Oxidative damage to DNA, p53 gene expression and p53 protein level in the process of aging in rat brain

Levels of 8-oxo2'dG (HPLC), p53 mRNA (PCR) and p53 protein (Western Blot) were estimated in four structures of rat brain, including grey matter (GM) of cerebral cortex, cerebral white matter (WM), cerebellum (C) and medulla oblongata (MO) of control (3.0-3.5-month-old) rats, 12- and 24-month-old rats. The level of oxidative DNA was statistically significantly higher in C of 24-month-old animals. Expression of p53 gene increased in C and also in the all other investigated brain parts, while the protein level of p53 was enhanced only in GM of 24-month-old rats. These data indicated that DNA oxidative damage and p53 gene expression increased significantly in aged brain. The higher expression of p53 gene in aged brain may suggest the activation of DNA repair processes.     

Arsenic salt-induced DNA damage and expression of mutant p53 and COX-2 proteins in SV-40 immortalized human uroepithelial cells

Arsenic is widely distributed in the environment, and is a proven toxic and carcinogenic agent that is associated with various human malignancies, including bladder cancer. However, the mechanisms of its carcinogenic action are still not well understood. In addition, over-expression of mutant p53 and cyclooxygenase-2 (COX-2) frequently occurs in a variety of human malignancies. It is therefore of interest to study the genotoxicity of arsenic salts on human uroepithelial cells and the expression of oncoproteins p53 and COX-2. In this study, the relative genotoxicity of sodium arsenite was evaluated in SV-40 immortalized human uroepithelial cells (SV-HUC-1) using the alkaline comet assay. The expression of mutant p53 and COX-2 was also evaluated by immunocytochemistry and western blotting. Our results revealed that sodium arsenite was able to induce DNA damage, and that its genotoxicity is correlated with its concentration. In addition, the expression of mutant p53 increased in parallel with comet scores, and the maximal expression of mutant p53 was observed at 4 microM arsenite. Similarly, sodium arsenite stimulated a concentration-dependent increase in COX-2 expression. In conclusion, this study demonstrated that sodium arsenite is genotoxic to uroepithelial cells in vitro, and that it will induce expression of mutant p53 and COX-2 proteins, indicating a possible key event in carcinogenesis. This study provides us with knowledge of the relationship between p53 and COX-2 over-expression in arsenite-treated urothelial cells and suggests a potential therapeutic role of COX-2 inhibitors in human urothelial malignancies.     

电脉冲与恶性淋巴瘤细胞p53和bcl-2基因表达

目的: 探讨电化学疗法(ECT)与肿瘤细胞基因表达的关系。方法: 采用Tunel法和免疫组化S-P法, 分别检测肿瘤未治疗对照组和ECT组B细胞淋巴瘤组织的细胞凋亡率和p53、bcl-2基因的表达。结果: ECT组肿瘤细胞凋亡率(5.18)显著高于对照组(1.05), p53、bcl-2在ECT组表达分别为80%、25%, 对照组表达分别为15%、90%。ECT组中p53表达与癌细胞凋亡率呈正相关, 而bcl-2则与癌细胞凋亡率呈负相关。结论: ECT可诱导癌细胞凋亡, 其发生可能与p53和bcl-2基因调控有关。     

Purification and characterisation of the E7 oncoproteins of the high-risk human papillomavirus types 16 and 18

E7 proteins are major oncoproteins of human papillomaviruses (HPVs) which play a key role in virus-associated cervical carcinogenesis. The E7 oncoprotein of HPV-16 has been shown to interact with a variety of cellular target proteins and these interactions are considered essential for the transforming properties of this oncoprotein. Several additional HPV types associated etiologically to cervical cancer have been described, the second most common being HPV-18. Less is known about the biochemical functions and interactions of HPV-18 E7. As a first step to determine biochemical properties common to the E7 proteins of the high-risk HPV types 16 and 18 these E7 proteins were expressed in bacteria and purified to homogeneity. Purified E7 proteins were used to investigate the in vitro interaction with the pocket protein p107 and insulin-like growth factor-binding protein-3 (IGFBP-3) that are known to interact with the amino-terminal and the carboxyl-terminal part of IGFBP-3, respectively. Both purified E7 proteins interacted strongly with p107 and, as demonstrated here for the first time, HPV-18 E7 was capable of binding to IGFBP-3, albeit to a lesser extent than HPV-16 E7. These findings suggest that the purified recombinant E7 proteins retain, at least in part, their biochemical activities.     

