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1.
目的: 研究在低氧条件下,奥巴克拉(OBX)联合吉西他滨(GEM)对乳腺癌细胞MCF-7、BT-20的细胞活性、迁移、侵袭及凋亡的影响。 方法: 选取乳腺癌细胞MCF-7与BT-20细胞,分组为正常氧组,低氧组,GEM组,OBX+GEM组。正常氧组:37℃,5% CO 2培养箱培养24 h与48 h;低氧组:37℃,1%O 2,5% CO 2 ,94% N 2条件下培养24 h与48 h; GEM组:37℃,1%O 2,5% CO 2 , 94% N 2,加入终浓度为10 μmol/L的GEM培养24 h与48 h;OBX+ GEM组:7℃,1%O 2,5% CO 2 ,94% N 2,加入终浓度为10 μmol/L的GEM与终浓度为50 nmol/L的OBX培养24 h与48 h。利用Western blot检测正常氧及低氧条件下MCF-7与BT-20细胞中低氧诱导因子(HIF-1α)的表达;利用CCK-8实验检测各组中MCF-7与BT-20细胞活性,每组设置15个复孔;利用划痕实验检测各组MCF-7与BT-20细胞迁移能力,每组设置6个复孔;利用Western blot检测各组MCF-7细胞中vimentin、E-Cadherin及p53蛋白的表达。 结果: HIF-1α在低氧条件下培养的细胞中的表达远远高于其在正常氧条件下培养的细胞中的表达( P<0.05),说明低氧条件成功;与低氧组相比较,GEM可降低MCF-7与BT-20细胞迁移能力和细胞活性( P<0.05),减少细胞中vimentin的表达( P<0.01),促进E-Cadherin和p53的表达( P<0.01);与GEM组相比较,OBX联合GEM组可明显降低细胞活性和MCF-7与BT-20细胞的迁移能力( P<0.01),显著降低细胞中vimentin的表达( P<0.01),显著升高E-Cadherin和p53的表达( P<0.01)。 结论:在低氧条件下,OBX联合小剂量GEM可显著抑制乳腺癌细胞的生长、迁移、侵袭,增强GEM对乳腺癌细胞的促凋亡作用,具体机制尚需要进一步研究。 相似文献
3.
Follicular growth is characterized by an augmented vascularization, possibly driven by a fall in the oxygen supply. The present study was undertaken to investigate the effects of hypoxia on swine granulosa cells. At first, we quantified oxygen partial pressure ( pO 2) in follicular fluid from different size follicles; the granulosa cells collected from large follicles (>5 mm) were subjected for 18 h to normoxia (19% O 2), partial (5% O 2) or total hypoxia (1% O 2). The effects of these conditions were tested on the main parameters of granulosa cell function, steroidogenesis and cell proliferation, and on vascular endothelial growth factor (VEGF), nitric oxide (NO) and superoxide anion (O 2−) production. Oxygen tension in follicular fluid was negatively related to follicular size, pointing out a gradual reduction during follicular growth. Severe hypoxic conditions determined a reduction of both 17β estradiol and progesterone production, while partial hypoxia did not seem to affect them. Hypoxia increased VEGF as well as O 2− production in swine granulosa cells without impairing cell growth; in addition, it decreased NO output. We may conclude that physiological hypoxia could play a pivotal role in the follicular angiogenic process stimulating VEGF synthesis by granulosa cells. ROS are possibly involved in hypoxic signalling. 相似文献
4.
采用气雾法栽培系统,研究了根际低氧(10% O 2和5% O 2)胁迫对网纹甜瓜果实发育期间植株生长、根呼吸代谢及抗氧化酶活性的影响.结果表明:与对照相比,低氧胁迫下,网纹甜瓜株高、根长降低,植株鲜、干物质量显著下降;根呼吸速率极显著低于对照(21% O 2),且5% O 2处理下降幅度大于10% O 2处理;乳酸脱氢酶(LDH)、乙醇脱氢酶(ADH)和丙酮酸脱羧酶(PDC)活性较对照显著升高,而苹果酸脱氢酶(MDH)活性显著降低;根系中超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量显著高于对照,其中10% O 2处理抗氧化酶活性升高幅度显著大于5% O 2处理,而MDA含量5% O 2处理高于10% O 2处理.说明网纹甜瓜果实发育期间根际氧浓度降到10%及其以下时,根系有氧呼吸明显受阻,无氧呼吸代谢被促进,同时根系抗氧化酶发生应激反应,但随低氧胁迫时间的延长,根细胞质膜过氧化程度加剧,根系受到伤害,植株生长受到抑制,最终导致果实产量和品质下降. 相似文献
6.
