Institute of Nutritional and Metabolic Disorder in Domestic Animals and Fowls, Nanjing Agricultural University, Nanjing, China.
J Trace Elem Med Biol. 2012 Oct;26(4):255-61. doi: 10.1016/j.jtemb.2012.02.001. Epub 2012 Mar 16.
This experiment was designed to compare the effect of two selenium sources at the dosage of therapeutic level on hepatocarcinogenesis and angiogenic cytokines in DEN-induced hepatocarcinoma rats to further approach their possible anticancer's mechanism. One hundred and seventy-eight Sprague-Dawley (SD) rats (average weight being 100-120g) were randomly divided into 5 groups (I-V). Animals in group I, group II and group III served as the negative control, sodium selenite control (SS) and positive controls respectively, and received 0.1, 3.0, and 0.1mg/kg selenium from sodium selenite supplemented diets during the whole experimental time. Rats in group IV and group V were fed with selenium from selenium-enriched malt (SEM) and sodium selenite (SS) supplemented diets (3mg/kg respectively). To balance the nutritional content among each group, normal malt which was not treated with selenium was added into the diets of the challenge groups. The nutrition contents, except the selenium of the diet in each group, were similar and in accordance with NRC standards. Rats in groups III-V were treated by aqueous diethylnitrosamine solution (100mg/L) at the dosage of 10mg/kg body weight every day for 16 weeks to induce hepatocarcinoma, and drank sterilized water for an additional two weeks. Rats in group I and group II drank sterilized water throughout the experiment. At 4th, 8th, 12th, 16th week, five rats in each group were then sacrificed by cervical decapitation. At the termination of the study, at 18th week, the surplus rats were sacrificed by cervical decapitation. Feed was withheld from the rats for 12h before sampling. The number of hepatoma nodules in liver and mortality of rats were calculated. The values of the following items, including α-fetoprotein (AFP), gamma-glutamyltranspeptidase (GGT), tumor necrosis factor-α (TNF-α), insulin-like growth factors-II (IGF-II), nitric oxide (NO) and total nitric oxide synthase (T-NOS) in plasma were determined. At the same time, the positive numbers of vascular endothelial growth factor (VEGF) and protein kinase C-α (PKCα) staining cells in tumor tissue were analyzed by immunohistochemistry using the Envision two step methods with a kit. The results indicated that SEM could significantly decrease the mortality of rats and the number of hepatoma nodules, values of GGT and AFP, and the levels of IGF-II, NO and NOS and lessen the positive numbers of VEGF and PKCα staining cells in tumor tissue. Moreover, SEM could increase the levels of TNF-α in the initiated time of hepatocarcinogenesis, whereas, decrease the levels of TNF-α in the progressive time of hepatocarcinogenesis. SS could only significantly inhibit the positive numbers of PKCα staining cells in tumor tissue, decrease the levels of GGT, AFP and TNF-α at minority sampling times, and increase the levels of NO. In conclusion, SEM could reduce the mortality. It might be related to deaden significantly the lesion of liver, delay the cause of hepatocarcinogenesis, and inhibit the progress of angiogenesis to increase the livability of DEN-induced hepatocarcinoma rats. SS at the same therapeutic dosage had less effect on the hepatocarcinogenesis by inhibiting angiogenesis and relative cytokines to some extent.
本实验旨在比较两种硒源在治疗剂量下对 DEN 诱导的肝癌大鼠肝癌发生和血管生成细胞因子的影响,以进一步探讨其可能的抗癌机制。178 只 Sprague-Dawley(SD)大鼠(平均体重 100-120g)被随机分为 5 组(I-V)。组 I、组 II 和组 III 作为阴性对照、亚硒酸钠对照(SS)和阳性对照,分别在整个实验期间接受 0.1、3.0 和 0.1mg/kg 硒的亚硒酸钠补充饮食。组 IV 和组 V 分别用富硒麦芽(SEM)和亚硒酸钠(SS)补充饮食(分别为 3mg/kg)喂养。为了平衡各组的营养含量,在挑战组的饮食中加入了未经硒处理的普通麦芽。各组饮食的营养含量除硒外均相似且符合 NRC 标准。第 3-5 组大鼠每天接受 10mg/kg 体重的水溶液二乙基亚硝胺溶液(100mg/L)处理 16 周,诱导肝癌,并额外饮用灭菌水 2 周。组 I 和组 II 整个实验期间均饮用灭菌水。在第 4、8、12 和 16 周时,每组各取 5 只大鼠断头处死。在研究结束时,第 18 周,剩余的大鼠被断头处死。在取样前,大鼠禁食 12 小时。计算肝癌结节数和大鼠死亡率。测定血浆中α-胎蛋白(AFP)、γ-谷氨酰转肽酶(GGT)、肿瘤坏死因子-α(TNF-α)、胰岛素样生长因子-II(IGF-II)、一氧化氮(NO)和总一氧化氮合酶(T-NOS)的含量。同时,采用 Envision 两步法试剂盒,用免疫组织化学法检测肿瘤组织中血管内皮生长因子(VEGF)和蛋白激酶 C-α(PKCα)染色细胞的阳性数。结果表明,SEM 能显著降低大鼠死亡率和肝癌结节数、GGT 和 AFP 值以及 IGF-II、NO 和 NOS 水平,减少肿瘤组织中 VEGF 和 PKCα 染色细胞的阳性数。此外,SEM 能在肝癌发生的起始时间增加 TNF-α 的水平,而在肝癌发生的进展时间减少 TNF-α 的水平。SS 只能显著抑制肿瘤组织中 PKCα 染色细胞的阳性数,在少数采样时间点降低 GGT、AFP 和 TNF-α 的水平,增加 NO 的水平。总之,SEM 可以降低死亡率。这可能与显著抑制肝损伤、延缓肝癌发生的原因以及抑制血管生成从而提高 DEN 诱导的肝癌大鼠的存活率有关。在相同的治疗剂量下,SS 通过在一定程度上抑制血管生成和相关细胞因子,对肝癌发生的影响较小。
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