p63与肿瘤发生调控网络研究进展

p63是p53家族成员之一,由于启动子和选择性剪切的不同,编码两类功能相异的蛋白异构体(TAp63与△Np63),在多种鳞状上皮源性肿瘤中发生表达改变,与肿瘤发生发展关系密切。p63作为转录因子通过调节下游靶基因及激活多种信号通路而发挥作用。由于p63的两类异构体功能相悖,当△Np63-TAp63表达动态平衡偏倚时,可引起细胞生物学行为的改变,但调控关系复杂,许多机制并未明了。该文结合当前研究进展,对p63各亚型的结构特点、活性调节及其参与细胞增殖、分化、凋亡和黏附迁移等几方面的调控作用作一综述,并对其未来研究方向进行了展望。     

p63与p21在鼻咽癌细胞中的表达及相互作用的初步研究

鼻咽癌是中国南方地区常见的恶性肿瘤,p63是新发现的p53家族成员.本研究利用免疫组化方法对p63、p53及p21基因在鼻咽癌中的表达进行了检测,发现三者在鼻咽癌中均有表达;并利用染色质免疫共沉淀(ChIP)的方法对p63及p21的相互作用进行了初步研究,发现P63蛋白能与p21基因启动子区域的一个位点结合.     

p73基因在血液系统恶性肿瘤中的生物学行为

p73是肿瘤抑制基因p53家族新成员.它表达多种具有不同功能特点的蛋白质异构体.综述p73蛋白的分子结构、功能以及在血液系统恶性肿瘤中的生物学行为,旨在探索p73与血液系统恶性肿瘤的关系,为血液系统恶性肿瘤的诊断、治疗及预后提供理论依据.     

肿瘤抑制蛋白p53的活性调控

p53 又称为分子警察或基因的保护神.在面对不同类型和强度的应激时,细胞究竟选择细胞周期停滞、凋亡还是衰老时 p53发挥中心调节作用.作为一种转录调控因子它主要通过对下游的目的基因进行转录调控来发挥功能.p53 结合 DNA 启动子能力也可通过多种方式被调节.这些调节机制主要包括 p53 的亚细胞定位调控、p53 的蛋白稳定性调控和 p53 的翻译后修饰.     

p73基因研究进展

新近发现的p53家族成员－p53基因,其结构和功能均与p53有相似之处。p53蛋白可与多种病毒,胞内信号分子,p53蛋白及其他调节蛋白作用,参与粒细胞分化及T细胞凋亡等多种生理过程;还不清楚p53介否作为一种抑癌基因。     

p53家族及其通路相关蛋白调节母性生殖的新功能

p53是一种重要的抗癌基因,同时它也是机体感受环境压力并进行相应调节的关键基因之一。最近的研究发现东亚人群p53 Arg72Pro受到冬季温度自然选择,表明p53可能在生殖中发挥作用。同时,p53及其通路中的癌基因鼠双微体2(Murinedoubleminute2,Mdm2)、MdmX和Hausp(Herpesvirus-associated ubiquitin-specific protease)基因的单核苷酸多态性(Single nucleotide polymorphisms,SNP)与女性生殖疾病易感性相关。P53蛋白通过其DNA结合区(DNA-binding domain,DBD)调控白血病抑制因子(Leukaemiainhibitory factor,LIF)表达,从而影响胚胎植入过程,实现其在母性生殖中的作用。p53通路中Mdm2、MdmX和Hausp可以调控P53蛋白的表达水平和活性,同时还可以在胚胎植入时准确的调控p53的表达水平,促进胚胎植入;P53家族成员P63、P73具有P53相似的DBD区,但P63和P73是通过别的途径影响到母性生殖;在卵母细胞受到射线或者化学损伤后,P63能促进其凋亡,减少畸型的产生;P73能影响纺锤体复合物的组装,而纺锤体复合物缺失将导致胚泡质量低下,微管结合的动粒缺失和细胞非整倍性的增加。文章主要综述了p53家族、p53通路中的相关蛋白对母性生殖的影响,为提高IVF-ET成功指出了新方法,同时也为不明原因的不孕患者提供了新的诊断思路,将有助于制定合理的个性化治疗不孕方案。     

肺癌组织中PCNA、p63和p53蛋白的表达及临床意义

目的:检测蛋白增殖细胞核抗原(PCNA)、p63和p53在肺癌组织中的表达情况,以探讨三者在肺癌的发生、发展中的生物学作用和临床意义。方法:选取195例肺癌组织(其中57例有癌旁组织),应用组织芯片技术和免疫组织化学方法观察三种蛋白的表达情况,并研究三者之间及其与临床病理参数的关系。结果:PCNA、p63和p53蛋白在肺癌组织中的阳性表达率分别为96.41%、38.46%及58.46%,但三者在癌旁组织中均无表达,差异有统计学意义(均P0.05);在肺癌组织中,PCNA、p63和p53蛋白的表达情况均与组织分型有关(P0.05),且PCNA、p53蛋白表达与分化程度有关(P0.05),分化越差,表达越高;p53表达与PCNA表达呈正相关(r=0.352,P=0.043),p63与p53、PCNA的表达不相关(P0.05)。结论:肺癌组织中PCNA、p63和p53蛋白的表达升高,三者均在肺癌的发生、发展中发挥着重要作用,并且临床可通过检测三者的蛋白水平,作为鉴别肺鳞状细胞癌与其他类型癌的重要参考指标,为病理诊断提供依据。     

p63亚型及其与疾病的相关性

p63足p53家族成员的核转录因子,根据N端及C端的不同,已经发现TAp630α、TAp63β、rap63y、ANp630α、△Np63β、△Np63β、△Np63δ、△Np63δ种亚型。p63的表达受到多种转录因子的调控,其mRNA的稳定性由RNPCI调节,蛋白的稳定性主要由HECT家族成员Itch／AIP4、WWPI调节。p63在上皮细胞分化、组织发育过程中起着关键性作用,因此,p63基因突变可以导致外胚层发育不良的相关疾病,同时,p63在肿瘤的形成和转移的过程中具有重要的调控作用。     

