p53-dependent delayed effects of radiation vary according to time of irradiation of p53 + / ? mice

We previously reported that in p53 ^{+ / −} mice that had been given a whole-body dose of 3 Gy at 8 weeks of age, p53-dependent delayed effects of radiation, as manifested in T-cell receptor (TCR) variant fractions (VF) instability in mouse splenocytes, were biphasic, namely, induction of TCR-VF mutation reappeared at 44 weeks. The manifestation of the delayed effects and the measures of biological markers varied according to the timing of irradiation. We also reported that the decrease in function of the p53 gene was related to the effects of a delayed mutation. In the present study, we investigated the functions and mutations of the p53 gene in old age for p53 ^{+ / −} mice following irradiation at various ages. p53 ^{+ / −} mice were given a whole-body dose of 3 Gy at 8, 28 or 40 weeks of age. There were significant differences for all variables tested at 8 weeks of age. This was similarly the case for mice irradiated at 28 weeks of age, in which there were also significant differences in TCR VF and the percentage of apoptosis. In mice irradiated at 40 weeks of age, there were significant differences for all considered variables except for the p53 allele. We demonstrated that the different patterns of delayed mutation of the p53 gene at 56 weeks of age depended on the age at which mice had undergone 3-Gy whole-body irradiation. Our conclusions are limited to variation in p53-dependent delayed effects according to the time of irradiation.     

Effect of age on the sensitivity of the rat thyroid gland to ionizing radiation

Exposure to ionizing radiation during childhood is a well-known risk factor for thyroid cancer. Our study evaluated the effect of age on the radiosensitivity of rat thyroid glands. Four-week-old (4W), 7 -week-old (7W), and 8-month-old (8M) male Wistar rats were exposed to 8 Gy of whole-body X-ray irradiation. Thyroids were removed 3–72 h after irradiation, and non-irradiated thyroids served as controls. Ki67-positivity and p53 binding protein 1 (53BP1) focus formation (a DNA damage response) were evaluated via immunohistochemistry. Amounts of proteins involved in DNA damage response (p53, p53 phosphorylated at serine 15, p21), apoptosis (cleaved caspase-3), and autophagy (LC3, p62) were determined via western blotting. mRNA levels of 84 key autophagy-related genes were quantified using polymerase chain reaction arrays. Ki67-positive cells in 4W (with high proliferative activity) and 7W thyroids significantly decreased in number post-irradiation. The number of 53BP1 foci and amount of p53 phosphorylated at serine 15 increased 3 h after irradiation, regardless of age. No increase in apoptosis or in the levels of p53, p21 or cleaved caspase-3 was detected for any ages. Levels of LC3-II and p62 increased in irradiated 4W but not 8M thyroids, whereas expression of several autophagy-related genes was higher in 4W than 8M irradiated thyroids. Irradiation increased the expression of genes encoding pro-apoptotic proteins in both 4W and 8M thyroids. In summary, no apoptosis or p53 accumulation was noted, despite the expression of some pro-apoptotic genes in immature and adult thyroids. Irradiation induced autophagy in immature, but not in adult, rat thyroids.     

Irradiation-injured brain tissues can self-renew in the absence of the pivotal tumor suppressor p53 in the medaka ( Oryzias latipes ) embryo

The tumor suppressor protein, p53, plays pivotal roles in regulating apoptosis and proliferation in the embryonic and adult central nervous system (CNS) following neuronal injuries such as those induced by ionizing radiation. There is increasing evidence that p53 negatively regulates the self-renewal of neural stem cells in the adult murine brain; however, it is still unknown whether p53 is essential for self-renewal in the injured developing CNS. Previously, we demonstrated that the numbers of apoptotic cells in medaka ( Oryzias latipes ) embryos decreased in the absence of p53 at 12–24 h after irradiation with 10-Gy gamma rays. Here, we used histology to examine the later morphological development of the irradiated medaka brain. In p53-deficient larvae, the embryonic brain possessed similar vacuoles in the brain and retina, although the vacuoles were much smaller and fewer than those found in wild-type embryos. At the time of hatching (6 days after irradiation), no brain abnormality was observed. In contrast, severe disorganized neuronal arrangements were still present in the brain of irradiated wild-type embryos. Our present results demonstrated that self-renewal of the brain tissue completed faster in the absence of p53 than wild type at the time of hatching because p53 reduces the acute severe neural apoptosis induced by irradiation, suggesting that p53 is not essential for tissue self-renewal in developing brain.     

