Black rice extract protected HepG2 cells from oxidative stress-induced cell death via ERK1/2 and Akt activation

BACKGROUND/OBJECTIVES

The objective of this study was to evaluate the protective effect of black rice extract (BRE) on tert-butyl hydroperoxide (TBHP)-induced oxidative injury in HepG2 cells.

MATERIALS/METHODS

Methanolic extract from black rice was evaluated for the protective effect on TBHP-induced oxidative injury in HepG2 cells. Several biomarkers that modulate cell survival and death including reactive oxygen species (ROS), caspase-3 activity, and related cellular kinases were determined.

RESULTS

TBHP induced cell death and apoptosis by a rapid increase in ROS generation and caspase-3 activity. Moreover, TBHP-induced oxidative stress resulted in a transient ERK1/2 activation and a sustained increase of JNK1/2 activation. While, BRE pretreatment protects the cells against oxidative stress by reducing cell death, caspase-3 activity, and ROS generation and also by preventing ERKs deactivation and the prolonged JNKs activation. Moreover, pretreatment of BRE increased the activation of ERKs and Akt which are pro-survival signal proteins. However, this effect was blunted in the presence of ERKs and Akt inhibitors.

CONCLUSIONS

These results suggest that activation of ERKs and Akt pathway might be involved in the cytoprotective effect of BRE against oxidative stress. Our findings provide new insights into the cytoprotective effects and its possible mechanism of black rice against oxidative stress.     

COX-2抑制剂NS-398对肝癌HepG2细胞凋亡蛋白Bcl-2和Caspase 3表达的影响

目的探讨选择性环氧合酶2(COX-2)抑制在肝癌HepG2细胞凋亡中的作用。方法用选择性COX-2抑制剂NS-398处理HepG2细胞,流式细胞术测定细胞凋亡和半胱氨酸酶3(Caspase3)活性变化;Western blotting法检测不同浓度NS-398处理后凋亡相关蛋白Bcl-2、Caspase3表达变化。结果流式细胞术显示NS-398(0、100、200、300、400μmol/L)作用HepG2细胞24h后,对照组未见凋亡峰,各试验组(100、200、300、400μmol/L)出现明显的凋亡峰,其凋亡率分别为(10.51±1.04)%、(27.79±2.40)%、(45.72±3.32)%、(60.22±2.03)%,呈明显剂量依赖性(P<0.01),不同浓度NS-398处理后Bcl-2表达下降,Caspase3表达增加,随着NS-398处理浓度的增加,表达活性Caspase3的细胞百分率分别为(2.67±0.22)%、(9.53±0.15)%、(21.28±0.43)%、(39.63±0.8)%、(63.40±0.69)%,呈明显剂量依赖性(P<0.01)。结论选择性COX-2抑制剂NS-398可能通过下调Bcl-2蛋白表达活化Caspase3,从而诱导肝癌细胞HepG2凋亡,COX-2抑制也许可作为新的肝癌的治疗方法。     

Coxsackievirus B3 induces autophagy in HeLa cells via the AMPK/MEK/ERK and Ras/Raf/MEK/ERK signaling pathways

In a previous study, the number of autophagosomes increased after coxsackievirus B3 (CVB3) infection. However, the exact mechanism by which CVB3 regulates the number of autophagosomes is unclear. Earlier studies have found that infection with CVB3 activates extracellular signal-regulated kinase (ERK). ERK is essential for CVB3 replication and can increase the number of autophagosomes. In the current study, extracellular signal-regulated kinase 1/2 was activated in HeLa cells after CVB3 infection. The ERK kinase inhibitor, U0126, was then used to inhibit the activity of ERK. Treatment with U0126 led to a significant reduction in the number of autophagosomes indicating that the CVB3-induced autophagosome accumulation may have occurred via the ERK pathway. The relationship between CVB3 infection and ERK pathway activation was also investigated. The results showed that the RasGAP protein could be further cleaved, leading to the activation of the Ras/Raf/MEK (mitogen/extracellular signal-regulated kinase)/ERK pathway and that CVB3 infection could result in an increase in the concentration of calcium in the cytoplasm, resulting in mitochondrial damage, a decrease in the concentration of ATP and activation of the AMPK (AMP-activated protein kinase)/MEK/ERK pathway. In summary, CVB3 might directly or indirectly induce autophagy via AMPK/MEK/ERK and Ras/Raf/MEK/ERK signaling pathways in the host cells, representing a pivotal mechanism for CVB3 pathogenesis.     

