Role of the p53 protein in cell proliferation as studied by microinjection of monoclonal antibodies

Understanding p53 functions through p53 antibodies

TP53 is the most frequently mutated gene across all cancer types. Our understanding of its functions has evolved since its discovery four decades ago. Initially thought to be an oncogene, it was later realized to be a critical tumour suppressor. A significant amount of our knowledge about p53 functions have come from the use of antibodies against its various forms. The early anti-p53 antibodies contributed to the recognition of p53 accumulation as a common feature of cancer cells and to our understanding of p53 DNA-binding and transcription activities. They led to the concept that conformational changes can facilitate p53’s activity as a growth inhibitory protein. The ensuing p53 conformational-specific antibodies further underlined p53’s conformational flexibility, collectively forming the basis for current efforts to generate therapeutic molecules capable of altering the conformation of mutant p53. A subsequent barrage of antibodies against post-translational modifications on p53 has clarified p53’s roles further, especially with respect to the mechanistic details and context-dependence of its activity. More recently, the generation of p53 mutation-specific antibodies have highlighted the possibility to go beyond the general framework of our comprehension of mutant p53—and promises to provide insights into the specific properties of individual p53 mutants. This review summarizes our current knowledge of p53 functions derived through the major classes of anti-p53 antibodies, which could be a paradigm for understanding other molecular events in health and disease.

Ploidy and Proliferation Evaluated by Flow Cytometry. An Overview of Techniques and Impact in Oncology

Flow cytometric methods for the assessment of nuclear and chromosomal DNA content and of cell proliferation (including methods based on pulse-chase of bromodeoxyuridine and on monoclonal antibodies against nuclear oncoproteins and proliferation-associated antigens) are illustrated by examples and analyzed critically. The impact of most of these techniques for the study of human solid tumors, with exception of nuclear DNA content evaluation, appears still limited. In particular, new studies of cell lines and clinical material from human tumors using new proliferation markers and multiparameter flow cytometry are necessary to solve a considerable number of methodologic and scientific problems.

Elucidating the cancer-specific genetic alteration spectrum of glioblastoma derived cell lines from whole exome and RNA sequencing

Cell lines derived from tumor tissues have been used as a valuable system to study gene regulation and cancer development. Comprehensive characterization of the genetic background of cell lines could provide clues on novel genes responsible for carcinogenesis and help in choosing cell lines for particular studies. Here, we have carried out whole exome and RNA sequencing of commonly used glioblastoma (GBM) cell lines (U87, T98G, LN229, U343, U373 and LN18) to unearth single nucleotide variations (SNVs), indels, differential gene expression, gene fusions and RNA editing events. We obtained an average of 41,071 SNVs out of which 1,594 (3.88%) were potentially cancer-specific. The cell lines showed frequent SNVs and indels in some of the genes that are known to be altered in GBM- EGFR, TP53, PTEN, SPTA1 and NF1. Chromatin modifying genes- ATRX, MLL3, MLL4, SETD2 and SRCAP also showed alterations. While no cell line carried IDH1 mutations, five cell lines showed hTERT promoter activating mutations with a concomitant increase in hTERT transcript levels. Five significant gene fusions were found of which NUP93-CYB5B was validated. An average of 18,949 RNA editing events was also obtained. Thus we have generated a comprehensive catalogue of genetic alterations for six GBM cell lines.

Prognostic value of p53 and Ki67 expression in fiberoptic bronchial biopsies of patients with non small cell lung cancer

Background

Overexpression of the tumor suppressor gene p53 and the marker for cellular proliferation Ki67 in open lung biopsies are indicated as predictor factors of survival of patients with lung cancer. However, the prognostic value of p53 and Ki67 in fiberoptic bronchial biopsies (FBB) has not been fully investigated. We evaluated p53 and Ki67 immunostaining in FBB from 19 with Non Small-Cell Lung Cancer (NSCLC: 12 adenocarcinomas, 5 squamous cell carcinomas and 2 NSCLC-NOS).

Methods

FBB specimens were fixed in formalin, embedded in paraffin, and immunostained using anti-p53 and anti-Ki67 antibodies. Slides were reviewed by two independent observers and classified as positive (+ve) when the number of cells with stained nuclei exceeded 15% for p53 or when >25% positive cells were observed throughout each section for Ki67.

