自噬基因Beclin 1与肿瘤关系的研究进展

Beclin 1是第一个被克隆的自噬相关基因,在肿瘤发生、发展中扮演重要角色.Beclin 1不仅促进真核细胞自噬,同时也参与细胞凋亡调节.研究表明,Beclin 1可抑制肿瘤的发生和发展,但也有研究表明,Beclin 1可以通过诱导适当的自噬使肿瘤细胞得以存活.笔者就Beclin 1及其在肿瘤发生、发展中的作用作一综述.     

自噬基因Beclin 1在SKOV3细胞中的表达及其调控相关信号传导途径的研究

目的探讨自噬基因Beclin 1在人卵巢癌SKOV3细胞中过表达后自噬相关信号调控通路PI3K/PKB途径中ClassⅠPI3K（p110α）、p-PKB和ClassⅢPI3K（hvps34）的表达变化以及对肿瘤细胞的自噬活性的影响.方法将自噬基因Beclin 1的真核表达载体pcDNA3.1/Beclin1转染SKOV3细胞;分别用荧光定量RT-PCR和Western blot在mRNA和蛋白水平检测用流式细胞仪检测Beclin1、p110α、hvps34和p-PKB的表达;在电镜和荧光显微镜下观察自噬现象,用流式细胞仪检肿瘤细胞自噬情况.结果 pcDNA3.1/Beclin1转染后SKOV3细胞Beclin1表达在mRNA和蛋白质水平明显高于转染空质粒pcDNA3.1和未转染细胞;PcDNA3.1/Beclin1转染后hvps34表达上调,而p110α、p-PKB的表达下调.PcDNA3.1/Beclin1转染SKOV3细胞后在在电镜下可见大量自噬囊泡形成.在荧光显微镜下见pcDNA3.1/Beclin1转染后SKOV3细胞中MDC阳性细胞明显增加.流式细胞仪检测pcDNA3.1/Beclin1转染后SKOV3细胞MDC平均荧光强度高于pcDNA3.1转染组和未转染组.Beclin 1在SKOV3中的过表达后抑制肿瘤细胞在体外的生长,抑制率为58.68%.结论自噬基因Beclin1在人卵巢癌细胞SKOV3中过表达可使ClassⅢPI3K（hvps34）表达上调,ClassⅠPI3K（p110α）及其下游的p-PKB表达下调,诱导肿瘤细胞自噬活性增加,抑制SKOV3在体外的增殖.     

自噬基因Beclin1与妇科肿瘤的研究进展

随着肿瘤基因治疗研究的进展,自噬性细胞死亡受到广大学者的关注。许多研究发现抗肿瘤药物不仅可以通过促使肿瘤细胞凋亡来达到其治疗肿瘤的目的,还可以诱导肿瘤细胞自噬性死亡。操纵自噬已成为肿瘤治疗的新前景。Beclin1是至今唯一发现的哺乳动物自噬基因,它不仅参与自噬体的形成,还可通过调节自噬活性对肿瘤的发生、发展发挥重要作用。     

Urocortin inhibits Beclin1-mediated autophagic cell death in cardiac myocytes exposed to ischaemia/reperfusion injury

Autophagy is known to be a feature of cardiomyopathies and chronic ischaemia. Here we demonstrate that autophagy is also induced by a single cycle of ischaemia/reperfusion (I/R in neonatal and adult rat cardiac myocytes). Consistent with the critical role for Beclin1 in autophagocytosis, reduction of Beclin1 expression in cardiac myocytes by RNAi reduces I/R-induced autophagy and this is associated with enhanced cell survival. Autophagy is also reduced by urocortin, an endogenous cardiac peptide which we have previously shown to reduce other forms of myocyte cell death induced by I/R. The inhibition of autophagy by urocortin is mediated in part by inhibition of Beclin1 expression, an effect which is mediated by activation of the PI3 kinase/Akt pathway but which does not involve activation of p42/p44 MAPK.     

Adaptive changes in autophagy after UPS impairment in Parkinson's disease

Aim:

Ubiquitin-proteasome system (UPS) and autophagosome-lysosome pathway (ALP) are the most important machineries responsible for protein degradation in Parkinson''s disease (PD). The aim of this study is to investigate the adaptive alterations in autophagy upon proteasome inhibition in dopaminergic neurons in vitro and in vivo.

