Overexpression of MDM2 protein in intrahepatic cholangiocarcinoma: relationship with p53 overexpression, Ki-67 labeling, and clinicopathological features

Aberration of the p53 gene is thought to be the most frequent genetic alteration in human cancers. Tp53 protein may be inactivated by the binding of the MDM2 protein. MDM2, the product of the mdm2 gene, is an oncoprotein that binds to Tp53 and inhibits the p53- mediated transactivation. MDM2 overexpression has been reported in several human cancers, but not in intrahepatic cholangiocarcinoma (ICC). Therefore, we have evaluated the immunohistochemical overexpression of MDM2 and the relationship between its expression and histological grade, clinicopathological features, Tp53 overexpression, and Ki-67 labeling index in 47 cases of ICC. MDM2 and Tp53 were found to be overexpressed in 38% and 57% of the tumor, respectively. MDM2 and Tp53 were not expressed in non-tumorous liver tissue. There was no significant difference between the MDM2 overexpression and ICC tumor grade. However, MDM2 overexpression correlated with the presence of metastases (P<0.01) and advanced tumor stage (P<0.05). MDM2 overexpression also correlated with Tp53 overexpression (P<0.03) and Ki-67 labeling index (P<0.03). Our findings suggest that MDM2 overexpression may play a role in the late stage of human ICC. Received: 6 October 1999 Accepted: 31 January 2000     

PDCD5、MDM2、Tip60和P53在食管鳞状细胞癌中的表达及其相关性

目的 探讨PDCD5、MDM2、Tip60和P53在新疆食管鳞癌患者的癌组织、癌旁组织和正常组织中的表达及相关性.方法 RT-PCR检测PDCD5、MDM2和Tip60 mRNA表达;免疫组织化学法检测PDCD5、MDM2、Tip60和P53蛋白的表达(18例哈萨克族、22例汉族).结果 癌组织中PDCD5、MDM2和...     

MDM2和P53蛋白表达与原发性肝细胞肝癌发生的关系

目的:研究MDM2和突变型P53蛋白表达与原发性肝细胞肝癌(HCC)发生的关系。方法: 用免疫组织化学SP法,检测55例HCC癌组织、23例癌旁组织、10例正常肝组织MDM2和突变型P53蛋白表达情况。结果: 55例HCC中MDM2蛋白阳性表达17例(30.9%),突变型P53蛋白阳性表达23例(41.8%),二者均阳性表达11例(20%),MDM2和突变型P53蛋白表达有相关性(r=0.310, P＜0.05)。23例癌旁组织MDM2蛋白阳性1例,突变型P53蛋白阳性表达2例,肝癌组织和癌旁组织MDM2和突变型P53蛋白表达有差异(P＜0.05)。10例正常肝组织无MDM2和突变型P53蛋白表达。结论: 肝细胞癌组织有MDM2和突变型P53过量表达,MDM2蛋白和/或 p53 基因突变使 p53 基因功能失活在HCC发生中可能有重要作用。     

No evidence for functional inactivation of wild-type p53 protein by MDM2 overexpression in gastric carcinogenesis