Results

Positive (+ve) immunostaining was found in 9 patients for p53 (47.37%) and 8 patients for Ki67 (42.10%). We examined overall survival curves of the patients with Mantel's logrank test, both p53 -ve and Ki67 -ve patients had significantly higher survival rates than p53 + ve (p < 0.005) and Ki67 + ve (p < 0,0001), respectively.

Conclusion

This study suggests that negative immunostaining of fiberoptic bronchial biopsies for p53 and Ki67 could represent a better prognostic factor for patients with NSCLC.

p53 is correlated with low BMI negative progesterone receptor status and recurring disease in patients with endometrial cancer

OBJECTIVE

P53 tumor suppressor gene plays a role in endometrial carcinogenesis. Former studies described correlations between p53 protein overexpression in endometrial cancer and prognostic factors, measured by immunohistochemistry. But data is still controversial. The aim of this study was to measure p53 and phospho-p53 overexpression by Western blot and evaluate correlations between overexpression and prognostic and clinical factors. Phospho-p53 seems to be the functional p53 protein and was examined for the first time in endometrial cancer.

METHODS

40 patients with endometrial cancer were included in the study. A control group of 20 patients with normal endometrial tissue samples was used. Western blot was performed for detection of p53 and phospho-p53. Clinical and pathological parameters were obtained from medical records. Statistical analysis was performed using the log-rank test, the Mann-Whitney test for two independent groups and the Fisher's exact test for dichotomous groupings.

RESULTS

In 17.5% of the patients with endometrial cancer a p53 overexpression could be evaluated. There was a correlation between a p53 overexpression and recurring disease (p: 0.014), a negative progesterone receptor status (p: 0.021) and a low BMI (p: 0.022). Only one of 40 patients had a phospho-p53 expression.

CONCLUSION

Western blot is a valid method for the detection of p53 overexpression. As other authors described before, p53 overexpression seems to correlate with negative prognostic factors. The correlation between p53 overexpression and a low BMI may underline the relationship between p53 alterations and biological aggressive endometrial carcinomas.

G1 cell cycle arrest signaling in hepatic injury after intraperitoneal sepsis in rats

OBJECTIVE AND DESIGN

Hepatocytes emerge from a quiescent state into a proliferative state to recover from septic injury. We hypothesize that hepatocyte cell cycle regulation after sepsis potentially contributes to the recovery of liver function.

METHODS

An animal model of sepsis was induced by cecal ligation and puncture (CLP) in rats. At serial time points after CLP, hepatocyte expression of p21, P53, cyclin D1, cyclin E, CDK2, CDK4 and PCNA was determined by immunoblot analysis, and the DNA content of isolated hepatocytes was analyzed using flow cytometry.

RESULTS

Sepsis-induced liver injury of rats was associated with G1 cell cycle arrest. Recovery of liver function was related to cell cycle progression 48 h after CLP. The upregulation of p53 and p21 correlated with G1 cell arrest 48 h after CLP. The upregulation of cyclin D1/CDK4 and cyclin E/CDK2 also correlated with the G1/S transition 48 h after CLP, resulting in PCNA expression.

CONCLUSIONS

The data suggests that G1 cell cycle arrest and p53, p21, CDKs, cyclins and PCNA expression may be involved in the injury/recovery of liver function after intraperitoneal sepsis.

The role of TP53 and p21 gene polymorphisms in breast cancer biology in a well specified and characterized German cohort

OBJECTIVE

Abrogation of the function of TP53 gene is supposed to lead to a more aggressive breast cancer phenotype that produces a less favorable clinical outcome. The p21 gene on chromosome 6p21.2 can be stimulated by an activated TP53 gene. A product of transcription, the p21 protein, an inhibitor of cyclin-dependent kinases, has its function in gene repair and angiogenesis during cell division, and can regulate apoptosis. The purpose of this analysis was to examine for an association between the genotypes measured on two single nucleotide polymorphisms (SNPs) located within the TP53 and p21 genes.

