自噬的特异性抑制对肝癌细胞凋亡的调控及其相关机制

目的:研究自噬特异性抑制剂3-甲基腺嘌呤(3-methyladenine,3-MA)对奥沙利铂(oxaliplatin,OX)诱导的肝癌细胞系HepG2存活率的影响,并探讨其机制。方法:MDC与DAPI双重染色后,采用荧光显微镜对自噬进行定性观察;以CCK8检测3-MA抑制剂自噬前后,经OX诱导的HepG2细胞存活率;并用RT-PCR检测自噬特异性基因LC3表达的变化,以Western印迹法分别检测自噬特异性蛋白LC3及凋亡活化蛋白Caspase-3的变化。结果:OX可诱导肝癌细胞HepG2产生自噬,且自噬在基因及蛋白水平的表达均增加;3-MA与OX联合作用可明显增强HepG2细胞的凋亡。结论:OX诱导肝癌细胞系HepG2凋亡的过程中自噬起到保护性作用;抑制自噬可明显增强OX诱导的HepG2细胞凋亡。3-MA可能为提高肝癌对化疗敏感性提供新思路。     

索拉菲尼对肝细胞癌凋亡和自噬相关蛋白表达的影响及耐药分析

目的:分析索拉菲尼对肝细胞癌凋亡及自噬相关蛋白表达的影响,及肝细胞癌对其耐药的机制.方法:常规培养人肝癌SMMC-7721细胞,以1.25、2.5、5、10、20μmol/L索拉菲尼处理细胞,观察其对细胞增殖的影响.观察索拉菲尼和自噬抑制剂3-甲基腺嘌呤(3-MA)对细胞凋亡和自噬,及其相关蛋白表达的影响.结果:随着索...     

急性缺血缺氧诱导肝癌细胞自噬及其相关机制

目的:研究急性缺血/缺氧时肝癌细胞HepG2增殖率及自噬的变化,探讨自噬的作用及机制。方法 :以Western印迹法检测缺氧诱导因子-1(hypoxia induced factor-1,HIF-1)表达并确定体外模拟模型的可靠性;吖啶橙染色后采用荧光显微镜定性观察自噬;以自噬特异性蛋白LC3及P62(P62/SQSTM1)信号蛋白的变化表明自噬的诱导和可能的调控机制;以CCK8检测3-甲基腺嘌呤(3-MA)抑制自噬前后急性缺血/缺氧下HepG2细胞的增殖率变化。结果:急性缺血/缺氧2 h后,HepG2细胞显著表达HIF-1α蛋白,表明体外急性缺血/缺氧模型的可靠性。急性缺血/缺氧可快速诱导肝癌细胞HepG2产生自噬,继而出现HepG2细胞显著增殖活跃;3-MA抑制自噬后,可特异性抑制急性缺血/缺氧所诱导的HepG2细胞增殖;急性缺血/缺氧条件下HepG2细胞P62信号蛋白表达显著下调,自噬抑制后逐渐恢复正常表达水平。结论:自噬在肝癌体外急性缺血/缺氧过程中对肿瘤起到保护作用,其机制可能与P62蛋白的清除有关;抑制自噬可显著降低肝癌细胞增殖率。自噬可能成为肝癌治疗的新靶点。     

