Cyclin D1表达异常与肿瘤的发生及预后

<正>Cyclin D1基因位于染色体11q13,长度为120kb。Cyclin D1作为原癌基因,在调节细胞从G1期进入S期中发挥重要作用[1]。在G1→S期的转换中,Rb蛋白与转录因子E2F结合,像闸门一样抑制G1→S期转换,但是Rb蛋白的细胞周期抑制功能可以通过磷酸化作用被解除。     

氧诱导新生小鼠视网膜病变中血管新生和氧应激相关基因表达的变化

目的建立氧诱导新生小鼠视网膜病变(oxygen-induced retinopathy,OIR)模型,观察视网膜血管新生情况,检测OIR病变过程中调控血管新生和氧应激相关基因表达的变化。方法新生小鼠出生后d 7,置75.5%高氧环境中饲养5 d,再返回正常氧环境继续饲养5 d,建立OIR模型。运用视网膜免疫荧光染色检测OIR小鼠视网膜中血管新生情况;运用Real-time PCR技术检测基因表达情况。结果视网膜免疫荧光染色结果显示,OIR小鼠视网膜在高氧诱导视网膜微血管消退的基础上,相对缺氧状态诱导出现明显的新生血管。Real-time PCR结果显示OIR模型小鼠视网膜中:血管内皮细胞生长因子(vascular endothelial growth factor,VEGF)及其受体(VEGFR)家族中:VEGFA、VEGFD、VEGFR1、VEGFR2的基因表达分别上调1.73、1.71、1.48、1.80倍;血小板衍生生长因子(platelet-derived growth factor,PDGF)及其受体(PDGFR)家族中:PDGFA、PDGFB、PDGFRa、PDGFRb的基因表达分别上调1.29、1.71、1.42、1.42倍;基质金属蛋白酶(matrix metalloproteinases,MMPs)中的MMP2基因表达上调1.48倍;参与调控氧化应激的核转录因子Nrf2[nuclear factor(erythroid-derived 2)-like 2]及受其调控的下游基因包括谷氨酸-半胱氨酸连接酶(glutamatecysteine ligase,GCL)的催化(GCLC)和调节(GCLM)亚单位的基因表达均下调,表达量分别为正常的0.28、0.76、0.49。结论 OIR小鼠视网膜病变过程中,视网膜中促进血管新生相关基因表达上调,而抗氧化相关基因表达下调。     

Gene expression in the liver of Long-Evans cinnamon rats during the development of hepatitis

The Long-Evans cinnamon (LEC) rat, an authentic model for Wilson disease, is characterized by a mutation in the Atp7b gene leading to a defective copper excretion and, as a consequence, to an accumulation of the metal in the liver and copper-associated hepatotoxicity. In the present communication expression profiles of genes in the liver from wild-type Long-Evans agouti (LEA) and LEC rats at different stages of copper accumulation and liver disease were investigated. Disease states were defined according to serum aspartate aminotransferase activity and bilirubin levels in serum and from histopathology of the liver. Gene expression was determined with the Affymetrix RTU34 oligonucleotide array covering 1031 genes. Compared to the LEA rat, the nondiseased LEC rat with already increased hepatic copper level showed an enhanced expression of genes, particularly related to oxidative stress and DNA damage. During the progression of the liver disease, in particular genes related to oxidative stress, DNA damage, apoptosis and inflammation with acute-phase reaction were upregulated.Electronic Supplementary Material Supplementary material is available in the online version of this article at     

Involvement of constitutive androstane receptor in liver hypertrophy and liver tumor development induced by triazole fungicides

