胃癌组织中p53基因突变及p53和mdm2蛋白表达的研究

目的探讨mdm2和p53基因异常在胃癌发生发展中的作用以及两者相关性。方法应用免疫组化技术检测58例胃癌组织以及相应癌旁组织中mdm2和p53蛋白的表达;PCR-SSCP银染技术检测p53基因exon5~8突变情况。结果胃癌组p53和mdm2蛋白阳性率分别为86·21%(50/58)和29·31%(17/58),癌旁组织组p53和mdm2蛋白均为阴性,胃癌组p53和mdm2蛋白阳性率明显高于癌旁组织组,两两间差异有统计学意义,P=0·0000、P=0·0001。胃癌组织中p53和mdm2蛋白表达率与肿瘤大小、组织学类型、分化程度、淋巴结转移以及患者年龄等无显著相关性,P>0·05。mdm2蛋白阳性表达与p53蛋白过表达呈显著正相关,χ2=11·1839,P=0·0008,r=0·4391。2例胃癌组织检测到p53基因突变,突变均位于exon5,58例相应癌旁组织均未检测到p53基因突变。结论mdm2和p53蛋白异常表达与胃癌发生有关,p53基因突变可能并非胃癌组织中p53蛋白异常累积的主要原因,mdm2蛋白在胃癌发生发展中的作用可能与p53蛋白密切相关。     

EB病毒相关胃癌与mdm2，p53及p21基因异常的研究

 目的 探讨p53基因突变以及mdm2，p53和p21蛋白表达异常在EBV相关胃癌（EBVaGC）发生发展中的作用。方法 应用免疫组化技术检测13例EBVaGC、45例临床病理资料与之匹配的EBV阴性胃癌（EBVnGC）组织中 mdm2，p53和p21蛋白的表达；PCR-SSCP银染技术结合DNA序列分析检测p53基因exon 5~8突变；RT-PCR检测EBV相关基因的表达。结果 E-BVaGC组与EBVnGC组相比，两组间mdm2，p53和p21蛋白的阳性检出率差异无统计学意义（P = 0.830 0；P = 0.791 2；P = 0.353 1），但EBVaGC组p53蛋白过表达率（15.38 %）明显低于EBVnGC组（57.78 %），两组间差异有统计学意义（P = 0.008 5）。mdm2蛋白阳性表达与p53蛋白过表达呈显著正相关（P = 0.000 8，r = 0.439 1）；p21与p53蛋白共同表达率较高，但经计数资料相关性统计学分析表明两者无显著相关性（P = 0.2501，r = 0.202 5）。2例EBVnGC检测到p53基因突变，突变均位于exon 5，13例E-BVaGC和58例相应癌旁组织均未检测到p53基因突变。13例EBVaGC核抗原基因EBNA1均为阳性，潜伏膜蛋白基因LMP1均为阴性，即刻早期基因BZLF1，早期基因BARF1和BHRF1阳性率分别为46.15 %（6／13），46.15 %（6／13）和15.38 %（2／13），三者与EBVaGC组织中mdm2，p21和p53蛋白的表达均无显著相关性（P＞0.05）。 结论 EBV感染以及mdm2，p53和p21蛋白表达异常与胃癌发生有关； p53基因突变可能并非胃癌组织中p53蛋白异常累积的主要原因；胃癌组织中EBV感染与p53蛋白的异常表达有关，而与mdm2和p21蛋白的异常表达以及p53基因突变无显著相关性。     

宫颈鳞癌组织中p53和mdm2蛋白异常表达研究

[目的]探讨p53和mdm2基因异常在宫颈癌发生发展中的作用以及两者间的相互关系.[方法]应用PCR-SSCP和免疫组化技术检测12例宫颈原位癌、45例宫颈癌和20例正常宫颈组织中p53基因突变以及p53和mdm2蛋白表达.[结果]①45例宫颈癌标本中测得exon 5和exon 7突变各1例,合计突变率为4.44%,宫颈原位癌和正常宫颈组织中均未检测到p53基因突变.②宫颈原位癌组织中p53和mdm2蛋白阳性率分别为25.00%和41.67%;宫颈癌组织中p53和mdm2蛋白阳性率分别为42.22%和53.33%.宫颈原位癌和宫颈癌组织中p53和mdm2蛋白的阳性率明显高于正常宫颈组织(P均<0.05).③p53蛋白的表达与宫颈癌临床分期有显著相关性(P=0.042).④22例p53蛋白阳性宫颈原位癌和宫颈癌组织中有17例同时检测到mdm2的表达,两者间有显著相关性(X2=9.988,P=0.0016).[结论]宫颈癌组织中p53基因突变率较低,提示p53基因突变并非宫颈癌组织中p53蛋白异常表达的主要原因.p53蛋白异常表达的宫颈原位癌和宫颈癌组织中多伴有mdm2表达,推测mdm2蛋白可能通过干扰p53的功能参与宫颈癌的发生.     

