Drug-resistant human bladder-cancer cells are more sensitive to adenovirus-mediated wild-type p53 gene therapy compared to drug-sensitive cells.

We investigated the therapeutic potential and molecular mechanism of adenovirus-mediated wt p53 gene therapy for drug-resistant human bladder cancers. KK47, a human bladder-cancer cell line, along with the drug-resistant sublines KK47/DDP10, KK47/DDP20 (cisplatin-resistant) and KK47/ADM (doxorubicin-resistant) were used for the experiments. All 4 KK47 cell lines had genetically normal p53 genes. Using an in vitro cytotoxicity assay, the drug-resistant cell lines were more sensitive to Ad-CMV-p53 cell killing than the KK47 parental cell line. Ad-CMV-p53 induced higher levels of p53 protein and mRNA in the drug-resistant cell lines than in the parental cell line and, consequently, higher levels of p21 and Bax mRNA, which resulted in higher percentages of G(1) cell-cycle arrest and apoptosis. The higher efficiencies of adenoviral gene transfer in the drug-resistant cell lines were confirmed by X-gal staining after infection with Ad-CMV-beta-gal. In conclusion, adenovirus-mediated wt p53 gene therapy was more effective in the drug-resistant bladder-cancer cell lines than in the drug-sensitive bladder-cancer cell line.     

The p53 tumor suppressor gene in breast cancer

Summary Alterations of the p53 tumor suppressor gene are the most common genetic changes found so far in breast cancer, suggesting that the gene plays a central role in the development of the disease. p53 functions as a negative regulator of cell growth, and alterations in the gene lead to loss of this negative growth regulation and more rapid cell proliferation. A number of independent groups using different methods of detection have shown that p53 alterations are associated with more aggressive tumor biologic factors and a poorer prognosis in breast cancer patients. Because of its possible role in the regulation of apoptosis and response to DNA damage, p53 status could also be a predictive marker for response to hormonal or chemotherapy.     

Proteasome inhibition mediates p53 reactivation and anti-cancer activity of 6-Gingerol in cervical cancer cells

Human papilloma virus (HPV) expressing E6 and E7 oncoproteins, is known to inactivate the tumor suppressor p53 through proteasomal degradation in cervical cancers. Therefore, use of small molecules for inhibition of proteasome function and induction of p53 reactivation is a promising strategy for induction of apoptosis in cervical cancer cells. The polyphenolic alkanone, 6-Gingerol (6G), present in the pungent extracts of ginger (Zingiber officinale Roscoe) has shown potent anti-tumorigenic and pro-apoptotic activities against a variety of cancers. In this study we explored the molecular mechanism of action of 6G in human cervical cancer cells in vitro and in vivo. 6G potently inhibited proliferation of the HPV positive cervical cancer cells. 6G was found to: (i) inhibit the chymotrypsin activity of proteasomes, (ii) induce reactivation of p53, (iii) increase levels of p21, (iv) induce DNA damage and G2/M cell cycle arrest, (v) alter expression levels of p53-associated apoptotic markers like, cleaved caspase-3 and PARP, and (vi) potentiate the cytotoxicity of cisplatin. 6G treatment induced significant reduction of tumor volume, tumor weight, proteasome inhibition and p53 accumulation in HeLa xenograft tumor cells in vivo. The 6G treatment was devoid of toxic effects as it did not affect body weights, hematological and osteogenic parameters. Taken together, our data underscores the therapeutic and chemosensitizing effects of 6G in the management and treatment of cervical cancer.     

乳腺增生病p53基因第8外显子突变及p53蛋白表达

目的：探讨p53基因在乳腺癌发生早期的作用。方法：用免疫组化检测36例乳腺单纯增生，31例不典型增生，30例乳腺癌组织中p53蛋白表达，用PCR－RFLP检测p53基因第8外显子第278密码子突变。结果：乳腺单纯性增生，不典型增生和乳腺癌中p53蛋白表达率分别为0，22．6％，46．7％。p53基因第8外显子的突变率分别为0，3．2％，10．0％，均为杂合子突变。结论：乳腺癌不典型增生中存在p53蛋白表达和该基因第8外显子突变，该突变可能在乳腺增生病向乳腺癌进展过程中起一定作用。     

