自噬及其与肿瘤关系的研究进展

自噬是真核细胞特有的普遍生命现象,在维持细胞自我稳态、促进细胞生存方面起重要作用,广泛参与多种生理和病理过程.自噬与肿瘤细胞的存话与死亡密切相关,预示着自噬将成为肿瘤研究中的一个新热点.本文对自噬的概念及生物学特性以及与肿瘤的关系作一概述.     

自噬及其与肿瘤关系的研究进展

自噬是真核细胞特有的普遍生命现象,在维持细胞自我稳态、促进细胞生存方面起重要作用,广泛参与多种生理和病理过程.自噬与肿瘤细胞的存话与死亡密切相关,预示着自噬将成为肿瘤研究中的一个新热点.本文对自噬的概念及生物学特性以及与肿瘤的关系作一概述.     

自噬在肿瘤发生中的作用机制及临床价值研究

随着对肿瘤研究的不断深入,人们发现肿瘤的发生、发展与紊乱的程序性细胞死亡密切相关.近年来的研究发现自噬性细胞死亡是程序性细胞死亡的一种新的存在形式.在多种通路的调控下,自噬和肿瘤可以进行双向调节.不仅如此,自噬可以通过不同的机制对肿瘤进行双重调节.由于自噬与肿瘤之间存在大量调节通路,所以将自噬与肿瘤免疫治疗相结合是一种新型有效并具有一定可行性的多模式治疗策略.本文总结了自噬与肿瘤研究的相关内容,并且着重讨论了自噬与肿瘤发生、发展的相关机制以及自噬在新型多模式治疗中的应用价值.     

自噬与胰腺癌相关研究进展

胰腺导管腺癌( pancreatic ductal adenocarcinoma,PDA)是一种恶性程度极高的消化系统恶性肿瘤,约占胰腺癌发病率的90％,其发病隐匿,进展迅速,治疗效果极差,且是预后最差的恶性肿瘤之一[1].胰腺癌早期发现困难且易转移,诊断时常常分期较晚,临床治疗以化疗为主,但是胰腺癌对大多数化疗方案不...     

程序性细胞死亡因子4在肿瘤中的研究进展

程序性细胞死亡因子4(PDCD4)为新近发现的抑癌基因,其表达受PDCD4基因甲基化、多种微小RNA的抑制.PDCD4编码的蛋白质可增强多种肿瘤细胞对抗肿瘤药物的敏感性,抑制肿瘤的发生发展和侵袭转移进程,在多种肿瘤中发挥重要作用,有望成为临床上判断肿瘤预后的重要指标.     

自噬与肿瘤干细胞的研究进展

细胞自噬是以细胞质空泡化为特征的溶酶体依赖性降解途径,对维持细胞内环境稳定有重要意义,异常自噬与肿瘤发生密切相关.肿瘤干细胞是存在于肿瘤组织中一类数量较少但具有干细胞特性的肿瘤细胞,可诱导肿瘤发生并对肿瘤的发展、转移、复发起重要作用.肿瘤干细胞中自噬的调节已成为研究热点,将为肿瘤的临床治疗提供新的理论依据.     

自噬与肿瘤

自噬在维持细胞的正常代谢及生存过程中有着重要作用,其在肿瘤的发生机制中也不容忽视,自噬的过程源于自噬小体的形成,包括了诱导、成核、延长、形成完整隔离膜4个步骤。本文就自噬的分子机制、检测方法及其与肿瘤方面的研究进展加以综述。     

自噬在三阴性乳腺癌中的研究进展

细胞自噬是真核细胞对细胞内物质进行周转的重要过程,对于维持细胞内环境的稳定和营养物质的循环利用至关重要。自噬在肿瘤细胞的治疗中起到双重的作用,既可引起癌细胞自噬性死亡,提高细胞对放化疗的敏感性,有助于肿瘤的治疗,又可在不良环境中保护细胞,增加癌细胞的耐药性及提高癌细胞的生存率。在目前的研究报道中,调控自噬活性的信号分子将可能成为三阴性乳腺癌潜在的诊治靶点。笔者针对细胞自噬与三阴性乳腺癌的增殖、迁移、侵袭等功能,放射治疗、药物治疗及预后等方面的研究进展进行综述。     

细胞自噬调控在肿瘤中作用的研究进展

自噬是溶酶体介导的细胞自行消化,其构成了一个被损坏的细胞器和长寿命蛋白质的循环动态途径,在机体内环境稳态和肿瘤发生机制中发挥着重大作用,以保证细胞在营养不足、肿瘤微环境等应激条件下可获得持续利用的能量,并以此来维持体内平衡及生存能力。自噬不仅依赖于肿瘤中的环境、细胞种类和阶段,而且还受肿瘤细胞与微环境之间相互串扰的调节。自噬在肿瘤的早期阶段能抑制肿瘤发生,然而肿瘤晚期阶段自噬促进肿瘤发生,并增加肿瘤细胞生长和转移。本文将就自噬机制及其在肿瘤细胞增殖发展中的作用进行综述,深入研究自噬在癌症生物学中作用,有助于针对自噬相关靶点抗肿瘤的新药设计和临床转化研究。     