低剂量电离辐射对放射工作人员细胞遗传学影响

目的 分析低剂量电离辐射对放射工作人员细胞遗传学影响.方法 采用放射场所辐射剂量、个人剂量、细胞遗传学指标检测及流行病学横断面调查研究方法.结果 射线接触组染色体畸变率(0.16%)高于对照组(0.04%),染色体畸变检出率(17.05%)高于对照组(5.1%),微核率(1.03‰)高于对照组(0.2‰),微核检出率(48.06%)高于对照组(12.25%),差异均有统计学意义(χ²=8.45,P<0.01;χ²=7.59,P<0.01;χ²=57.23,P<0.01;χ²=32.52,P<0.01);不同年剂量、累积剂量组染色体畸变率、微核率与对照组比较,差异均有统计学意义;随着个人年剂量、累积剂量水平的增加,染色体畸变率、微核率、微核阳性检出率有增高趋势.结论 长期低剂量电离辐射,对淋巴细胞产生的辐射效应导致的染色体畸变率、微核率的增加并与放射人员个人累积吸收剂量密切相关.     

GST-π与p53在大肠癌和肠道异型增生病变中的表达及临床意义

目的探讨谷胱甘肽S转移酶π(GST-π)与p53在大肠癌和肠道异型增生病变中的表达及临床意义。方法应用免疫组织化学SP法检测30例大肠癌、40例肠道异型增生、20例正常肠道黏膜组织中GST-π与p53的表达情况。结果30例大肠癌、40例肠道异型增生病变、20例正常肠道黏膜组织中GST-π的阳性表达率分别为86.7%、52.5%和15.0%,各组相比差异有统计学意义(P<0.05);p53的阳性表达率分别为80.0%、47.5%和0,各组相比差异有统计学意义(P<0.05),p53阳性者GST-π阳性率高于p53阴性者。结论肠道病变由正常黏膜、异型增生向恶性变化的过程中,组织内GST-π与p53也逐渐升高,说明GST-π与p53和肠道病变的发生、发展有关,可作为大肠癌及癌前病变的标志物之一。     

肝癌p53基因等表达异常及相关性研究

目的：从分子生物学及病理学角度对肝癌中抑癌基因p53和肿瘤志标志物AFP（甲胎蛋白）、CEA（癌胚抗原）的表达及相关性进行研究。方法：收集40例肝细胞（HCC）患癌组织连带部分癌旁组织，用免疫组织化学法检测p53基因、AFP、CEA等。结果：p53基因癌内表达率为80％，癌旁组织为50％；AFP癌内表达率为87．5％，癌旁组织为80％；CEA癌内表达率为55％，癌旁组织表达不明显。结论：检测p53基因，并与其它肿瘤标志物和相关基因一起，在基因水平诊断肝癌，估计预后及制定术后治疗方案等有着重要作用。     