腺病毒介导的野生型p53基因对肺腺癌细胞株生长的抑制作用

为研究野生型p53基因对肺腺癌细胞株GLC-82细胞生长的作用,确立腺病毒介导的野生型p53基因在肿瘤治疗中的意义,应用分子克隆技术首先构建了野生型p53复制缺陷型腺病毒重组体,应用生化染色方法确定了重组体的转染效率,以免疫组化法及PCR技术分别确定了腺病毒载体介导的p53基因转染GLC-82细胞后p53蛋白和p53 cDNA的表达情况;最后应用细胞生物学方法检测了p53对GLC-82细胞扩增及细胞周期的影响.结果表明所构建的重组体可以高效、快速转染GLC82细胞,抑制GLC-82细胞扩增,使细胞合成期和分裂后期的量减少,出现细胞凋亡现象:提示野生型p53基因导入可作为治疗肺腺癌的途径之一     

重组腺病毒p53基因治疗肝癌研究进展

目的：探讨重组腺病毒p53基因（recombinant humanAd—p53,rAd—p53）治疗肝癌的抗肿瘤机制及临床应用。方法：应用PubMed、万方和CNKI数据库,以“肝癌、重组腺病毒p53基因、基因治疗、实验研究和临床应用”为关键词,检索1994—06—01—2013—11—31文献739篇,纳入标准：1）p53基因与肝癌发生的相关性;2）重组腺病毒p53基因抗肿瘤机制;3）重组腺病毒p53治疗肝癌的实验研究;4）重组腺病毒p53治疗肝癌的临床应用研究。根据纳入标准选择符合分析的文献36篇。结果：p53基因是公认的肿瘤抑制基因,具有促使肿瘤细胞自杀和帮助缺陷细胞修复的作用。rAd—p53是复制缺陷型5型腺病毒载体与人p53基因重组的肿瘤基因治疗制品。rAd-p53通过多种途径发挥抗肿瘤作用,包括使肿瘤的细胞周期阻滞和发生程序性死亡,促进放射线对肿瘤细胞引起的细胞周期阻滞和凋亡,刺激机体产生抗肿瘤免疫反应,抑制肿瘤血管内皮生长因子,控制肿瘤的血管生成,使注射部位瘤组织产生局部血供障碍和坏死。此外,还能增加肝癌细胞的放化疗敏感性,间接增强抗肿瘤疗效。rAd-p53基因疗法为肝癌治疗开辟了崭新的途径,多项-l盘床研究疗效良好。结论：rAd—p53基因对肿瘤的作用机制体现了在抗肿瘤治疗方面的有效性,并在基础研究及临床应用中均取得了显著进展,再肝癌的防治中将取得更大的突破。     

Reactivating p53 functions by suppressing its novel inhibitor iASPP: a potential therapeutic opportunity in p53 wild-type tumors

Although mutational inactivation of p53 is found in 50% of all human tumors, a subset of tumors display defective p53 function, but retain wild-type (WT) p53. Here, direct and indirect mechanisms leading to the loss of WT p53 activities are discussed. We summarize the oncogenic roles of iASPP, an inhibitor of WT p53, in promoting proliferation, invasion, drug or radiation-resistance and metastasis. From the therapeutic view, we highlight promising perspectives of microRNA-124, peptide and small molecules that reduce or block iASPP for the treatment of cancer. High iASPP expression enhances proliferation, aggressive behavior, the resistance to radiation/chemotherapy and correlates with poor prognosis in a range of human tumors. Overexpression of iASPP accelerates tumorigenesis and invasion through p53-dependent and p53-independent mechanisms. MicroRNA-124 directly targets iASPP and represses the growth and invasiveness of cancer cells. The disruption of iASPP-p53 interaction by a p53-derived peptide A34 restores p53 function in cancer cells. The inhibition of iASPP phosphorylation with small molecules induces p53-dependent apoptosis and growth suppression. The mechanisms underlying aberrant expression of iASPP in human tumors should be further investigated. Reactivating WT p53 functions by targeting its novel inhibitor iASPP holds promise for potential therapeutic interventions in the treatment of WT p53-containing tumors.     