Inactivation of wild-type p53 during gastric carcinogenesis is usually caused by mutations within exons 5–8 of the p53 gene leading to mutated, usually immunohistochemically detectable p53 proteins. However, functional inactivation of wild-type p53, mimicking mutational inactivation, may also result from binding to overexpressed MDM2 protein. While these two mechanisms of p53 inactivation are considered to be mutually exclusive, no data exist as to whether MDM2 overexpression occurs during gastric carcinogenesis. MDM2 protein overexpression was therefore studied in relation to p53 protein accumulation in gastric carcinogenesis. Forty-five paraffin-embedded gastrectomy specimens from early gastric carcinomas were examined for the presence of chronic active gastritis, chronic atrophic gastritis, subtypes of intestinal metaplasia, and dysplasia. The Lauren type was reassessed for all early carcinomas. p53 protein accumulation was examined using the monoclonal antibody DO-7. MDM2 protein overexpression was assessed with the monoclonal antibody SMP-14. Complete absence of nuclear p53 protein accumulation was observed in chronic active gastritis, chronic atrophic gastritis, and intestinal metaplasia, irrespective of the subtype. In gastric dysplasia (one mild, two moderate, one severe), only severe dysplasia was p53-positive. Intestinal-type (n=20) and diffuse-type early gastric carcinoma (n=25) were p53-positive in 70 and 52 per cent of the cases, respectively. MDM2 protein overexpression was not observed during gastric carcinogenesis, either in the p53-positive or in the p53-negative cases. In conclusion, it appears that functional inactivation of wild-type p53 by MDM2 protein overexpression plays no role in (early) gastric carcinogenesis. © 1998 John Wiley & Sons, Ltd.     

肺癌p53蛋白表达和基因突变与临床病理的相关研究

目的 检测肺癌中ｐ５３蛋白表达和基因突变状况及其与临床病理和预后的相关性。方法：应用免疫组织化学（ＬＳＡＢ法）和聚合酶链反应－单链构象多态性分析（ＰＣＲ－ＳＳＣＰ）二种方法。结果 检测肺鳞癌４６例，共９５例。免疫组化ｐ５３蛋白总阳性率为５０．５％（４８／９５例），肺鳞癌阳性率为５６．５％（２６／４６例）、肺腺癌为４４．７％（２２／４９例）。ＰＣＲ－ＳＳＣＰ检测ｐ５３基因突变率为４１．１％（３９／９     

Immunohistochemical inactivation of p14ARF concomitant with MDM2 overexpression inversely correlates with p53 overexpression in oral squamous cell carcinoma

The CDKN2 gene encodes two structurally different proteins: a cyclin-dependent kinase inhibitor called p16, which regulates retinoblastoma protein (pRb)-dependent G1 arrest, and a cell cycle inhibitor designated p14ARF, which arrests cell growth in G1-S and also in G2-M. Whereas inactivation of p16 has been described as a frequent event in various cancers, including oral cancer, the current function of p14ARF is still poorly understood. A physical association between p14ARF and MDM2 blocks MDM2-induced p53 degradation, resulting in increased levels of p53, which in turn leads to cell cycle arrest. The present study immunohistochemically examined the expression of p16 and p14ARF together with pRb, MDM2 and p53 status in a series of oral cancers. The results showed that p14ARF was frequently absent in the oral cancers (15/37, 41%) as was p16 immunostaining. Concomitant immunopositivity for p14ARF and MDM2 overexpression was frequently observed in a subset of the cancers, whereas an inverse correlation between p14ARF and MDM2 expression and the diffuse staining of p53 was clearly detected. Moreover, the results showed that in most cases of oral cancer (35/37, 95%) at least one protein was altered, and lymph node metastasis was more frequent in the tumors with alterations in both the p16/pRb and p14ARF/p53 pathway (8/16, 50%) than in the tumors with one or no alteration of these two major pathways.     

High TRIM44 expression in endometrial carcinoma is associated with a poorer patient outcome

Background

Tripartite motif‐containing protein 44 (TRIM44) has been recently identified as a novel oncogene that is overexpressed in several types of human cancers; however, its role in endometrial cancer (EC) remains unknown. The purpose of the current study was to investigate the TRIM44 protein expression and clinicopathological significance of TRIM44 in EC.

