FOXO1在肿瘤中的自噬调节作用及其研究进展

FOXO1是FOX家族O亚族FOXOs中的一员,是人体内重要的转录因子.近来研究表明FOXO1在肿瘤自噬调节中发挥重要作用,深入研究其调节机制有望为肿瘤治疗提供新的靶点和治疗方案.该文就FOXO1的结构与功能、自噬的调节功能、FOXO1与自噬调节的关系、FOXO1-自噬调节在肿瘤中的作用与机制及其在肿瘤治疗和预后方面的...     

肾癌中细胞自噬的作用及自噬调节剂在肾癌治疗中的研究进展

细胞自噬是细胞体内的一种“自我吞噬”的分解代谢过程,通过将细胞内衰老的细胞器、受损蛋白和其他细胞成分包裹于自噬溶酶体中,从而实现能量供应和物质的循环利用。研究表明,细胞自噬与肾癌的发生、发展和转归密切相关,其不仅参与肾癌的发生,而且在肾癌发展的不同阶段分别起促进或抑制的双重作用。有针对性地靶向调节不同阶段肾癌的自噬水平可能是治疗肾癌的新策略。该文对细胞自噬的发生过程及其在肾癌发展进程中的作用进行综述,并探讨自噬调节剂(自噬抑制剂/诱导剂)在肾癌治疗中的潜在作用。     

自噬与肿瘤关系的研究进展

自噬是细胞适应环境变化、防御病原微生物侵袭、维持内环境稳定的重要机制.在多种人类肿瘤中存在有自噬活性的改变,自噬在肿瘤的发生发展过程中起到了促进和抑制的双重作用.对自噬研究的不断深入,不仅进一步揭示了真核生物自身调控的复杂性和多样性,更为肿瘤的基因治疗及克服肿瘤耐药性提供了新的思路.现将自噬与肿瘤的发生、发展的研究进展做一综述.     

自噬及其在肿瘤中的作用研究

 自噬（autophagy）是由 Ashford 和 Porter 在 1962 年发现细胞内有“自己吃自己”的现象后提出的，是指从粗 面内质网的无核糖体附着区脱落的双层膜包裹部分胞质 和细胞内需降解的细胞器、蛋白质等成分形成自噬体（autophagosome），并与溶酶体融合形成自噬溶酶体，降解其所包裹的内容物，以实现细胞本身的代谢需要和某些细胞器的更新^[1]。自噬在机体的生理和病理过程中都能见到，其所起的作用是正面还是负面的尚未完全阐明，对肿瘤的研究尤其如此，值得关注。 1 自噬的功能与作用机制 自噬主要的生理功能是将胞质中的大分子物质（如 蛋白质、RNA、过量储存的糖原等）和一些细胞内源性底物（包括由于生理或病理原因引起的衰老、破损的细胞器）在单位膜包裹的囊泡中大量降解，实现再循环，以维持细胞自身的稳定。这个过程对于细胞成分更新、保持旺盛的生理状态是至关重要的^[2]。在此过程中，自噬体的形成是关键，其直径一般为 300 ~ 900 nm，平均 500 nm，囊泡内常见的包含物有胞质成分和某些细胞器如线粒体、内吞体、过氧化物酶体等。与其他细胞器相比，自噬体的半衰期很短，只有 8 min 左右，说明自噬是细胞对于环境变化的有效反应。根据细胞物质运到溶酶体内的途径不同，自噬分为以下几种。①大自噬：由内质网来源的膜包绕待降解物形成自噬体，然后与溶酶体融合并降解其内容物^[3]；②小自噬：溶酶体的膜直接包裹长寿命蛋白等，并在溶酶体内降解；③分子伴侣介导的自噬（CMA）：胞质内蛋白结合到分子伴侣后被转运到溶酶体腔中，然后被溶酶体酶消化。CMA 的底物是可溶的蛋白质分子，在清除蛋白质时有选择性，而前两者无明显的选择性^[4]。     

有氧耐力运动调控大鼠心肌细胞自噬的机制

背景：近年来,衰老相关的慢性病研究在世界范围内受到广泛关注,心脏随着年龄增长可能会出现过早衰老,运动作为一种安全健康的干预措施可以延缓其衰老。目的：观察实施规律有氧运动对心肌细胞增龄性老化的影响并探讨其机制。方法：纳入SD大鼠68只,3月龄(青年)20只,13月龄(中年)和22月龄(老年)各24只,每个年龄组再随机均分为静息组及运动组。对3个运动组实施为期10周的递增负荷有氧跑台运动,其中早期递增负荷6周,晚期恒负荷4周;3个静息组不进行有氧运动干预。干预结束后采用实时荧光定量PCR和免疫组化法检测心肌Beclin-1、Ca MKⅡα1、AMPKα1/p AMPKα1和PI3K/Akt/m TOR等通路相关蛋白与基因的表达。结果与结论：(1)实施规律有氧运动后,与青、中、老3个年龄的静息组相比,3个年龄的运动组大鼠心肌细胞自噬Beclin-1表达水平均下调;同时3个年龄的运动组大鼠心肌Ca MKⅡα1 m RNA表达水平也下调;(2)3个年龄静息组p AMPKα1和AMPKα1蛋白表达水平均呈现增龄性趋势;青年、中年和老年运动组的AMPKα1表达水平分别上调16.50%(Ρ<0....     

