Expression of the p53 protein in oral squamous cell carcinomas associated with Epstein-Barr virus

The behaviour of the p53 protein has been investigated in some human carcinomas associated with Epstein-Barr virus (EBV) but not in EBV-positive oral squamous cell carcinomas (OSCC). The present study aimed to compare the p53 protein expression in EBV-positive OSCC with that in EBV-negative OSCC. The cases had been gathered in a study previously published. An immunohistochemical technique with BP53-12 monoclonal antibody was applied on 74 of the 107 OSCC from the earlier work. The nuclear or cytoplasmic expression of the p53 protein was classified as, absent (0% of neoplastic cells positive), mild (<25% positive), moderate (25-30% positive), or extensive (>50% positive). The p53 protein was expressed by 60.8% of the OSCC. Out of the fourteen EBV-positive OSCC, 57.1% (8 cases) expressed p53, always in the nucleus and never in the cytoplasm. Of the 60 EBV-negative OSCC, 61.6% (37 cases) expressed the p53 protein. Of 37 cases 33 (89.1%) showed nuclear expression of p53 and nineteen cases (51.3%) revealed cytoplasmic expression. There was a statistically significant inverse correlation between cytoplasmic expression of the p53 protein and the presence of EBV DNA (p <0.01). Thus, the EBV-positive tumours less frequently expressed p53 in the cytoplasm. No evidence of an accumulation of the p53 protein in OSCC associated with EBV was recorded.     

肝细胞癌p53蛋白过表达的免疫组织化学研究

为探讨肿瘤抑制基因ｐ５３ 在肝癌细胞中的变化, 本实验对３８ 例人肝细胞癌组织ｐ５３ 蛋白的表达进行了免疫组织化学检测, 并与其临床和病理观察进行了比较研究。免疫组化检查显示, １５例肝癌组织ｐ５３蛋白免疫染色阳性, 其突变率为３９．５％ （１５／３８）。比较表明, 肝细胞癌ｐ５３ 蛋白的过度表达与病人的年龄、性别和肿瘤大小无关, 而与肝癌的转移和分化程度有关, 在高分化肝癌中其阳性率为９．１％ （１／１１）, 在中分化肝癌为２２．２％ （２／９）, 在低分化肝癌则高达６６．７％ （１２／１８）。因此, ｐ５３ 蛋白检测可作为肝癌预后判断的指标之一     

Cellular protein alterations in colorectal cancer: p28, p53 and p65 studies

The expression and intracellular distribution of the p28 protein (MW 28 kD), which is electrophoretically specific for tumour cells, the p53 protein (MW 53 kD), one of the most frequently mutated in cancer, and the oncofoetal p65 protein (MW 65 kD), were investigated in colorectal cancer and normal colonic mucosa. The correlation between the expression of these proteins and the stage of the cancer, was evaluated. Neoplastic and normal tissues were fractionated by differential centrifugation, and protein analysis was performed by means of the Western blot technique in the presence of polyclonal (anti-p28 and anti-p65) or monoclonal (anti-p53) antibodies. Among the colorectal cancer cases examined 69% (11/16), 53% (10/19) and 77% (17/22) were positive for p28, p53 and p65, respectively. Immunoblot analysis revealed that the tumour specific p28 protein expression was mainly evident in the nuclear fraction, while the p53 and p65 proteins accumulated in the cell nuclei and the cytoplasm, although to different extents. The p65 protein appeared to be specifically expressed in the early stages of colorectal cancer, while a high level of p53 protein was typical for more invasive colorectal cancer stages.     

Inhibition of stress-inducible kinase pathways by tumorigenic mutant p53

More than 50% of human cancers contain p53 gene mutations and as a result accumulate altered forms of the full-length p53 protein. Although certain tumor types expressing mutant p53 protein have a poor prognostic process, the precise role of mutant p53 protein in highly malignant tumor cells is not well defined. Some p53 mutants, but not wild-type p53, are shown here to interact with Daxx, a Fas-binding protein that activates stress-inducible kinase pathways. Interaction of Daxx with p53 is highly dependent upon the specific mutation of p53. Tumorigenic mutants of p53 bind to Daxx and inhibit Daxx-dependent activation of the apoptosis signal-regulating kinase 1 stress-inducible kinases and Jun NH(2)-terminal kinase. Mutant p53 forms complexes with Daxx in cells, and consequently, mutant p53 is able to rescue cells from Daxx-dependent inhibition of proliferation. Thus, the accumulation of mutant p53 in tumor cells may contribute to tumorigenesis by inhibiting stress-inducible kinase pathways.     

