P53、MDM2蛋白在宫颈癌中的表达及相关性研究

目的 探讨MDM2及p53蛋白在宫颈癌中表达及两者的相关性.方法 用免疫组织化学EnVision法,检测37例宫颈鳞癌(SCC)、16例宫颈腺癌(AUC)、45例宫颈上皮内瘤样变(CIN)及20例正常宫颈(NC)组织中MDM2及p53蛋白的表达.结果 p53蛋白在NC、CIN、AUC、SCC中的阳性率分别为0、26.67%(12/45)、68.75%(11/16)及59.46%(22/37),在AUC、SCC中的阳性率均明显高于NC及CIN组(P＜0.01、P＜0.01;P＜0.01、P＜0.01),在CIN组的阳性率明显高于NC组(P＜0.05);MDM2蛋白在NC、CIN、AUC、SCC中的阳性率分别为0、13.33%(6/45)、43.75%(7/16)及43.24%(16/37),在AUC、SCC组中的阳性率均明显高于NC及CIN组,差异有显著性(P＜0.01、P＜0.01;P＜0.05、P＜0.01);在CIN和SCC的p53 组中,MDM2 阳性率(41.67%、54.54%)明显高于p53组(3.03%、6.67%)(P＜0.01、P＜0.01),列联系数分别为0.503、0.610.结论 p53、MDM2蛋白的异常表达可能是宫颈癌中的基因事件,与宫颈癌的发生、发展密切相关;宫颈癌中p53和MDM2蛋白表达呈明显的正相关性.     

p53 as a drug target in cancer therapy

The tumour suppressor gene p53 is mutated in various human cancers. The loss of p53 function predisposes to cancer and it has been suggested that the efficacy of chemotherapy and radiotherapy depends on the presence of a functional p53. The central role of p53 in cancer has stimulated intense research activity and various strategies to identify new anticancer compounds that modulate the p53 pathway are currently under investigation. These approaches rely on very different principles. Some involve replacement gene therapy where p53 is reintroduced into tumour cells or engineered viruses that selectively eliminate cells with an altered p53 pathway. Others are based on the synthesis of new molecules that stabilise the structure of the mutant proteins or that activate either wild type or mutant proteins. Finally, others use antibodies that specifically interact with tumour cells. In this review, recent patent applications and the progress currently being made on these different approaches are analysed.     

Peptides and peptidomimetics in the p53/MDM2/MDM4 circuitry - a patent review

Introduction: Restoration of the p53 tumor suppressor function is an attractive anticancer strategy. Despite the development of several therapeutics targeting the two main p53 negative regulators, MDM2 and MDM4, no one has yet reached clinical application. In the past, several efforts have been employed to develop more specific and efficient compounds that can improve and/or overcome some of the features related to small molecule compounds (SMC). Peptides and peptidomimetics are emerging as attractive molecules given their increased selectivity, reduced toxicity and reduced tendency to develop tumor-resistance compared to SMC.

Area covered: This article reviews publications and patents (publicly available up to April 2016) for peptides and derivatives aimed to reactivate the oncosuppressive function of p53, with a particular focus on inhibitors of MDM2/MDM4. Emphasis is placed on the efficacy of these compounds compared to the p53-reactivating small molecules developed so far.

Expert opinion: A number of promising peptides for p53 reactivation in cancer therapy have been developed. These compounds appear to possess improved features compared to SMC, especially for their ability to simultaneously target the MDM2/MDM4 inhibitors, and their increased specificity.     