This study determined the effect of in utero hypoxia on fetal heart and brain pro- and antioxidant trace metals. Dunkin-Hartley guinea pigs (50–60 days gestation) were exposed to 1 h hypoxia (7% O 2/93% N 2) followed by 4 h reoxygenation in room air. Fetal hearts and brains were harvested and analyzed for copper, iron, magnesium and zinc. Fetal brain iron was significantly increased 28% after hypoxia and 35% by 1 h posthypoxia. Fetal brain magnesium demonstrated progressive decreases of 18% by 4 h posthypoxia. No significant effects of hypoxia were observed on heart trace metals. These results indicate that prooxidant metals may be increased and antioxidant metals may be decreased in posthypoxic fetal brain during a time when these tissues may be vulnerable to oxidative injury. 相似文献
7.
Ground-level ozone (O 3) and drought are two key factors limiting plant growth. O 3 can enter into the plant tissue through the stomata, then causing the formation of reactive oxygen species (ROS) which inspires programmed cell death. Drought usually induces the accumulation of ROS due to damage to antioxidant systems of plants. The effects of two kinds of stress on plants are similar due to the accumulation of ROS, resulting in reduced photosynthesis rate and physiological metabolism, eventually decreased plant growth and biomass. Nevertheless, O 3 and drought interacts synergistically to accumulate detrimental effects or antagonistically to reduce harmful effects. Actually, it is complex interactive process between O 3 and drought. On the one hand, O 3 triggers stomatal sluggishness or even dysfunction, which exacerbates water transpiration of leaves, water loss from plants and further O 3 phytotoxicity. On the other hand, drought induces stomatal closure, and thus protecting plants against the O 3 influx and evaporation of water. However, prolonged drought could limit the uptake of CO 2 and thus result in reduced plant growth. The response of plants to both O 3 and drought not only depends on the occurring sequence and duration of any factor but also rely on the difference in physiological metabolism of the plant itself. The interactive effects of O 3 and drought on stomatal characteristics, photosynthetic carbon mechanism, antioxidant response and growth development are reviewed in this paper and the aspects to be further studied are also suggested. 相似文献
8.
Abstract. The initiation of DNA synthesis and further cell cycle progression in cells during and following exposure to extremely hypoxic conditions in either G 1 or G 2+M has been studied in human NHIK 3025 cells. Populations of cells, synchronized by mitotic selection, were rendered extremely hypoxic (< 4 p.p.m. O 2) for up to 24n h. Cell cycle progression was studied from flow cytometric DNA recordings. No accumulation of DNA was found to take place during extreme hypoxia. Cells initially in G 1 at the onset of treatment did not enter S during up to 24 h exposure to extreme hypoxia, but started DNA synthesis in a highly synchronous manner within 1.5 to 2.25 h after reoxygenation. The duration of S phase was only slightly affected (increased by ≅10%) by the hypoxic treatment. This suggests that the DNA synthesizing machinery either remains intact during hypoxia or is rapidly restored after reoxygenation. Cells initially in G 2 at the onset of hypoxia were able to complete mitosis, but further cell cycle progression was blocked in the subsequent G^ Following reoxygenation, these cells progressed into S phase, but the initiation of DNA synthesis was delayed for a period corresponding to at least the duration of normal G 1 and did not appear in a synchronous manner. In fact, cell cycle variability was found to be increased rather than decreased as a result of exposure to hypoxia starting in G 2. We interpret these findings as an indication that important steps in the preparation for initiation of DNA synthesis take place before mitosis. Furthermore, the change in cell cycle duration induced by hypoxia commencing in G 1 is of a nature other than that induced by hypoxia commencing in other parts of the cell cycle. 相似文献
9.
目的:观察急性间歇性低氧刺激后大鼠颈动脉体对低氧的敏感性以及多巴胺对颈动脉体低氧敏感性的影响。方法:将分离SD大鼠的颈动脉体-窦神经移入到孵育槽,然后把分离的窦神经吸入到记录的玻璃电极中行电信号记录。记录基线部分缓冲液充入气体为95%O2+5%CO2混合气,低氧应激给予5%O2+5%CO2+90%N2混合气,低氧刺激给予30 s,95%O2+5%CO2给予90 s,共10个循环,每组实验大鼠数量n大于等于5。结果:大鼠离体的颈动脉体,给予急性间歇性低氧应激,再给予低氧刺激,窦神经较之前低氧刺激放电活动增强。但加入多巴胺后,可以抑制窦神经对低氧的反应,急性间歇性低氧后,多巴胺对窦神经的低氧放电活动抑制作用加强。结论:大鼠颈动脉体给予急性间歇性低氧可增强窦神经对低氧的反应,多巴胺可抑制急性低氧诱导的颈动脉体对低氧敏感性的增强。 相似文献
10.
