p53 overexpression in oral lichen planus

Oral lichen planus (OLP) is considered as a premalignant lesion, but some argue that only lichenoid lesions with dysplasia is precancerous. To address the question whether OLP without dysplasia is premalignant, we investigated the immunohistochemical expression of p53 in OLPs without dysplasia. Half of the OLPs showed p53 positive cells in the basal epithelium. SSCP-PCR analysis of 4 p53 positive OLPs failed to demonstrate mutations. What is the significance of p53 expression in these OLPs? The confinement of p53 positive cells to the basal cells seems to be against false positivity. Since the pathogenesis of OLPs involves cell-mediated cytotoxicity (CMC) which causes marked apoptosis, it is possible that the p53 expression represents wild-type p53 that may be regulating the apoptosis. Alternatively p53 protein may be stabilized by some mechanisms other than gene mutation as a result of cellular insults from CMC.     

P53 overexpression in normal oral mucosa of heavy smokers

The observation that p53 alterations are early events in the tumorigenesis of head and neck cancer and the association with cigarette smoking have prompted us to search for p53 overexpression in the oral mucosa of heavy smokers who have no overt precancerous or cancerous lesions. Formalin-fixed paraffin embedded tissue sections, obtained from oral mucosa of 30 otherwise healthy heavy smokers, were evaluated for tobacco related changes, and immunostained with a mouse monoclonal antibody p53-DO7 for p53 immunoreactivity. Histopathological evaluation revealed hyperplastic changes in twenty eight samples (93%), eight of which also demonstrated dysplastic changes. Positive immunoreaction for p53 was detected in six (20%) of the tissue samples. The study provided significant information about the frequency of hyperplasia, dysplasia, and p53 overexpression in individuals who were heavy smokers. It is suggested, also, that chemoprevention might have some impact in this particular group of individuals.     

Clinicopathological characteristics of p53 overexpression in endometrial cancers

Using immunohistochemical methods, we analyzed the association between nuclear p53 overexpression and various clinico-pathological parameters in patients with endometrial cancers. Formalin-fined and paraffin-embedded tissue sections from 139 cases of endometrial cancer (endometrioid type, 126; serous papillary type, 12; and clear-cell type, 1) were stained with anti-p53 monoclonal antibody (MAb) DO7. Overexpression of p53 was associated with high malignant potential, including extensive muscular invasion, advanced surgical stage, high histological grade, serous papillary type and a personal history of cancer. Lymph-node metastasis was also related to p53 overexpression with marginal significance. Survival curves determined by the Kaplan-Meier method and univariate analysis showed p53 overexpression to be associated with a poor outcome in endometrial cancer patients. However, multivariate analysis using the stepwise Cox proportional-hazard model showed that whereas lymph-node metastasis, a personal history of cancer and muscular invasion were related to poor survival rates, p53 overexpression was not. Consequently, p53 overexpression itself does not appear to be an independent prognostic factor in endometrial cancer, although a still larger sample of patient material would be required to assess this issue definitively. © 1994 Wiley-Liss, Inc.     

Therapeutic potential of recombinant p53 overexpression in breast cancer cells expressing endogenous wild-type p53

Reconstitution of the p53-dependent apoptotic pathway by gene transfer of a recombinant wild-type p53 minigene leads to rapid apoptotic cell death in breast and other cancer cell types expressing null or mutant p53. Tumour cells expressing wild-type p53 have been reported to be more resistant to this treatment strategy, presumably as a result of mutations in downstream regulators of p53-dependent apoptotic signalling. The MCF-7 breast cancer cell line is representative of this class of tumour cell. Our recent observation of a p53-dependent apoptotic response following adenovirus-mediated HSV thymidine kinase gene transfer and gancyclovir treatment led us to reexamine recombinant p53 cytotoxicity in MCF-7 cells. Infection with a recombinant adenovirus expressing wild-type p53 resulted in a dramatic increase in p53 protein levels and was accompanied by an increase in p21^{WAF 1/CIP1} protein levels and G1 arrest within 24 hours post-infection. A significant decrease in MCF-7 cell viability was first observed at 5 days post-infection and coincided with the appearance of morphological and biochemical changes consistent with apoptotic cell death. By day 7 post-treatment, cell viability decreased to 45% and clonogenic survival was reduced to 12% of controls. The results demonstrate that persistent, high level expression of recombinant p53 can induce programmed cell death in MCF-7 cells. While the mechanism by which p53 overexpression overcomes the defect in downstream apoptotic signalling is not clear, our data suggests that this treatment strategy may be beneficial for the class of tumour cells represented by the MCF-7 cell line.     