Translational approaches targeting the p53 pathway for anti-cancer therapy

The p53 tumour suppressor blocks cancer development by triggering apoptosis or cellular senescence in response to oncogenic stress or DNA damage. Consequently, the p53 signalling pathway is virtually always inactivated in human cancer cells. This unifying feature has commenced tremendous efforts to develop p53-based anti-cancer therapies. Different strategies exist that are adapted to the mechanisms of p53 inactivation. In p53-mutated tumours, delivery of wild-type p53 by adenovirus-based gene therapy is now practised in China. Also, remarkable progress has been made in the development of p53-binding drugs that can rescue and reactivate the function of mutant or misfolded p53. Other biologic approaches include the development of oncolytic viruses that are designed to specifically replicate in and kill p53-defective cells. Inactivation of wt-p53 frequently results from dysregulation of MDM2, an E3 ligase that regulates p53 levels. Small-molecule drugs that inhibit the interaction of MDM2 and p53 and block p53 degradation are currently tested in clinical trials. This survey highlights the recent developments that attempt to modulate the function of p53 and outlines strategies that are being investigated for pharmacological intervention in the p53 pathway.     

Small-molecule MDM2/X inhibitors and PROTAC degraders for cancer therapy: advances and perspectives

Blocking the MDM2/X–P53 protein–protein interaction has been widely recognized as an attractive therapeutic strategy for the treatment of cancers. Numerous small-molecule MDM2 inhibitors have been reported since the release of the structure of the MDM2–P53 interaction in 1996, SAR405838, NVP-CGM097, MK-8242, RG7112, RG7388, DS-3032b, and AMG232 currently undergo clinical evaluation for cancer therapy. This review is intended to provide a comprehensive and updated overview of MDM2 inhibitors and proteolysis targeting chimera (PROTAC) degraders with a particular focus on how these inhibitors or degraders are identified from starting points, strategies employed, structure–activity relationship (SAR) studies, binding modes or co-crystal structures, biochemical data, mechanistic studies, and preclinical/clinical studies. Moreover, we briefly discuss the challenges of designing MDM2/X inhibitors for cancer therapy such as dual MDM2/X inhibition, acquired resistance and toxicity of P53 activation as well as future directions.     

抗肿瘤药物研制的新靶点MDM2-p53

癌基因MDM2编码的蛋白可与抑癌蛋白p53结合并抑制p53的功能，促进p53的降解。MDM2的过度表达是肿瘤发生和发展的重要因素之一。本文简述了MDM2的结构与功能，MDM2与p53相互作用的机制与模式，以及根据MDM2－p53复合物结构研制开发抗肿瘤药物的进展与前景。     

Therapeutic targeting of the p53 pathway in cancer stem cells

Introduction: Cancer stem cells (CSCs) are a high profile drug target for cancer therapeutics due to their indispensable role in cancer progression, maintenance and therapeutic resistance. Restoring wild-type (WT) p53 function is an attractive new therapeutic approach for the treatment of cancer due to the well-described powerful tumor suppressor function of p53. As emerging evidence intimately links p53 and stem cell biology, this approach also provides an opportunity to target CSCs.

Areas covered: This review covers the therapeutic approaches to restore the function of WT p53, cancer and normal stem cell biology in relation to p53 and the downstream effects of p53 on CSCs.

Expert opinion: The restoration of WT p53 function by targeting p53 directly, its interacting proteins or its family members holds promise as a new class of cancer therapies. This review examines the impact that such therapies may have on normal and CSCs based on the current evidence linking p53 signaling with these populations.     

p53、Bcl-2表达与非小细胞肺癌放射治疗预后的相关分析

目的：探讨p53与Bcl-2基因表达与非小细胞肺癌放射治疗预后的关系。方法：回顾性分析58例接受单纯性放射治疗（15mv,dt=66～68Gy／33～34f／45～49d。SSD=100cm,剂量率为2Gy）的非小细胞肺癌肺癌的患者的生存时间与p53、Bcl-2表达的相关关系,应用SPSS10．0软件进行kaplan-meier生存分析,并用log-rank法进行检验,进一步应用COX-regression进行多因素分析。结果：p53、Bcl-2的表达与非小细胞肺癌放疗预后呈负相关关系。结论：p53、Bcl-2是预测非小细胞肺癌患者放射治疗预后有意义的临床指标。     