We clarified the involvement of constitutive androstane receptor (CAR) in triazole-induced liver hypertrophy and tumorigenesis using CAR-knockout (CARKO) mice. Seven-week-old male CARKO and wild-type (WT) mice were treated with 200 ppm cyproconazole (Cypro), 1500 ppm tebuconazole (Teb), or 200 ppm fluconazole (Flu) in the diet for 27 weeks after initiation by diethylnitrosamine (DEN). At weeks 4 (without DEN) and 13 (with DEN), WT mice in all treatment groups and CARKO mice in Teb group revealed liver hypertrophy with mainly Cyp2b10 and following Cyp3a11 inductions in the liver. Teb also induced Cyp4a10 in both genotypes. Cypro induced slight and duration-dependent liver hypertrophy in CARKO mice. At week 27, Cypro and Teb significantly increased eosinophilic altered foci and/or adenomas in WT mice. These proliferating lesions were clearly reduced in CARKO mice administered both compounds. The eosinophilic adenomas caused by Flu decreased in CARKO mice. The present study indicates that CAR is the main mediator of liver hypertrophy induced by Cypro and Flu, but not Teb. In contrast, CAR played a crucial role in liver tumor development induced by all three triazoles.     

Altered gene expression patterns during the initiation and promotion stages of neonatally diethylstilbestrol-induced hyperplasia/dysplasia/neoplasia in the hamster uterus

Neonatal treatment of hamsters with diethylstilbestrol (DES) induces uterine hyperplasia/dysplasia/neoplasia (endometrial adenocarcinoma) in adult animals. We subsequently determined that the neonatal DES exposure event directly and permanently disrupts the developing hamster uterus (initiation stage) so that it responds abnormally when it is stimulated with estrogen in adulthood (promotion stage). To identify candidate molecular elements involved in progression of the disruption/neoplastic process, we performed: (1) immunoblot analyses and (2) microarray profiling (Affymetrix Gene Chip System) on sets of uterine protein and RNA extracts, respectively, and (3) immunohistochemical analysis on uterine sections; all from both initiation stage and promotion stage groups of animals. Here we report that: (1) progression of the neonatal DES-induced hyperplasia/dysplasia/neoplasia phenomenon in the hamster uterus involves a wide spectrum of specific gene expression alterations and (2) the gene products involved and their manner of altered expression differ dramatically during the initiation vs. promotion stages of the phenomenon.     

Altered expression of the Olr59, Ethe1, and Slc10a2 genes in the liver of F344 rats by neonatal thyroid hormone disruption

Many concerns have been expressed regarding the possible adverse effects of thyroid hormone‐disrupting chemicals in the environment. The disruption of thyroid hormones in the neonatal period may lead to permanent effects on thyroid hormone homeostasis as well as related developmental disorders, as thyroid hormones are essential for regulating the growth and differentiation of many tissues. To understand the long‐term alteration in gene expressions by neonatal administration of thyroid hormone‐like chemicals in general, we identified genes whose expression was altered in the liver, an important component of the thyroid hormone axis, by neonatal exposure to triiodothyronine (T3). T3 was administered to male F344 rats on postnatal days 1, 3, and 5 (week 0). At 8 weeks of age, cDNA microarray analysis was used to identify hepatic genes whose expression was altered by neonatal exposure to T3. Among the up‐regulated genes that were identified, the expression of Olr59 , Ethe1 , and Slc10a2 increased specifically in rats neonatally exposed to T3. Interestingly, altered hepatic expression of these genes indeed increased when a hydroxylated polybrominated diphenyl ether (PBDE), OH‐BDE42, which is capable of binding to the TR, was given neonatally. Our data demonstrated that neonatal exposure to thyroid hormones could affect the long‐term expression of the genes, which could be useful markers for neonatal effects by thyroid hormone‐disrupting chemicals. Copyright © 2017 John Wiley & Sons, Ltd.     