17p allelic deletions and p53 protein overexpression in Barrett's adenocarcinoma.

Barrett's esophagus is a condition in which the stratified squamous epithelium of the esophagus is replaced by metaplastic columnar epithelium that predisposes to the development of esophageal adenocarcinoma. Allelic deletions of 17p and alterations of p53 including elevated p53 protein levels have been observed in many different tumors. To investigate the presence of 17p allelic deletions and p53 protein overexpression in Barrett's adenocarcinomas, we have combined the use of restriction fragment length polymorphism analysis, multiparameter flow cytometry, and DNA content cell sorting. The combined use of these methodologies permits the purification of aneuploid tumor cells for restriction fragment length polymorphism analysis of 17p allelic deletions and the evaluation of p53 protein expression by multiparameter flow cytometry in the same aneuploid tumor cell populations. We analyzed 15 aneuploid populations and one tetraploid populations from 13 Barrett's adenocarcinomas for 17p allelic deletions and p53 protein overexpression to determine whether both of these alterations are involved in carcinogenesis in Barrett's esophagus. Twelve of 13 tumors (92%) had 17p allelic deletions, and 8 of 13 tumors (62%) had p53 protein overexpression. Eight of the 12 tumors (67%) with 17p allelic deletions also had p53 protein overexpression. These data indicate that both 17p allelic deletions and p53 protein overexpression are frequently involved in carcinogenesis in Barrett's esophagus.     

Immunohistochemical evidence of p53 overexpression in gastric epithelial dysplasia.

Molecular abnormalities of the p53 gene in chromosome 17p may be among the most commonly observed in human cancer. Their role in gastric carcinogenesis is suggested by their frequent detection in invasive adenocarcinomas. To investigate the chronology with which these abnormalities appear in the gastric carcinogenesis process, the expression of p53 proteins was investigated in late stages of the process, namely dysplasia, and in superficial carcinomas. A polyclonal antibody, CM-1, against both wild-type and mutant proteins was applied to paraffin-embedded biopsy and gastrectomy specimens previously fixed in buffered formalin. Positive nuclear stain was obtained in 36.4% of 33 cases of gastric epithelial dysplasia, corresponding to 19% of mild, 27.3% of moderate, and 64.3% of severe dysplasias. Eight of 13 (61.5%) invasive carcinomas showed positive stain. The data indicate an increased incidence of p53 abnormalities in the late stages of gastric carcinogenesis.     

p53 mutations and overexpression in locally advanced breast cancers.