Genetic polymorphisms in cell cycle regulatory genes MDM2 and TP53 are associated with susceptibility to lung cancer

The tumor suppressor TP53 pathway plays a crucial role in preventing carcinogenesis through its ability to impose cell cycle arrest and apoptosis following DNA damage and oncogene activation. MDM2 is a key negative regulator of the TP53 pathway and is overexpressed in many cancers as oncoprotein. We investigated the association between genetic variation in the promoter region of MDM2 (c.-5+309G>T, rs2279744:g.G>T) and the coding region of TP53 (c.215G>C, rs1042522:g.G>C, designated Arg72Pro) and the risk of developing lung cancer. The genotypes of 1,106 patients and 1,420 controls were determined by tetra-primer amplification refractory mutation system (ARMS)-PCR or PCR-based restriction fragment length polymorphism (RFLP). Associations with risk of lung cancer were estimated by logistic regression. We observed an increased lung cancer risk associated with the MDM2 GG (odds ratio [OR] = 1.83, 95% confidence interval [CI] = 1.45-2.32) and TG (OR = 1.33, 95% CI = 1.09-1.63) genotypes. An increased risk was also associated with the TP53 Pro/Pro genotype (OR = 1.47, 95% CI = 1.17-1.85, P = 0.003) compared to the Arg/Arg genotype. The gene-gene interaction of MDM2 and TP53 polymorphisms increased lung cancer risk in a supermultiplicative manner (OR for the presence of both MDM2 GG and TP53 Pro/Pro genotypes = 4.56, 95% CI = 2.76-7.54). Significant interactions were observed between these polymorphisms (respectively and jointly) and smoking (OR = 10.41, 95% CI = 5.26-20.58) for smokers with both the MDM2 GG and TP53 Pro/Pro genotypes. In conclusion, genetic polymorphisms in cell cycle regulatory genes MDM2 and TP53 contribute to the risk of developing lung cancer.     

P53、P21WAFI、MDM2及BAX在食管鳞癌中的表达和相关性分析

目的：检测P53、MDM2、P21^WAFI、BAX在食管鳞癌中的表达,探讨它们与食管鳞癌临床病理特征之间的关系。方法：采用免疫组化检测食管鳞癌、正常食管粘膜和不典型增生组织中上述基因蛋白的表达。结果：各指标在上述组织中的表达有显著性差异。MDM2在淋巴结转移组中的阳性表达率为80％,未转移组中为35．7％,两者之间有显著性差异。随着食管鳞癌组织学分级的增高,P53、MDM2的表达逐渐增高,P21^WAFI、BAX的表达逐渐降低。结论：P53、P21、MDM2、BAX多个基因的异常在食管癌的发生、发展过程中共同发挥作用;MDM2过表达与肿瘤的侵袭性和转移有关。P53、P21^WAFI、MDM2在食管鳞癌中的表达无相关性,P53与BAX的表达呈负相关。     

青蒿琥酯对吉西他滨体外抗胰腺癌活性的作用

目的:探讨青蒿琥酯辅助治疗对吉西他滨抗胰腺癌活性的影响和机制。方法:分别采用分子克隆及RNA干扰方法于人胰腺癌细胞Capan-2中过表达和干扰鼠双微体蛋白2(MDM2),MTT实验检测p53野生型胰腺癌细胞系Capan-2的细胞活力。Western blot实验检测Capan-2细胞中MDM2、p53、Noxa和Puma的表达水平,细胞色素C和凋亡诱导因子的释放,以及caspase-9和caspase-3的活化。流式细胞术检测Capan-2细胞的线粒体膜电位和凋亡水平。结果:吉西他滨联合青蒿琥酯组Capan-2的相对细胞活力显著低于吉西他滨单处理组(P 0. 05)。青蒿琥酯处理显著抑制Capan-2细胞中MDM2的表达水平(P 0. 05)。吉西他滨联合青蒿琥酯组的p53、Noxa及Puma表达水平均明显高于吉西他滨单处理组(P 0. 05)。青蒿琥酯明显促进吉西他滨依赖的Capan-2细胞线粒体膜电位的下降,细胞色素C和凋亡诱导因子的释放,caspase-9和caspase-3的活化,以及凋亡的发生。转染MDM2表达质粒后,青蒿琥酯联合吉西他滨对Capan-2细胞的凋亡诱导途径受到显著抑制。结论:青蒿琥酯通过MDM2/p53途径提高吉西他滨的抗胰腺癌活性。     