乳腺增生病p53基因第5外显子突变及其蛋白表达

目的：探讨p53基因在乳腺癌发生早期的作用。方法：用免疫组化方法检测36例乳腺单纯性增生、31例不典型增生、14例原位癌和16例浸润癌中p53蛋白的表达，用PCR－SSCP检测了上述组织中p53基因第5外显子突变。结果：p53蛋白在单纯性增生、不典型增生、导管内癌、浸润癌中的表达率分别为0、22.6%(7/31)、42.8%(6/14)、50％（8／16），PCR－SSCP在各组中均未检测到该基因第5外显子突变。结论：乳腺癌发生早期阶段有p53基因的参与，但与第5外显子突变无明显关系。     

芯片电泳相对迁移时间DNA长度计算方法鉴定高危型人乳头状瘤病毒基因

目的 建立一种能够消除电泳分析中迁移时间漂移对于DNA片段长度预测精确性影响的芯片电泳相对迁移时间比例方法,并联用多重PCR鉴定高危型人乳头状瘤病毒(HPV).方法 在芯片电泳分析中引入上位和下位内标,依据待测DNA片段相对于上位及下位内标的迁移时间比例进行长度预测,建立芯片电泳相对迁移时间比例的测定方法.考察不同实验条件下芯片电泳DNA分析中相对迁移时间比例的重现性和DNA片段长度预测精确性.选取2007年10月至2008年12月间广州医学院附属广州市第一人民医院妇科就诊的114例患者的富颈上皮细胞样品,经细胞学检查划分为正常组(n=30)、不典型鳞状细胞组(ASCUS组,n=30)、低度鳞状上皮内病变组(LSIL组,n=30)和高度鳞状上皮内病变和(或)鳞状细胞癌组[HSIL和(或)SCC组,n=24].对应活检组织经病理诊断,划分为宫颈高度病变组(n=90)和对照组(n=24).利用多重PCR联合芯片电泳相对迁移时间比例方法检测宫颈上皮细胞样本中5种高危型HPV感染状况.参考组织病理学检测结果评价芯片电泳相对迁移时间比例的方法分析对于宫颈高度病变诊断的临床价值.结果 芯片电泳相对迁移时间比例方法具有良好的重现性和DNA片段长度相关性.使用芯片电泳相对迁移时间比例方法能够满足HPV基因分型多重PCR产物的准确鉴定.各个细胞学分类级别对应的5种高危HPV检出率分别为正常组33.3％、ASCUS组60％、LSIL组76.6％、HSIL和(或)SCC组83.3％.HPV感染率随细胞和组织学病变级别增加有上升趋势,与细胞学(x2=19.319,P＜0.05)和组织学(x2=7.268,P＜0.05)分级具有明显的关联.结论 芯片电泳相对迁移时间比例方法简单可靠,可以实现高危HPV基因型快速判定,具有筛查宫颈高度病变的价值.     

Immunohistochemical detection of p53 protein in cutaneous lesions from transplant recipients harbouring human papillomavirus DNA

Human papillomaviruses (HPV) are thought to be involved in the malignant evolution of cutaneous lesions from transplant recipients. As E6 proteins from potentially oncogenic HPV types degradep53 tumour suppressor gene product in vitro, we analysed p53 protein status in benign, premalignant and malignant skin lesions from grafted patients, to determine whether HPV may interfere with p53 function. With immunohistochemistry, p53 protein accumulation was detected in 70% of skin lesions from grafted patients. p53 immunoreactivity was confined to basal keratinocytes in benign lesions (warts, condylomas), while suprabasal keratinocytes were also stained in premalignant and malignant skin lesions (precancerous keratoses, squamous cell carcinomas). Multiple HPV carriage was detected with in situ hybridization in benign and malignant skin lesions from transplant recipients: low risk HPV types 1, 2, 6, 11 and potentially oncogenic HPV types 5, 16, 18 were frequently found. There was no clear correlation between p53 detection and the presence of the HPV types under study. The frequent detection of p53 protein in cutaneous lesions from grafted patients is suggestive of p53 protein accumulation interfering with normal function. Our results may reflect the presence of mutated p53 proteins due to the mutagenic effect of ultra-violet (UV), or wild-type p53 protein accumulation in response to UV-induced DNA damage, or may be produced by the interaction with HPV-encoded E6 proteins.     