Therapeutic potential of recombinant p53 overexpression in breast cancer cells expressing endogenous wild-type p53

Reconstitution of the p53-dependent apoptotic pathway by gene transfer of a recombinant wild-type p53 minigene leads to rapid apoptotic cell death in breast and other cancer cell types expressing null or mutant p53. Tumour cells expressing wild-type p53 have been reported to be more resistant to this treatment strategy, presumably as a result of mutations in downstream regulators of p53-dependent apoptotic signalling. The MCF-7 breast cancer cell line is representative of this class of tumour cell. Our recent observation of a p53-dependent apoptotic response following adenovirus-mediated HSV thymidine kinase gene transfer and gancyclovir treatment led us to reexamine recombinant p53 cytotoxicity in MCF-7 cells. Infection with a recombinant adenovirus expressing wild-type p53 resulted in a dramatic increase in p53 protein levels and was accompanied by an increase in p21^{WAF 1/CIP1} protein levels and G1 arrest within 24 hours post-infection. A significant decrease in MCF-7 cell viability was first observed at 5 days post-infection and coincided with the appearance of morphological and biochemical changes consistent with apoptotic cell death. By day 7 post-treatment, cell viability decreased to 45% and clonogenic survival was reduced to 12% of controls. The results demonstrate that persistent, high level expression of recombinant p53 can induce programmed cell death in MCF-7 cells. While the mechanism by which p53 overexpression overcomes the defect in downstream apoptotic signalling is not clear, our data suggests that this treatment strategy may be beneficial for the class of tumour cells represented by the MCF-7 cell line.     

Small molecule restoration of wildtype structure and function of mutant p53 using a novel zinc-metallochaperone based mechanism

NSC319726 (ZMC1) is a small molecule that reactivates mutant p53 by restoration of WT structure/function to the most common p53 missense mutant (p53-R175H). We investigated the mechanism by which ZMC1 reactivates p53-R175H and provide evidence that ZMC1: 1) restores WT structure by functioning as a zinc-metallochaperone, providing an optimal concentration of zinc to facilitate proper folding; and 2) increases cellular reactive oxygen species that transactivate the newly conformed p53-R175H (via post-translational modifications), inducing an apoptotic program. We not only demonstrate that this zinc metallochaperone function is possessed by other zinc-binding small molecules, but that it can reactivate other p53 mutants with impaired zinc binding. This represents a novel mechanism for an anti-cancer drug and a new pathway to drug mutant p53.Significance: We have elucidated a novel mechanism to restore wild-type structure/function to mutant p53 using small molecules functioning as zinc-metallochaperones. The pharmacologic delivery of a metal ion to restore proper folding of a mutant protein is unique to medicinal chemistry and represents a new pathway to drug mutant p53.     

Adenovirus-mediated p53 gene delivery potentiates the radiation-induced growth inhibition of experimental brain tumors

Patients with malignant gliomas continue to have very poor prognosis even after surgical resection, radiation and chemotherapy. Because these tumors often have alterations in the p53 tumor suppressor gene, which plays a key role in the cellular response to DNA damaging agents, we investigated the role of p53 gene therapy in conjunction with ionizing radiation in a rat brain tumor model. Exposure of cultured rat 9L gliosarcoma cells, which contain a mutant p53 gene, to a recombinant adenovirus-vector bearing the wild-type p53 gene (Adp53), induced apoptosis within 24 hours. Although ionizing radiation had no additional effect on apoptosis within this time frame, it caused G₁ arrest in non-apoptotic cells after Adp53 therapy. In contrast, wild-type 9L cells demonstrated little G₁ arrest after X-irradiation. When animals bearing brain tumors were irradiated after intratumoral Adp53 injections, more than 85% reduction in tumor size was noted. Moreover, the group of rats receiving both radiation and Adp53 therapy had a significant increase in survival as compared to animals receiving either therapy alone. These results support the use of p53 gene therapy as an adjunct to radiation in treatment of malignant brain tumors.     