自噬调控机制及与肿瘤关系研究进展

自噬是真核细胞通过降解自身的细胞质和细胞器实行“自我消化”的一系列生化过程，它是广泛存在于真核细胞中的生命现象。近年来的研究发现肿瘤的增殖、凋亡信号途径与自噬信号途径相互交错影响，自噬与肿瘤细胞的生存死亡有重要的关系，这预示着自噬将成为肿瘤研究中的一个新热点。     

氟奋乃静通过自噬诱导U87胶质瘤细胞死亡及其机制探讨

目的：观察氟奋乃静（FPZ）通过自噬诱导U87胶质瘤细胞死亡的机制。方法体外培养U87胶质瘤细胞并经FPZ处理,采用细胞活力和集落形成方法分析细胞的生存率,采用Western blot检测自噬相关蛋白及PI3K/AKT/mTOR通路蛋白的表达。结果 FPZ处理后,U87胶质瘤细胞活力显著降低（P﹤0.05）,菌落数显著降低（P﹤0.05）;微管相关蛋白1轻链3-Ⅱ型（LC3-Ⅱ）显著增加,并呈时间和剂量依赖性;p-AKT水平及其下游p-mTOR水平显著下降,并呈时间依赖性。采用PI3K抑制剂LY294002处理U87胶质瘤细胞后,LC3-Ⅱ生成明显增加。结论 FPZ可通过抑制PI3K/AKT/mTOR通路调节自噬,发挥细胞毒性作用。     

Lapatinib induces autophagic cell death and inhibits growth of human hepatocellular carcinoma

Lapatinib, an orally adminstered small-molecule tyrosine kinase inhibitor targeting epidermal growth factor receptors (EGFR) and Her2/Neu, has been widely accepted in the treatment of breast cancer. In this study, we found that lapatinib induced cytotoxicity in human hepatoma Huh7, HepG2 and HA22T cells. For the mode of cell death, we found lapatinib induced a higher percent of dead cells and a lower percent of hypodiploid cells, suggesting non-apoptotic cell death in lapatinib-treated hepatoma cells. Moreover, lapatinib-induced autophagy in hepatoma cells was confirmed by the detection of autophagic LC3-II conversion, the up-regulation of autophagy-related proteins, and the down-regulation of p62 by immunoblotting. Autophagic cell death was demonstrated by images of punctuated LC3 patterns, a higher percent of acridine orange positive cells, as well as a partial rescue of cell death by autophagy inhibitor 3-methyladenine or chloroquine. We also found massive vacuoles in lapatinib-treated hepatoma cells by electronic microscopy. In addition, the shRNA of knocked-down autophagy-related proteins rescued the hepatoma cells from lapatinib-induced growth inhibition. We also demonstrated a reduction of tumorigenesis by lapatinib in vivo. In conclusion, lapatinib induced autophagic cell death and the growth of human hepatoma cells. Our study provides potential cancer therapies by using lapatinib as a treatment for hepatoma.     

Programmed cell death and radioresistance

Whereas apoptosis is a critical mode of cell deletion in normal organism development, apoptotic cells are also observed in tumors, especially following cytotoxic treatments, leading to questions about their role in tumor response to therapy. We have conducted a series of studies using murine tumor models and found that the ability of the tumor cells to undergo apoptosis correlates with tumor response to radiation. The best correlation was with the pretreatment apoptotic index, suggesting that apoptosis in some tumors may govern radiocurability by regulating the number of tumor clonogens. However, other roles for apoptosis in tumor response to radiation have not been ruled out. One of the important observations that has come from this work has been the heterogeneity in apoptosis propensity both within the cell population of a given tumor and among different types of tumors. Such findings underscore the fact that apoptosis is under complex genetic control and that some of the same oncogenes and tumor suppressor genes that are responsible for tumor initiation and progression to malignancy also dictate the apoptotic response to treatment. Understanding the biochemical and molecular pathways that govern this process may ultimately allow the development of strategies for modulating apoptosis for therapeutic benefit.     