膛胱移行细胞癌中c—erbB—2,p53及p16蛋白的表达

目的 探讨膛胱癌组织中ｐ１６、ｃ－ｅｒｂＢ－２和ｐ５３蛋白表达与胱癌病理分级、临床分期和转移的关系。方法 应用免疫组化ＳＰ法对７５例膛胱癌组织中ｐ１６、ｐ５３及ｃ－ｅｒｂＢ－２蛋白表达进行检测。结果 ７５例膛胱癌中ｐ１６、ｐ５３及ｃ－ｅｒｂＢ－２的阳性率分别为４１．３％（３１／７５）、４４．０％（３３／７５）和４０．０％（３０／７５）,ｐ１６和ｃ－ｅｒｂＢ－２蛋白在膛胱癌中的阳性率与肿瘤中的阳性率     

膀胱移行细胞癌中c-erbB-2、p53及p16 蛋白的表达

目的　探讨膀胱癌组织中p16、c erbB 2和p5 3蛋白表达与膀胱癌病理分级、临床分期和转移的关系。方法　应用免疫组化SP法对 75例膀胱癌组织中p16、p5 3及c erbB 2蛋白表达进行检测。结果　 75例膀胱癌中p16、p5 3及c erbB 2的阳性率分别为 41.3% (31 75 )、44 .0 % (33 75 )和40 0 % (30 75 ) ,p16和c erbB 2蛋白在膀胱癌中的阳性率与肿瘤病理分级和临床分期有显著意义 (P<0 0 5 ) ,p5 3和c erbB 2阳性率与肿瘤临床分期及转移有密切的关系 (P <0 .0 1)。 77.3% (5 8 75 )肿瘤有上述蛋白的阳性表达 ,其中 5 3.3% (40 75 )的肿瘤同时有多个蛋白的阳性表达。结论　肿瘤的多因素分析比单因素分析更有价值 ,癌基因c erbB 2和抑癌基因p5 3、p16蛋白的表达异常及协同作用在膀胱癌的发生发展中起重要作用     

The oncoproteins c-erb-B2, c-fos and the tumour suppressor protein p53 in human embryos and fetuses

 Oncoproteins and tumour-suppressor proteins are thought to possess an antagonistic function in the regulation of growth and differentiation processes during embryonic and fetal development. In contrast, in the adult, tumour growth is associated with the overexpression of oncoproteins or the malfunction of tumour-suppressor proteins. We examined the occurrence of the tumour proteins c-erb-B2 and c-fos and the tumour-suppressor protein p53 in 17 human embryos and fetuses with the help of immunohistochemistry. C-erb-B2 was detected mainly in embryonic tissue that are not known for c-erb-B2-overexpression in tumours in the adult. In contrast, c-fos was almost always located in fetal tissues corresponding to its location in adult tumours. Staining for p53 was found in a wide variety of embryonic and fetal tissues. C-erb-B2 and p53 were localized in the same tissue structures of the developing skin, heart and muscle. In other tissues, e.g. muscle and bone, c-fos was found together with p53, suggesting an antagonistic action of these proliferative and antiproliferative factors. Furthermore, c-erb-B2, c-fos and p53 appear to be important for growth and differentiation processes in human development as the occurrence of these proteins was not only restricted to specific tissues but also to specific stages of development of these tissues. Accepted: 30 September 1996     

Low- and high-risk human papillomavirus E7 proteins regulate p130 differently

The E7 protein of high-risk human papillomaviruses (HR HPVs) targets pRb family members (pRb, p107 and p130) for degradation; low-risk (LR) HPV E7 only targets p130 for degradation. The effect of HR HPV 16 E7 and LR HPV 6 E7 on p130 intracellular localization and half-life was examined. Nuclear/cytoplasmic fractionation and immunofluorescence showed that, in contrast to control and HPV 6 E7-expressing cells, a greater amount of p130 was present in the cytoplasm in the presence of HPV 16 E7. The half-life of p130, relative to control cells, was decreased in the cytoplasm in the presence of HPV 6 E7 or HPV 16 E7, but only decreased by HPV 6 E7 in the nucleus. Inhibition of proteasomal degradation extended the half-life of p130, regardless of intracellular localization. These results suggest that there may be divergent mechanisms by which LR and HR HPV E7 target p130 for degradation.     