p27和p53基因在大肠癌中的表达及临床意义

目的 研究大肠癌患者癌组织中p27、p53基因的表达及其相互之间的关系,以探讨p27、p53基因在大肠癌发生中的作用及临床意义。方法 运用原位杂交方法及免疫组化SP法检测58例大肠癌组织及正常黏膜中p27mRNA和P27蛋白的表达,同时运用免疫组化法分析相同组织中P53蛋白表达状况。结果 p27mRNA在大肠癌组织及正常黏膜中的表达阳性率均为100%。P27蛋白在大肠癌组织中的表达阳性率为55.17%,在正常黏膜中的表达阳性率为96.55%（P〈0.01）;癌组织中P53蛋白表达阳性率为53.45%,正常黏膜未见P53蛋白表达（P〈0.01）;大肠癌组织中P27与P53蛋白表达无明显相关性。P27蛋白的表达与肿瘤分化程度呈负相关（P〈0.01）,与临床其它病理因素均无相关性（P〉0.05）。大肠癌组织中P53蛋白表达与临床病理因素亦无相关性（P〉0.05）。结论 P27蛋白表达的调控主要在转录后水平,P27蛋白检测可作为评价大肠癌恶性程度和预后判断的重要指标。P27及P53蛋白在大肠癌的发生发展过程中具有重要作用。     

广东食管癌中Epstein-Barr病毒感染与细胞增殖p53的关系

目的 :研究食管癌中 EB病毒感染情况 ,探讨其与肿瘤细胞增殖及抑癌基因 p5 3的关系。方法 :应用聚合酶链反应技术 (PCR)检测食管癌中 EB病毒 DNA的感染。用免疫组化方法检测其中 p5 3的表达及肿瘤细胞增殖。结果 :2 4例食管癌中 ,EB病毒 DNA阳性率为 95 .8% (2 3/2 4)。 2 3例阳性病例中存在 p5 3蛋白积聚者为 16例 ,积聚率为 6 9.6 % (16 /2 3) ;1例 EB病毒 DNA阴性者 ,p5 3蛋白染色阴性。 p5 3蛋白积聚与增殖细胞核抗原的表达密切相关 (P<0 .0 5 )。结论 :广东食管癌中普遍存在 EB病毒的感染。有 EB病毒感染的病例 ,亦存在 p5 3蛋白积聚。 EB病毒可能与 p5 3的改变有关 ,从而导致细胞增殖。     

P~（53） PROTEIN OVEREXPRESSION IN PREMALIGNANT AND MALIGNANT LESIONS OF ORAL MUCOSA：IMMUNOHISTOCHEMICAL OBSERVATION

Ｐ~（５３）　ＰＲＯＴＥＩＮ　ＯＶＥＲＥＸＰＲＥＳＳＩＯＮ　ＩＮ　ＰＲＥＭＡＬＩＧＮＡＮＴ　ＡＮＤ　ＭＡＬＩＧＮＡＮＴ　ＬＥＳＩＯＮＳ　ＯＦ　ＯＲＡＬ　ＭＵＣＯＳＡ：ＩＭＭＵＮＯＨＩＳＴＯＣＨＥＭＩＣＡＬ　ＯＢＳＥＲＶＡＴＩＯＮＰ~（５３）ＰＲＯＴＥＩ...     

散发性大肠癌组织及粪便脱落细胞p53蛋白的检测

为了解大肠癌组织及粪便脱落细胞中 p5 3蛋白表达对大肠癌诊断的临床意义 ,采用 S- P法对 38例大肠癌患者的癌组织及其中的 30例患者的粪便脱落细胞 p5 3蛋白进行检测。大肠癌组织中 p5 3蛋白阳性表达率为 39.47% (15 / 38) ,p5 3蛋白阳性与癌组织的分化程度及是否存在淋巴结转移均无相关性 (P>0 .0 5 )。粪便脱落细胞 p5 3蛋白阳性表达率为 36 .6 7%(11/ 30 ) ,脱落细胞与相应患者的癌组织中的 p5 3表达一致率为 83.33% (2 5 / 30 )。表明粪便中脱落细胞 p5 3蛋白的表达忠实反映了相应癌组织的 p5 3突变情况 ,对其检测有望成为大肠癌诊断及筛查的无创分子途径。同时表明粪便中脱落细胞核保持了肿瘤抗原决定簇的主要结构及生物特征 ,进行免疫细胞化学检测是可行的 ,为进行脱落细胞核其它肿瘤标志物或其它生物研究奠定了可行性的基础     