抑制自噬对5-氟尿嘧啶治疗肝癌疗效的影响及机制研究

目的研究自噬特异性抑制剂3-甲基腺嘌呤（3-MA）对5-氟尿嘧啶（5-FU）诱导肝癌细胞系SMMC7721凋亡的影响,并初步探讨其机制。方法利用单丹（磺）酰戊二胺（MDC）染色技术,在荧光显微镜下对细胞自噬进行定性观察;以CCK8法检测3-MA抑制细胞自噬前后经5-FU诱导SMMC7721细胞的存活,凋亡以AnnexinⅤ/PI流式细胞分析法检测;以Western blot法分别检测自噬特异性蛋白LC3及凋亡蛋白caspase-3活化片段和PARP裂解片段的表达。结果 5-FU处理肝癌SMMC7721细胞48 h后,可诱导其发生自噬,细胞存活率为（60.73±2.65）%,凋亡率为（40.42±2.34）%;联合应用3-MA处理48 h后,可使肝癌SMMC7721细胞存活率明显降低（P〈0.01）,为（42.31±1.32）%,而细胞凋亡率显著增加（P〈0.01）,为（60.92±2.99）%,同时引起自噬特异性蛋白LC3-Ⅱ及凋亡蛋白caspase-3活化片段和PARP裂解片段表达增加,其灰度值比较差异均有统计学意义（均P〈0.01）。结论自噬在5-FU诱导肝癌细胞系SMMC7721凋亡过程中起保护性作用,抑制自噬可提高肝癌SMMC7721细胞对5-FU的敏感性,其可能主要通过激活caspase-3及剪切PARP来实现的。因此,自噬特异性抑制剂3-MA可能为提高肝癌对5-FU的敏感性提供新思路。     

3-甲基腺嘌呤促进吡柔比星诱导膀胱癌BIU-87细胞凋亡及机制

目的 探讨3-甲基腺嘌呤(3-MA)自噬抑制剂联合吡柔比星(THP)对膀胱癌BIU-87细胞杀伤作用及机制.方法 膀胱癌BIU-87细胞分为对照组、3-MA(10 mmol/L)组、THP(5 mg/L)组、3-MA(10 mmol/L)+ THP(5 mg/L)组.噻唑蓝(MTT)法检测细胞增殖;流式细胞术检测细胞凋亡;Western blot检测各组细胞中自噬蛋白微管相关蛋白1轻链3(LC3)-Ⅱ、Beclin-1以及凋亡蛋白半胱氨酰天冬氨酸特异性蛋白酶(Caspase)-3和Caspase-9的表达.结果 药物作用24h后,各组细胞增殖率分别为(86.64±3.09)％、(63.70±5.62)％、(58.43±3.89)％、(37.55±4.17)％,其中3-MA+THP组细胞增殖下降最明显(P ＜0.05);3-MA与THP联合应用后,自噬蛋白LC3-Ⅱ、Beclin-1的表达明显减弱,而凋亡蛋白Caspase-3和Caspase-9的表达在各组中最强(P＜0.05).结论 3-MA抑制膀胱癌BIU-87细胞对化疗药物保护性自噬反应,增加膀胱癌细胞对THP细胞毒杀伤作用的敏感性.     

自噬抑制剂3-甲基腺嘌呤对结直肠腺癌细胞生长与Notch1蛋白表的影响

目的：探讨自噬抑制剂3-甲基腺嘌呤（3-MA）对人大肠癌SW480细胞生长与Notch1蛋白表达的影响。方法：将3-MA（5 mmol/L）作用于SW480细胞24 h后（以培养相同时间无处理的SW480细胞为对照）,分别免疫组化和Western blot法检测细胞Notch1蛋白的表达,用CCK-8法和Annexin/PI双染法检测细胞增殖与凋亡。结果：免疫组化与Western blot结果均显示,3-MA作用后,SW480细胞Notch1蛋白的表达明显下调（均P<0.05）;增殖与凋亡检测结果显示,3-MA作用后,SW480细胞增殖率明显降低,而凋亡率明显增加（均P<0.05）。结论： 3-MA能抑制结直肠癌细胞的增殖并促进其凋亡,该作用可能与3-MA抑制Notch1蛋白表达从而改变细胞自噬水平有关。

     