Resveratrol improves sperm parameter and testicular apoptosis in cisplatin-treated rats: Effects on ERK1/2, JNK,and Akt pathways

This study aimed to investigate the protective role of resveratrol (RES) against cisplatin (Cis)-induced testicular damage and reproductive dysfunction in rats and to examine the underlying mechanisms of protection including its effect on endoplasmic reticulum (ER) stress, P53, extracellular signal-regulated kinase (ERK)-1/2, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), and Protein kinase B (Akt) signaling. Eight-week-old Rats were divided into four groups (n = 12 each) of 1) control group: received normal saline (i.p.) as vehicle for 45 days, 2) RES-treated group: received RES (20 mg/kg, i.p) for 45 days, 3) Cis-treated group: received Cis (3 mg/kg) for 3 days and then continued on normal saline, and 4) Cis + RES-treated group: received Cis for the first 3 days and then continued on RES for the next 45 days. Serum sex hormones levels, sperm parameters, and levels of testicular antioxidant potential and inflammatory mediators were assessed in all rats. In addition, activation of ER stress, P53, ERK1/2, JNK, and Akt and markers of apoptosis were evaluated in rats’ testis. Cis lowered sperm count and motility and increased sperm morphological abnormalities. Testis of Cis-treated rats had low expression of antioxidant enzymes including SOD, CAT, and GPx and decreased the level of GSH. Concomitantly, Cis upregulated levels of cleaved caspase-3, P53, calpain-1/cleaved caspase-12, p-ERK1/2, and p-SAPK/p-JNK. However, RES administration post-Cis administration restored all sperm parameters and prevented testicular apoptosis mediated by inhibition of all above-mentioned apoptotic pathways. Moreover, RES enhanced testosterone, FSH, and LH levels and upregulated p-Akt/p-Bad levels in both control and Cis-treated rats. In conclusion, RES protects against Cis-induced testicular damage and reproductive dysfunction via improving testosterone levels, increasing sperm count, reducing testicular apoptosis via an antioxidant potential, inhibition of ER stress, P53, ERK1/2, JNK, and activation of Akt.

Abbreviations: RES: resveratrol, Cis: cisplatin; ER: endoplasmic reticulum; ERK1/2: extracellular signal-regulated kinase1/2; SAPK/JNK: stress-activated protein kinase/c-Jun N-terminal kinase; Akt: protein kinase B; HPG axis: hypothalamic-pituitary-gonadal axis; PUFAs: polyunsaturated fatty acids; FSH: Follicular stimulating hormone; LH: Luteinizing hormone; PBS: phosphate buffered saline; GSH: reduced glutathione; GSSG: glutathione disulfide; TNF-α: tumor necrosis factor-α; IL-6: interleukin-6; GRx: glutathione reductase; SOD: superoxide dismutase; CAT: catalase; 4HNE: 4-hydroxynonenal.     

Influence of quercetin and rutin on growth and antioxidant defense system of a human hepatoma cell line (HepG2)