Cell death and growth arrest in response to photodynamic therapy with membrane-bound photosensitizers

Photodynamic therapy (PDT) is a treatment for cancer and for certain benign conditions that is based on the use of a photosensitizer and light to produce reactive oxygen species in cells. Many of the photosensitizers currently used in PDT localize in different cell compartments such as mitochondria, lysosomes, endoplasmic reticulum and generate cell death by triggering necrosis and/or apoptosis. Efficient cell death is observed when light, oxygen and the photosensitizer are not limiting ("high dose PDT"). When one of these components is limiting ("low dose PDT"), most of the cells do not immediately undergo apoptosis or necrosis but are growth arrested with several transduction pathways activated. This commentary will review the mechanism of apoptosis and growth arrest mediated by two important PDT agents, i.e. pyropheophorbide and hypericin.     

Activated kRas protects colon cancer cells from cucurbitacin-induced apoptosis: the role of p53 and p21

Cucurbitacins have been shown to inhibit proliferation in a variety of cancer cell lines. The aim of this study was to determine their biological activity in colon cancer cell lines that do not harbor activated STAT3, the key target of cucurbitacin. In order to establish the role of activated kRas in the responsiveness of cells to cucurbitacins, we performed experiments in isogenic colon cancer cell lines, HCT116 and Hke-3, which differ only by the presence of an activated kRas allele. We compared the activity of 23, 24-dihydrocucurbitacin B (DHCB) and cucurbitacin R (CCR), two cucurbitacins that we recently isolated, with cucurbitacin I (CCI), a cucurbitacin with established antitumorigenic activity. We showed that cucurbitacins induced dramatic changes in the cytoskeleton (collapse of actin and bundling of tubulin microfilaments), inhibited proliferation and finally induced apoptosis of both HCT116 and Hke-3 cells. However, the presence of oncogenic kRas significantly decreased the sensitivity of cells to the three cucurbitacins tested, CCR, DHCB and CCI. We confirmed that mutational activation of kRas protects cells from cucurbitacin-induced apoptosis using nontransformed intestinal epithelial cells with inducible expression of kRasV12. Cucurbitacins induced the expression of p53 and p21 predominantly in HCT116 cells that harbor mutant Ras. Using HCT116 cells with targeted deletion of p53 or p21 we confirmed that p53 and p21 protect cells from apoptosis induced by cucurbitacins. These results demonstrated that sensitivity of human colon cancer cell lines to cucurbitacins depends on the kRas and p53/p21 status, and established that cucurbitacins can exert antitumorigenic activity in the absence of activated STAT3.     

p27和p53在乳腺癌中的表达及意义

目的研究p27和p53在乳腺癌表达的意义。方法以免疫组化法分别检测56例乳腺癌和36例乳腺良性肿瘤患者p27及p53的表达水平。结果（1）p27和p53均与乳腺癌的TNM分期相关。p27的表达水平还与p53相关。（2）生存率的比较分析结果,p27高表达组5年无病生存率为91．9％,明显优于低表达组（42．1％）（P〈0．01）,p53高表达组5年无病生存率为61．3％,明显低于低表达组（92．0％）（P〈0．01）。结论检测p27和p53对乳腺癌的预后有重要价值。     

p53–Mdm2 inhibitors: patent review (2009 – 2010)

Introduction: p53 plays a central role in protecting the integrity of the genome. Its activity is ubiquitously lost in cancers, either by inactivation of its protein (p53 pathway) or by mutation in the p53 gene, thereby indicating its importance in understanding cancer and as a therapeutic target. Activated p53 is known to induce cell cycle arrest thereby leading to apoptosis and has been the subject of intensive research in the area of medicinal chemistry. Efforts are in progress to synthesize a variety of scaffolds that could inhibit the p53–Mdm2 interaction by binding to Mdm2 in the region where p53 is likely to bind. These molecules have the potential to be developed as anticancer drug candidates and have been largely explored by both academia and industry. Interestingly, some of these molecules are in the early stage of clinical trials.