Common polymorphisms in the MDM2 and TP53 genes and the relationship between TP53 mutations and patient outcomes in glioblastomas

MDM2 SNP309 is associated with younger age of tumor onset in patients with Li-Fraumeni syndrome, and TP53 codon 72 polymorphism decreases its apoptotic potential. Glioblastomas frequently show genetic alterations in the TP53 pathway. In the present study, we assessed MDM2 SNP309 in 360 glioblastomas, and correlated these with patient age and survival, as well as other alterations in the TP53 pathway. Frequencies of the MDM2 SNP309 T/T, T/G and G/G genotypes in glioblastomas were 40%, 46% and 14%, respectively. Multivariate analysis showed that MDM2 SNP309 G/G allele was significantly associated with favorable outcome in female glioblastoma patients (hazard ratio 0.54; 95% CI = 0.32–0.92). There was a significant association between MDM2 SNP309 G alleles and TP53 codon 72 Pro/Pro in glioblastomas. Glioblastoma patients with TP53 codon 72 Pro/Pro genotype were significantly younger than Arg/Arg carriers (mean 50.2 vs. 56.1 years; P  = 0.018). Multivariate analysis showed that those with TP53 codon 72 Arg/Pro allele had significantly shorter survival than those with Arg/Arg allele (hazard ratio 1.35; 95% CI = 1.07–1.71). Detailed analyses revealed that TP53 codon 72 Pro allele was significantly associated with shorter survival among patients with glioblastomas carrying a TP53 mutation, and among those treated with surgery plus radiotherapy.     

MDM2-P53蛋白质相互作用的小分子抑制物

p53作为重要的抑癌基因已经成为一个治疗癌症重点的突破目标之一.直接调节p53基因或调节P53和MDM2蛋白质相互作用是再激活p53基因的两种重要机制.对于表达野生型P53的癌症设计小分子阻断剂阻断MDM2与P53蛋白相互作用是一个很有前景的治疗癌症的方向.文章主要总结了作为治疗癌症的新方法-MDM2-P53蛋白相互作用小分子抑制物的最新研究进展,其中最新的是人工合成化合物Nutlin-3和MI-219.     

癌基因MDM_2和抑癌基因p53在肉瘤组织中的变化及其相关性

目的：研究ＭＤＭ２癌基因和ｐ５３抑癌基因在人肉瘤发生中的作用。方法：应用分子杂交和免疫组化技术检测了５０例肉瘤组织、１３例良性间叶瘤和１０例癌组织中ＭＤＭ２及ｐ５３的分子改变。结果：ｐ５３过表达率在肉瘤为２４／５０（４８％）；ＭＤＭ２扩增和过表达在肉瘤为１９／４９（３８．８％）和２７／４９（５５％），而在良性间叶瘤分别为１／１３（７．７％）和１／１２（８．３％），癌组均为１／１０（１０％）；ＭＤＭ２基因的异常在不同类型肉瘤间存在差异性；ＭＤＭ２扩增和过表达间存在不一致性：１９例扩增中１６例有过表达，而１１例过表达者无基因扩增。两基因改变的相关分析发现，２４例ｐ５３阳性中１８例有ＭＤＭ２改变。结论：ＭＤＭ２癌基因异常与间叶性肿瘤的恶性表型高度相关，并有一定类型特异性；ＭＤＭ２与ｐ５３的改变在肉瘤的发生中密切相关     

Overexpression of p53 protein and MDM2 in papillary carcinomas of the thyroid: Correlations with clinicopathologic features