自噬在吉西他滨诱导胰腺癌细胞凋亡中的作用

目的:研究自噬在吉西他滨(gemcitabine,Gem)诱导胰腺癌细胞SW1990凋亡中的作用,并以氯喹特异性抑制自噬,以探讨其可能机制。方法:采用CCK8法检测Gem对胰腺癌细胞增殖的影响,并用实时定量PCR检测自噬相关基因LC3的表达,以p62免疫荧光染色检测细胞内自噬泡,通过Western印迹法检测自噬相关蛋白LC3、Beclin 1的表达,并用AnnexinⅤ/PI流式细胞方法检测Gem诱导后细胞凋亡的变化。进一步通过氯喹抑制自噬,检测自噬抑制前后细胞增殖、自噬及凋亡的变化。结果:Gem对胰腺癌细胞SW1990增殖具有部分抑制作用,Gem作用能迅速激活细胞自噬从而产生耐药。LC3的mRNA表达升高1.4~2.2倍(P<0.05),LC3-Ⅱ蛋白水平升高1.5~2.7倍(P<0.05)。Gem和氯喹联合用药组较Gem单药组细胞凋亡蛋白Caspase-3表达升高,细胞存活率从64.3%±3.1%降低为35.2%±3.4%(P<0.05)。结论:自噬在Gem诱导胰腺癌细胞凋亡的过程中可能起到保护作用,氯喹抑制自噬后可增强Gem的促凋亡作用。     

HO-1对醋酸铅诱导肾小管上皮细胞氧化应激的保护机制

目的:探讨血红素氧合酶-1(HO-1)对醋酸铅(LA)诱导的肾小管上皮细胞损伤的保护机制,为铅性肾病的治疗提供一定的理论依据。方法:采用醋酸铅孵育人肾小管上皮细胞48 h建立细胞损伤模型,原卟啉氯化钴(Co PP)诱导HO-1表达,自噬抑制剂(3-MA)抑制自噬,CCK-8方法检测细胞活性;流式细胞术检测细胞凋亡率; Western blot检测自噬标志蛋白LC3Ⅱ/LC3Ⅰ、p62及氧化应激相关蛋白超氧化物歧化酶(SOD2)、过氧化氢酶(CAT)、丙二醛(MDA)含量。结果:醋酸铅处理48 h后细胞活性、HO-1及自噬水平较Control组均明显下降,在补充Copp激活HO-1后细胞自噬水平上升,细胞活性明显恢复; Copp可明显改善细胞抗氧化酶CAT、SOD2表达,降低MDA,降低细胞凋亡率; 3-MA抑制自噬导致细胞CAT、SOD2表达进一步降低,MDA含量增加,细胞凋亡率升高,并且补充Copp后细胞CAT和MDA水平仅部分改善,SOD2表达未见明显恢复,提示抑制自噬减弱了HO-1的抗氧化作用。结论:HO-1可通过上调自噬减轻醋酸铅诱导的肾小管上皮细胞氧化应激损伤,减少细胞凋亡,HO-1可能可以作为治疗铅性肾病的一个干预靶点。     

AMPK在二甲双胍诱导结肠癌细胞SW480自噬中的作用

目的研究二甲双胍是否影响人结肠癌SW480细胞中AMPK活性,并探讨AMPK在二甲双胍诱导自噬中的作用。方法用不同剂量(0、1、5、10 mmol/L)二甲双胍处理SW480细胞24 h,Western blot检测AMPK、p-AMPK以及自噬相关蛋白LC3、p62蛋白表达;荧光定量PCR检测LC3 mRNA表达。二甲双胍与自噬抑制剂3-甲基腺嘌呤(3-Methyladenine,3-MA)单独或联合处理后,Western blot检测LC3、p62表达。沉默AMPK后,10 mmol/L二甲双胍处理SW480细胞24 h,Western blot检测LC3、p62蛋白表达,荧光定量PCR检测LC3mRNA表达情况。结果不同浓度二甲双胍(1、5、10 mmol/L)处理SW480细胞后,AMPK磷酸化水平递增上升,LC3蛋白及mRNA递增表达增加,p62递减表达降低。二甲双胍与3-MA联合处理SW480细胞后,LC3表达降低,p62表达升高。3-MA有抑制二甲双胍的作用。沉默AMPK后,LC3蛋白及mRNA表达下降,p62蛋白表达增加。结论二甲双胍可诱导SW480细胞中AMPK活化,AMPK的活化参与了二甲双胍诱导的自噬。     