Summary Background Dietary polyphenols like quercetin and rutin are considered beneficial because of their potential protective role in the pathogenesis of multiple diseases associated to oxidative stress such as cancer, coronary heart disease and atherosclerosis. However, many of these effects may depend on the concentration of the polyphenol utilized since high doses of some phenolic compounds may be prooxidant and negatively affect cell growth and viability. Aim of the study To test the potential chemoprotective effects of quercetin and rutin, two flavonols with high antioxidant capacity, on cell growth, viability and the response of the antioxidant defense system of a human hepatoma cell line (HepG2). Methods Cell growth was measured by diaminobenzoic acid and bromodeoxyuridine assays, cell toxicity by lactate dehydrogenase leakage assay, reduced glutathione was quantified by a fluorimetric assay, cellular malondialdehyde was analyzed by high–performance liquid chromatography, reactive oxygen species were quantified by the dichlorofluorescein assay, antioxidant enzyme activities were determined by spectrophotometric analysis and their gene expression by northern blot. Results Short-term exposure (4 h) to these flavonols had no antiproliferative nor cytotoxic effect. High doses of quercetin (50–100 μM) increased glutathione concentration and gene expression of Cu/Zn superoxide dismutase and catalase inhibiting the activity of the latter enzyme, whereas lower doses (0.1–1 μM) decreased gene expression of Cu/Zn superoxide dismutase and increased that of glutathione peroxidase. All doses of quercetin and rutin diminished reactive oxygen species and high doses (10–100 μM) decreased malondialdehyde concentration. Conclusion The results indicate that both natural antioxidants induce favorable changes in the antioxidant defense system of cultured HepG2 that prevent or delay conditions which favor cellular oxidative stress.     

Effects of soy isoflavones on apoptosis induction and G2-M arrest in human hepatoma cells involvement of caspase-3 activation,Bcl-2 and Bcl-XL downregulation,and Cdc2 kinase activity

Genistein, biochanin-A, and daidzein, the predominant soy isoflavones, have been reported to lower the risk of cancer, but it is not known whether they protect against human hepatoma cancer. This study was designed to investigate their effects on cell growth, the cell cycle, and apoptosis induction in the human hepatoma cell lines, HepG2, Hep3B, Huh7, PLC, and HA22T. Genistein, biochanin-A, and daidzein inhibited growth of all five lines in a dose-dependent manner. DNA fragmentation studies and the TUNEL assay demonstrated that isoflavones caused tumor cell death by induction of apoptosis. Activation of caspase-3 and cleavage of the caspase-3 substrate, poly(ADP-ribose)polymerase, was seen in hepatoma cells after 24 hours' exposure to isoflavones. In addition, isoflavone cytotoxicity correlated with downregulation of Bcl-2 and Bcl-XL expression. Synergistic effects of the three isoflavones were observed on cell growth inhibition, apoptosis induction, and anti-apoptotic protein expression. Flow cytometry showed that genistein, but not biochanin-A or daidzein, induced progressive and sustained accumulation of hepatoma cancer cells in the G2/M phase as a result of inhibition of Cdc2 kinase activity. Coapplication of caffeine prevented this cell cycle arrest, but not apoptosis, showing that cell cycle arrest was not necessary for apoptosis. Furthermore, the isoflavones combination also had a significant tumor-suppressive effect in nude mice. These results suggest that isoflavones might be promising agents for the treatment of human hepatoma.     