Expression of p53 protein and MDM2 was evaluated in paraffin-embedded tissue from 78 patients with papillary carcinomas of the thyroid (PCT), in order to elucidate the relationship between them and their correlations with some clinicopathologic features implicated in tumor progression. These proteins were expressed in nuclei of tumor cells, but not in non-tumor cells. Staining was defined as positive when 10% or more of tumor cells expressed these proteins. The number of cases positive for p53 protein was 21/78 (27%), and that positive for MDM2 was 26/78 (33%). Co-overexpression of p53 protein and MDM2 was observed in 12/78 cases (15%). A significant positive relationship was found between them (P < 0.01); p53-positive cases tended to be also positive for MDM2 and vice versa. Statistical analysis revealed that overexpression of p53 protein significantly correlated with large tumor size (P = 0.0271) and the presence of capsular invasion (P = 0.04). There were significant positive correlations between tumor size and intrathyroidal invasion and between tumor size and capsular invasion in PCT, suggesting that p53 protein overexpression is associated only with tumor progression (tumor size). However, we could not find any significant correlations between MDM2 expression and clinicopathologic features. Our findings suggest that overexpression of p53 protein and MDM2 in papillary carcinoma of the thyroid is associated with the progression of the tumors, and that p53 may be a marker of the progression of PCT.     

幽门螺杆菌感染通过 MDM2 / P53 通路调控食管癌细胞凋亡的作用及机制

目的 研究幽门螺杆菌 (helicobacter pylori, Hp) 感染通过 MDM2 / P53 通路调控食管癌细胞凋亡的作用及机制。 方法 收集手术切除的食管癌组织, 检测 Hp 感染情况及 MDM2、 P53 的表达水平。 培养食管癌 TE-1 细胞株, 给予 Hp 感染、 生理盐水 (NS) 或泛素-蛋白酶体抑制剂 PS341 干预、 转染阴性对照(NC) siRNA 或 MDM2 siRNA, 检测细胞活力、 凋亡率、 MDM2 及 P53 的表达水平、 P53 的泛素化水平。 结果 Hp 阳性的食管癌组织中 MDM2 的表达水平高于 Hp 阴性的食管癌组织、 P53 的表达水平低于 Hp 阴性的食管癌组织 (P< 0. 05); Hp 组 TE-1 细胞的细胞活力、 MDM2 表达水平、 P53 泛素化水平高于对照组,凋亡率、 P53 表达水平低于对照组; PS341 + Hp 组 TE-1 细胞的 P53 的表达水平高于 NS + Hp 组 (P< 0. 05);si-MDM2 + Hp 组 TE-1 细胞的细胞活力、 MDM2 的表达水平、 P53 的泛素化水平均低于 si-NC + Hp 组, 凋亡率、 P53 的表达水平高于 si-NC + Hp 组 (P< 0. 05)。 结论 Hp 感染抑制食管癌细胞凋亡的作用与增加MDM2 表达、 促进 P53 的泛素化降解有关。     

Co-expression of p53 and MDM2 in human atherosclerosis: implications for the regulation of cellularity of atherosclerotic lesions