p53表达在石英诱导的细胞周期改变及DNA损伤修复中的作用

目的 探讨p53表达在石英致人胚肺成纤维细胞(HELF)细胞周期改变及DNA双链断裂(DNA double strand breaks,DSBs)修复中的作用.方法 3种方式分组处理细胞:(1)不同浓度(0、25、50、100、200、300、400μg/ml)的石英刺激HELF细胞12 h;(2)200 μg/ml石英刺激HELF细胞O、1、2,6、12、24 h;(3)200μg/ml石英刺激H-CMV和H-p53细胞O、12、24 h.用中性彗星试验检测石英所致的DSBs损伤强度,并计算DNA修复能力(DNA repair compentence,DRC),用免疫印迹法检测蛋白表达和磷酸化水平,用流式细胞仪检测细胞周期的变化.结果 (1)200μg/ml的石英作用HELF细胞不同时间,p53表达及p53-Ser15磷酸化水平随着作用时间的延长逐渐升高,12 h达峰值,24 h较12 h略有降低;不同浓度的石英作用HELF细胞12 h,随着石英浓度的增加,p53表达及p53-Ser15磷酸化水平逐渐增强,呈现剂量-反应关系.(2)石英作用于p53 siRNA的阴性对照细胞H-CMV,DRC为57.19%:石英作用沉默p53表达的H-p53细胞后,DSBs的修复能力增强,DRC为87.68%.(3)石英作用p53siRNA的阴性对照细胞24 h后,S期细胞比例由(24.3±3.8)%增加到(31.8±1.1)%,差异有统计学意义(P<0.05);沉默p53表达后,石英诱导的HELF细胞S期细胞比例[(41.4±0.6)%]与同期对照组[(25.4±1.9)%]相比有明显增加.差异有统计学意义(P<0.05).结论 石英可诱导p53表达及磷酸化水平的增加,p53表达上调可抑制石英所致S期细胞百分比的增加及石英所致DNA双链断裂的修复.     

联合转染p53与血管生成抑素基因对人胃癌细胞系SG7901生长的影响

目的探讨联合转染p53和血管生成抑素(AS)基因对人胃癌细胞系SG7901生长的影响。方法用脂质体转染法分别将p53、AS基因、p53和AS基因转染人胃癌细胞系SG7901。以RT-PCR法检测转染后细胞目的基因的表达,通过细胞集落形成实验、MTT生长曲线、细胞周期检测观察其生物学特性变化。结果p53或AS基因均能抑制转染细胞的生长,而联合转染两种基因的细胞生长抑制更明显。结论p53和AS基因具有协同抑制恶性肿瘤细胞生长作用,提示联合多种基因可能有利于恶性肿瘤的基因治疗。     

碘染色联合p53、Survivin及端粒酶检测对早期食管癌及癌前病变的诊断价值

目的探讨内镜下碘染色联合组织p53、Survivin及端粒酶检测对早期食管癌及癌前病变的诊断价值。方法本院因上消化道症状接受胃镜检查且食管黏膜有可疑病变的门诊及住院患者300例进行卢戈碘液染色。对直径≥5mm的不染区或淡染区取活检送病理。用免疫组化方法对病理组织学检查证实为黏膜不典型增生、早期食管癌及30例正常对照者分别检测p53、Survivin及端粒酶表达情况。结果碘染色对食管黏膜不典型增生轻、中、重度及早期鳞状细胞癌检出率分别为16．3％、9．7％、3．7％和4．3％。不典型增生及早癌组织中p53蛋白、Survivin及端粒酶表达相关性有统计学意义,并且碘不染色与p53、Survivin及端粒酶阳性表达相关性也有统计学意义（P均〈0．01）;碘染色联合p53、Survivin及端粒酶检测对重度不典型增生和早期食管癌诊断的敏感性、特异性和准确率分别达100％、92．3％和91．8％。结论碘染色联合p53、Survivin及端粒酶检测对诊断早期食管癌及其癌前病变具有重要价值。     

骨巨细胞瘤中p185和p53的免疫组化研究

目的　探讨p185和p53在骨巨细胞瘤 (GCT)的表达及GCT病理分级和复发的关系。方法　应用SP免疫组织化学方法检测 p53和 p185在 52例GCT(GCT按Jaffe分级 :Ⅰ级 15例、Ⅱ级 2 5例、Ⅲ级 12例 )中的表达。结果　 11例 p185表达呈阳性 ,阳性率 2 1 2 % ,14例 p53表达阳性 ,阳性率 2 6 9%。其阳性表达与病理分级差异均无显著性 (P >0 0 5)。p53和 p185在复发和无复发的病例中 ,阳性表达率分别为 38 5%、15 4 %和4 6 2 %、2 0 5%。两者同时阳性表达的有 4例 ,p53和p185同时过表达与GCT病理分级无关 (P >0 0 5)而与其复发有显著性差异 (χ2 =6 12 5,P <0 0 5)。结论　p185和p53在GCT中的表达与病理分级无关而与其复发有关。所以 ,我们认为骨巨细胞瘤时 p53和 p185过度表达的临床意义有待进一步研究。     