茶多酚联合原花青素改善AD大鼠记忆作用及机制

  目的  探讨三七皂苷Rg1（NRg1）对大鼠肾缺血再灌注损伤（RIRI）的保护作用及其对氧化应激水平和外周血Th1/Th2细胞因子的调节作用。  方法  健康雄性SD大鼠60只,随机分为假手术组、模型组及NRg1 2.5、5.0、10.0 mg/kg组,每组12只;建立RIRI模型再灌注后24 h后处死大鼠,检测尿蛋白及血清肌酐和尿素氮含量,苏木精 – 伊红（HE）染色和末端脱氧核苷酸转移酶介导的dUTP缺口末端标记测定法（TUNEL）染色检测各组大鼠肾脏组织病理损伤和细胞凋亡,酶联免疫吸附实验（ELISA）检测超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GSH-Px）含量,蛋白印迹法检测凋亡相关蛋白B细胞淋巴瘤因子2（Bcl-2）和Bcl-2相关X蛋白（Bax）的表达及核转录相关因子2（Nrf2）、谷胱甘肽 – S – 转移酶（GST）和醌氧化还原酶1（NQO1）的表达,流式细胞仪检测外周血中Th1（iNOS⁺）和Th2（IL-10⁺）细胞因子的含量。  结果  与模型组比较,NRg1 2.5、5.0、10.0 mg/kg组大鼠尿蛋白含量[分别为（34.1 ± 6.3）、（25.2 ± 4.5）、（11.7 ± 3.4）mg/24 h]均减少、血清肌酐含量[分别为（1.04 ± 0.15）、（0.84 ± 0.09）、（0.62 ± 0.12）mg/dL]均减少、尿素氮含量[分别为（28.6 ± 4.6）、（19.4 ± 3.4）、（15.2 ± 3.2）mg/dL]均减少、肾脏细胞凋亡率[分别为（43.6 ± 7.5）%、（32.4 ± 8.1）%、（11.7 ± 6.3）%]均降低、Bcl-2蛋白表达[分别为（0.12 ± 0.03）、（0.07 ± 0.02）、（0.04 ± 0.01）]均减少、Bax蛋白表达[分别为（0.06 ± 0.03）、（0.09 ± 0.04）、（0.16 ± 0.04）]均增加、GSH-Px含量[分别为（55.29 ± 9.31）、（80.14 ± 11.58）、（106.41 ± 14.16）U/mL]均增加、SOD含量[分别为（0.71 ± 0.13）、（1.26 ± 0.15）、（1.50 ± 0.23）U/mL]均增加、Nrf2蛋白表达[分别为（0.04 ± 0.03）、（0.10 ± 0.04）、（0.18 ± 0.05）]均增加、GST蛋白表达[分别为（0.07 ± 0.02）、（0.14 ± 0.03）、（0.22 ± 0.06）]均增加、NQO1蛋白表达[分别为（0.04 ± 0.02）、（0.09 ± 0.04）、（0.14 ± 0.05）]均增加、Th1（iNOS⁺）含量[分别为（9.13 ± 1.05）%、（5.26 ± 0.84）%、（2.63 ± 0.61）%]均减少、Th2（IL-10⁺）含量[分别为（0.92 ± 0.34）%、（2.93 ± 0.57）%、（4.41 ± 0.62）%]均增加（均P < 0.01）。  结论  NRg1能通过减轻氧化应激水平和炎性损伤,改善大鼠肾缺血再灌注造成的损伤。     

Low-dose of ionizing radiation enhances cell proliferation via transient ERK1/2 and p38 activation in normal human lung fibroblasts

This study shows the human cellular responses and the mechanism of low-dose ionizing radiation in CCD 18 Lu cells, which are derived from normal human lung fibroblasts. Cell proliferation and viability assay were measured for the cells following gamma-irradiation using trypan blue, BrdU incorporation, and Wst-1 assay. We also examined genotoxicity using a micronuclei formation assay. The activation of the MAPKs pathway was determined by Western blot analysis, and the siRNA system was used to inhibit the expression of ERK1/2 and p38. We found that 0.05 Gy of ionizing radiation stimulated cell proliferation and did not change Micronuclei frequencies. In addition, 0.05 Gy of ionizing radiation activated ERK1/2 and p38, but did not activate JNK1/2 in cells. A specific ERK1/2 inhibitor, U0126, decreased the phosphorylation of ERK1/2 proteins induced by 0.05 Gy of ionizing radiation, and a similar suppressive effect was observed with a p38 inhibitor, PD169316. Suppression of ERK1/2 and p38 phosphorylation with these inhibitors decreased cell proliferation, which was stimulated by 0.05 Gy of ionizing radiation. Furthermore, downregulation of ERK1/2 and p38 expression using siRNA blocked the cell proliferation that had been increased by 0.05 Gy of ionizing radiation. These results suggest that 0.05 Gy of ionizing radiation enhances cell proliferation through the activation of ERK1/2 and p38 in normal human lung fibroblasts.     