自噬激活对带状疱疹后神经痛模型小鼠脊髓背角GABA能神经元凋亡的影响

目的探讨不同自噬程度对带状疱疹后神经痛(postherpetic neuralgia,PHN)模型小鼠脊髓背角GABA能神经元凋亡的影响。方法使用SPSS 19.0的随机数字发生器将48只昆明小鼠,6~8周龄,体重18~22 g,随机分为树脂毒素+自噬诱导剂组(PHN+Rapa组)、树脂毒素组(PHN组)、树脂毒素+自噬抑制剂组(PHN+3-MA组)和空白对照组(C组),每组12只。C组不做任何处理,其余各组均腹腔注射0.2μg/g树脂毒素(resiniferatoxin,RTX)制备PHN模型。在构建模型成功后,PHN+Rapa组给予1μg·kg-1·d-1的自噬诱导剂雷帕霉素(rapamycin,Rapa),PHN组给予生理盐水,PHN+3-MA组给予2μg·kg-1·d-1的自噬抑制剂3-MA,连续14 d腹腔注射。检测机械缩足阈值(mechanical withdrawal threshold,MWT)、热缩足潜伏期(thermal withdrawal latency,TWL)至稳定后处死各组小鼠,采用荧光Tunel法检测脊髓凋亡细胞数;提取脊髓L4~6节段组织,采用Western blot法检测抑凋亡蛋白bcl-2、促凋亡Bax和自噬相关蛋白LC3的相对表达量;免疫荧光标记脊髓背角GABA能神经元数。结果与C组比较,PHN+Rapa组、PHN组和PHN+3-MA组的LC3-II/I和Bax的蛋白相对表达量均明显升高,凋亡细胞数量明显增多,bcl-2蛋白相对表达量明显降低,脊髓背角GABA能神经元数明显减少(P0.05);与PHN组比较,PHN+Rapa组的LC3-II/I比值和Bax的蛋白相对表达量,凋亡细胞数量明显增多,bcl-2蛋白相对表达量明显降低,脊髓背角GABA能神经元数明显减少(P0.05)。与PHN组比较,PHN+3-MA组的LC3-II/I比值和Bax的蛋白相对表达量明显降低,凋亡细胞数量明显减少,bcl-2蛋白相对表达量明显升高,脊髓背角GABA能神经元数明显增多(P0.05)。结论自噬过度激活可能是导致带状疱疹后神经痛脊髓背角GABA能神经元凋亡的机制之一。     

自噬在顺铂诱导的食管癌细胞死亡中的作用

目的 观察自噬在食管癌EC9706细胞顺铂处理过程中的表达,探讨其表达与细胞死亡的关系.方法 对数生长期EC9706细胞与顺铂共同作用0、3、6、12、24 h后,Western blot法检测微管相关蛋白轻链3(LC3)的表达;自噬特异性阻断剂3-甲基腺嘌呤(3-MA)分别在顺铂前1 h、后1 h加入共同作用24 h,用CCK-8法和流式细胞术检测细胞死亡率和凋亡率的变化.结果 顺铂处理细胞0、3、6、12、24 h后LC3相对灰度值为0.33±0.04、1.13±0.18、1.92±0.25、0.89±0.12、0.58±0.08;在顺铂加入前、后1 h加入3-MA细胞的抑制率分别为(33.58±2.45)%、(21.37±1.21)%,细胞凋亡率分别为(18.30±0.92)%、(12.80±0.61)%.结论 顺铂可以诱导食管癌EC9706细胞自噬,在顺铂给药前期,自噬对细胞有保护作用,可以延迟凋亡的发生;而在顺铂给药后期,自噬则可能作为一种细胞死亡程序,进一步促进细胞死亡.     

自噬调节在结肠癌细胞化疗耐药性的作用机制研究

目的:探究自噬调节在结肠癌细胞化疗过程中耐药性的作用机制.方法:以顺铂诱导人结肠癌细胞系EC9706细胞自噬,观察自噬抑制剂3-MA对EC9706细胞的影响.CCK8法测定细胞生长情况.流式细胞术检测细胞凋亡和细胞周期.MDC检测自噬.Western blot法检测Beclin-1、PI3K Ⅲ、LC3-Ⅰ、LC3-Ⅱ...     