EBV相关胃癌与P53基因异常的研究

[目的]探讨EBV感染和p53基因异常在胃癌发生发展中的病因学作用.[方法]应用免疫组化技术检测13例EBV相关胃癌(EBV associated gastric carcinoma,EBVaGC),45例临床指标与之匹配的EBV阴性胃癌(EBV negative gastric carcinoma,EBVnGC)以及58例相应癌旁组织中p53蛋白的表达;PCR-SSCP银染技术检测p53基因exon 5～8突变情况.[结果]①胃癌组p53蛋白阳性率为86.2%(50/58),而相应癌旁组织均为阴性,胃癌组p53蛋白的阳性率明显高于癌旁组织组,两组间有极显著性差异(P=0.0000).②EBVnGC p53蛋白阳性率为86.7%(39/45),过表达率为57.8%(26/45);EBVaGC p53蛋白阳性率为84.6%(11/13),过表达率仅为15.4%(2/13).两组间p53蛋白的阳性检出率无明显差异(P=0.7912),但EBVaGC组p53蛋白过表达率明显低于EBVnGC组,两组间有显著性差异(P=0.0085).③2例EBVnGC检测到p53基因突变,突变均位于exon 5,13例EBVaGC和58例相应癌旁组织均未检测到p53基因突变.[结论]p53基因异常与胃癌的发生密切相关,EBVaGC组织中存在p53蛋白的表达和过表达,但p53蛋白的异常累积可能并非p53基因突变所致.     

胃癌中p27、p53蛋白及TGF—βRⅡ的关系和预后意义

目的：探讨p27、p53蛋白及TβRⅡ在胃癌中的表达关系和预后意义。方法：用免疫组化法同步检测人胃癌组织中27,p53,TβRⅡ的表达。结果：62例胃癌中p27蛋白失表达率为58．1％，高于胃癌旁组织20.0%;p53和TβRⅡ阳性率在胃癌中分别为43．5％和17．7％，而癌旁组织分别为0和50％。p27阳性组的p53,TβRⅡ阳性率（分别为65.4%,31.0%)显著高于p27阴性组（P＜0．05),p27与p53及TβRⅡ呈正相关；而p53与TβRⅡ差异无显著性（P＞0．05）。Kaplan-Meier曲线显示p27,TβRⅡ阴性组及p53阳性组患者的预后较对照组差（P＜0．05），Cox回归模型分析显示，p27与预后弱相关（P=0.0561),p53和TβRⅡ与预后密切相关（P＜0．05）。结论：p27,p53,TβRⅡ相互作用，对胃癌发生发展起重要作用；p27和TβRⅡ表达愈强,p53表达愈弱，说明预后较好，反之则差。联合检测p27,p53，TβRⅡ，可辅助胃癌诊断，估计预后，选择治疗方案。     

食管鳞癌组织中p53与p27及mdm2蛋白的表达及其意义

目的:探讨癌基因蛋白p53、p27及mdm2在食管鳞癌组织中的表达及其意义。方法:采用免疫组织化学EnVision二步法对85例食管鳞癌及其癌旁组织进行p53、p27及mdm2蛋白表达的检测。结果:85例食管鳞癌组织中p53阳性表达率为70·6%(60/85),癌旁组织为75·0%(39/52);p27与mdm2蛋白在癌组织中的阳性率分别为72·9%(62/85)和83·5%(71/85),明显高于癌旁组织的34·6%(18/52)和53·8%(28/52),P<0·05;且从鳞状上皮非典型增生→原位癌→鳞癌的发展过程中,p27蛋白的阳性表达率逐渐上升。p27蛋白阳性表达与组织学分级呈正相关,r=0·234,P<0·05;而mdm2阳性表达与组织学分级呈负相关,r=-0·272,P<0·05;三者阳性表达率均与浸润深度及淋巴结转移无关,P>0·05;p53与p27和mdm2蛋白的表达无相关性,P>0·05。结论:检测p53、p27及mdm2蛋白在食管鳞癌的表达有助于了解食管癌的发生发展以及推断临床预后。     