Estimates of the risk of bladder tumor promotion by saccharin in rats

Tumor data from an initiation-promotion bioassay in rats are used to illustrate how urinary bladder tumor risk estimates can be modified to reflect tumor promotion by saccharin. Assuming equal carcinogenic potency in humans and rats, the estimated human risk is equal to the probability of tumors in rats due to saccharin promotion following administration of an initiator times the ratio of the proportion of humans that are initiated to the proportion of initiated rats. The proportion of initiated humans may be somewhere between the proportion of deaths due to bladder cancer in the U.S. population, 0.005, and 1.0. The proportion of initiated animals in the bioassay may be somewhere between the proportion of animals with bladder tumors, 0.41, as observed in an initiated group, and 1.0. Hence, the ratio of the proportion of initiated humans to animals may be between 0.005 and 2.4. Then, the risk of bladder tumors is estimated to be between 0.005 and 2.4 times the estimated risk of tumors in rats promoted by saccharin following administration of an initiator. An upper limit on bladder tumor risk is estimated to be between 0.00038 and 0.18 times the percentage of saccharin in the diet. If a threshold dose exists for saccharin bladder tumor promotion which is above the saccharin consumption level of all humans, then the risk is zero.     

Lack of hepatotoxicity or promotion of enzyme-altered liver foci development in rats treated with harman or norharman

The modifying effects of harman or norharman on liver carcinogenesis were investigated in male F344/DuCrj rats initially treated with N-nitrosodiethylamine (DEN). Two weeks after a single dose of DEN (200 mg/kg, intraperitoneally), rats were given harman or norharman at dietary levels of 1000 and 200 parts per million (ppm), or sodium phenobarbital (PB) at 500 ppm as a positive control, for 6 wk. At wk 3 following DEN administration, all animals were subjected to partial hepatectomy. Marked retardation of body weight gain was observed in rats treated with harman or norharman at 1000 ppm, but not at 200 ppm. Increased relative kidney but not liver weights were associated with harman or norharman treatment, especially in the higher dose groups. Although no toxicity-related hepatocyte lesions were found, severe renal toxic tubular lesions and regeneration were evident. Neither harman nor norharman significantly increased the numbers or areas of glutathione S-transferase placental form (GST-P) positive foci observed after DEN initiation, in clear contrast to PB. The results thus demonstrated that harman and norharman are nontoxic for the liver and lack modifying potential for liver carcinogenesis in our medium-term bioassay system.     

Metallothionein expression during liver regeneration after partial hepatectomy in cadmium-pretreated rats

Metallothionein is a low molecular mass protein inducible mainly by heavy metals, having high affinity for binding cadmium, zinc and copper. In the present study we investigated the expression of metallothionein in regenerating liver, at different time intervals, in cadmium pretreated partially hepatectomized rats. Liver metallothionein is highly expressed during regeneration in-duced by partial hepatectomy in rats, providing zinc within the rapidly growing tissue. Cadmium pretreatment caused inhibition of the first peak of liver regeneration, while metallothionein expression was markedly more prominent in the liver residues of cadmium-pretreated rats. These results demonstrate that although metallothionein able to bind temporarily metal ions as zinc and cadmium has been highly expressed, the liver regenerative process was inhibited possibly due to the effects of cadmium on other pivotal events necessary to the DNA replication.     

Fucoxanthin, a natural carotenoid, induces G1 arrest and GADD45 gene expression in human cancer cells

BACKGROUND: Although the antitumor effects of fucoxanthin are known, the precise mechanism of action has yet to be elucidated. MATERIALS AND METHODS: HepG2 and DU145 cells were used for these investigations. The effect of fucoxanthin on gene expression was assayed using a DNA microarray system. Northern blot and/or quantitative RT-PCR were carried out to confirm any changes in gene expression. The effect of fucoxanthin on cell cycle progression was analyzed using flow cytometry. RNA interference experiments were employed for the GADD45 gene. RESULTS: Fucoxanthin markedly induced GADD45A, a cell cycle-related gene, in HepG2 and DU145 cells. Concomitant G1 arrest, but not apoptosis, was observed in both cell types following treatment with fucoxanthin. The introduction of siRNA against GADD45A partially perturbed the induction of Gi arrest by fucoxanthin in both cell types. CONCLUSION: Fucoxanthin induced G1 arrest in HepG2 and DU145 cells. GADD45A may be involved in fucoxanthin-induced G1 arrest.     