Cyanidin-3-O-beta-glucopyranoside, a natural free-radical scavenger against aflatoxin B1- and ochratoxin A-induced cell damage in a human hepatoma cell line (Hep G2) and a human colonic adenocarcinoma cell line (CaCo-2)

Recent findings have suggested that oxidative damage might contribute to the cytotoxicity and carcinogenicity of aflatoxin B1 (AFB1). Induction of oxidative stress also plays an important role in the toxicity of another mycotoxin, ochratoxin A (OTA). In the present study, the protective effect of cyanidin-3-O-beta-glucopyranoside (C-3-G; an anthocyanin contained in oranges, blackberries, strawberries and cranberries) against AFB1- and OTA-induced cytotoxicity was investigated in a human hepatoma-derived cell line (Hep G2) and a human colonic adenocarcinoma cell line (CaCo-2). The ability of C-3-G to reduce the production of reactive oxygen species (ROS), the inhibition of protein and DNA synthesis and the apoptosis caused by the two mycotoxins was also investigated in both cell lines. Our experiments proved the significant cytoprotective effect of C-3-G in vitro against OTA- and AFB1-induced cell damage. In particular, 24 h of pretreatment with 50 microm-C-3-G inhibited the cytotoxicity of 10 microm-AFB1 (by 35 %) and of 10 microm-OTA (by 25 %) in Hep G2 cells (P < 0.001) and of 10 microm-AFB1 (by 10 %, P < 0.01) and of 10 microm-OTA (by 14 %, P < 0.05) in CaCo-2 cells. Moreover, 50 microm-C-3-G attenuated ROS production induced by the two toxins in both cell lines (P < 0.05). Inhibition of DNA and protein synthesis induced by the mycotoxins was counteracted by pretreatment with the antioxidant at 50 microm. Similarly, apoptotic cell death was prevented as demonstrated by a reduction of DNA fragmentation and inhibition of caspase-3 activation. The in vitro free-radical scavenging capacity of the anthocyanin was tested with the Briggs-Rauscher oscillating reaction. This system works at pH approximately 2. The results showed good scavenging power, in accordance with the observed inhibition of ROS production.     

Enhancement of glutathione and g-glutamylcysteine synthetase,the rate limiting enzyme of glutathione synthesis,by chemoprotective plant-derived food and beverage components in the human hepatoma cell line HepG2

Glutathione (GSH) is an important antioxidant and cofactor of detoxifying metabolism. Therefore, elevation of GSH as achieved by inducing g-glutamylcysteine synthetase (GCS), the limiting enzyme of GSH synthesis, may contribute to chemoprevention against cancer. In previous animal studies, increases in GCS were mainly found in liver and other organs that are not easily accessible in humans. Thus, employment and evaluation of alternative systems such as human-derived cell lines are encouraged. In the present experiment, we used the hepatoma cell line HepG2 to investigate the response of GCS and GSH to five plant-derived chemoprotectants contained in regularly consumed foodstuffs and beverages (kahweol/cafestol [K/C] [15.5-62.0 mM], a-angelicalactone [100-400 mM], benzyl isothiocyanate [1.7-5.0 mM], diallyl sulfide [175-700 mM], and quercetin [10-50 mM]). All treatments led to dose-dependent increases in both GCS activity and GSH concentration. Time course studies with K/C indicated that the enhancement of GCS preceded that of GSH, suggesting a causal relationship. K/C did not enhance g-glutamyl transpeptidase, a further enzyme that assists GSH-related chemoprotection. Although GCS induction has been suggested to require an initial short-lived GSH depletion, we did not find any decrease in GSH after 3 h of incubation with K/C. In summary, HepG2 cells were shown to be a useful model to investigate the capacity of potential chemoprotectants to enhance GCS and GSH. To our knowledge, the present study is also the first to show increases in GCS by K/C and a-angelicalactone in vitro and by diallyl sulfide and quercetin in any system.     