自噬相关基因Beclin 1与肿瘤

自噬性细胞死亡是一种不同于凋亡、不依赖于caspase的程序性细胞死亡。研究发现自噬活性的变化、自噬性细胞死亡与恶性肿瘤的发生、发展有关。某些癌基因、抑癌基因参与了自噬活性的调节，其中对Beclin1研究较多，它作为自噬相关基因参与调节自噬活性，从而在肿瘤的发生、发展中发挥作用。现对Beclin1、自噬与肿瘤发生、发展关系的最新进展作一综述。     

自噬在熊果酸抑制人肺癌PC9细胞增殖中的作用

目的:研究自噬在熊果酸(UA)抑制人肺癌PC9细胞增殖中的作用及机制。方法:应用MTT法和台盼蓝拒染法检测UA对PC9细胞增殖的影响。吖啶橙染色法在荧光显微镜下观察UA对PC9细胞自噬的影响。Western blot检测自噬相关蛋白LC3及ATG5的表达情况。采用自噬抑制剂3-甲基腺嘌呤(3-MA)观察UA对PC9细胞增殖的抑制作用。结果:UA可以显著抑制PC9细胞的活力(P0.05或P0.01),随着给药剂量和时间的增加,UA对PC9细胞的生长抑制率显著上升。UA诱导PC9细胞自噬体表达增加,并诱导自噬相关蛋白LC3-Ⅱ和ATG5表达的增加(P0.01)。自噬抑制剂3-MA提高了UA对PC9细胞的抑制作用(P0.01)。结论:UA抑制PC9细胞的增殖,并诱导细胞发生自噬。UA诱导PC9细胞自噬的机制有可能依赖ATG5细胞自噬途径。自噬抑制剂3-MA能够增强UA对PC9细胞的增殖抑制作用,有望为肺癌的临床治疗提供新的联合治疗方案。     

自噬/苄氯素1调节因子1在自噬与凋亡中作用的研究进展

细胞凋亡(Ⅰ型程序性死亡)和自噬性细胞死亡(Ⅱ型程序性死亡)这2种细胞死亡方式可通过一些蛋白的相互作用而介导形成平衡对立状态.一方面,细胞凋亡由胱天蛋白酶(caspase,CASP)依赖性通路经内源性、外源性或内质网应激诱导途径予以控制,而死亡信号则可经这3种途径介导受损或感染细胞的清除[1-2].另一方面,细胞自噬由...     

细胞周期素依赖性激酶2及p27^kip1与血管瘤

目的：进一步探讨细胞周期素依赖性激酶2（CDK2）及p27^kip1在血管瘤发生、发展及退化过程中的作用机制。方法：采用免疫组织化学SP法检测49例皮肤毛细血管瘤增生期、退化期及正常皮肤组织中CDK2和p27^kip1的表达水平；采用HPIAS-1000高清晰度彩色病理图文报告管理系统，对CDK2和p27^kip1表达的平均光密度和阳性面积率进行图像分析。结果：增生期组CDK2的表达明显高于退化期组和正常皮肤组织组；增生期血管瘤内皮细胞p27^kip1的表达显著低于退化期血管瘤内皮细胞。结论：p27^kip1能抑制血管瘤内皮细胞的增殖，在血管瘤的退化过程中起了重要作用；而CDK2能促进血管瘤内皮细胞增殖，在血管瘤的增生过程中起了重要作用。     

自噬在免疫及免疫相关疾病中的研究进展

自噬是细胞内溶酶体/内体参与的,涉及细胞增殖,分化及稳态平衡调节的降解过程.遗传学研究发现其在物种进化过程中较保守,从酵母到哺乳动物细胞中均有自噬相关基因的存在,提示自噬广泛参与各类生物正常的生理过程.近年来,随着研究的不断深入,人们发现自噬在许多疾病尤其在免疫相关疾病中亦扮演着重要角色,在感染,自身免疫,肿瘤免疫中所起的作用可为今后研究提供依据.     