Hypoxia, a dissolved oxygen concentration (DO) below 2 mg l – 1, is a significant stressor in many estuarine ecosystems. Many sedentary organisms, unable to move to avoid hypoxic areas, have metabolic and behavioral adaptations to hypoxic stress. We tested the effects of hypoxia on the behavior and mortality of the clam Macoma balthica, using four levels of dissolved oxygen in flow-through tanks. We used five replicates of each of four treatments: (1) Hypoxic (DO mean ± SE = 1.1 ± 0.06 mg O 2 l – 1), (2) Moderately hypoxic (DO 2.6 ± 0.05 mg O 2 l – 1), (3) Nearly normoxic (DO 3.2 ± 0.04 mg O 2 l – 1), (4) Normoxic (DO = 4.9 ± 0.13 mg O 2 l – 1). We lowered the dissolved oxygen with a novel fluidized mud-bed, designed to mimic field conditions more closely than the common practice of solely bubbling nitrogen or other gasses. This method for lowering the DO concentrations for a laboratory setup was effective, producing 1.4 l min –1 of water with a DO of 0.8 mg O 2 l – 1 throughout the experiment. The setup greatly reduced the use of compressed nitrogen and could easily be scaled up to produce more low-DO water if necessary. The lethal concentration for 50% of the M. balthica population (LC 50) was 1.7 mg O 2 l – 1 for the 28-day experimental period. M. balthica decreased its burial depth under hypoxic and moderately hypoxic (~2.5 mg O 2 l – 1) conditions within 72 hours of the onset of hypoxia. By the sixth day of hypoxia the burial depth had been reduced by 26 mm in the hypoxic tanks and 10 mm in the moderately hypoxic tanks. Because reduced burial depth makes the clams more vulnerable to predators, these results indicate that the sub-lethal effects of hypoxia could change the rate of predation on M. balthica in the field. 相似文献
11.
Despite the dramatic fall in plasma estrogen levels at menopause, only minor differences in breast tissue estrogen levels have been reported comparing pre- and postmenopausal women. Thus, postmenopausal breast tissue has the ability to maintain concentrations of estrone (E 1) and estradiol (E 2) that are 2–10- and 10–20-fold higher than the corresponding plasma estrogen levels. This finding may be explained by uptake of estrogens from the circulation and/or local estrogen production. Local aromatase activity in breast tissue seems to be of crucial importance for the local estrogen production in some patients while uptake from the circulation may be more important in other patients. Beside aromatase, breast tissue expresses estrogen sulfotransferase and sulfatase as well as dehydrogenase activity, allowing estrogen storage and release in the cells as well as conversions between estrone and estradiol. The activity of the enzyme network in breast cancer tissue is modified by a variety of factors like growth factors and cytokines. Aromatase inhibitors have been used for more than two decades in the treatment of postmenopausal metastatic breast cancer and are currently investigated in the adjuvant treatment and even prevention of breast cancer. Novel aromatase inhibitors and inactivators have been shown to suppress plasma estrogen levels effectively in postmenopausal breast cancer patients. However, knowledge about the influence of these drugs on estrogen levels in breast cancer tissue is limited. Using a novel HPLC-RIA method developed for the determination of breast tissue estrogen concentrations, we measured tissue E 1, E 2 and estrone sulfate (E 1S) levels in postmenopausal breast cancer patients before and during treatment with anastrozole. Our findings revealed high breast tumor tissue estrogen concentrations that were effectively decreased by anastrozole. While E 1S was the dominating estrogen fraction in the plasma, estradiol was the estrogen fraction with the highest concentration in tumor tissue. Moreover, plasma estrogen levels did not correlate with tissue estrogen concentrations. The overall experience with aromatase inhibitors and inactivators concerning their influences on breast tissue estrogen concentrations is summarized. 相似文献
12.