Alterations in the p53 gene were analysed in 39 patients with locally advanced breast cancers (LABCs) (stage III-IV) with inflammatory signs in most cases (UICC stage T4d = 32 patients) by molecular and immunohistochemical (IHC) approaches. All patients were included in the same therapy protocol. Using polymerase chain reaction (PCR) and a single-strand conformational polymorphism migration technique (SSCP), the presence of mutations in exons 2-11, covering the entire coding sequence of the p53 gene, was evaluated. Using the mouse specific anti-human p53 monoclonal antibody (PAb 1801), we also looked for overexpression of the p53 protein in tissue sections. In 16 cases shifted bands were reproducibly identified by PCR-SSCP, and all but one (localised to exon 10) were in exons 5-8, the usual mutational hotspots. Fifteen of these 16 samples were sequenced and 14 of the suspected mutations (36%) were confirmed. Most of them (12) were single nucleotide substitutions, and transitions were more frequent (eight cases) than transversions (four cases). Fourteen of the tumour samples were positively stained with the monoclonal antibody PAb 1801, 11 with nuclear staining only, two with mixed cytoplasmic and nuclear staining and one with cytoplasmic staining only. Staining patterns were very heterogeneous in terms of the percentage of positive cells (10-75%) and their distribution in the tissue section (isolated foci or dispersed cells). In 11 of the 14 mutated cases a positive immunostaining was observed. The presence of a p53 mutation was significantly associated with larger tumour diameter (chi 2 = 7.490, P = 0.0062) and the presence of clinical metastases (stage IV) (chi 2 = 10.113, P = 0.0015). A non-statistically significant trend of association was observed between p53 mutation, negative oestrogen receptors and lower response rate to therapy. Our results in this group of patients and the heterogeneity of the staining of tumour cells in tissue sections suggest that p53 mutations could be a late event in this non-familial form of breast cancer.     

启东肝癌组织p53过表达的免疫组化检测

目的　了解p5 3突变在启东地区的肝癌发生中所起的作用。方法　应用免疫组化 (IHC)的方法对 90例肝癌和 75例癌旁组织切片进行p5 3蛋白检测。结果　在 90例肝癌中 ,有 4 0例 (44 .4 % )在核中表达为强阳性 ,2 5例 (2 7.8% )在核中表达为弱阳性 ;在 75例癌旁中 ,没有细胞核强阳性表达 ,仅 1例 (1.3% )有核弱阳性表达 ;肝癌的p5 3核表达显著高于癌旁 (P =0 .0 0 0 )。另外 ,在肝癌中有 9例 (10 % )为细胞质p5 3表达阳性 ,在癌旁中有 17例 (2 2 .7% )为细胞质表达阳性 ,肝癌的胞质p5 3表达显著低于癌旁 (P =0 .0 2 6 )。结论　p5 3基因突变和p5 3的功能失活在启东的肝癌发展中有着重要意义。     

Prognostic significance of p53 overexpression and mutation in colorectal adenocarcinomas.

The p53 tumour-suppressor gene is found altered in the majority of colorectal cancers. Lesions include allelic loss, mutation of the gene and overexpression of the p53 protein. All of these lesions have been analysed for prognostic significance, and whereas both mutation and allelic loss have been shown to be reasonably useful markers of prognosis, the utility of overexpression of the p53 protein is more ambiguous. Given that many authors use p53 overexpression as a marker for point mutation this issue is of some importance. We have therefore examined 100 colorectal carcinomas for mutation of the p53 gene, as well as overexpression of the p53 protein. Results show that whereas mutation of the p53 gene is associated with p53 overexpression, the degree of association depends, at least in part, upon the particular antibody used. Moreover, although mutation of the p53 gene does provide prognostic information, overexpression of the p53 protein, as detected with two antibodies, does not. These results suggest that immunohistochemistry is not a suitable alternative to direct detection of mutation in assessing prognosis in colorectal cancer patients.     

p53 protein overexpression and p53 mutation analysis in patients with intestinal metaplasia of the cardia and Barrett's esophagus

p53 mutation is a common genetic change in human cancers, but the clinical significance is controversial. We studied 68 patients and estimate the prevalence of intestinal metaplasia of cardia (IMC), Barrett's esophagus (BE), and p53 protein overexpression, and described molecular alterations of p53 gene exons 5 to 8. Immunohistochemical analysis showed positive p53 in 56.1–39.1% (IMC) and 60.9% (BE). Molecular analysis showed 36.6% altered cases in exon 5 and 9.8% in exon 7. In conclusion, p53 protein overexpression is common in IMC and BE. The molecular alterations observed may be due to LOH, genomic instability or other unknown alteration.     