胃癌患者p53基因甲基化的研究

作者应用限制性内切酶ＨｐａⅡ和ＭｓｐⅠ酶切胃癌组织及正常胃组织ＤＮＡ，经ＰＣＲ扩增ｐ５３基因第５外显子，琼脂糖凝胶电泳分析其电泳图谱，比较胃癌组织及正常胃组织ｐ５３基因第５外显子特定序列５′－ＣＣＧＧ－３′位点甲基化差异。结果显示：１５例胃癌组织中１２例ｐ５３基因第５外显子出现高甲基化状态，而１０例正常胃组织为低甲基化状态，结果提示，ｐ５３基因高甲基化状态与胃癌发生有关。     

Suppression of ATAD2 inhibits hepatocellular carcinoma progression through activation of p53- and p38-mediated apoptotic signaling

The ATPase family, AAA domain containing 2 (ATAD2) is highly expressed in multiple cancers. We aim to understand the clinical and biological significance of ATAD2 over-expression in hepatocellular carcinoma (HCC), as a means to validate it as a therapeutic target in HCC. We demonstrated that ATAD2 was over-expressed in HCC patients, where high ATAD2 levels were significantly correlated with aggressive phenotypes such as high AFP levels, advanced tumor stages, and vascular invasion. Using RNA interference, suppression of ATAD2 in HCC cell lines decreased cell viability, migration, and invasion, and induced apoptosis in vitro. Furthermore, we identified p53 and p38 as key proteins that mediate apoptosis induced by ATAD2 suppression. In HCC cells, we demonstrated that ATAD2 directly interacted with MKK3/6, which prevented p38 activation and therefore inhibited p38-mediated apoptosis. In vivo, suppression of ATAD2 impaired the growth of HepG2 and Hep3B subcutaneous xenografts, accompanied by enhanced apoptosis and p-p53 and p-p38 levels. Our results validate that ATAD2 is an important negative regulator of apoptosis, and that neutralizing its activity has promising anti-tumor effects in HCC cells.     

抑癌基因p53在胃癌组织的表达及临床意义

目的：探讨ｐ５３基因在胃癌的表达与临床、病理因素及预后的关系,探索ｐ５３基因异常表达在胃癌发生过程中的作用。方法：使用抗ｐ５３蛋白单克隆抗体ＤＯ－７,对９９例人胃癌组织ｐ５３的表达进行免疫组化研究。结果：４８例胃癌组织ｐ５３基因表达阳性（４９％）。ｐ５３基因表达与胃癌的大体类型、分化工、淋巴结转移等指标均无明显关系。在１０例不典型增生的癌旁组织中,２例呈阳性反应;在４例有肠上皮化生的癌旁组织中及其     

乳腺癌中的p53基因mRNA高表达的研究

应用反转录-半定量PCR技术检测47例乳腺癌组织中p53基因mRNA表达，并与临床预后因素进行统计学分析。结果发现：在乳腺正常腺体中有稳定的p53mRNA中度表达，而在乳腺癌组织中，p53mRNA呈高表达者为40．4％（19／47），且以在ER阴性的乳腺癌中增高明显（P＜0．05）。本文提示：p53基因在人类乳腺癌形成和肿瘤演进过程中起重要的作用，p53mRNA高表达的病人浸润性强、预后差。反转录一半定量PCR技术具有快速、简单、敏感可适于临床大规模应用之优点。     

检测肺癌患者血清p53抗体的临床意义

目的:探讨检测肺癌患者血清p53抗体的临床意义。方法:采用酶联免疫吸附法检测120例肺癌患者血清p53抗体,并以30例肺部良性疾病患者和120例正常健康人作对照。结果:肺癌患者血清p53抗体水平明显高于肺部良性疾病患者和正常人(P<0.05),而正常人与肺部良性疾病患者间无显著性差异(P>0.05)。120例肺癌中26例p53抗体阳性,阳性率为21.7%,而30例肺部良性疾病患者和120例正常人无1例阳性。肺癌者血清p53抗体与肺癌细胞分化程度和临床分期有密切关系(P<0.01)。结论:检测血清p53抗体水平有助于肺部良恶性疾病的诊断及鉴别诊断。     

Growth inhibition of human laryngeal cancer cell with the adenovirus-mediated p53 gene

Mostmalignanciesarediseasegeneratedwithaprocessofgeneticalteration.Basedonthistheory,newapproachestocancertherapyarebeingdevel0ped.Oneoftheseisgenetherapy.Amongthegeneshavingtherapeuticpotentialforcancertreatment,thep53tumorsuppressorgenehasbeenmostextensivelystudied.[l]Wild-typep53hasbeenshownt0beinvolvedintranscirptionalregulation.ItarrestscellsattheGllScheckpoint,blocksDNAreplicati0nandinducesap0ptosis."'Recentstudieshavesh0wnthatwild-typep53genecansuppressthegrowthofsomehumancancercelll…