Autonomy in tumor cell proliferation

Autonomous replication of tumor cells seems to be an essential factor in the definition of the malignant tumor itself, although tumor cell proliferation is, in general, controlled by the host response including immunological reactions and microenvironment. The cause of the autonomy can hypothetically be classified into four categories as follow: (a) auto- and paracrine growth stimulation; (b) growth factor receptor abnormalities; (c) abnormal signal transduction; (d) self-incitement of 'initiator-replicon' system in DNA replication. These intracellular mechanisms may play important roles in the autonomy as shown in autocrine growth factors from the data obtained in protein-free cell culture. Hypothetically, negative regulation systems on the initiator-replicon may play roles of cell replication in multicellular organisms. Oncogene products and growth factors may affect this regulation system.     

Computer simulation of tumor cell motility and proliferation

Tumor growth is considered to depend on tumor cell proliferation and on tumor cell motility. The present study investigates in which way these two cellular properties influence the evolving morphological pattern. Computer simulations were performed, where cells were either dividing or moving for a variable distance at a present probability. The simulation parameters (probability of motility, maximum moving distance) were set interactively. The resulting patterns were evaluated by binary morphological criteria, 13 of 17 binary criteria showed a significant relationship with the simulation parameters (median test: p = less than 0.05). Discriminant analysis of two sets of simulations with different simulation parameters provided a correct classification with an efficiency of 100% (k-nearest-neighbour method; jack-knife-procedure). The results indicate that cell proliferation and motility affect morphological patterns in a reproducible way and that the patterns in turn provide morphological clues for the quantitative estimation of motility and proliferation.     

lncRNA HOTAIR在胃癌中的表达及对胃癌细胞增殖及自噬的影响

目的研究lncRNA HOTAIR在胃癌中的表达及其对胃癌细胞增殖和自噬的影响,探讨lncRNA HOTAIR调控胃癌细胞自噬的机制。方法收集2015年1月—2017年12月于中国医科大学附属肿瘤医院确诊为胃癌的60例癌组织及其配对癌旁组织;实时荧光定量PCR (RT-PCR)检测HOTAIR表达水平,CCK-8实验检测siHOTAIR及si-ATG3对细胞增殖影响,蛋白免疫印迹实验检测HOTAIR对细胞自噬水平及ATG3表达水平影响,免疫荧光实验检测HOTAIR对胃癌细胞自噬的影响。结果 HOTAIR在胃癌组织及癌细胞株MGC-803、BGC-823、SGC-7901中表达水平显著高于癌旁正常组织及人胃黏膜细胞株GES-1。通过转染si-HOTAIR,构建胃癌HOTAIR干扰细胞株;与空载对照组相比,HOTAIR干扰组胃癌细胞增殖水平降低,胃癌细胞自噬标志蛋白LC3表达水平降低,LC3-Ⅱ/Ⅰ比例降低,P62表达增高,自噬相关蛋白ATG3表达亦降低。结论胃癌组织中HOTAIR表达上调,抑制HOTAIR促进了胃癌细胞增殖能力;且HOTAIR能够通过ATG3促进自噬水平。     

Correlation of intratumoral endothelial cell proliferation with microvessel density (tumor angiogenesis) and tumor cell proliferation in breast carcinoma.

Tumor angiogenesis is essential for tumor growth and metastasis, and intratumoral microvessel density correlates with prognosis in breast carcinoma. Yet, how intratumoral microvessel density correlates with tumor cell and intratumoral endothelial cell proliferation remains incompletely understood. To this end, we stained 57 formalin-fixed, paraffin-embedded breast carcinomas with antibody MIB1 to determine tumor cell Ki67 labeling index and with anti-CD34 to observe microvessels. We correlated the tumor cell Ki67 labeling index and mitotic figure index with intratumoral microvessel density. Using a double labeling technique combining antibody MIB1 and anti-CD34, we measured intratumoral endothelial cell proliferation in 20 of these cases and correlated these findings with tumor cell Ki67 labeling index, mitotic figure index, and intratumoral microvessel density. The intratumoral Ki67-labeling index was 45-fold greater (P < 0.000001) than that of microvessels in adjacent benign breast. Yet, endothelial cell Ki67 labeling index did not correlate with intratumoral microvessel density, tumor cell Ki67 labeling index, or mitotic figure index nor did intratumoral microvessel density correlate with tumor cell Ki67 labeling index or mitotic figure index. These findings suggest that, although endothelial cells are actively proliferating within the tumor, intratumoral microvessel density and intratumoral endothelial cell proliferation are independent of each other and of tumor cell proliferation. Thus, intratumoral microvessel density, endothelial cell proliferation, and tumor cell proliferation may be regulated by separate mechanisms.     