Aurora kinase A suppresses metabolic stress-induced autophagic cell death by activating mTOR signaling in breast cancer cells

Aberrant Aur-A signaling is associated with tumor malignant behaviors. However, its involvement in tumor metabolic stress is not fully elucidated. In the present study, prolonged nutrient deprivation was conducted into breast cancer cells to mimic metabolic stress in tumors. In these cells, autophagy was induced, leading to caspase-independent cell death, which was blocked by either targeted knockdown of autophagic gene ATG5 or autophagy inhibitor 3-Methyladenine (3-MA). Aur-A overexpression mediated resistance to autophagic cell death and promoted breast cancer cells survival when exposed to metabolic stress. Moreover, we provided evidence that Aur-A suppressed autophagy in a kinase-dependent manner. Furthermore, we revealed that Aur-A overexpression enhanced the mammalian target of rapamycin (mTOR) activity under metabolic stress by inhibiting glycogen synthase kinase 3β (GSK3β). Inhibition of mTOR activity by rapamycin sensitized Aur-A-overexpressed breast cancer cells to metabolic stress-induced cell death. Consistently, we presented an inverse correlation between Aur-A expression (high) and autophagic levels (low) in clinical breast cancer samples. In conclusion, our data provided a novel insight into the cyto-protective role of Aur-A against metabolic stress by suppressing autophagic cell death, which might help to develop alternative cell death avenues for breast cancer therapy.     

Beclin-1-independent autophagy mediates programmed cancer cell death through interplays with endoplasmic reticulum and/or mitochondria in colbat chloride-induced hypoxia

Autophagy has dual functions in cell survival and death. However, the effects of autophagy on cancer cell survival or death remain controversial. In this study, we show that Autophagy can mediate programmed cell death (PCD) of cancer cells in responding to cobalt chloride (CoCl₂)-induced hypoxia in a Beclin-1-independent but autophagy protein 5 (ATG5)-dependent manner. Although ATG5 is not directly induced by CoCl₂, its constitutive expression is essential for CoCl₂-induced PCD. The ATG5-mediated autophagic PCD requires interplays with endoplasmic reticulum (ER) and/or mitochondria. In this process, ATG5 plays a central role in regulating ER stress protein CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) and mitochondrial protein second mitochondria derived activator of caspases (Smac). Two pathways for autophagic PCD in cancer cells responding to hypoxia have been identified: ATG5/CHOP/Smac pathway and ATG5/Smac pathway, which are probably dependent on the context of cell lines. The former is more potent than the latter for the induction of PCD at the early stage of hypoxia, although the ultimate efficiency of both pathways is comparable. In addition, both pathways may require ATG5-mediated conversion of LC3-I into LC3-II. Therefore, we have defined two autophagy-mediated pathways for the PCD of cancer cells in hypoxia, which are dependent on ATG5, interplayed with ER and mitochondria and tightly regulated by hypoxic status. The findings provide a new evidence that autophagy may inhibit tumor cell proliferation through trigger of PCD, facilitating the development of novel anti-cancer drugs.     

程序性死亡受体1和程序性死亡受体配体1在非小细胞肺癌组织中的表达情况及临床意义

目的探讨程序性死亡受体1(PD-1)和程序性死亡受体配体1(PD-L1)在非小细胞肺癌(NSCLC)组织中的表达情况及临床意义。方法选择150例NSCLC患者的NSCLC组织及其癌旁组织,采用实时荧光定量聚合酶链反应(PCR)检测两种组织中PD-1 mRNA和PD-L1 mRNA的相对表达量。采用免疫组织化学染色法检测NSCLC组织中PD-1和PD-L1的表达情况,分析PD-1和PD-L1表达情况与患者临床特征的关系。采用流式细胞术检测NSCLC组织和癌旁组织中CD4^+-PD-1、CD8^+-PD-1、CD14^+-PD-L1、CD68^+-PD-L1的表达水平。结果NSCLC组织中PD-1 mRNA和PD-L1 mRNA的相对表达量分别为(5.03±1.92)和(4.95±1.09),分别高于癌旁组织的(1.72±0.81)和(1.25±0.24),差异均有统计学意义(P﹤0.05)。TNM分期为Ⅲ~Ⅳ期、低分化、有淋巴结转移、有远处转移的NSCLC患者NSCLC组织中PD-1和PD-L1的高表达率均明显高于TNM分期为Ⅰ~Ⅱ期、高+中分化、无淋巴结转移、无远处转移的患者,差异均有统计学意义(P﹤0.01)。NSCLC组织中CD4^+-PD-1、CD8^+-PD-1、CD14^+-PD-L1、CD68^+-PD-L1的表达水平均明显高于癌旁组织,差异均有统计学意义(P﹤0.01)。结论PD-1和PD-L1在NSCLC组织中高表达,可能成为一种新的生物标志物,PD-1/PD-L1信号通路可能参与了NSCLC的免疫逃逸过程,对其逃逸机制进行研究可以为NSCLC患者的临床治疗提供新靶点。     