Study of p53 protein expression in prostate cancer

The aim of this study was the immunohistochemical evaluation of p53 protein expression in localized prostate cancer (Pca) following radical prostatectomy and analysis of its relationship to chosen anatomo-clinical and morphological parameters of the tumours. The present investigation included material from 28 randomly selected patients undergoing radical prostatectomy. Tissue sections were fixed in 10% buffered formaldehyde solution, embedded in paraffin and stained immunohistochemically with the anti-human p53 protein monoclonal antibody. The immunolocalization of p53 protein was performed using the Labelled Streptavidyn Biotin (LSAB) method. The p53 protein expression was semiquantitatively assessed in neoplastic cells and the reaction present in more then 25% of tumour cells was accepted as the threshold of positivity. No correlation was found between p53 protein expression and Gleason score, pT stage, lymph node metastases, seminal vesicles invasion, positive or negative surgical resection margins, age of patients. However, p53 protein expression and capsular penetration was found statistically significantly correlated.     

Detection of p53 protein and Ki-67 proliferation antigen in human papillomavirus (HPV)-positive and HPV-negative cervical lesions by immunohistochemical double-staining

In HPV-associated genital lesions, low or absent expression of p53 has been attributed to the rapid degradation of p53 through its binding with HPV E6 protein. In this study, we examined p53 protein expression with two antibodies (CM1 polyclonal and PAb 1801 monoclonal antibodies), and Ki-67 proliferation antigen (monoclonal antibody) using an immunohistochemical (IHC) double-staining technique in 77 HPV-positive cervical lesions (HPV6, HPV11, HPV16, HPV18, HPV31, and HPV33) and in 15 HPV-negative cases. p53 protein expression was detected in 36/92 (39.1%) of the specimens. of the p53-positive cases, 80.6% (29/36) were HPV-positive samples, including 10/23 (43.5%) of HPV16- and 3/10 (30%) of HPV18-positive biopsies. In 52.8% of the p53-positive samples, the expression was found in less than 5% of the basal cells which were also positive for Ki-67.
Ki-67 proliferation marker was found in 91/92 specimens, most intensely in those infected by HPV16. p53 was more abundant in progressive or persistent lesions, but no differences were found between HPV-positive and HPV-negative samples. the positive IHC double-staining of both p53 and Ki-67 proliferation antigen in the same basal (and parabasal) cells indicates that these two normal cell-cycle proteins are being expressed while the cells are entering from the G₁ to the S phase of the cell cycle. Since the latter property is only attributed to the wild-type p53 (but not to mutated p53), the p53 protein detected in HPV lesions by IHC is likely to be the wild-type p53 rather than mutated p53, and the result was also confirmed by using p53 mutant specific antibody PAb 240. Accordingly, the concept of HPV inactivating the wild-type p53 protein should be re-examined, and other mechanisms for HPV-mediated carcinogenesis should be considered.     

Immunohistochemical co-expression of c-erbb-2/Neu oncoprotein, altered tumour suppressor (p53) protein, EGF-R and EMA in histological subtypes of infiltrating duct carcinoma of the breast

Carcinoma of the breast has an unpredictable biological behaviour. Several oncogenes have been implicated in the progression of breast cancer. Immunohistochemical staining of c-erbB-2 (Neu) oncoprotein and mutant p53 protein on 45 cases of infiltrating duct carcinoma (IDC) of the breast revealed 33% membrane positivity of c-erbB-2 oncoprotein, 46% nuclear positivity of mutated p53 protein, 33% and 84% membrane positivity of EGF-R and EMA respectively. Staining profile of c-erb-B2 oncoprotein in various histological subtypes of IDC of the breast indicated a high positivity rate in comedo followed by NOS and cibriform subtype. Similarly, high incidence of immunopositivity of mutated p53 protein was observed in comedo and cibriform subtypes while papillary carcinoma were found exclusively positive for mutated p53 protein. Interestingly, tubular subtype of IDC was not positive for c-erbB-2 oncoprotein as well as p53 mutant protein. Further, comedo and cibriform subtypes of IDC revealed 'high grade' histological features of tumour of the breast with high mitotic count, presence of marked pleomorphism and multinucleation thus, reflecting a positive relationship with overexpression of c-erbB-2 (Neu) oncoprotein as well as mutant p53 protein. The results on immunoexpression of c-erbB-2 oncoprotein and mutated p53 protein in various histological subtypes of IDC of the breast demonstrated c-erbB-2 status as an important predictor and also indicated that oncogene product may be involved in growth factor response pathway.     