Modulation of apoptosis by human papillomavirus (HPV) oncoproteins

Summary. The regulation of host-mediated apoptosis by the E6 and E7 oncoproteins has garnered attention because it is believed to be an important strategy employed by high-risk (HR)-human papillomaviruses (HPVs) to evade immune surveillance. Additionally, the revelation that E5 can protect cells from tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis suggests that it may also play a role in undermining host defense mechanisms. Cellular transformation is an unintended consequence of persistent infection by HR-HPVs, and it is therefore likely that the primary function of E5, E6 and E7 is to regulate cell survival throughout the normal viral life cycle in order to ensure viral replication and promote the spread of progeny. The purpose of this article is to review the literature on the regulation of host-mediated apoptosis by E5, E6 and E7 that describes the mechanisms employed by HR-HPVs to persist in the host and create the conditions necessary for cellular transformation.     

High-grade dysplasia and superficial adenocarcinoma in Barrett's esophagus: histological mapping and expression of p53, p21 and Bcl-2 oncoproteins

In order to characterize the early morphological and molecular stages of the neoplastic progression of Barrett's mucosa, we performed the entire histological examination of ten specimens of resected Barrett's esophagus with high-grade dysplasia or superficial adenocarcinoma. The expression of p53, p21 and Bcl-2 proteins was assessed by immunohistochemistry. The surface of Barrett's mucosa ranged from 2.6 cm(2) to 31 cm(2). Dysplasia and adenocarcinoma always developed in specialized mucosa and often occupied small surfaces. High-grade dysplasia was multifocal in eight cases. There was no preferential site for neoplastic transformation into high-grade dysplasia or superficial adenocarcinoma in Barrett's mucosa. Three superficial adenocarcinomas and four high-grade dysplasias overexpressed p53 protein. p21 protein was focally expressed in nondysplastic mucosa and overexpressed in two superficial adenocarcinomas, one high-grade dysplasia and two low-grade dysplasias. In most cases, the expression of p21 and p53 proteins was unrelated. Bcl-2 protein was detected in only one area of low-grade dysplasia. In our study, high-grade dysplasia and superficial adenocarcinoma appeared as tiny lesions, often multifocal for high-grade dysplasia confirming the need for an extensive sampling of Barrett's mucosa in the endoscopic surveillance. p53 dysfunction plays a major role in the progression from dysplasia to carcinoma in Barrett's esophagus and appears unrelated to p21 and Bcl-2 expression.     

p53 codon 72 polymorphism and human papillomavirus associated skin cancer

BACKGROUND/AIMS: Non-melanoma skin cancers frequently harbour multiple human papillomavirus (HPV) types. A recent report suggests that a polymorphism of the p53 tumour suppressor gene that results in the substitution of a proline residue with an arginine residue at position 72 of the p53 protein might act as a risk factor in HPV associated malignancies. This study aimed to determine the following: (1) the relation between HPV infection and the development of cutaneous squamous cell carcinoma (SCC), and (2) whether there is a correlation between p53 codon 72 polymorphism and the development of SCC. METHODS: Blood samples were taken from 55 patients with skin cancer (both renal transplant recipients and immunocompetent patients with skin cancer) and 115 ethnically matched volunteers. A polymerase chain reaction based assay was used to determine p53 codon 72 genotypes. In addition, 49 benign and malignant lesions from 34 of the patients with skin cancer and 20 normal human skin samples from 20 of the control volunteers were examined for HPV. RESULTS: The proportions of p53 codon 72 genotypes found were 78% arginine homozygous, 2% proline homozygous, and 20% heterozygous among patients with skin cancer and 79% arginine homozygous, 3.5% proline homozygous, and 17.5% heterozygous among the control population. Statistical analysis showed no significant differences in the distribution of the two p53 isoforms between the patients with skin cancer and the control population. The predominant viral types detected in both the patients and the control group were EV associated HPVs, although the incidence was lower in normal skin samples than in malignant lesions or viral warts. CONCLUSIONS: These results suggest that in a Celtic population there is no correlation between the presence of HPV, the p53 codon 72 arginine polymorphism, and the development of skin cancer.     