Maspin蛋白在宫颈鳞癌中的表达及其与p53蛋白表达的关系

目的研究maspin蛋白在宫颈鳞癌组织中的表达及其与p53蛋白表达的相关性。方法应用免疫组化SP法检测maspin蛋白和p53蛋白在宫颈鳞癌、宫颈上皮内瘤样变、正常宫颈三种组织中的表达。分析maspin蛋白表达与宫颈鳞癌各临床病理参数之间的关系,及宫颈鳞癌组织中maspin与p53蛋白表达的相关性（本研究遵循程序符合本院人体试验委员会制定的伦理学标准,得到该委员会批准）。结果①从正常宫颈上皮组织→宫颈上皮内瘤样变→宫颈鳞癌,maspin蛋白表达逐渐下调,三者比较,差异有显著意义（P〈0．05）。②临床分期越高,分化程度越低的宫颈鳞癌组织中,maspin阳性表达越少。有淋巴结转移的宫颈鳞癌中,maspin阳性率低于无淋巴结转移者,两者比较,差异有显著意义（P〈0．05）。③Maspin与p53蛋白在宫颈鳞癌组织中的表达呈负相关（rs=-0．399,P=0．003）。结论Maspin在宫颈鳞癌的发生、发展过程中起重要的抑制作用,可作为判断宫颈鳞癌患者病情进展、恶性程度及转移潜能的指标之一。Maspin与p53蛋白表达呈负相关,MASPIN可能是P53的效应基因。     

Protective effect of triphlorethol-A from Ecklonia cava against ionizing radiation in vitro

We studied the cytoprotective effect of triphlorethol-A against gamma-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 gamma-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.     

联合转染p53与血管生成抑素基因对人胃癌细胞系SG7901生长的影响

目的 探讨联合转染p53和血管生成抑素（AS）基因对人胃癌细胞系SG7901生长的影响。方法 用脂质体转染法分别将p53、AS基因、p53和AS基因转染人胃癌细胞系SG7901。以RT-PCR法检测转染后细胞目的基因的表达，通过细胞集落形成实验、MTT生长曲线、细胞周期检测观察其生物学特性变化。结果 p53或AS基因均能抑制转染细胞的生长，而联合转染两种基因的细胞生长抑制更明显。结论 p53和AS基因具有协同抑制恶性肿瘤细胞生长作用，提示联合多种基因可能有利于恶性肿瘤的基因治疗。     

p53对低剂量UVB诱导的MEF细胞辐射损伤中miR-365表达的影响

目的探讨低剂量中波紫外线UVB造成MEF损伤过程中,p53对MEF细胞miR-365表达的影响。方法以MEF细胞为研究对象,分为野生型小鼠胚胎成纤维细胞组(MEFP53+/+组),p53缺失的小鼠胚胎成纤维细胞组(MEFP53-/-组),CCK-8法检测低剂量UVB(30 J/m2)照射后3、6、12、18、24 h细胞增殖情况,流式细胞术分析细胞周期G2/M期比例变化,蛋白质印迹法检测两种细胞p53蛋白表达量,实时荧光定量PCR检测miR-365的表达。结果 UVB照射后两组细胞存活率存下降;而两组细胞在12、18、24、36 h的存活率相比差异有统计学意义(t值分别为2.4、3.1、3.2、2.8,P值均0.05);MEFP53+/+细胞在照射后6、12、18、24 h的G2/M期细胞比例上升,与0 h组相比差异均有统计学意义(t值分别为2.1、2.3、2.5、2.8,P值均0.05);p53在MEFP53-/-细胞中几乎不表达;UVB照射后,MEFP53-/-细胞中miR-365的mRNA在6、12、18、24、36 h显著下降(t值分别为2.0、3.2、3.3、2.9、2.8, P值均0.05),而MEFP53+/+细胞中只有18 h显著下降(t=4.2,P0.05)。12、18、24、36 h四个时间点,两组细胞之间miR-365差异有统计学意义(t值分别为2.2、2.6、2.4、2.3,P值均0.05)。结论 p53可能通过调控miR-365参与低剂量UVB引起的MEF细胞G2/M期阻滞。     