凋亡抑制蛋白Survivin在胃癌中的表达及其与bcl-2、p53蛋白相关性研究

目的：研究凋亡抑制蛋白Survivin、bcl-2、p53在胃癌组织中的表达及其与临床病理特征之间的关系，并探讨Survivin与bcl-2、p53蛋白表达的相关性。方法：采用链霉菌抗生物素蛋白-过氧化酶连接（S-P）免疫组化方法，检测Survivin、bcl-2、p53蛋白在正常胃粘膜组织及胃癌组织中的表达。结果：Survivin蛋白在正常胃粘膜组织中无表达，而在58例胃癌中41例（70．7％）表达阳性，差异有统计学意义（P〈0．01）；Survivin蛋白表达与胃癌组织病理分化程度、淋巴结转移、TNM分期相关，而与浸润程度不相关；胃癌bcl-2蛋白表达的阳性与阴性中，Survivin蛋白表达阳性率分别为81．0％（34／42）和43．8％（7／16），两者比较差异显著（P〈0．01）；p53蛋白表达的阳性和阴性中，Survivin蛋白表达阳性率分别为58．1％（18／31）和22．2％（6／27），两者比较亦有显著性差异（P〈0．05），Survivin蛋白的表达与胃癌组织中的bcl-2蛋白及p53蛋白表达密切相关。结论：Survivin蛋白异常表达可引起细胞凋亡抑制，在胃癌的发生中起一定作用，其过度表达提示胃粘膜细胞增生极度活跃；Sur-vivin蛋白表达与胃癌中bcl-2蛋白及p53蛋白的异常表达密切相关。     

肝细胞癌临床病理学特征与p53蛋白表达的关系

应用免疫组织化学技术检测29例肝细胞癌（肝癌）和23例肝硬化标本中突变型p53蛋白的表达，并探讨后者与肝癌临床病理学特征之间的关系。结果：肝癌突变型p53蛋白表达阳性率为70％（20／29），癌旁组织阳性率为60％（18／29），肝硬化组织阳性率为30％（7／23），有血管侵犯的12例肝癌变变型p53蛋白表达均为阳性，而无血管侵犯的17例中仅8例为阳性（P＜0．05）；突变型p53蛋白阳性组血清甲胎蛋白（AFP）明显高于阴性组（8370±4764ng／ml比98．7±64．3ng／ml，P＜0．05）。提示：P53蛋白表达在肝硬化时即发生了异常；p53蛋白异常可能是AFP基因被激活的原因之一；p53蛋白异常有利于肝癌向门静脉转移。     

膀胱癌中mdm2、p53蛋白和粘着斑激酶表达的病理意义

目的探讨mdm2、p53蛋白和粘着斑激酶(FAK)在膀胱移行细胞癌(TCC)中的表达与肿瘤生物行为的关系.方法采用免疫组织化学方法,测定mdm2、p53蛋白和FAK在81例TCC中的表达情况.结果mdm2、p53蛋白和FAK在TCC组织中的表达明显高于癌旁粘膜,mdm2在p53阳性TCC组中的表达明显高于阴性组.结论mdm2和p53在TCC发展过程中可能具有协同作用,联合检测mdm2、p53蛋白和FAK可作为TCC有价值的诊断指标.     

P-gp、p53过表达与胃癌及乳腺癌转移的关系

目的研究胃癌和乳腺癌组织P-耐药糖蛋白(P-gp),p53蛋白表达及临床意义.方法应用免疫组化SABC法检测93例胃腺癌组织及60例乳腺癌组织中p-gp、p53蛋白的表达.结果乳腺癌组织中P-gp阳性率为38.3%,p53阳性率为56.7%;胃腺癌组织中P-gp阳性率为55.9%,p53阳性率为44.1%;P-gp、p53蛋白表达均与淋巴结转移有关(P＜0.05)P-gp表达与p53表达有显著的协同性(P＜0.05).结论p53突变蛋白和P-gp过表达在胃癌和乳腺癌淋巴结转移中起重要作用.p53基因突变对于多药耐药基因(mdr-1)编码产物P-gp表达增高有一定影响,早期进行p53蛋白和P-gp检测有重要的临床意义.     