应用免疫组织化学技术检测非小细胞性肺癌的P53蛋白

正常P53蛋白半衰期短,用普通免疫组织化学方法检测不出。而突变后的P53蛋白主要通过与病毒蛋白结合使其稳定性增强,延长其半衰期,从而细胞内P53蛋白增多,使用普通免疫组织化学方法即可检出。Iggo等通过对P53蛋白和p53基因的检测分析,发现p53基因在肿瘤组织中的高表达可以预示p53基因产生了点突变,从而可以采用较简便的方法来对     

P_(53)突变、表达及人乳头状瘤病毒感染与宫颈癌

利用免疫组化、聚合酶链反应(PCR)、单链构象多态性(SSCP)分析等方法, 对49例同一标本宫颈癌组织中p53蛋白、P53外显子7～8变异、HPV6、11、16、18-DN A进行检测,以探讨它们在宫颈癌形成中的作用、相互关系和临床意义.结果表明: a.P5 3基因外显子7～8突变率14.29％、p53蛋白阳性率48.98％、HPV-DNA阳性率87.76％.b.P53基因突变不一定伴有p53蛋白阳性,但P53基因突变而p53蛋白阴性的标 本必是HPV-DNA阳性;91.67％的p53蛋白阳性标本具有HPV-DNA阳性.c.HPV16-DNA阳 性率显著高于HPV6、11、18-DNA阳性率.证明：宫颈癌的发生主要与HPV16感染有关,其 次是P53基因突变所致;p53蛋白阳性由HPV感染和/或P53基因突变所致.     

Biological functions of p53 isoforms through evolution: lessons from animal and cellular models

The TP53 tumour-suppressor gene is expressed as several protein isoforms generated by different mechanisms, including use of alternative promoters, splicing sites and translational initiation sites, that are conserved through evolution and within the TP53 homologues, TP63 and TP73. Although first described in the eighties, the importance of p53 isoforms in regulating the suppressive functions of p53 has only become evident in the last 10 years, by analogy with observations that p63 and p73 isoforms appeared indispensable to fully understand the biological functions of TP63 and TP73. This review summarizes recent advances in the field of 'p53 isoforms', including new data on p63 and p73 isoforms. Details of the alternative mechanisms that produce p53 isoforms and cis- and trans-regulators identified are provided. The main focus is on their biological functions (apoptosis, cell cycle, aging and so on) in cellular and animal models, including mouse, zebrafish and Drosophila. Finally, the deregulation of p53 isoform expression in human cancers is reviewed. Based on these latest results, several developments are expected in the future: the identification of drugs modulating p53 isoform expression; the generation of animal models and the evaluation of the use of p53 isoform as biomarkers in human cancers.     

Interrelations between p73 and p53: a model, neuroblastoma

Homologies in sequence and gene organization of p53 and their relatives, p73 and p63, suggest similar biological functions. However differences exist between the p53 family members. Indeed in human tumors p53 is often mutated while p63 and p73 are very rarely mutated. In addition, in contrast to p53 which is transcribed in a unique mRNA species spanning all gene exons, each homologue expresses two types of isoforms: some with transactivation domain (TAD) showing tumor suppressive properties, the others deprived of TAD, with oncogenic properties. If p53 responds to immediate genotoxic stress, its homologues participate to the cell homeostasis of specific tissues along their development and differentiation, neuronal tissue for p73, epithelial for p63. However a collaboration between the three p53 family members has been shown to occur in response to cell genotoxic damages. Neuroblastic tumors characterized by a large spectrum of neuronal differentiation constitute a good model to study relationship between p73 and p53 as well as the regulation of their respective expression.     

DNA-binding and transactivation activities are essential for TAp63 protein degradation

The p53-related p63 gene encodes six isoforms with differing N and C termini. TAp63 isoforms possess a transactivation domain at the N terminus and are able to transactivate a set of genes, including some targets downstream of p53. Accumulating evidence indicates that TAp63 plays an important role in regulation of cell proliferation, differentiation, and apoptosis, whereas transactivation-inert deltaNp63 functions to inhibit p63 and other p53 family members. Mutations in the p63 gene that abolish p63 DNA-binding and transactivation activities cause human diseases, including ectrodactyly ectodermal dysplasia and facial clefting (EEC) syndrome. In this study, we show that mutant p63 proteins with a single amino acid substitution found in EEC syndrome are DNA binding deficient, transactivation inert, and highly stable. We demonstrate that TAp63 protein expression is tightly controlled by its specific DNA-binding and transactivation activities and that p63 is degraded in a proteasome-dependent, MDM2-independent pathway. In addition, the N-terminal transactivation domain of p63 is indispensable for its protein degradation. Furthermore, the wild-type TAp63gamma can act in trans to promote degradation of mutant TAp63gamma defective in DNA binding, and the TA domain deletion mutant of TAp63gamma inhibits transactivation activity and stabilizes the wild-type TAp63 protein. Taken together, these data suggest a feedback loop for p63 regulation, analogous to the p53-MDM2 feedback loop.