低氧条件下γ射线对Hep-2细胞p53表达的影响

目的 模拟在体肿瘤细胞微环境,体外建立不同氧供状态下的细胞模型,探讨乏氧再氧合条件下60 Coγ,射线照射对人喉鳞癌Hep-2细胞凋亡的影响.方法 将体外培养的人喉鳞癌细胞分为3组:A组(常氧组)、B组(低氧组)、C组(低氧再氧合组).流式细胞仪检测HIF-1α、p53蛋白表达及细胞凋亡;细胞爬片免疫组化检测各组细胞HIF-1α、p53蛋白表达;RT-PCR检测各组细胞HIF-1amRNA.结果 低氧能明显增加Hep-2细胞HIF-1α蛋白及其mRNA表达,同时p53蛋白表达相应上调.再氧合之后HIF-1α蛋白及其mRNA表达均呈现下调趋势,p53蛋白表达下调.同低氧(B组)相比再氧合之后(C组)Hep-2细胞凋亡率明显升高(P<0.05).结论 低氧降低60Coγ射线照射对Hep-2细胞的诱凋亡作用,再氧合之后其诱凋亡作用明显提高.但在Hep-2细胞凋亡率明显升高的同时却并未出现p53蛋白表达的增强,提示低氧再氧合之后60Coγ射线诱导Hep-2细胞凋亡作用可能是通过p53以外的其它促凋亡途径实现的.     

n-6/n-3 PUFA对乳腺癌大鼠ER及p53表达影响

目的 探讨不同比例的n-6/n-3多不饱和脂肪酸(PUFA)对N-甲基亚硝基脲(MNU)诱导的乳腺癌大鼠乳腺组织中雌激素受体(ER)和p53表达的影响。方法 雌性SD大鼠随机分为n-6 PUFA、10:1 n-6/n-3、5:1n-6/n-3、1:1 n-6/n-3和正常对照5组,前4组以50mg/(kg·bw)MNU单次腹腔注射诱导乳腺肿瘤发生,正常对照组注射等体积无菌生理盐水。给药后立即分组喂养不同饲料,在8和18周时处死动物,RT-PCR和蛋白印迹(Western blot)技术检测各组大鼠乳腺组织ER和p53表达。结果 4组乳腺癌大鼠乳腺组织中ER和p53的表达均较正常对照组((0.73±0.11),(0.08±0.01))有所升高,其中n-6组最高((1.32±0.18),(1.43±0.56)),其余各组随n-6/n-3比值减小而下降,1:1 n-6/n-3组((0.95±0.12),(0.12±0.06))显著低于n-6组(P<0.05)。结论 不同比例n-6/n-3多不饱和脂肪酸对MNU诱导的乳腺癌大鼠乳腺组织ER和p53的表达具有不同影响,1:1 n-6/n-3膳食脂肪酸构成能有效抑制乳腺癌大鼠乳腺组织ER和p53表达的升高。     

多层螺旋CT电离辐射的探讨

目的:对多层螺旋CT电离辐射进行评价,提出合理化防护措施建议,保障各类人员的健康与安全。方法:采用相关的放射卫生规范规定的方法,对多层螺旋CT电离辐射的特性、剂量、危害等进行总结归纳。结果:在人类接受到的电离辐射中,医疗辐射占48%,而CT的辐射剂量占所有医疗辐射的49%,CT辐射致癌的可能性比以往认为的可能性更大。结论:通过各种安全防护功能和扫描模式降低辐射剂量,重视合理化防护措施,同时更重视过量使用CT的风险。