p53 and chemosensitivity

Background: Although hematologic malignancies and some solid tumors such as germ cell tumors and pediatric malignancies can be cured by cytotoxic treatment, the most prevalent solid tumors are relatively resistant to these interventions. Apoptosis is involved in the cell kill of anticancer drugs and p53 is believed to be of principal importance in this process. However p53 also plays a role in cell cycle arrest and DNA repair, cellular processes that can decrease the sensitivity to chemotherapy. Therefore, p53 may play a dual role after exposure to cytotoxic treatment, activating either mechanisms that lead to apoptosis or launching processes directing to DNA repair and survival of the cell.Design: In this article, we review in details the p53functions involved in the mediation of chemosensitivity. The preclinical and clinical data published in the recent years about the relation between p53 and chemosensitivity are discussed and the potential pitfalls associated to most of these studies, and that may account for the contradictory results produced so far are also mentioned.     

p53 and apoptosis

One of the several biological functions attributed to p53 is the ability to induce apoptotic cell suicide. It has become clear that this apoptotic activity of p53 is central to its role as a tumor suppressor. A summary of current knowledge concerning the mechanisms of p53-mediated apoptosis is presented. The pivotal 'choice' between p53-induced viable growth arrest and apoptosis is discussed.     

p53 protein accumulation and p53 gene mutation in colorectal cancer

Comparison of immunohistochemical methods for detection of protein p53 accumulation and molecular techniques for analysis p53 gene mutation in colorectal cancer is presented. Thirty eight patients were included: all underwent surgery without preoperative treatment. Sex of patients, tumor localisation, macro and microscopic type of cancer and staging according to Astler-Coller and Jass classifications were evaluated. Protein p53 accumulation was detected by the streptavidin-biotin method using DO-7 (Dako) antibody. The number of cells stained were classified semiquanititatively according to a scoring system: (-)no positive cells, (+) : 10-30% positive cells, (++) : 40-70% positive cells, (+++) : >70% positive cells. For all cancer samples, exons 5 to 9 of p53 gene were amplified from isolated genomic DNA. PCR products were subjected to single standed conformational polymorphism analysis. All product were also directly sequenced on ABI PRISM 377 apparatus using fluorescent dideoxyterminators chemistry. The protein p53 accumulation was detected in 53% (20/38), whereas p53 gene mutation was seen in 55% (21/38). Among them, 15 patients (39%) with overexpression showed mutation in exon 5-8 gene p53. Discrepancies between results were noted in 29%. In conclusion, the necessity of both methods immunohistochemical and molecular is indicated for the objective evaluation of functional and structural status of p53 gene and protein.     

p53-Dependent and p53-independent activation of autophagy by ARF

The ARF tumor suppressor is a crucial component of the cellular response to hyperproliferative signals, including oncogene activation, and functions by inducing a p53-dependent cell growth arrest and apoptosis program. It has recently been reported that the ARF mRNA can produce a smARF isoform that lacks the NH(2)-terminal region required for p53 activation. Overexpression of this isoform can induce autophagy, a cellular process characterized by the formation of cytoplasmic vesicles and the digestion of cellular content, independently of p53. However, the level of this isoform is extremely low in cells, and it remains unclear whether the predominant form of ARF, the full-length protein, is able to activate autophagy. Here, we show that full-length ARF can induce autophagy in 293T cells where p53 is inactivated by viral proteins, and, notably, expression of the NH(2)-terminal region alone, which is required for nucleolar localization, is sufficient for autophagy activation, independently of p53. Given the reported ability of p53 to induce autophagy, we also investigated the role of p53 in ARF-mediated autophagy induction. We found that full-length ARF expression induces p53 activation and promotes autophagy in a p53-positive cell line, and that ARF-mediated autophagy can be abrogated, at least in part, by RNAi-mediated knockdown of p53 in this cellular context. Thus, our findings modify the current view regarding the mechanism of autophagy induction by ARF and suggest an important role for autophagy in tumor suppression via full-length ARF in both p53-dependent and p53-independent manners, depending on cellular context.     