Loss of heterozygosity of the p53 gene and deregulated expression of its mRNA and protein in human brain tumors

Tumor-specific alterations at the p53 gene locus were analyzed in 40 human brain tumor samples. Gliomas were more prevalent in young males and meningiomas in old females. Structural changes at the intron 1 region of the p53 gene were analyzed in these tumors by Southern blotting. Among the 40 tumors, 33 were informative and 21 of these (63.6%) informative cases showed loss of heterozygosity (LOH). This is the first report showing LOH at the intron 1 region of p53 gene in human brain tumors. The level of p53 mRNA, p53 protein and Ser 392 phosphorylated p53 protein were also analyzed in all tumor samples. Normal sized p53 mRNA and protein were present in all the tumor samples; however, their levels were 1.5- to 4-fold higher compared to the control suggesting deregulated p53 pathway in these tumors. No correlation was found between LOH status and the levels of p53 mRNA and protein. In all high-grade glioblastomas majority of the p53 protein existed as Ser 392 phosphorylated form as compared to low-grade gliomas. In addition, the percentage of Ser 392 phosphorylated form of p53 protein was lower in meningiomas and other brain tumor types irrespective of tumor grade. These results suggest involvement of Ser 392 phosphorylated form of p53 protein during the later stages of glioma development. These results also indicate that deregulation of p53 gene could occur at various steps in p53 pathway and suggest an overall deregulation of p53 gene in most brain tumor types.     

食管鳞癌p53、c-erbB-2蛋白表达研究

为探讨p53、c-erbB-2蛋白表达与食管鳞癌生物学行为的关系,应用免疫组化LSAB法研究181例食管鳞癌中p53、c-erbB-2蛋白的表达。结果发现,正常食管粘膜均无p53、c-erbB-2蛋白的表达。47％食管鳞癌出现p53表达,p53阳性病例癌旁非典型增生上皮出现p53表达,p53阴性病例癌旁非典型增生上皮亦为阴性。p53阳性表达率与患年龄、性别、肿瘤大小、组织学分级,临床TNM分期无关,且与预后无关。51.4%食管鳞癌呈现c-erbB-2蛋白表达,癌旁非典型增生上皮无c-erbB-2表达。c-erbB-2阳性率与肿瘤组织学分级、浸润深度、淋巴结转移及肝转移有关,c-erbB-2阳性表达预后较差。结果提示,p53表达在食管鳞癌发生中起重要作用;c-erbB-2表达在食管鳞癌浸润转移中起重要作用。同时进行p53、c-erbB-2蛋白免疫组化检测,有助于对食管鳞癌进行早期诊断,监测病情和判断预后。     

bcl-2癌基因蛋白在甲状腺癌中的表达及其意义

利用免疫组织化学技术,对６４例甲状腺癌进行了ｂｃｌ－２蛋白表达的检测,同时进行ｐ５３蛋白的对照检测。结果显示,甲状腺癌中ｂｃｌ－２蛋白阳性表达率为８１．３％（５２／６４）,但未分化癌无阳性表达。ｐ５３蛋白在甲状腺癌的阳性表达率为２０．３％（１３／６４）,而未分化癌全部为阳性表达。两种抗体在甲状腺癌的阳性表达率有显著性差异（Ｐ＜０．０１）。结果提示ｂｃｌ－２蛋白在甲状腺癌的表达与肿瘤细胞的分化程度有关,并与ｐ５３蛋白呈反比关系,ｂｃｌ－２与ｐ５３蛋白表达的不同分布可作为判断甲状腺癌预后的一个重要参考指标     