Areas covered: Areas covered in this review include patents relating to p53–Mdm2 inhibitors during the time period 2009 – 2010. The focus of the review was on small-molecule inhibitors.

Expert opinion: Inducing apoptosis in cancerous cells by the activation of p53 is an area that is being actively explored. There are strong indications that it could become a therapeutic method for the treatment of cancer. As a result, extensive research is being performed by both academia and industry. It is observed that small molecules that are present in early clinical trials are expected to be developed as potential drugs for cancer therapy.     

结直肠癌bcl-2、p53蛋白的表达

目的 了解bcl-2,p53蛋白表达与结直肠癌的关系。寻求早期诊断结直肠癌的分子生物学参考指标。方法 采用免疫组织化学S-P法检测63份结直肠癌手术切除标本中bcl-2,p53的表达情况,观察其在癌组织中的表达状态,分析其与结直肠癌变的关系及对预后的影响。结果 63位结直肠癌标本中bcl-2蛋白表达为77.8%,p53蛋白的表达为63.5%。结论 bcl-2,p53蛋白的表达与结直肠癌的发生、发展及预后有密切关系,可作为早期诊断结直肠癌的重要参考指标。     

p53 dependent and independent sensitivity to oxaliplatin of colon cancer cells

Oxaliplatin is an efficient chemotherapeutic agent used for the treatment of metastatic human colon cancer, but cancer cells are frequently resistant. The aim of this study was to analyse the underlying mechanisms in a panel of 10 human colorectal cancer cell lines submitted to a short (2h) oxaliplatin treatment period, accordingly to the usual therapeutic procedure in humans. Sensitivity to oxaliplatin was a characteristic of p53 wild-type colon cancer cells. In contrast, all p53-mutated cell lines had a high IC50 to oxaliplatin, with the exception of the V9P cell line. Exposure to oxaliplatin resulted in G0/G1 arrest in p53 wild-type cell lines, and in S phase in p53-mutated cell lines. In our treatment conditions, no DNA accumulation in sub G0/G1 phase, no caspase-3 activation nor PARP cleavage were detected after oxaliplatin treatment, except for the V9P cell line. The major role of the p53-p21 pathway in oxaliplatin sensitivity was confirmed in the p53 wild-type HCT116 cell line, using siRNA duplex, and knockdown of the TAp73 protein also enhanced resistance to oxaliplatin in this cell line. Surprisingly, siRNA duplex invalidation revealed a residual effect of the mutant p53 protein in p53-mutated cell lines. Persistent sensitivity to oxaliplatin of the p53-mutated V9P cell line was associated with oxalipatin-induced apoptosis but TAp73 was not the responsible alternative pathway.     

p53和c-erbB-2的表达阳性率与胃癌浸润深度的关系

目的探讨p53和c-erbB-2的表达阳性率与胃癌浸润深度的关系。方法收集139例胃癌手术切除标本,包括黏膜内癌23例、浸润至黏膜下层31例、浸润至肌层47例、浸润至浆膜或浆膜外38例,切片采用免疫组化S-P法染色。结果p53和c-erbB-2的阳性表达分别从肿瘤局限于黏膜内和侵及黏膜下层时开始出现。不同浸润深度的胃癌中p53的阳性率比较,仅黏膜内癌组和浸润至浆膜或浆膜外组（P〈0.01）及浸润至黏膜下层组和浸润至浆膜或浆膜外组存在显著差异性（P〈0.05）,其余均无统计学意义。而各组c-erbB-2的表达阳性率比较均存在显著差异性（P〈0.01）。c-erbB-2表达阳性率与p53存在相关性（P〈0.05）。p53和c-erbB-2的不同表达方式中,浸润深度p53＋c-erbB-2＋组或p53-c-erbB-2＋组〉p53＋c-erbB-2-组〉p53-c-erbB-2-组（P〈0.05）,但p53＋c-erbB-2＋组与p53-c-erbB-2＋组比较无统计学意义（P〉0.05）。结论p53和c-erbB-2在胃癌中的表达不是同步的,p53突变有利于c-erbB-2的表达。在胃癌的浸润中,癌基因c-erbB-2突变或者抑癌基因p53突变是独立发挥作用的,并且二者没有明显的协同作用;表达c-erbB-2的胃癌病例比表达p53的病例更具有侵袭性。     