Tumorigenesis in p27/p53- and p18/p53-double null mice: functional collaboration between the pRb and p53 pathways

Mice lacking both p18(Ink4c) and p27(Kip1) develop a tumor spectrum similar to pRb(+/-) mice, and loss of p53 function accelerates tumorigenesis in pRb(+/-) mice. We hypothesized that codeletion of either p18 or p27 in conjunction with p53 deletion will also accelerate tumorigenesis. Mice lacking both p18 and p53 develop several tumors not reported in either single null genotype, including hepatocellular carcinoma, testicular choriocarcinoma, hemangiosarcoma, leiomyosarcoma, fibrosarcoma, and osteosarcoma. Mice lacking both p27 and p53 exhibit a decreased lifespan and develop unique tumors, including papillary carcinoma of the colon, hemangiosarcoma, and leiomyosarcoma. In both p18/p53 and p27/p53 double null genotypes, the incidence and spectra of tissues that develop lymphoma are also increased, as compared to the single null genotypes. The development of p27/p53 double null colon tumors correlates with secondary changes in cell-cycle protein expression and CDK (cyclin-dependent kinase) activity, perhaps contributing to the progression of colorectal cancer. We concluded that p18 and p27 can, not only functionally collaborate with one another, but also can independently collaborate with p53 to modulate the cell cycle and suppress tumorigenesis in a tissue-specific manner.     

p29ING4 and p28ING5 bind to p53 and p300, and enhance p53 activity

We identified and characterized two new ING family genes, p29ING4 and p28ING5,coding for two proteins of 249 and 240 amino acids, respectively. Both p29ING4 and p28ING5 proteins have a plant homeodomain finger motif also found in other ING proteins, and which is common in proteins involved in chromatin remodeling. p29ING4 or p28ING5 overexpression resulted in a diminished colony-forming efficiency, a decreased cell population in S phase, and the induction of apoptosis in a p53-dependent manner. Both p29ING4 and p28ING5 activate the p21/waf1 promoter, and induce p21/WAF1 expression. p29ING4 and p28ING5 enhance p53 acetylation at Lys-382 residues, and physically interact with p300, a member of histone acetyl transferase complexes, and p53 in vivo. These results indicate that p29ING4 and p28ING5 may be significant modulators of p53 function.     

软组织肉瘤中p53基因的突变和蛋白的表达研究

目的检测软组织肉瘤中p53基因的突变和蛋白的表达情况。方法应用PCR-SSCP和DNA测序的方法检测p53基因的突变,免疫组织化学技术Envision二步法检测p53蛋白的表达。结果 63例软组织肉瘤中检测到p53基因突变18例（28.6%）,突变位点主要在第6外显子和第7外显子,突变和组织学分级间无明显相关性;63例p53蛋白的表达44例,蛋白的表达与组织学分级间无明显相关性;且p53基因的突变与p53蛋白的表达无明显相关性。结论 p53基因的突变和p53蛋白的表达可能作为软组织肉瘤发生的一个重要因素。     

p53-dependent and p53-independent pathways for radiation-induced immature thymocyte differentiation

The pre-T-cell receptor (TCR) delivers essential survival/differentiation signals to the developing thymocytes. Severe combined immunodeficient (SCID) and recombination-activating gene (RAG)-deficient mice are unable to assemble antigen receptor genes, and therefore cannot express a pre-TCR. Consequently, T lymphocyte differentiation is arrested at an early stage in the thymus of these animals, and immature thymocytes are eliminated through apoptotic processes. This maturation arrest can be relieved and thymocyte differentiation rescued after the exposure of these mice to whole-body gamma-irradiation. Whereas the promotion of immature thymocyte survival/differentiation was shown to require p53 activity in irradiated SCID mice, it was suggested, on the other hand, that p53 activation prevents immature thymocytes survival/differentiation in irradiated RAG-deficient mice. However, SCID mice have impaired responses to ionizing radiation. In this paper, we analysed p53 requirement in radiation-induced thymocyte differentiation in CD3epsilon(Delta5/Delta5) mice, where pre-TCR deficiency also results in an early block of lymphocyte development. Our results show at the cellular and molecular levels that, in this DNA repair-proficient model, irradiation-induced thymocyte differentiation proceeds either by a p53-dependent or by a p53-independent pathway, which differ in their sensitivity to the radiation dose delivered.