Expression profiles of p53 and p66shc during oxidative stress-induced senescence in fetal bovine fibroblasts

Somatic cells undergo a permanent cell cycle arrest, called cellular senescence, after a limited number of cell divisions in vitro. Both the tumor suppressor protein p53 and the stress-response protein p66(shc) are suggested to regulate the molecular events associated with senescence. This study was undertaken to investigate the effect of different oxygen tensions and oxidative stress on cell longevity and to establish the role of p53 and p66(shc) in cells undergoing senescence. As a model of cellular senescence, primary fetal bovine fibroblasts were cultured in either 20% O(2) or 5% O(2) atmospheres until senescence was reached. Fibroblasts cultured under 20% O(2) tension underwent senescence after 30 population doublings (PD), whereas fibroblasts cultured under 5% O(2) tension did not exhibit signs of senescence. Oxidative stress, as measured by protein carbonyl content, was significantly elevated in senescent cells compared to their younger counterparts and to fibroblasts cultured under 5% O(2) at the same PD. p53 mRNA gradually decreased in 20% O(2) cultured fibroblasts until senescence was reached, whereas p53 protein levels were significantly increased as well as p53 phosphorylation on serine 20, suggesting that p53 might be stabilized by posttranslational modifications during senescence. Senescence was also associated with high levels of p66(shc) mRNA and protein levels, while the levels remained low and stable in dividing fibroblasts under 5% O(2) atmosphere. Taken together, our results show an effect of oxidative stress on the replicative life span of fetal bovine fibroblasts as well as an involvement of p53, serine 20-p53 phosphorylation and p66(shc) in senescence.     

Downregulation of proapoptotic proteins Bax and Bcl-X(S) in p53 overexpressing hepatocellular carcinomas

As the occurrence of structural p53 mutations in hepatocellular carcinoma (HCC) in Thailand was previously reported to be much lower than that found in other high-incidence HCC areas, we analyzed 16 HCC samples from Thailand to determine the expression and functionality of p53 protein. We observed the overexpression of p53 protein in 69% of HCC, despite the prevalence of the wild-type p53 gene. However, the overexpressed p53 protein was nonfunctional as suggested by its inability to modulate the expressions of several p53 effector proteins (p21 and Bcl-2 family proteins). In addition, we observed significant underexpression of two proapoptotic proteins, Bax and Bcl-X(S), in 81% (P = 0.02) and 64% (P = 0.03) of HCC, respectively. Consequently, the ratios of proapoptotic to antiapoptotic BCL-2 family proteins were reduced in 88% of the HCC tumor tissues when compared to normal tissues, such that the rheostat between BCL-2 family proteins is strongly skewed toward enhanced cell survival in the tumor cells.     

Serum p53 protein and anti-p53 antibodies are associated with increased cancer risk: a case–control study of 569 patients and 879 healthy controls

The aim of this study to determine whether serum p53 protein and antibodies are associated with malignant tumors. A case–control study was conduct in 569 patients with various types of malignant tumors and 879 healthy controls. Serum p53 protein and antibodies were analyzed by enzyme-linked immunosorbent assay (ELISA).The rate of positive p53 protein in patients with various malignant tumors was 4.22% compared with 0.34% in healthy controls (P < 0.001). The rate of anti-p53 antibodies in patients with various malignant tumors was 14.59% compared with 1.02% in healthy controls (P < 0.001). The adjusted odd ratio (OR) for p53 protein was 17.55 (95% CI = 4.98–61.94). The adjusted odd ratio for anti-p53 antibodies was 14.27 (95% CI = 6.75–30.16). The study strongly suggested that serum p53 protein and antibody are associated with increased cancer risk and can be used as early serological markers in the diagnosis of malignancies tumors.     

Mdmx and Mdm2: Brothers in Arms?

The p53 tumor suppressor pathway is inactivated in most if not all human tumors. In about 50% of the cases this is accomplished directly by gene mutations. The tumors that retain wild type p53 frequently show defects either in effector target genes, or in the expression of p53 regulatory proteins. The Mdm2 protein is generally considered THE master regulator of the p53 tumor suppressor activity. Recently, however, the Mdm2-related protein Mdmx is taking the stage in the p53-Mdm2-Mdmx play. We summarize here observations unambiguously assigning a critical role for the Mdmx protein in the regulation of p53 function during development and tumor formation.