Cordyceps sinensis alleviates β-glycerophosphate-induced vascular smooth muscle cell calcification through promoting autophagy

Objective To investigate the influence mechanism of Cordyceps sinensis (CS) on β-glycerophosphate-induced vascular smooth muscle cell (VSMC) calcification. Methods The effect of CS on VSMC cell viability was detected by CCK-8. The cellular models of rat VSMC calcification were established by treating with β-glycerophosphate (β-GP, 10 mmol/L); then CS (10 mg/L), autophagy inhibitor 3-methyladenine (3-MA, 5 mmol/L), and AMPK inhibitor compound C (CC, 10 μmol/L) were added to the cell cultures. There were a total of 5 experiment groups: VSMC cultured in normal medium (Control), VSMC treated with β-GP, VSMC treated with β-GP and CS, VSMC treated with 3-MA, β-GP and CS, and VSMC treated with CC, β-GP and CS. The calcium nodules and calcium content were examined with alizarin red S staining and the O-cresolphthaleincomplexone method, respectively. The autophagosomes within the VSMC were observed using transmission electron microscope (TEM). Immunofluorescence showed the accumulation of microtubule-associated protein 1 light chain 3 (LC3) puncta. In addition, levels of osteogenic related proteins, autophagy related proteins, and AMPK/mTOR pathway related proteins were evaluated by Western blotting. Results CS increased the number of autophagosomes and the accumulation of LC3 puncta within VSMC. It also up-regulated the protein levels of LC3Ⅱ/LC3Ⅰ, beclin1, α-SMA, and p-AMPK; whereas, the protein levels of Runx2 and p-mTOR, as well as calcium nodules and calcium content were reduced (all P＜0.01). When the cells were pretreated with 3-MA before treating with β-GP and CS, the autophagosomes, accumulation of LC3 puncta, and protein levels of LC3Ⅱ/LC3Ⅰ, beclin1, and α-SMA were decreased (all P＜0.01); however, the protein level of Runx2, and the calcium nodules and calcium content were increased (all P＜0.01). Nevertheless, when the cells were pretreated with CC before giving β-GP and CS, the autophagosomes, the accumulation of LC3 puncta, and the expression levels of p-AMPK, LC3Ⅱ/LC3Ⅰ, beclin1, and α-SMA were significantly down-regulated (all P＜0.01); whereas, the expression levels of Runx2 and p-mTOR, as well as calcium nodules and calcium content were increased (all P＜0.01). Conclusions CS can effectively alleviate β-GP-induced VSMC calcification, which may be due to the activation of autophagy by AMPK/mTOR signaling pathway.     

Autophagy alleviate podocytes injury induced by contrast media via oxidative stress

Objective To evaluate the effects of autophagy on oxidative stress induced by contrast media in podocytes. Methods The differentiated mouse podocytes were exposed to contrast media (Iopromide, 50 mg/L)、rapamycin (Rap, autophagy enhancer, 1 ng/L), 3-methyladenine (3-MA, autophagy inhibitor, 2 mmol/L) for 2 hours. The expression of autophagy protein LC3-Ⅱand Beclin-1 as well as oxidative stress-related proteins Catalase, MnSOD were detected by Western blot. The formations of autophagy were observed by MDC staining, and the levels of reactive oxygen species (ROS) by CM-H2DCFDA staining. Cell activity was evaluated by CCK8 assay. Results Both the levels of oxidative stress and autophagy in podocytes increased when stimulated by contrast media, the expression of LC3-Ⅱand Beclin-1 were enhanced, Catalase and MnSOD were inhibited (all P＜0.05). Rapamycin increased the expression of Catalase, MnSOD and cell activity of podocytes, reduced the generation of ROS (all P＜0.05), but in Rap group, cell activity showed no significant difference (P＞0.05). 3-MA decreased the expression of Catalase、 MnSOD and inhibited the cell activity of podocyte, increased the generation of ROS (all P＜0.05). Conclusion Autophagy protects podocyte from contrast media by the means of reducing oxidative stress.     

