曲格列酮诱导人心肌细胞氧化应激和自噬的作用

目的研究曲格列酮的心肌细胞毒性特征,并从线粒体氧化应激和自噬角度探讨其潜在的毒作用机制。方法人源心肌细胞AC16给予不同浓度曲格列酮0~40μmol·L^-1孵育24 h。倒置显微镜观察细胞形态,CCK-8法检测细胞存活率,漏出法检测乳酸脱氢酶(LDH)释放量;荧光探针TMRM检测线粒体膜电位和CM-H2DCFDA检测全细胞活性氧的含量;Western印迹法检测微管相关蛋白Ⅱ/Ⅰ轻链3(LC3-Ⅱ/LC3-Ⅰ)比值和P62蛋白表达水平。结果与细胞对照组相比,曲格列酮可浓度依赖性地引起细胞质皱缩、细胞存活率下降(r=-0.928,P<0.05)和LDH释放量增加(r=0.746,P<0.05);曲格列酮10和20μmol·L^-1可明显降低细胞线粒体膜电位(P<0.05),增加全细胞活性氧含量(P<0.05);显著增加LC3-Ⅱ/LC3-Ⅰ比值,上调P62蛋白表达(P<0.05)。结论曲格列酮可引起心肌细胞损伤和线粒体功能障碍,其机制与线粒体氧化应激和自噬体降解受阻密切相关。     

Inhibition of autophagy increases apoptosis during re‐warming after cold storage in renal tubular epithelial cells

Prolonged cold storage and re‐warming (CS/REW) of kidneys are risk factors for delayed graft function (DGF). Studies in renal tubular epithelial cells (RTECs) have determined apoptosis and autophagy in models of either cold storage (CS) or re‐warming alone. The effect of both cold storage and re‐warming on apoptosis and autophagy, in RTECS is not known and is relevant to DGF as the kidney is subjected to both CS and re‐warming. We hypothesized that CS/REW of RTECs would induce autophagy that protects against apoptosis. In CS/REW, there was increased autophagic flux of RTECs. Autophagy inhibition using an Atg5 siRNA resulted in increased cleaved caspase‐3 and increased apoptotic cells (on both morphology and annexin V staining) during CS/REW. The effect of autophagy inhibition on necrosis in RTECs is unknown. There were increased necrosis and caspase‐1, a mediator of necrosis, during CS/REW, and the Atg5 siRNA had no effect on necrosis and caspase‐1. In a kidney transplant model, there was an increase in LC3 II, a marker of autophagy, in kidneys transplanted after cold storage. In summary, autophagic flux is increased during CS/REW. Autophagy inhibition resulted in increased cleaved caspase‐3 and increased apoptosis during CS/REW without an effect on necrosis or caspase‐1. In conclusion, autophagy inhibition in RTECs after CS/REW induces apoptotic cell death and may be deleterious as a therapy to decrease DGF.     

自噬抑制剂在内质网应激状态下对肝癌HepG2细胞和正常肝细胞L-02作用的差异

目的：研究自噬在内质网应激( ERS)状态下对肝癌HepG2细胞和正常肝细胞L-02作用的差异。方法体外常规培养的人肝癌HepG2细胞和正常肝细胞L-02,分别给予衣霉素( TM)单药和TM联合自噬抑制剂3-甲基腺嘌呤( TM+3-MA)或氯喹( TM+CQ)作用12、24、48 h后,采用噻唑蓝( MTT)法检测细胞活力变化,流式细胞术检测细胞凋亡率, Western blot法检测自噬蛋白LC3的变化。结果 TM可引起HepG2细胞和L-02细胞死亡并呈时间依赖关系,3-MA或CQ均可增加TM对HepG2细胞的生长抑制作用,24 h细胞存活率分别为TM+3-MA组(60%)、TM+CQ组(72%)、TM组(86%),差异有统计学意义(P<0．01);但对于L-02细胞,其存活率分别为83%、84%、83%,活力没有明显差异;流式细胞术显示TM+3-MA、TM+CQ和TM组对HepG2细胞的凋亡率分别为15%、11%、7%,差异有统计学意义( P<0．01),但对L-02细胞,凋亡率分别为16%、17%、16%,未见明显差异;Western blot法结果显示TM作用引起两种细胞自噬增加,自噬抑制剂3-MA与CQ可引起两种细胞自噬作用减弱。结论自噬抑制剂(3-MA 或 CQ)均可显著增加TM对肝癌HepG2细胞的生长抑制作用,但对正常肝细胞L-02的生长抑制作用差异无统计学意义。自噬在ERS状态下可对肝癌细胞的生存提供保护,但对正常肝细胞无保护作用。     