Influence of oxygen on the electron transfers of photosynthesis. I. Influence of some oxygen concentrations on some Hill reactionsThe influence of O2 concentrations on the Hill reactions in the presence of p-benzoquinone, ferricyanide, NADP+, NADP+ plus ferredoxin has been studied with isolated spinach chloroplasts. Because of the partial reoxidation of the hydroquinone, which is depending upon the O2 concentration, it does not seem possible to localize a site of action for O2. With ferricyanide the influence of O2 is weak. However, the rate of ferricyanide reduction is increased in the presence of O2. The observed stimulation is greater for 21% O2 than for 70% O2. Bicarbonate stimulates the ferricyanide reduction and decreases the stimulating effect of 21% O2. O2 decreases the rate of NADP+ reduction. Ferredoxin as well as bicarbonate stimulate the NADP+ reduction and reduce the O2 inhibition. These results seem to indicate that O2 may enter the electron transport chain at a site situated near Photosystem I and before the ferredoxin's site. The inhibitory effect of O2 on the Hill reactions with p-benzoquinone and NADP+ is depending upon the plants' growth conditions. It is greater with plants grown under weak light. 相似文献
14.
通过开顶箱(OTCs)模拟,以环境臭氧(O 3)浓度约40 nmol·mol -1为对照,研究大气O 3浓度升高(80和160 nmol·mol -1O 3)对冷季型草坪草高羊茅生长、亚细胞结构及其活性氧代谢的影响.结果表明: 14 d的80 nmol·mol -1O 3熏蒸使高羊茅株高和叶宽降低,总生物量降低43.7%,老叶变黄,而160 nmol·mol -1O 3处理高羊茅叶出现大量枯死褐斑,叶尖坏死,新叶卷曲,总生物量降低46.2%,叶肉细胞膜卷曲,叶绿体和线粒体受损严重.与对照相比,80和160 nmol·mol -1O 3熏蒸下高羊茅叶片超氧阴离子(O 2-·)产生速率、过氧化氢(H 2O 2)和丙二醛(MDA)含量显著增加,抗氧化酶活性显著升高,但叶片总酚含量和抗氧化能力随O 3浓度升高而先升高后降低.在明显O 3伤害症状出现之前,O 3已对高羊茅的生长和抗氧化代谢产生不利影响;高羊茅抗氧化系统虽对O 3浓度的升高存在一定的适应性反应,但其不能抵御过高浓度的长期胁迫和伤害. 相似文献
15.
Isolated hepatocytes incubated with selenite (30–100 μM) exhibited changes in the glutathione redox system as shown by an increase in O 2 consumption, oxidation of glutathione and loss of NADPH. Selenite (50 μM) raised O 2 consumption within the 1 h and induced an partial depletion of thiols with a concomitant increase in oxidized glutathione, as well as a decrease in NADPH levels within 2 h. With 100 μM selenite more pronounced effects were obtained such as a total depletion of thiols. This concentration of selenite also lysed cells within 3 h. Arsenite, HgCl 2 and KCN prevented the increase in O 2 uptake, counteracted loss of thiols and delayed selenite induced lysis. p-Tert-butylbenzoic acid, an inhibitor of gluconeogenesis, decreased selenite dependent O 2 consumption and potentiated the effect on NADPH levels as well as the toxic effect. Finally, methionine further enhanced O 2 consumption by selenite and also delayed loss of thiols and potentiated selenite toxicity. These results indicated that selenite catalyzed a reduction of O 2 in glutathione dependent redox cycles with NADPH as an electron donor. With subtoxic concentrations of selenite (50 μM) there were indications that O 2 reduction was terminated by selenite biotransformation to methylated metabolites. With toxic concentrations of selenite (100 μM) it appeared that O 2 reduction was eventually limited by the capacity of the cell to regenerate NADPH. It is suggested that a depletion of NADPH mediated the observed cytotoxicity of selenite. 相似文献
16.
Fluctuating oxygen levels characterize the microenvironment of many cancers and tumor hypoxia is associated with increased invasion and metastatic potential concomitant with a poor prognosis. Similarly, the expression of lysyl oxidase (LOX) in breast cancer facilitates tumor cell migration and is associated with estrogen receptor negative status and reduced patient survival. Here we demonstrate that hypoxia/reoxygenation drives poorly invasive breast cancer cells toward a more aggressive phenotype by up-regulating LOX expression and catalytic activity. Specifically, hypoxia markedly increased LOX protein expression; however, catalytic activity (beta-aminopropionitrile inhibitable hydrogen peroxide production) was significantly reduced under hypoxic conditions. Moreover, poorly invasive breast cancer cells displayed a marked increase in LOX-dependent FAK/Src activation and cell migration following hypoxia/reoxygenation, but not in response to hypoxia alone. Furthermore, LOX expression is only partially dependent on hypoxia inducible factor-1 (HIF-1alpha) in poorly invasive breast cancer cells, as hypoxia mimetics and overexpression of HIF-1alpha could not up-regulate LOX expression to the levels observed under hypoxia. Clinically, LOX expression positively correlates with tumor progression and co-localization with hypoxic regions (defined by HIF-1alpha expression) in ductal carcinoma in situ and invasive ductal carcinoma primary tumors. However, positive correlation is lost in metastatic tumors, suggesting that LOX expression is independent of a hypoxic environment at later stages of tumor progression. This work demonstrates that both hypoxia and reoxygenation are necessary for LOX catalytic activity which facilitates breast cancer cell migration through a hydrogen peroxide-mediated mechanism; thereby illuminating a potentially novel mechanism by which poorly invasive cancer cells can obtain metastatic competency. 相似文献
17.