Role of prolyl hydroxylases 2 in the cellular response to hypoxia activated autophagy in human renal epithelial cell model

Objective To test the hypothesis of autophagy that silencing PHD2 gene could increase hypoxia inducible factor (HIF)-1α levels in the renal medulla and attenuate hypoxia injury in cultured human renal proximal tubular epithelial cell (HK-2) under cobalt dichloride (CoCl2) exposure. Methods HK-2 cells were harvested at hour 0, 6, 12, 24, 36 and 48 after exposure to CoCl2 (200 μmol/L). The role of HIF/PHD pathway in CoCl2-induced cell apoptosis/autophagy was studied by employing small-interfering RNA (siRNA). Dynamic profiles of apoptosis markers (Bax, Bcl-xl) and autophagy marker (LC3) of HK-2 cells within 48 h after exposing to CoCl2 were recorded. Alamar Blue assay was used for quantitative analysis of cellular growth and viability. Electron microscopy analysis was employed to evaluate the changes in autophagic structures. Results The protein expressions of PHD2 were gradually increased after exposing to CoCl2 (200 μmol/L), with statistics significance at 24 h and reached the peak at 48 h (both P＜0.01). PHD2 siRNA reduced PHD2 levels by＞60% and significantly increased HIF-1α protein levels (P＜0.01), but had little effect on HIF-2α. The protein expression of Bcl-xl was significantly up-regulated, while the level of Bax and LC3-Ⅱ/LC3-Ⅰ were down-regulated in PHD2 siRNA group (all P＜0.01), compared with the negative control group. Meanwhile, either 3-Methyladenine (an autophagy inhibitor) treatment or PHD2 knockdown rescued cell death and increased cell viability through autophagy inactivation. The ratio of LC3-Ⅱ/LC3-Ⅰand the quantity of autophagosomes were decreased, and the cell ultrastructure was also relatively intacter than the negative control group. Of interest, co-administration of HIF-1α siRNA with PHD2 siRNA abrogated renoprotective effect conveyed by PHD2 siRNA alone, suggesting that activation of endogenous HIF-1α-dependent pathways mediated the autophagy inactivation effects of PHD2 silencing. Conclusions Direct inhibition of PHD2 promotes renal epithelia cell survival against CoCl2-induced cell apoptosis/autophagy. Activation of the HIF-1α signaling pathway is required to reduce apoptosis and autophagy via up-regulating the expression of Bcl-xl protein.     

Initiation of apoptosis and autophagy by photodynamic therapy

BACKGROUND AND OBJECTIVES: This study was designed to examine modes of cell death after photodynamic therapy (PDT). STUDY DESIGN: Murine leukemia L1210 cells and human prostate Bax-deficient DU145 cells were examined after PDT-induced photodamage to the endoplasmic reticulum (ER). Phase contrast, fluorescence and electron microscopy were used to identify changes in cellular morphology, chromatin condensation, loss of mitochondrial membrane potential, and formation of phagolysosomes. Western blots were used to assess the processing of LC3-I to LC3-II, a marker for autophagy. Inhibitors of apoptosis and/or autophagy were used to delineate the contributions of the two pathways to the effects of PDT. RESULTS: Both apoptosis and autophagy occurred in L1210 after ER photodamage with the latter predominating after 24 hours. In DU145 cells, PDT conditions causing comparable cytotoxicity only initiated autophagy. PI3-kinase inhibitors suppressed autophagy in both cell lines as indicated by inhibition of vacuolization and LC3 processing. CONCLUSIONS: Both autophagy and apoptosis were observed in L1210 cells following ER photodamage. In the Bax-deficient DU145 cell line only autophagy was observed. Current information suggests that autophagy can function as either a survival or death pathway. We propose that in the context of PDT, this may also be true.