Association between MBL2 gene functional polymorphisms and high-risk human papillomavirus infection in Brazilian women

We studied the association between high-risk human papillomavirus (HPV) infection and MBL2 functional polymorphisms in a group of 180 high-risk HPV-infected women and 180 healthy control subjects. The most frequent high-risk HPV genotypes were 16 (47.2%), 31 (11.7%), 33 (5%), and 18 (2.2%), respectively. Of the 180 HPV-infected women, 99 presented with uterine cervical cancer and 81 did not. No differences in MBL2 genotype or in allelic or haplotype frequencies were found between HPV patients who developed cervical uterine cancer and those who did not. When considering combined genotypes grouped according to MBL production (designated as high, low, and deficient producers), we detected a significant difference between healthy controls and high-risk HPV-positive patients, the latter group showing increased frequencies of deficient-producer genotypes (14.4% vs 9.4% in the healthy control group, corrected p = 0.04). In conclusion, a correlation between MBL2 polymorphisms and high-risk HPV infection was found in this study.     

Infrequent alteration in the p53R2 gene in human transitional cell carcinoma of the urinary tract.

OBJECTIVE: Functional defects in DNA repair have been shown to be associated with genomic instability followed by cancer. Recently, p53R2 [p53-inducible ribonucleotide reductase (RR) small subunit 2 homologous] was identified as a novel RR gene which is directly regulated by p53 protein in the G1 and G2 phases of the cell cycle supplying nucleotides to repair damaged DNA. METHODS: We performed genetic analyses of p53R2 to determine whether p53R2 alterations play significant roles in urothelial tumorigenesis. Genomic DNA from 108 primary transitional cell carcinomas (TCCs; 81 of the urinary bladder and 27 of the renal pelvis or ureter) was analyzed for mutation in the p53R2 gene by direct sequencing. We focused on three domains of the p53R2 gene: one RR small subunit signature involving codons 120-146 (region 1) and two putative nuclear localization signal sequences, involving codons 149-155 (region 2) and codons 163-169 (region 3). In addition, a p53-binding site of 20 nucleotides in intron 1 of p53R2 was also analyzed. RESULTS: One renal pelvic TCC (0.9%: 1/108) had a single-base substitution in p53R2 with a G to T transversion resulting in the amino acid substitution Glu136 --> Asp. This base substitution was localized within the domain of exon 4 encoding the RR small subunit signature, and causes an amino acid substitution in one of the most highly conserved regions of p53R2, in which human R2 and yeast RNR2 and RNR4 proteins are highly homologous. CONCLUSION: This finding provides the in vivo evidence for the infrequent involvement of alterations in p53R2 inhuman urothelial TCCs.     

Cell differentiation-related gene expression of human papillomavirus 33

The gene expression of human papillomavirus (HPV) 33, which can be detected both in benign and malignant genital tumors, was analyzed in a cervical condyloma acuminatum by in situ hybridization using open reading frame-specific RNA probes. Viral mRNA concentrations increased with the degree of differentiation of the keratinocytes. The probes for reading frames E4 and E5 generated the most intense signals. The patterns of the specific viral mRNAs were very similar to those in condylomas induced by HPV 6 or 11, which are only rarely associated with malignancies. This implies that in tumors of the same degree of morphological differentiation the gene expression program of different HPV types is essentially identical. The pattern observed here most likely corresponds to a productive phase of viral infection.     

Prognostic significance of p53 gene mutations and p53 protein expression in synovial sarcomas

Alterations to p53 seem to be of prognostic significance in soft tissue sarcomas, but their significance for synovial sarcomas has not been studied. We analysed 34 synovial sarcomas in 19 patients for p53 alterations (p53 gene mutations + p53 immunopositivity) and examined this factor for its prognostic value in a group of 15 primary tumours. DNA was prepared from paraffin-embedded tumour material by a modified proteinase K/phenol/chloroform extraction. p53 gene mutations of exons 5–8 were analysed by the PCR-SSCP-sequencing method. p53 protein expression was evaluated by immunohistochemistry using the murine monoclonal antibody DO1. We found two missense mutations (5.9%) and ten p53 immunopositive cases (29.4%). Both tumours with p53 mutations showed p53 protein expression. There was no significant correlation between p53 alteration and histological subtype, age, sex, or tumour size. The 5-year survival rate was 24.1%. Overall survival was significantly reduced in patients having synovial sarcomas with p53 alterations (P<0.001). In the multivariate Cox’s analysis, only p53 alterations (P=0.032) and tumour size (P=0.023) emerged as independent prognostic factors. We suggest that p53 alterations may be a useful prognostic indicator in synovial sarcomas, allowing rational clinical treatment and follow-up. Received: 13 April 1999 / Accepted:18 May 1999