-7721 cells showed hyper-radiosensitive response at low doses and increased radio-resistance at larger single doses for the carbon ions (LET = 45.2 keV/mu m) and the gamma-rays. However, the HRS/IRR effect caused by high-LET irradiation is different from that by low-LET radiation. This might possibly be due to the difference in the mode of energy deposition by particle beam and low-LET irradiation.

Effect of p53 on lung carcinoma cells irradiated by carbon ions or X-rays

The study is to investigate the feasibility and advantages of heavy ion beams on radiotherapy. The cellular cycle and apoptosis, cell reproductive death and p53 expression evaluated with flow cytometry, clonogenic survival assays and Western blot analysis were examined in lung carcinoma cells after exposure to 89.63 MeV/u carbon ion and 6 MV X-ray irradiations, respectively. The results showed that the number colonyforming assay of A549 was higher than that of H1299 cells in two radiation groups; A549 cellular cycle was arrested in G(2)/M in 12 It and the percentage of apoptosis ascended at each time point of carbon ion radiation with doses, the expression of p53 upregulated with doses exposed to X-ray or carbon ion. The cell number in G(2)/M of H1299 and apoptosis were increasing at all time points with doses in C-12(6+) ion irradiation group. The results suggested that the effects of carbon ions or X rays irradiation on lung carcinoma cells were different, C-12(6+) ion irradiation could have more effect on upregulating the expression of p53 than X-ray, and the upregulated expression of p53 might produce the cellular cycle G(2)/M arrested, apoptosis increasing; and p53 gene might affect the lung cancer cells radiosensitivity.

Potential role of DNA-dependent protein kinase in cellular resistance to ionizing radiation

In this paper, we study the ability of DNA-PK-deficient (M059J) and -proficient (M059K) cells to undergo the rate of cellular proliferation, cell cycle distribution and apoptosis after 10 Gy X-ray irradiation, and the role of DNA-PK in radiosensitivity. The results showed that M059J cells exhibited hyper-radiosensitivity compared with M059K cells. A strong G2 phase arrest was observed in M059J cells post irradiation. Significant accumulation in the G2 phase in M059J cells was accompanied by apoptosis at 12 h. Altogether, the data suggested that DNA-PK may have two roles in mammalian cells after DNA damage, a role in DNA DSB repair and a second role in DNA-damaged cells to traverse a G2 checkpoint, by which DNA-PK may affect cellular sensitivity to ionizing radiation. 地址: [Li Ning; Zhang Hong; Wang Yanling; Hao Jifang] Chinese Acad Sci, Inst Modern Phys, Lanzhou 730000, Peoples R China; [Li Ning; Zhang Hong; Wang Yanling; Hao Jifang] Key Lab Heavy Ion Radiat Med Gansu Prov, Lanzhou 730000, Peoples R China; [Li Ning; Wang Yanling] Chinese Acad Sci, Grad Sch, Beijing 100039, Peoples R China; [Wang Xiaohu] Gansu Tumor Hosp, Dept Radiotherapy, Lanzhou 730050, Peoples R China

High-efficiency transfer and expression of AdCMV-p53 in human hepatocellular carcinoma cells induced by low-dose carbon-ion radiation

Objective To investigate whether the irradiation with C-beam could enhance adenovirus-mediated transfer and expression of p53 in human hepatocellular carcinoma. Materials and methods HepG2 cells were exposed to C-beam or gamma-ray and then infected with replicationdeficient adenovirus recombinant vectors containing human wild-type p53 or green fluorescent protein, respectively. The transfer efficiency and expression level of the exogenous gene were detected by flow cytometric analysis. Cell survival fraction was detected by clonogenic assay. Results The transfer frequency in C-beam or gamma-irradiated groups increased by 50-83% and 5.7-38.0% compared with the control, respectively (P < 0.05). Compared with C-beam alone, p53 alone, and gamma-ray with p53, the percentages of p53 positive cells for 1 Gy C-beam with p53 increased by 56.0-72.0%, 63.5-82.0%, and 31.3-72.5% on first and third day after the treatments, respectively (P < 0.05). The survival fractions for the 2Gy C-bearn and AdCMV-p53 infection groups decreased to similar to 2%. Conclusion C-beam irradiation could significantly promote AdCMV-green fluorescent protein transfer and expression of p53.

抑制survivin表达增强人肝癌HepG2细胞对高线性能量转移射线的辐射敏感性；Inhibiting Survivin Expression Increases The Radiosensitivity of Human Hepatoma HepG2 Cells to High-LET Radiation

探讨了肿瘤细胞中survivin的表达对高线性能量转移(LET)射线辐射敏感性的影响.根据Gen Bank提供的survivin序列,合成特异性survivin-siRNA寡核苷酸,转染人肝癌HepG2细胞,抑制survivin的表达.发现siRNA转染后诱导了HepG2细胞G2/M期阻滞,增加了自发性和辐射诱导的细胞凋亡.在高线性能量转移(LET)碳离子辐照后,siRNA转染细胞的克隆存活率明显下降.这些结果表明survivin表达是HepG2细胞产生对高LET射线辐射抗性的关键因素.