Atherosclerosis is a fibroproliferative disease of the arterial intima. It was recently found that wild-type p53 (wt p53) accumulates in human atherosclerotic tissue. Wt p53 is a cell cycle regulator involved in DNA repair, DNA synthesis, cell differentiation, and apoptosis and might therefore make an important contribution to the cellularity of atherosclerotic plaques. The product of the MDM2 gene is a nuclear protein which forms a complex with p53, thereby inhibiting the negative regulatory effects of wt p53 on cell cycle progression. In order to address a potential role of the interaction of p53 with MDM2 for the regulation of cellularity in atherosclerotic tissue, 22 carotid atheromatous plaques from patients undergoing endarterectomy were studied to determine the presence of p53 immunoreactivity (IR), MDM2 IR, cell proliferation as evidenced by MIB1/Ki-67 IR and DNA fragmentation by in situterminal transferase-mediated dUTP 3′ end labelling (TUNEL), as a marker for apoptosis. p53 IR localized to areas with evidence of chronic inflammation (22/22) and was observed in virtually all cell types in 68·79±7·51 per cent of the nuclei. p53 staining in the control tissue from human internal mammary arteries was present in 0·2±0·29 per cent of the cells (P≤0·002). MDM2 IR was present in all cases (22/22) in macrophages and smooth muscle cells (SMCs) in 60·53±8·32 per cent of the nuclei (controls: 0·8±0·65 per cent, P≤0·002) and co-localized with p53 IR as shown by examination of adjacent sections and by double immunofluorescence labelling. Importantly, co-immunoprecipitation and western blot analysis revealed that p53 and MDM2 were physically associated, indicating that MDM2–p53 complex formation takes place in vivoin human atherosclerotic tissue. Positive TUNEL staining and MIB1/Ki-67 IR present in 3·01±1·27 per cent of the nuclei (controls: 0 per cent, P≤0·002) localized to the same plaque compartments as p53 IR and MDM2 IR. Thus, the fate of cells with p53 accumulation may depend on the interaction and the stoichiometry of the p53 and MDM2 proteins. Cells were indeed found with strong p53 accumulation and nuclear morphology typical for apoptosis and there were a few MIB1/Ki-67-positive cells with co-expression of MDM2, indicating a possible role for MDM2 in reversing the negative regulatory effects of p53 for cell cycle progression. The nuclear co-localization of p53 IR with MDM2 IR and the co-immunoprecipitation assay indicate the presence of p53–MDM2 complex formation in vivo in human atherosclerotic tissue. The destiny of individual p53 and MDM2-co-expressing cells either to undergo p53-dependent apoptosis or to re-enter the cycle of cell proliferation may depend on the relative ratios of the two proteins. p53 and MDM2 may therefore play an important role in regulating cellularity and inflammatory activity in human atherosclerotic plaques. © 1998 John Wiley & Sons, Ltd.     

p53 gene mutation and MDM2 overexpression in a case of primary malignant fibrous histiocytoma of the jejunum

Primary malignant fibrous histiocytoma of the gastrointestinal tract is extremely rare. To date, only 10 cases of primary malignant fibrous histiocytoma arising in the small intestine have been reported in the English literature. We describe here the genetic alterations and morphologic features of a primary malignant fibrous histiocytoma arising in the jejunum. Immunohistochemically, the tumor cells expressed vimentin, CD68 and alpha-1-antitrypsin, but were negative for other markers. Ultrastructurally, they showed features of fibroblasts and histiocytes. Immunohistochemical overexpression of p53 and MDM2 was observed. Mutation analysis of the p53 gene detected a missense mutation in codon 158 of exon 5. Our results suggest that p53 gene mutations and MDM2 overexpression may play an important role in the tumorigenesis. To our knowledge, the present report is the first genetic study of this rare lesion.     

Assessment of TP53 Polymorphisms and MDM2 SNP309 in Premenopausal Breast Cancer Risk

Germline polymorphic variants in cancer predisposition genes such as TP53 have been shown to impact the risk of premenopausal cancer. Accordingly, the aim of this study was to assess the spectrum of polymorphisms in TP53 and its negative regulatory gene, MDM2 (SNP309:T>G) in patients with premenopausal breast cancer. Our findings in a cohort of 40 female patients demonstrate no significant correlation between the studied polymorphisms and risk of premenopausal breast cancer. Although one polymorphism is found in high frequency in this cohort (rs1800372:A>G, 9.0%), it was not associated with the risk of developing cancer before the age of 35 years in an extended cohort of 1,420 breast cancer cases. Functional studies of the rs1800372:A>G polymorphic allele reveal that it does not affect p53 transactivation function. Further study of variants or mutations in other cancer susceptibility genes is warranted to refine our understanding of the germline contribution to premenopausal breast cancer susceptibility.