MiR-218 inhibits HMGB1-mediated autophagy in endometrial carcinoma cells during chemotherapy

Endometrial carcinoma is the most common gynecological malignancy among women worldwide. Although treatment for EC has improved with the introduction of Paclitaxel (Tax) chemotherapy, the majority of patients will develop resistance to the treatment, leading to poor prognosis. One of the causes of chemoresistance is the increased ability to undergo autophagy. In this study, we identified that miR-218 was significantly down-regulated in Tax-resistant EC cells compared to the non-drug resistant cell lines, and overexpression of miR-218 sensitized paclitaxel resistant EC cells to paclitaxel. Moreover, we demonstrated that miR-218 directly binds to the 3’-UTR of HMGB1 gene. HMGB1 was upregulated in paclitaxel resistant EC cells, it mediated autophagy and contributed to chemotherapy resistance in endometrial carcinoma in vitro. HMGB1-mediated autophagy could be suppressed by miR-218 overexpression in Tax resistant EC cells. In summary, we determined the targeting role of miR-218 to HMGB1 and the regulation of miR-218 on the HMGB1-mediated cell autophagy during chemotherapy resistance in endometrial carcinoma cells. These results reveal novel potential role of miR-218 against chemotherapy resistance during the treatment of endometrial carcinoma.     

Upregulation of cell surface estrogen receptor alpha is associated with the mitogen-activated protein kinase/extracellular signal-regulated kinase activity and promotes autophagy maturation

Recently, accumulating evidence has implicated the dysregulation of autophagy as underlying the pathophysiology of several neurodegenerative diseases. The human neuronal cell line SH-SY5Y was exposed to 1-Methyl-4-phenylpyridinium (MPP⁺). The mechanism is that the sustained activation of the MAPK/ERK pathway by MPP⁺ alters autophagy selectively at the maturation step, significant increasing in autophagy formation and delaying in autophagy degradation in SHSY5Y cells. In this study, we provided evidences that estrogen was capable of promoting SHSY5Y cells survival in MPP⁺-treated group. In particular, the up-regulation of mERα, but not mERβ, was associated with a rapid and transient activation of ERK phosphorylation compatible with promoting autophagy maturation. The up-regulation of mERα changed the sustained activation of ERK phosphorylation in MPP⁺-treated group into a temporary activation. Taken together, these findings strongly support that the expression of mERα promotes the maturation of autophagosomes into functional autolysosomes by regulating ERK, determining SHSY5Y cells survival.     

Paeoniflorin protects HUVECs from AGE-BSA-induced injury via an autophagic pathway by acting on the RAGE

The aim of our study was to investigate the protective effects of Paeoniflorin (PF) against injury induced by AGE-modified bovine serum albumin (AGE-BSA) in human umbilical vein endothelial cells (HUVECs), and to examine the underlying mechanisms of these effects. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to determine cell viability. Protein expression levels were determined by western blotting. For function-blocking experiments, we used small interfering RNA molecules (siRNA) for function-blocking experiments. At 6 h, we found that 100 μg/mL AGE-BSA reduced the viability of HUVECs. However, pretreatment with PF restored cell viability in a dose-dependent manner. AGE-BSA increased the levels of microtubule-associated protein light chain 3-II (LC3-II) and the receptor for advanced glycation end products (RAGE). Expression of p62 protein was also increased, but not at a statistically significant level. Pretreatment with PF further increased levels of LC3-II and RAGE, but reduced the expression of p62. In cells transfected with Atg5 and RAGE siRNA, cell viability and expression of LC3-II decreased in both the AGE-BSA and PF + AGE-BSA treatments. PF can protect HUVECs from AGE-BSA-induced injury by upregulating autophagy and promoting the completion of autophagy flux. RAGE plays an important role in this autophagic protection effect.     