肺鳞癌细胞p~(53)蛋白及ras p~(21)的免疫组织化学定量研究

应用免疫组织化学方法检测２２例肺鳞癌组织标本的ｐ５３及ｒａｓｐ２１表达，用显微图像分析仪测定阳性细胞百分率Ｐ／Ａ（％）和平均光密度（ＡＯＤ），并采用阳性水平指数（ｐｏｓｉｔｉｖｅｌｅｖｅｌｉｎｄｅｘ，ＰＬＩ）作为免疫组化反应水平指标，对癌基因蛋白进行比较研究。结果显示：ｐ５３表达阳性率为５０％，ｒａｓｐ２１表达阳性率为６３６％。ｐ５３蛋白表达在非角化型鳞癌组高于角化型鳞癌组；ｒａｓｐ２１的表达随组织分化程度的增高而增高，ｒａｓｐ２１与ｐ５３的表达水平无直线相关关系。     

Prognostic significance of p53 overexpression in gastric and colorectal carcinoma.

p53 expression was examined in 55 gastric and 107 colorectal carcinomas with an immunoperoxidase technique, using the polyclonal antibody CM1 on routinely fixed, paraffin embedded tissue. p53 protein was detected in 47% gastric and in 46% colorectal carcinomas and found to correlate with stage of disease and unfavourable clinical outcome (P less than 0.001). Thus, the proportion of positively reacting neoplasms increased as the stage progressed, tumours which had invaded regional lymph-nodes overexpressed p53 more frequently than localised carcinomas and an elevated level of p53 was associated with early relapse and death. In colorectal carcinoma p53 positivity was also linked with site and macroscopic configuration of the primary tumour and was most frequently expressed in carcinomas from the rectum and in ulcerative tumours. p53 overexpression was irrespective of tumour grade. Uniform negative reactivity with anti-p53 antibody was seen in normal epithelium adjacent to carcinoma, intestinal metaplasia, atrophic gastritis and in colonic adenomas. There was a good correlation between immunohistochemical staining on paraffin and frozen sections. These studies suggest that in gastric and colorectal carcinoma, immunohistochemical detection of p53 protein in routinely fixed tissue can be used along with other established parameters to assess prognostic outcome, especially to identify patients with poor short-term prognosis.     

Adenovirus-mediated overexpression of p14(ARF) induces p53 and Bax-independent apoptosis

The human INK4a gene locus encodes two structurally unrelated tumor suppressor proteins, p16(INK4a) and p14(ARF), which are frequently inactivated in human cancer. Whereas p16(INK4a) acts through engagement of the Rb-cdk4/6-cyclin D pathway, both the pro-apoptotic and cell cycle-regulatory functions of p14(ARF) were shown to be primarily dependent on the presence of functional p53. Recent reports have also implicated p14(ARF) in p53-independent mechanisms of cell cycle regulation and apoptosis induction, respectively. To further explore the pro-apoptotic function of p14(ARF) in relation to functional cellular p53, we constructed a replication-deficient adenoviral vector for overexpression of p14(ARF) (Ad-p14(ARF)). As expected, Ad-p14(ARF) efficiently induced apoptosis in p53/Rb wild-type U-2OS osteosarcoma cells at low multiplicities of infection. Interestingly, Ad-p14(ARF) also induced apoptosis in both p53-deleted SAOS-2 osteosarcoma cells and HCT116 colon cancer cells with a bi-allelic knock-out of p53 (HCT116-p53(-/-)). Similarly, adenovirus-mediated overexpression of p14(ARF) induced apoptosis in p53/Bax-mutated DU145 prostate cancer cells as well as in HCT116 cells devoid of functional Bax (HCT116-Bax(-/-)). Restoration of Bax expression by retroviral gene transfer in DU145 cells did not further enhance p14(ARF)-triggered cell death. Infection with Ad-p14(ARF) induced activation of mitochondrial permeability shift transition, caspase activation and apoptotic DNA fragmentation irrespective of the presence or absence of either Bax or functional cellular p53. Nevertheless, overexpression of the anti-apoptotic Bcl-2 homolog Bcl-x(L) markedly inhibited p14(ARF)-induced apoptosis. This may indicate that p14(ARF) triggers a so far unknown activator of mitochondrial apoptosis which can be inhibited by Bcl-2 but which acts either independently or downstream of Bax. Taken together, this report demonstrates the participation of signaling pathways apart from the p53/Mdm-2 rheostat and Bax in p14(ARF)-mediated apoptosis.     