新型光敏剂CDHS801光动力学治疗T24细胞膀胱癌动物模型作用研究

目的研究光敏剂CDHS801体内光动力治疗膀胱癌机理。方法T24细胞悬液裸鼠皮下注射制备膀胱癌裸鼠动物模型后,灌胃给予CDHS801,12h后激光照射肿瘤后处死动物,取瘤体进行HE染色、Tahel染色及电镜观察。结果激光照射后6h,肿瘤表面皮肤水肿,浅表血管扩张充血。HE染色发现肿瘤血管充血、血管形成血栓、大片区域肿瘤细胞变形坏死,TUNEL染色发现肿瘤细胞核内出现棕黄色颗粒,电镜提示细胞核内染色质浓集、边集于核膜下并出现新月体样变化,伴有线粒体肿胀、膜破裂、嵴断裂或消失等现象。结论CHDS801光动力学体内治疗膀胱癌,诱导肿瘤发生凋亡是其杀灭肿瘤的主要机理。     

240例乳腺癌组织中p53、C-erbB-2表达的临床分析

目的 探讨乳腺癌组织中p53、C-erbB-2表达及临床意义.方法 对免疫组织化学染色SP法检测240例乳腺癌组织石腊切片上p53、C-erbB-2的表达结果进行回顾性分析.结果 p53和C-erbB-2阳性表达率分别为53.3%和63.3%;阳性产物主要位于细胞核中,p53和C-erbB-2的表达与肿瘤组织分级、淋巴结转移呈显著相关(P＜0.05),与PR、ER无显著相关.结论 p53和C-erbB-2与乳腺癌的发生发展密切相关,可作为判断肿瘤浸润转移、指导治疗和估计预后的参考指标.特别是p53的表达水平及淋巴结转移是判断乳腺癌预后的独立有效指标.     

Diepoxybutane induces caspase and p53-mediated apoptosis in human lymphoblasts

Diepoxybutane (DEB) is the most potent metabolite of the environmental chemical 1,3-butadiene (BD), which is prevalent in petrochemical industrial areas. BD is a known mutagen and human carcinogen, and possesses multiorgan systems toxicity that includes bone marrow depletion, spleen, and thymus atrophy. Toxic effects of BD are mediated through its epoxy metabolites. In working towards elucidating the cellular and molecular mechanisms of BD toxicity, we investigated the ability of DEB to induce apoptosis in human lymphoblasts. DEB induced a concentration and exposure time-dependent apoptosis, which accounted for the DEB-induced loss of cell viability observed in TK6 lymphoblasts. The DEB-induced apoptosis was inhibited by inhibitors of caspases 3 and 9. The role of p53 in mediating the DEB-induced apoptosis was also investigated. DEB induced elevated p53 levels in direct correlation to the extent of DEB-induced apoptosis, as the concentration of DEB increased up to 5 microM. The extent of DEB-induced apoptosis was dramatically higher in TK6 lymphoblasts as compared to the genetically paired p53-deficient NH32 lymphoblasts under the same experimental conditions. Our results confirm and extend observations on the occurrence of apoptosis in DEB exposed cells, and demonstrate for the first time the elevation of p53 levels in human lymphoblasts in response to DEB exposure. In addition, our results demonstrate for the first time that DEB-induced apoptosis is mediated by caspases 3 and 9, as well as the p53 protein. It is possible that DEB-induced apoptosis may explain BD-induced bone marrow depletion, spleen and thymus atrophy in BD-exposed animals.