PD-1/PD-L1拮抗剂在小细胞肺癌治疗中的研究进展

小细胞肺癌是以广泛转移和预后不良为特征的一种恶性肿瘤。虽然34%~85%的小细胞肺癌对化疗有效,但疾病进展迅速,后续的二线治疗效果很不理想,并且近几十年的治疗方案没有突破性进展。近几年生物治疗迅速发展,免疫治疗成为继靶向治疗后的又一次飞跃。程序性死亡蛋白-1(PD-1)与程序性死亡受体-配体1(PD-L1)结合,抑制了CD4^+和CD8^+T细胞的增殖和活化,负性调控机体免疫机制应答过程,从而介导肿瘤细胞的免疫逃逸,促进肿瘤生长。PD-1/PD-L1拮抗剂在SCLC中的临床前及临床研究中均获得了良好效果,让更多的小细胞肺癌患者受益,尽可能的延长生存时间。本文就PD-1/PD-L1拮抗剂在小细胞肺癌中的研究进展作一综述。     

Miconazole induces autophagic death in glioblastoma cells via reactive oxygen species-mediated endoplasmic reticulum stress

Miconazole is an antifungal agent that is used for the treatment of superficial mycosis. However, recent studies have indicated that miconazole also exhibits potent anticancer effects in various types of cancer via the activation of apoptosis. The main aim of the present study was to observe the effect of miconazole on autophagic cell death of cancer cells. Cytotoxicity was measured by viable cell counting after miconazole treatment in glioblastoma cell lines (U343MG, U87MG and U251MG). Induction of autophagy was analyzed by examining microtubule-associated protein light chain 3 (LC3)-II expression levels using western blotting and by detecting GFP-LC3 translocation using a fluorescence microscope. Intracellular ROS production was measured using a fluorescent probe, 2′,7′-dichlorodihydrofluorescein diacetate. It was found that miconazole induced autophagic cell death in the U251MG glioblastoma cell line via the generation of reactive oxygen species (ROS) and endoplasmic reticulum (ER) stress response. An association between miconazole-induced ROS production and autophagy was also identified; in particular, pretreatment of the cells with a ROS scavenger resulted in a reduction in the levels of LC3-II. Miconazole-induced ER stress was associated with increases in binding immunoglobulin protein (BiP), inositol-requiring enzyme 1α (IRE1α) and CHOP expression, and phospho-eIF2α levels. The inhibition of ER stress via treatment with 4-phenylbutyric acid or BiP knockdown reduced miconazole-induced autophagy and cell death. These findings suggest that miconazole induces autophagic cell death by inducing an ROS-dependent ER stress response in U251MG glioma cancer cells and provide new insights into the potential antiproliferative effects of miconazole.     

Expression of p75NTR in a human prostate epithelial tumor cell line reduces nerve growth factor–induced cell growth by activation of programmed cell death

Epithelial expression of the 75-kDa low-affinity neurotrophin receptor (p75^NTR) is inversely associated with the malignant progression of the human prostate. To elucidate the function of p75^NTR in the prostate, the human prostate epithelial tumor cell line TSU-pr1, which does not express p75^NTR, was stably and transiently transfected with the cDNA for the receptor. The stably transfected cells were assessed for levels of p75^NTR expression and categorized into low, intermediate, and high receptor-expressing clones by immunocytochemical and immunoblot analyses. Incorporation of [³H]thymidine was used to assess nerve growth factor (NGF)–induced changes in cell proliferation. TSU-pr1 epithelial cells transfected with a neomycin-resistance vector alone demonstrated a dose-dependent increase in the rate of NGF-stimulated [³H]thymidine uptake. Expression of p75^NTR decreased the dose-dependent NGF-mediated proliferation of the TSU-pr1 prostate epithelial cells. The greater the degree of expression of p75^NTR in the transfected clones, the less the stimulatory effect of exogenous NGF on cell proliferation. Furthermore, the ratio of p75^NTR to tropomyosin receptor kinase for each clone was inversely correlated with the ability of NGF to stimulate growth of the TSU-pr1 transfectants. To determine whether p75^NTR-mediated growth inhibition of prostate epithelia occurs by induction of programmed cell death, transiently transfected clones were analyzed by an in situ DNA nick-translation assay. NGF deprivation and anti-NGF treatment of transiently transfected TSU-pr1 cells significantly increased the proportion of epithelial cells undergoing programmed cell death by approximately fourfold above control levels. Conversely, addition of NGF was able to rescue p75^NTR-expressing clones from undergoing programmed cell death at levels not significantly different from those of mock-transfected clones. These results demonstrate that p75^NTR is a negative regulator of human prostate epithelial cell growth by induction of programmed cell death. Hence, loss of p75^NTR expression in human prostate epithelia eliminates a growth-inhibitory pathway, thereby contributing to the malignant progression of the prostate. Mol. Carcinog. 23:106–114, 1998. © 1998 Wiley-Liss, Inc.