Genetic alteration of p53, but not overexpression of intratumoral p53 protein, or serum p53 antibody is a prognostic factor in sporadic colorectal adenocarcinoma

Mutation of p53 is a common event in colorectal cancer and can result in cellular accumulation of p53 protein and induction of p53 antibodies. We investigated the association of colorectal cancer with alterations in p53 DNA, protein and serum antibody levels to determine their prognostic value in colorectal cancer. Colorectal cancer patients (n=167) who underwent surgery in Taipei Veterans General Hospital from January 1999 to December 2000 were enrolled [age 62.91+/-12.61 years (range: 22-85); 111 (66.5%) males]. Of these, 20 were stage I (12%), 54 stage II (32.3%), 58 stage III (34.7%), and 35 stage IV (21%). Median follow-up was 36.3 months (range: 4-58). p53 alteration was detected by DNA sequencing from exon 5 to 9 and loss of heterozygosity (LOH) at two microsatellite markers near p53; and demonstrating intratumoral accumulation of p53 protein and detection of serum p53 antibodies using ELISA. p53 mutation frequency was 41.9% (70/167). Of 127 informative cases for LOH analysis, 73 (57.5%) tumors that had LOH had at least one microsatellite marker. Genetic p53 alterations were found for 56.3% of cases when LOH and DNA sequencing methods were combined. Genetic p53 alterations were associated with advanced tumor stage and tumor differentiation. Overexpression of intratumoral p53 and anti-p53 antibody positivity were 44.9% and 28.1%. The presence of p53-Ab was associated with p53 mutations (chi2 test, 42.9% vs. 17.5%, p=0.001), but not with overexpression of intratumoral p53 protein. The mutations at exon 6 (57.1%) and 7 (53.3%) were associated with presence of serum p53-Ab. Of 132 potentially cured patients, 3-year disease-free survival (DFS) was affected by: advanced TNM stage (I, II, III: 90%, 84%, and 41%), genetic p53 alteration (89% vs. 43%), intratumoral p53 accumulation (71% vs. 56%), and preoperative CEA level >5 ng/ml (74% vs. 58%). In multivariate analysis, genetic alteration of p53 was the most significant independent prognostic factor [hazard ratio (HR) = 6.09; 95% confidence interval (CI): 2.45-15.11], followed by advanced tumor stage (HR = 3.93; 95% CI: 2.14-7.23), and preoperative CEA >5 ng/ml (HR = 1.98; 95% CI: 1.12-3.17). Genetic alterations in p53 but not intratumoral p53 protein accumulation or p53-Ab appear to play a significant role in the progression of colorectal cancer.     

p53基因突变和STK15基因过表达与喉癌发生的关系

目的　探讨p5 3基因突变和STK15基因表达与喉癌发生发展的关系。方法　自 5 5例术前未经化疗和放疗的喉鳞状细胞癌患者的新鲜手术标本中 ,分别取配对癌组织和癌旁正常组织进行以下检测 :(1)提取DNA ,采用聚合酶链反应 单链构象多态性 (PCR SSCP)银染结合DNA直接测序 ,检测喉鳞癌组织中p5 3基因第 7外显子 (p5 3E7)和第 8外显子 (p5 3E8)的突变情况 ;(2 )提取总RNA ,反转录合成cDNA ,以 β actin为内对照进行PCR扩增 ,分析STK15基因表达的水平。结果　 5 5例喉癌组织中 ,17例 (30 .9% )发生p5 3E7突变 ,未发现p5 3E8突变 ;癌组织STK15基因表达与 β actin表达平均密度比值 (ADV)为 1.2 2± 0 .4 9。癌旁正常组织发生p5 3E7突变 1例 (1.8% ) ,p5 3E8突变 1例 (1.8% ) ;癌旁正常组织ADV为 0 .99± 0 .5 4。喉癌组织p5 3E7突变率显著高于癌旁正常组织 (χ2 =8.6 6 ,P <0 .0 1)。癌组织STK15基因表达高于癌旁正常组织 (t=4 .5 39,P <0 .0 1)。 17例p5 3基因突变的患者中 ,14例 (82 .4 % )癌组织STK15基因表达高于癌旁正常组织 ;38例癌组织STK15基因表达高于癌旁正常组织的患者中 ,14例 (36 .8% )存在p5 3E7突变。 2 5 .5 %的喉癌患者同时发生p5 3E7突变与STK15基因表达增高。结论　同时发生p5 3基因突变和STK     