Altered development of responsiveness to clonidine in severely malnourished rats

To examine the effects of malnutrition on the ontogeny of alpha 2 noradrenergic receptor function, we compared the effects of clonidine during early development in severely malnourished and well-nourished rat pups. Independent groups of pups from dams given either 6% or 25% casein diets received one of five doses of clonidine at 5, 10, 15, 20 or 25 days of age and dose-response relationships for motor activity were determined. In the 25% pups the clonidine-induced locomotor activity was greatest at 5 and 10 days, intermediate at 15 days and not elevated at 20 and 25 days. The malnourished pups exhibited a significant delay in the transition from hyperactivity to hypoactivity, being activated by clonidine until at least 25 days. Wall-climbing measures indicated similar developmental trends as overall activity. These results are discussed in terms of the proposed mechanisms mediating the developmental change in the effects of alpha 2 receptor stimulation.     

Altered expression of GABA-A receptor subunits in the hippocampus of PTZ-kindled rats

Background

Changes in the expression of the GABA-A receptor subunits involved in phasic and tonic inhibition have been studied in a wide spectrum of animal models of epilepsy. However, there is no exhaustive data regarding the pentylenetetrazole (PTZ) kindling model of epilepsy.

CAR expression and inducibility of CYP2B genes in liver of rats treated with PB-like inducers

The expression of the CAR gene and inducibility of CYP2B protein in the liver of male Wistar rats treated with phenobarbital (PB) and triphenyldioxane (TPD) were investigated. To clarify the role of phosphorylation/dephosphorylation in these processes, rats were treated with inhibitors of Ca(2+)/calmodulin-dependent kinase II (W7) or protein phosphatases PP1 and PP2A (OA) before induction. Constitutive expression of the CAR gene in livers of untreated rats was detected by multiplex RT-PCR. Treatment with W7 resulted in a 2.8-fold induction of CAR gene expression, whereas OA led to a 2.4-fold decrease of the mRNA level. The same results were obtained for CYP2B genes expression, which were increased by W7 treatment (two-fold) and decreased by OA (2.3-fold). PB-induction did not lead to significant alteration in the level of CAR gene expression, although CYP2B genes expression was enhanced two-fold over control values. TPD caused a two-fold increase of both CAR and CYP2B mRNA levels. Both inducers reduced the effects of inhibitors on CAR gene expression. Results of EMSA showed that PB, TPD or W7 alone induced formation of complexes of NR1 with nuclear proteins. Appearance of the complexes correlated with an increase in CYP2B expression, and their intensities were modulated by the protein kinase inhibitors. Thus, our results demonstrate that constitutive expressions of CAR as well as CYP2B during induction are regulated by phosphorylation/dephosphorylation processes.     

小檗碱对高果糖饲养诱导大鼠胰岛素抵抗和肝脏TNF-α表达的影响

目的研究小檗碱对高果糖饲养诱导胰岛素抵抗大鼠的作用。方法高果糖饲料喂养SD大鼠6wk后,分为3组,模型组,小檗碱组(187.5mg.kg-1.d-1灌服)、二甲双胍组(184mg.kg-1.d-1灌服)作为对照,继续高果糖饮食。实验同时设立正常对照组,普通饮食喂养。4wk后处死大鼠;测定血糖、血清胰岛素、胰岛素抵抗指数及血脂的变化,用RT-PCR方法观察肝脏TNF-αmRNA的表达。结果模型组胰岛素、胰岛素抵抗指数、游离脂肪酸(free fatty acids,FFA)及甘油三酯(triglycerides,TG)水平均明显升高;肝脏TNF-αmRNA的表达与正常对照组比较明显升高。小檗碱降低了胰岛素抵抗大鼠的血糖、血清胰岛素、胰岛素抵抗指数、TG、FFA及TNF-αmRNA的表达。二甲双胍降低了大鼠的血糖、血清胰岛素、胰岛素抵抗指数及TG。结论小檗碱可以改善胰岛素抵抗,其机制可能包括抑制肝脏TNF-αmR-NA的表达与改善脂代谢紊乱。