Tissue-specific inhibition of cell proliferation in Ehrlich's ascites tumor

Extract of Ehrlich's ascites tumor cells (chalone) and its cell-free fluid have a marked inhibitory action on proliferation of these tumor cells 4 h after injection. The effect is tissue specific, it is more marked in the extract, and it depends on the dose of the agent. Mitotic activity in the tumor 8 h after injection of the extract or cell-free fluid is higher than in the control, evidence of a short-term effect of the chalone on the G₂ phase of the mitotic cycle and on synchronization of cell division.Department of General Biology and Genetics, Medico-Biological Faculty, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 12, pp. 1477–1479, December, 1976.     

Patterns of cellular proliferation in normal and tumor cell populations.

Three types of cell mosaics have been used in mammalian studies: hemopoietic shimeras, mosaics formed by aggregation of preimplatation embryos, and mosaics resulting from X-chromosome inactivation. The problems investigated with these cell mosaics have included normal tissue orgaization, cell selection, primordial cell pool sizes, and tumor cell kinetics. The emphasis in this review is on the application of X-chromosome inactivation mosaics to the analysis of tumor cell proliferation. The first application of mosaicism to tumor ontogeny involved leiomyomas and demonstrated single cell and independent origin of the tumors. Other tumor studies are reviewed including those of presumed multiple cell origin, especially those of hereditary origin and viral etiology. The concept of target size is invoked to explain these multiple cell origin tumors. The recent reports on the clonal nature of atherosclerotic plaques is also discussed. Emphasis is placed on resolving the relationship between the multiclonal underlying fatty streak and the clonal plaque in order to understand the implications of the clonal plaques.     

AMPK activation stimulates autophagy and ameliorates muscular dystrophy in the mdx mouse diaphragm

Duchenne muscular dystrophy (DMD) is characterized by myofiber death from apoptosis or necrosis, leading in many patients to fatal respiratory muscle weakness. Among other pathological features, DMD muscles show severely deranged metabolic gene regulation and mitochondrial dysfunction. Defective mitochondria not only cause energetic deficiency, but also play roles in promoting myofiber atrophy and injury via opening of the mitochondrial permeability transition pore. Autophagy is a bulk degradative mechanism that serves to augment energy production and eliminate defective mitochondria (mitophagy). We hypothesized that pharmacological activation of AMP-activated protein kinase (AMPK), a master metabolic sensor in cells and on-switch for the autophagy-mitophagy pathway, would be beneficial in the mdx mouse model of DMD. Treatment of mdx mice for 4 weeks with an established AMPK agonist, AICAR (5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside), potently triggered autophagy in the mdx diaphragm without inducing muscle fiber atrophy. In AICAR-treated mdx mice, the exaggerated sensitivity of mdx diaphragm mitochondria to calcium-induced permeability transition pore opening was restored to normal levels. There were associated improvements in mdx diaphragm histopathology and in maximal force-generating capacity, which were not linked to increased mitochondrial biogenesis or up-regulated utrophin expression. These findings suggest that agonists of AMPK and other inducers of the autophagy-mitophagy pathway can help to promote the elimination of defective mitochondria and may thus serve as useful therapeutic agents in DMD.     

Constitutive hedgehog signaling in chondrosarcoma up-regulates tumor cell proliferation

Chondrosarcoma is a malignant cartilage tumor that may arise from benign precursor lesions, such as enchondromas. Some cases of multiple enchondromas are caused by a mutation that results in constitutive activation of Hedgehog-mediated signaling. We found that chondrosarcomas expressed high levels of the Hedgehog target genes PTCH1 and GLI1. Treatment with parathyroid hormone-related protein down-regulated Indian Hedgehog (IHH) expression in normal growth plates but not in chondrosarcoma or enchondroma organ cultures. Treatment of the chondrosarcoma organ cultures with Hedgehog protein increased cell proliferation rate, whereas addition of chemical inhibitors of Hedgehog signaling decreased the proliferation rate. Chondrosarcoma xenografts from 12 different human tumors were established in NOD-SCID mice. Treatment with triparanol, an inhibitor of Hedgehog signaling, resulted in a 60% decrease in tumor volume, a 30% decrease in cellularity, and a 20% reduction in proliferation rate. These results show that Hedgehog signaling is active in chondrosarcoma and benign cartilage tumors and regulates tumor cell proliferation. Our data raise the intriguing possibility that Hedgehog blockade could serve as an effective treatment for chondrosarcoma, a tumor for which there are currently no universally effective nonsurgical management options.     

自噬与肿瘤研究现状

自噬对肿瘤的发生发展起抑制和促进双重作用,且能决定某些肿瘤的发展方向;通过激活或抑制自噬能达到肿瘤治疗效果。通过调控自噬,有可能成为肿瘤治疗的新靶点。