Several tumor-derived murine macrophage cell lines were evaluated
as cloned prototypes of tissue macrophages for their ability to metabolize arachidonic acid. Unexpectedly, two cell lines, J774A.1 and WR19M.1, rapidly converted exogenous 14C-arachidonic acid (AA) to a single major prostaglandin metabolite. The compound, PGD 2, was positively identified by TLC, HPLC, and GC-MS. The enzymatic formation of the PGD 2 was shown by inhibition of its formation by indomethacin and reduced formation of 14C-PGD 2 and 14C-PGD 2 in boiled cells. When J774A.1 cells were prelabeled with 3H-AA, cultured for 24 hours, and stimulated with lipopolysaccharide (LPS), PGD 2 was again the predominant product. No other tumor derived cell lines, including several other murine macrophage lines, produced significant amounts of PGD 2. Elicited and activated murine peritoneal macrophages produced only small amounts of PGD 2, but resident peritoneal macrophages produced modest amounts of PGD 2. Exaggerated formation of PGD 2 by J774A.1 and WR19M.1 cells may be a consequence of neoplastic transformation or the clonal expansion of a minor subpopulation of normal tissue macrophages. 相似文献
18.
Cancer stem cells (CSCs) represent a population of cancer cells that possess unique self-renewal and differentiation characteristics required for tumorigenesis and are resistant to chemotherapy-induced apoptosis. Lung CSCs can be enriched by several markers including drug-resistant side population (SP), CD133 pos and ALDH high. Using human non-small cell lung adenocarcinoma cell lines and patient-derived primary tumor cells, we demonstrate that SP cells represent a subpopulation distinct from other cancer stem/progenitor cell (CS/PC) populations marked by CD133 pos or ALDH high. The non-CS/PCs and CS/PCs of each subpopulation are interconvertible. Epithelial-mesenchymal transition (EMT) promotes the formation of CD133 pos and ALDH high CS/PC subpopulations while suppressing the SP CS/PC subpopulation. Rac1 GTPase activity is significantly increased in cells that have undergone EMT, and targeting Rac1 is effective in inhibiting the dynamic conversion of non-CS/PCs to CS/PCs, as well as the CS/PC activity. These results imply that various subpopulations of CS/PCs and non-CS/PCs may achieve a stochastic equilibrium in a defined microenvironment, and eliminating multiple subpopulations of CS/PCs and effectively blocking non-CS/PC to CS/PC transition, by an approach such as targeting Rac1, can be a more effective therapy. 相似文献
19.
Malignant brain tumors consist of a number of distinct subclonal populations. Each of these subpopulations may be characterized by its own behaviors and properties. These subpopulations arise from the constant genetic and epigenetic alteration of existing cells in the rapidly growing tumor. However, since each single-cell mutation only leads to a small number of offspring initially, very few newly arisen subpopulations survive more than a short time. The present work quantifies "emergence", i.e. the likelihood of an isolated subpopulation surviving for an extended period of time. Only competition between clones is considered; there are no cooperative effects included. The probability that a subpopulation emerges under these conditions is found to be a sigmoidal function of the degree of change in cell division rates. This function has a non-zero value for mutations which confer no advantage in growth rate, which represents the emergence of a distinct subpopulation with an advantage that has yet to be selected for, such as hypoxia tolerance or treatment resistance. A logarithmic dependence on the size of the mutated population is also observed. A significant probability of emergence is observed for subpopulations with any growth advantage that comprise even 0.1% of the proliferative cells in a tumor. The impact of even two clonal populations within a tumor is shown to be sufficient such that a prognosis based on the assumption of a monoclonal tumor can be markedly inaccurate. 相似文献
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