小肠电离辐射损伤研究进展；Advances in Small Intestinal Ionizing Radiation Injury Research

肠道的电离辐射损伤是腹部及盆腔肿瘤放射治疗过程中的剂量限制因素。综述了小肠电离辐射损伤的临床症状、小肠上皮及粘膜下层基质改变、信号分子表达变化、组织学变化和超微结构变化。简介了中国科学院近代物理研究所重离子束辐射生物医学重点实验室正在进行的有关小肠重离子辐射损伤及防护方面的研究工作。

空间辐射生物学研究进展；Research Progress on Space Radiation Biology

空间电离辐射尤其是高能带电粒子辐射可造成生物机体的严重损伤,是载人航天飞行的关键性限制因素之一。研究表明,带电粒子的生物学效应与其性质、剂量以及不同生物学终点有关;此外,微重力环境可能会影响空间辐射生物学效应。从多年来的空间搭载实验研究和地基模拟实验研究两个方面,综述了空间辐射的生物损伤效应及其与微重力环境复合作用的生物效应。

Survivin表达在高LET射线诱导细胞凋亡中作用机理的初步研究；A Preliminary Study on Action Mechanisms of Survivin Expression in Cell Apoptosis Induced by High-LET Radiation

先前的研究表明,肿瘤细胞中survivin的高表达与细胞对高传能线密度(LET)射线的辐射抗性相关。研究了survivin表达在高LET射线诱导的细胞凋亡中的作用,发现抑制survivin表达对高LETC离子辐射诱导的Bcl-2和Bax表达没有明显的影响。在高LET射线辐照中,survivin可能通过抑制caspase-3和-9活性的途径,抑制了细胞凋亡。

Radiosensitivity to high energy iron ions is influenced by heterozygosity for Atm, Rad9 and Brca1

Loss of function of DNA repair genes has been implicated in the development of many types of cancer. In the last several years, heterozygosity leading to haploinsufficiency for proteins involved in DNA repair was shown to play a role in genomic instability and carcinogenesis after DNA damage is induced, for example by ionizing radiation. Since the effect of heterozygosity for one gene is relatively small, we hypothesize that predisposition to cancer could be a result of the additive effect of heterozygosity for two or more genes critical to pathways that control DNA damage signaling, repair or apoptosis. We investigated the role of heterozygosity for Aim, Rad9 and Brad on cell oncogenic transformation and cell survival induced by 1 GeV/n Fe-56 ions. Our results show that cells heterozygous for both Aim and Rad9 or A tin and Brca1 have high survival rates and are more sensitive to transformation by high energy iron ions when compared with wild-type controls or cells haploinsufficient for only one of these proteins. Since mutations or polymorphisms for similar genes exist in a small percentage of the human population, we have identified a radiosensitive sub-population. This finding has several implications. First, the existence of a radiosensitive sub-population may distort the shape of the dose response relationship. Second, it would not be ethical to put exceptionally radiosensitive individuals into a setting where they may potentially be exposed to substantial doses of radiation. (C) 2010 COSPAR. Published by Elsevier Ltd. All rights reserved.

Inhibiting Survivin Expression Increases The Radiosensitivity of Human Hepatoma HepG2 Cells to High-LET Radiation

The influence of survivin expression on the radiosensitivity of tumor cells to high linear energy transfer (LET) radiation is investigated. Survivin-specific short-interfering RNA (siRNA) oligonucleotides were synthesized based on the survivin sequence provided by GenBank. Human hepatoma HepG2 cells were transfected with survivin-specific siRNA to inhibit its expressions. It was found that the transfection with surviving-specific siRNA increased the levels of G2/M arrest and the apoptotic rates induced by radiation in HepG2 cells. After exposure to high-LET carbon ions, a reduced clonogenic survival effect was observed in the cells treated with siRNA. These results show that survivin plays a key role in mediating the radioresistance of cells to high-LET radiation.

Neutron dose measurement in carbon ion radiation therapy at HIRFL (IMP)

For radiation protection purposes, the neutron dose in carbon ion radiation therapy at the HIRFL (Heavy Ion Research Facility in Lanzhou) was investigated. The neutron dose from primary C-12 ions with a specific energy of 100 MeV/u delivered from SSC was roughly measured with a standard Anderson-Broun rem-meter using a polyethylene target at various distances. The result shows that a maximum neutron dose contribution of 19 mSv in a typically surface tumor treatment was obtained, which is less than 1% of the planed heavy ion dose and is in reasonable agreement with other reports. Also the gamma-ray dose was measured in this experiment using a thermo luminescent detector.

诱发突变选育小麦新品种的研究探讨；The reseach of wheat variety breeding through radiation

概述了张掖市农科院小麦诱变育种研究的发展历程,介绍了小麦诱变育种的常用方法及辐照处理的参考剂量,并对张掖市小麦诱变育种今后发展的方向进行了探讨。

Effects of Ionizing Radiation on Three-Dimensional Human Vessel Models: Differential Effects According to Radiation Quality and Cellular Development

Little is known about the effects of space radiation on the human body. There are a number of potential chronic and acute effects, and one major target for noncarcinogenic effects is the human vasculature. Cellular stress, inflammatory response, and other radiation effects on endothelial cells may affect vascular function. This study was aimed at understanding the effects of space ionizing radiation on the formation and maintenance of capillary-like blood vessels. We used a 3D human vessel model created with human endothelial cells in a gel matrix to assess the effects of low-LET protons and high-LET iron ions. Iron ions were more damaging and caused significant reduction in the length of intact vessels in both developing and mature vessels at a dose of 80 cGy. Protons had no effect on mature vessels up to a dose of 3.2 Gy but did inhibit vessel formation at 80 cGy. Comparison with gamma radiation showed that photons had even less effect, although, as with protons, developing vessels were more sensitive. Apoptosis assays showed that inhibition of vessel development or deterioration of mature vessels was not due to cell death by apoptosis even in the case of iron ions. These are the first data to show the effects of radiation with varying linear energy transfer on a human vessel model. (C) 2011 In Radiation Research Society