Chromium VI-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and a lymphoblastic leukemia cell line (MOLT-4)

Hexavalent chromium compounds are well-documented human carcinogens. In vitro experiments show Cr (VI) induces cell death by apoptosis by activating p53 protein. The aim of this study was to evaluate Cr (VI)-induced apoptosis in a human bronchial epithelial cell line (BEAS-2B) and in a lymphoblastic leukemia cell line (MOLT-4). Cr (VI) caused a dose- and time-dependent increase in the apoptosis rate in both cell lines. Western blotting showed increased p53 protein expression in MOLT-4 cells, but not in BEAS-2B cells, after exposure to 0.5 and 3 muM hexavalent chromium for 12 hours and 4 hours, respectively. Apoptotic cell death induced by Cr (VI) was not decreased by pretreatment with caspase-3, -8, and -9 inhibitors. These preliminary results provide evidence of Cr (VI)-induced apoptosis, which deserves further investigation in occupationally exposed workers.     

氢醌对人白血病细胞凋亡及相关蛋白Bcl-2、Bax及Caspase-3表达的影响

目的 研究氢醌对白血病细胞株U937细胞凋亡及相关蛋白Bcl-2、Bax及Caspase-3表达的影响。方法 用不同浓度的氢醌处理U937细胞24 h、48 h后,采用MTT法来检测细胞增殖抑制率;经瑞-吉染色后,观察细胞形态变化;采用流式细胞仪检测细胞凋亡;采用免疫印迹法检测Bcl-2、Bax及Caspase-3蛋白表达。结果 (1)U937细胞的增殖抑制率随氢醌作用时间及浓度的增加而增加,呈时间-剂量依赖性(P<0.05);(2)氢醌作用后,部分细胞体积增大,胞浆中有空泡,胞核发生畸形;(3)流式细胞术结果显示,细胞凋亡率随着氢醌作用时间及浓度的增加而增加,呈时间-剂量依赖性(P<0.05);(4)免疫印迹结果显示,与空白组相比较,染毒48h时,细胞Bax蛋白的表达量增加(P<0.05),而Bcl-2蛋白表达量减少(P<0.05),Bcl-2/Bax比值下降(P<0.05),染毒24 h时,细胞Caspase-3蛋白的表达量增加(P<0.05);与染毒24 h各组相比较,染毒48 h时细胞Caspase-3蛋白的表达量随时间延长呈增加趋势(P<0.05)。结论 氢醌可以诱导U937细胞凋亡,其机制可能与调控凋亡相关蛋白Bcl-2、Bax及Caspase-3的表达有关。     

ERK和JNK/活化蛋白-1通路在苯并(a)芘诱导人胚肺成纤维细胞周期改变中的作用

目的探讨丝裂原活化蛋白激酶(MAPK)/转录因子活化蛋白-1(AP-1)信号通路在调控苯并(a)芘[B(a)P]致人胚肺成纤维细胞(HELF)周期改变中的作用。方法用AP-1荧光素酶报告基因技术检测AP-1荧光素酶活力,流式细胞术测定细胞周期时相分布,免疫印迹法检测MAPK[包括细胞外调节蛋白激酶(ERK)、c-Jun氨基末端激酶(JNK)和p38激酶]总量及磷酸化水平,用MAPK显性失活突变体(DN)(DN-ERK2、DN-JNK1和DN-p38)证明通路的上下游关系。结果2μmol/L B(a)P分别处理细胞0、6、122、4 h,AP-1活力在12 h达峰值,是对照组的2.22倍,差异有统计学意义(P<0.05);ERK1/2、JNK1/2和p38蛋白激酶的磷酸化水平明显提高,分别是对照组的2.5、14.0和2.1倍;B(a)P处理组S期细胞比例(50.2%±4.6%)与对照组(16.7%±8.1%)相比明显增加,差异有统计学意义(P<0.01);ERK2和JNK1显性失活突变体的过表达均可明显降低B(a)P诱导的AP-1活力增强,并且明显降低B(a)P处理组S期细胞比例(分别为33.3%±1.7%,30.8%±3.9%),差异均有统计学意义(P<0.05);p38显性失活突变体的过表达对B(a)P引起的AP-1活力增强及S期细胞比例增加无影响。AP-1化学抑制剂姜黄素(20μmol/L)可明显降低B(a)P引起的S期细胞比例增加(13.6%±2.9%),差异均有统计学意义(P<0.05)。结论ERK和JNK通过活化AP-1介导B(a)P诱导的细胞周期改变;而B(a)P诱导的AP-1活力增强及细胞周期改变与p38无关。     