p53 overexpression in normal and dysplastic tissues adjacent to p53 negative squamous cell carcinomas of the head and neck

p53 overexpression was present in the normal or dysplastic epithelium, but absent in the adjacent invasive cancers of five patients with head and neck squamous cell carcinomas (HNSCC), when p53 immunostaining (IHC) was performed. In three of the five p53 immunoreactive dysplasias and adjacent p53 negative invasive cancers single stranded conformation polymorphism (SSCP) results from exon 7 and 8 were also obtained. Bandshifts in exon 7 were detected in two dysplasias, and bandshifts in exon 8 were found in a third. Sequencing of exon 7 in the first dysplasia with bandshift indicated a deletion of codon 241-242 (loss of CT) resulting in a frame shift. In the second dysplasia with bandshift a mutation was observed in codon 244 resulting in a Gly-->Arg substitution in the protein sequence. In the adjacent IHC p53 negative invasive cancer lesions, no bandshifts could be observed by SSCP, and sequencing did not reveal any mutated p53. WAF1/p21 (IHC) expression was assayed to study p53 function. Image cytometry (ICM) DNA analysis, estimating genetic instability, showed progress in DNA aberration for invasive cancer lesions as compared with the dysplasias. Human papillomavirus (HPV DNA) was not detected by a polymerase chain reaction (PCR) in any of the five cancers thus excluding possible p53 degradation caused by HPV protein. In conclusion, the finding of p53 mutations in mild, moderate, and severe dysplasia indicates that p53 mutation, not only p53 immunoreactivity, can be an early event in HNSCC carcinogenesis. The lack of p53 immunoreactivity in the invasive cancers adjacent to p53 positive dysplasias could possibly be attributed to loss of the mutant allele, or clonal heterogeneity.     

Prognostic significance of p53 protein overexpression in betel- and tobacco-related oral oncogenesis

We have previously reported overexpression of p53 protein in tobacco-related oral dysplasia and squamous cell carcinoma (SCC) in the Indian population. A follow-up study was carried out to determine the prognostic significance of an accumulation of p53 protein during oral tumorigenesis. One hundred and two of 145 (70%) of oral SCCs and 39/75 (52%) of oral dysplasias showed overexpression of p53 protein, while only 3 of 107 (3%) normal oral tissues showed a detectable level of the protein. Follow-up studies of these patients suggest that an accumulation of p53 protein may be involved in the early phases of oral SCC development and indicate the predisposition of a particular premalignant lesion towards malignancy. In patients with premalignant lesions, the median transition time (premalignancy to malignancy) was significantly shorter in p53 positive cases than in p53 negative cases (p = 0.013). Among the oral cancer patients, univariate analysis showed that alteration in p53 expression was associated with significantly decreased disease-free survival. The p53 positive cases showed decreased median disease-free survival time (no recurrence/metastasis) compared with the p53 negative cases (p = 0.013), indicating that p53 accumulation may serve as a prognostic indicator in oral cancer patients. Int. J. Cancer (Pred. Oncol.) 79:370–375, 1998. © 1998 Wiley-Liss, Inc.