The role of C/EBP-α expression in human liver and liver fibrosis and its relationship with autophagy

Aim: To investigate the expression of CCAAT enhancer binding protein-α (C/EBP-α) in normal human liver and liver fibrosis and its probable association with autophagy. Methods: Double label immunohistochemistry was used to detect the location of C/EBP-α in hepatocytes and hepatic stellate cells (HSCs). The expression of C/EBP-α, Atg5, and Atg6 was also evaluated by immunohistochemistry in paraffin sections of human liver. HSC-T6 cells were treated with rapamycin and 3-methyladenine (3MA) to induce or inhibit autophagy, and the expression of C/EBP-α protein was detected by Western blotting. Results: Double label immunohistochemistry showed that C/EBP-α was predominantly located in hepatocytes and that its expression was significantly decreased in fibrosis compared with normal liver. Atg5 expression was increased in fibrosis but was located primarily in liver septa and peri-vascular areas, which was consistent with the distribution of HSCs. In contrast, Atg6 was not expressed in normal or fibrotic liver. Treatment of HSC-T6 cells in culture with rapamycin or 3MA decreased or increased C/EBP-α expression, respectively, as shown by Western blotting. Conclusion: C/EBP-α was primarily expressed in hepatocytes in normal liver, but its expression decreased significantly in liver fibrosis. Autophagy might play a role in liver fibrosis through its association with C/EBP-α, but this hypothesis warrants further investigation.     

Beclin 1 and p62 expression in non-small cell lung cancer: relation with malignant behaviors and clinical outcome

Autophagy plays a complicated role in tumorigenesis in a variety of cancers. Recently, many studies report that some autophagy-related markers could be detected in several types of human tumors. However, fewer studies have been conducted to evaluate the relationship between autophagy and lung cancer, especially in non-small cell lung cancer (NSCLC). In this study, the expression levels of autophagy-related markers Beclin 1 and p62 were detected by Western blot analysis and cell immunofluorescence staining in three human NSCLC cell lines A549, H1299 and HCC827. Then, tissue microarray and immunohistochemical staining were used to determine Beclin 1 and p62 expression in 104 NSCLC specimens collected from patients. Beclin 1 and p62 were observed to primarily distribute in the cytoplasm of the cells. Beclin 1 was expressed more predominantly in male and heavy-smoker and its expression was significantly correlated with the differentiation and lymph node metastasis. p62 expression was negatively correlated with TNM stage and lymph node metastasis. Univariate Cox regression analysis revealed that low expression of Beclin 1 and high expression of p62 were significantly associated with shorter survival. Meanwhile, multivariate Cox regression analysis indicated that Beclin 1 and p62 were independent risk factors related to overall survival for patients with NSCLC. Collectively, our study suggests that Beclin 1 and p62 could serve as potential indicators for the prognosis of patients with NSCLC.     

茶多酚对卵巢癌SKOV3细胞自噬水平的影响及相关机制研究

目的研究茶多酚(EGCG)对人卵巢癌SKOV3细胞自噬水平的影响及相关机制。方法用EGCG处理SKOV3细胞,Western blot检测自噬相关蛋白LC3-II及蛋白激酶B(PKB)信号通路相应蛋白表达变化。结果 EGCG处理SKOV3细胞后,自噬相关蛋白LC3-II表达上调,并呈一定的时间浓度依赖性。EGCG处理SKOV3细胞后,AKT的磷酸化水平下调,AKT激活剂胰岛素样生长因子1(IGF-1)预处理后,自噬相关蛋白LC3-II高表达被抑制。结论 EGCG通过AKT介导的信号通路诱导SKOV3细胞自噬水平升高。