阴道超声辐照后人胚绒毛滋养细胞凋亡及Bcl-2蛋白和Caspase-3蛋白表达的研究

目的:探讨阴道超声辐照对人胚绒毛滋养细胞凋亡的影响及其可逆性,同时探索Bcl-2蛋白及活化Caspase-3蛋白在滋养细胞凋亡中的作用。方法:选取符合条件的患者50例,随机分为5组,每组10例。4组实验组患者经阴道超声持续辐照10 min后分别于第1、3、5、7天行人工流产收集绒毛标本,第5组为对照组。采用TUNEL法检测各组绒毛滋养细胞的凋亡指数;同时采用免疫组化SABC法检测相应绒毛滋养细胞中Bcl-2蛋白及活化Caspase-3蛋白的表达水平。结果:阴道超声辐照对滋养细胞凋亡有影响。经阴道超声辐照10 min后,1天人胚绒毛滋养细胞的凋亡指数最高、Bcl-2蛋白的表达量最少、Caspase-3蛋白的表达量最多;随着取胚时间延长,凋亡指数逐渐下降、Bcl-2蛋白表达量逐渐增加、Caspase-3蛋白表达量逐渐减少;凋亡指数、Bcl-2蛋白及Caspase-3蛋白表达量分别于辐照后第5天、第3天、第5天开始与对照组比较差异无统计学意义(P>0.05)。结论:阴道超声辐照10 min可致人胚绒毛滋养细胞凋亡增加,但该改变呈近期可逆性。Bcl-2蛋白和活化Caspase-3蛋白在滋养细胞凋亡中起着重要作用。     

碱性成纤维细胞生长因子对卵巢癌的影响

目的观察Ras-Raf-ERK 1/2途径介导的碱性成纤维细胞生长因子(bFGF)对卵巢癌细胞系CAOV3细胞增殖和凋亡影响,探讨bFGF及其信号转导途径与卵巢癌发生发展关系。方法以bFGF和促细胞分裂剂激活性蛋白激酶1(MEK1)抑制剂PD98059处理CAOV3细胞,用四甲基偶氮噻唑蓝(MTT)法检测细胞增殖情况,流式细胞术检测细胞凋亡情况,蛋白印迹(Western blot)检测细胞外信号调节蛋白激酶1/2(ERK1/2)的活性。结果bFGF处理后细胞增殖比明显增加,且与bFGF水平呈剂量依赖关系,bFGF浓度为75 ng/ml时细胞增殖比最高为140%;bFGF使无血清诱导的凋亡细胞比例下降[(33.20±5.32)%~(2.38±3.36)%];bFGF诱导ERK1/2活性增高。PD98059可抑制bFGF的这些作用。结论bFGF通过Ras-Raf-ERK 1/2途径介导,促进卵巢癌CAOV3细胞增殖,抵抗无血清诱导凋亡。在卵巢癌发生发展过程中,bFGF信号传递发挥了重要作用。     