Methods:

Human dopaminergic neuroblastoma SH-SY5Y cells were treated with the proteasome inhibitor lactacystin (5 μmol/L) for 5, 12, or 24 h. The expression of autophagy-related proteins in the cells was detected with immunoblotting. UPS-impaired mouse model of PD was established by microinjection of lactacystin (2 μg) into the left hemisphere of C57BL/6 mice that were sacrificed 2 or 4 weeks later. The midbrain tissues were dissected to assess alterations in autophagy using immunofluorescence, immunoblotting and electron microscopy assays.

Results:

Both in SH-SY5Y cells and in the midbrain of UPS-impaired mouse model of PD, treatment with lactacystin significantly increased the expression levels of LC3-I/II and Beclin 1, and reduced the levels of p-mTOR, mTOR and p62/SQSTM1. Furthermore, lactacystin treatment in UPS-impaired mouse model of PD caused significant loss of TH-positive neurons in the substantia nigra, and dramatically increased the number of autophagosomes in the left TH-positive neurons.

Conclusion:

Inhibition of UPS by lactacystin in dopaminergic neurons activates another protein degradation system, the ALP, which includes both the mTOR signaling pathway and Beclin 1-associated pathway.     

Beclin1在胆管癌中的表达及意义

目的:探讨胆管癌中Beclin1的表达及意义.方法:应用免疫组化法检测67例胆管癌标本Beclin1蛋白的表达情况,并应用Western blot与Real-time RT-PCR检测新鲜胆管癌标本与正常胆管组织中Beclin1蛋白与基因的表达验证免疫组化结果.结果:胆管癌组Beclin1的表达与正常胆管组比较,胆管癌中Beclin1的表达降低,二组结果比较差异有显著性(P ＜0.05);Beclin1在胆管癌中的表达与肿瘤的分化以及TNM分期有关(P＜0.05),而与肿瘤大小、转移无关(P＞0.05).结论:Beclin1蛋白表达与胆管癌的发生、发展有关.     

自噬基因Beclin1过表达诱导人卵巢癌细胞SKOV3自噬和凋亡的研究

目的:探讨自噬基因Beclin 1在人卵巢癌SKOV3细胞中过表达对其体外生长活性的影响。方法:构建自噬基因Beclin 1的真核表达载体pcDNA3.1/Beclin1,将其稳定转染SKOV3细胞,实现Beclin 1在SKOV3中的过表达;用MTT法分析Beclin1过表达对SKOV3增殖的影响,用流式细胞仪检测凋亡和自噬情况,电镜和荧光显微镜下观察自噬现象。结果:pcD-NA3.1/Beclin1转染SKOV3细胞后Beclin 1在mRNA和蛋白水平均高于空质粒pcDNA3.1转染组和未转染组。Beclin 1在SKOV3中的稳定过表达后G1期细胞明显增多,S期细胞比例明显减少,细胞增殖受到抑制,凋亡率为(21.26±3.89)%,高于空质粒pcDNA3.1转染组和未转染组,差异有统计学意义(P<0.05);流式细胞仪检测pcDNA3.1/Beclin1转染SKOV3细胞后MDC标记的自噬囊泡平均荧光强度高于pcDNA3.1转染组和未转染组。pcDNA3.1/Beclin1转染SKOV3细胞后在电镜下可见大量自噬囊泡形成。在荧光显微镜下见pcDNA3.1/Beclin1转染后SKOV3细胞中MDC标记的自噬囊泡明显增加。结论:自噬基因Beclin1过表达可诱导人卵巢癌细胞SKOV3自噬和凋亡,针对自噬基因Beclin1的卵巢癌基因治疗可能具有可行性。     

自噬调控因子mTOR和Beclin1在良恶性多形性腺瘤中的表达及意义

目的 研究自噬调控中的主要因子西罗莫司靶蛋白(mTOR)及Beclin1在良、恶性多形性腺瘤中的表达及意义.方法 采用免疫组织化学显色检测Beclin1在35例腮腺瘤多形性腺瘤(CPA),37例腮腺良性多形性腺瘤(PA)和20例正常腮腺组织中的表达情况.用蛋白免疫印迹法(Western blot)测定p-mTOR、Beclin1在CPA、PA及正常腮腺组织中的表达情况.结果 p-mTOR在正常腮腺组织,PA,CPA中的阳性表达呈递增的趋势,三者间差异有统计学意义(P<0.05);Beclin1在3种组织中表达呈递减趋势,三者间差异也有统计学意义(P<0.05).结论 mTOR信号因子在CPA组织中过度表达,而Beclin1在CPA组织中的阳性表达受到抑制.