氟化钠对人成骨肉瘤Saos-2细胞PI3K/Akt信号表达及凋亡的影响

目的观察氟化钠(NaF)对人成骨肉瘤Saos-2细胞磷脂酰肌醇-3-激酶/蛋白激酶B(PI3K/Akt)信号表达及凋亡的影响。方法采用成组设计,按NaF剂量将Saos-2细胞分为0(对照)、5、10、20、40 mg/L染氟组(n=3)。体外培养24、48 h后收集细胞,采用蛋白免疫印迹(Western blot)法检测PI3K、Akt和线粒体凋亡途径相关分子Forkhead转录因子(FoxO)1的蛋白表达,采用流式细胞仪检测Saos-2细胞的凋亡水平。结果体外培养24、48 h时,各组Saos-2细胞PI3K、Akt蛋白表达比较,差异均无统计学意义(P均>0.05)。24 h时,5、10、20、40 mg/L染氟组磷酸化PI3K(p-PI3K)蛋白表达(0.40±0.06、0.45±0.02、0.37±0.06、0.32±0.06)均高于对照组(0.28±0.04,P均<0.05);48 h时,5、10 mg/L染氟组p-PI3K蛋白表达(0.46±0.06、0.58±0.03)均高于对照组(0.29±0.04,P均<0.05),而40 mg/L染氟组(0.21±0.03)低于对照组(P<0.05)。24 h时,5、10、20 mg/L染氟组磷酸化Akt(p-Akt)蛋白表达(0.27±0.01、0.30±0.03、0.27±0.03)均高于对照组(0.20±0.02,P均<0.05);48 h时,5、10 mg/L染氟组p-Akt蛋白表达(0.42±0.04、0.60±0.02)均高于对照组(0.27±0.01,P均<0.05),而40 mg/L组(0.18±0.02)低于对照组(P<0.05)。24 h时,10、20、40 mg/L染氟组FoxO1蛋白表达(0.38±0.07、0.41±0.06、0.47±0.08)均高于对照组(0.34±0.04,P均<0.05);48 h时,5、10、20、40 mg/L染氟组FoxO1蛋白表达(0.36±0.08、0.37±0.10、0.54±0.04、0.73±0.04)均高于对照组(0.28±0.04,P均<0.05)。24、48 h时,对照组和5、10、20、40 mg/L染氟组细胞凋亡率分别为(2.867±0.583)%、(3.647±0.035)%、(3.773±0.095)%、(5.440±0.325)%、(7.203±0.476)%,(3.707±0.286)%、(4.023±0.241)%、(4.970±0.368)%、(12.473±0.949)%、(19.387±1.892)%。24 h时,40 mg/L染氟组凋亡水平高于对照组(P<0.05);48 h时,20、40 mg/L染氟组凋亡水平均高于对照组(P均<0.05)。结论氟可以直接激活成骨细胞内的PI3K/Akt信号通路,进而产生抗凋亡作用。     

The antitumor ether lipid edelfosine (ET-18-O-CH3) induces apoptosis in H-ras transformed human breast epithelial cells: by blocking ERK1/2 and p38 mitogen-activated protein kinases as potential targets

We previously reported that a novel alkylphospholipid type antitumor agent edelfosine (ET-18-O-CH3 ; 1-O-octadecyl-2-O-methyl-glycero-3-phosphocholine) induced apoptosis in human breast epithelial cells transfected with the H-ras oncogene (MCF10A-ras) which was causally linked to cyclooxygenase-2 (COX-2) up-regulation and production of 15-deoxy-Delta 12,14-prostaglandins J2 (15d-PGJ2). ET-18-O-CH3 treatment also enhanced the production of prostaglandin E2 (PGE2), a major COX-2 product. In this study, we found that ET-18-O-CH3 treatment resulted in elevated mRNA expression of the PGE2 receptor subunit, EP2 receptor. Exogenously added PGE2 inhibited the growth of MCF10A-ras cells and induced proteolytic cleavage of caspase 3. ET-18-O-CH3 also inhibited constitutive activation of ERK1/2, p38 MAPK, and Akt/protein kinase B, which was blunted by a selective COX-2 inhibitor SC58635. In addition, ET-18-O-CH3 inhibited DNA binding activity of NF-kappa B in MCF10A-ras cells, and this was again attenuated by SC58635. Based on these findings, it is likely that ET-18-O-CH3 inactivates ERK1/2, Akt, and NF-kappaB signaling via COX-2 induction in MCF10A-ras cells, thereby inducing apoptosis of these cells.     

Incorporation of branched-chain fatty acid into cellular lipids and caspase-independent apoptosis in human breast cancer cell line,SKBR-3

Background  

13-Methyltetradecanoic acid (13-MTD), an iso-C15 branched- chain saturated fatty acid, has been shown to induce apoptotic cell death of numerous human cancer cells. However, the mechanism for the induction of apoptosis has not been fully understood. This study described the incorporation of 13-MTD into cellular lipid of SKBR-3 breast cancer cells and apoptosis related event to gain more insight into the mechanism action of this fatty acid.