METHODS

In a clinical epidemiological case-control study, 814 individuals were recruited. 550 samples (275 cases/275 control) of peripheral blood obtained from women (aged 22-87 years) with breast cancer and from healthy women (aged 23-87 years) were genotyped for frequencies of the following gene variances: R72P/rs1042522 (gene TP53) and S31R/ss4388499 (gene p21).

RESULTS

For the variance in gene TP53 no significant differences between the control group and women with breast cancer could be estimated. For the variance in gene p21 a statistically significant association between the SNP measured within p21 and breast cancer status was observed. The odds ratio for the increased risk for those carrying the CA genotype as opposed to the CC genotype is 1.74 (95% confidence ratio = 1.00-3.05).

CONCLUSION

Despite this finding p21 does not appear to act as an exclusive prognostic marker for breast cancer disease.

Drug discovery and mutant p53

Missense mutations in the p53 gene are commonly selected for in developing human cancer cells. These diverse mutations in p53 can inactivate its normal sequence-specific DNA-binding and transactivation function, but these mutations can also stabilize a mutant form of p53 with pro-oncogenic potential. Recent multi-disciplinary advances have demonstrated exciting and unexpected potential in therapeutically targeting the mutant p53 pathway, including: the development of biophysical models to explain how mutations inactivate p53 and strategies for refolding and reactivation of mutant p53, the ability of mutant p53 protein to escape MDM2-mediated degradation in human cancers, and the growing 'interactome' of mutant p53 that begins to explain how the mutant p53 protein can contribute to diverse oncogenic and pro-metastatic signaling. Our rapidly accumulating knowledge on mutant p53-signaling pathways will facilitate drug discovery programmes in the challenging area of protein-protein interactions and mutant protein conformational control.

Acute renal failure during sepsis: potential role of cell cycle regulation

OBJECTIVES

This study aimed to evaluate cell cycle regulation in acute kidney injury after intraperitoneal sepsis in rats.

METHODS

Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in rats. At 0, 6, 12, 24, 48, and 72 h after CLP, serum creatinine was evaluated. DNA content of isolated kidney cells was analyzed using flow cytometer. Furthermore, the expression of p21, p53, cyclin D1, cyclin E, CDK2, CDK4 and P-pRb was also measured by western blot.

RESULTS

After sepsis-induced by CLP, kidney injury of rat was associated with G1 cell cycle arrest, however, recovery of renal function related to cell cycle progression 48h after CLP. Results also showed that the upregulation of p53 and p21 was correlated with G1 cell arrest in 48h after CLP. Nevertheless, upregulation of cyclin D1/CDK4 and cyclin E/CDK2 induced pRb phosphorylation, which resulted in the G1/S transition 48 h after CLP.

CONCLUSION

The data suggest that G1 cell cycle arrest may play a role in the initiation of kidney injury, whereas, through regulating cell cycle, p53, p21, CDKs, cyclins and P-pRb may be involved in the injury or recovery of renal function after intraperitoneal sepsis.

Tissue array for Tp53, C-myc, CCND1 gene over-expression in different tumors

AIM: To rapidly detect molecular alterations in different malignancies and investigate the possible role of Tp53, C-myc, and CCND1 genes in development of tumors in human organs and their adjacent normal tissues, as well as the possible relation between well- and poorly-differentiated tumors.

METHODS: A tissue array consisting of seven different tumors was generated. The tissue array included 120 points of esophagus, 120 points of stomach, 80 points of rectum, 60 points of thyroid gland, 100 points of mammary gland, 80 points of liver, and 80 points of colon. Expressions of Tp53, C-myc, and CCND1 were determined by RNA in situ hybridization. 3’ terminal digoxin-labeled anti-sense single stranded oligonucleotide and locked nucleic acid modifying probe were used.

RESULTS: The expression level of Tp53 gene was higher in six different carcinoma tissue samples than in paracancerous tissue samples with the exception in colon carcinoma tissue samples (P < 0.05). The expression level of CCND1 gene was significantly different in different carcinoma tissue samples with the exception in esophagus and colon carcinoma tissue samples. The expression level of C-myc gene was different in esophagus carcinoma tissue samples (χ² = 18.495, P = 0.000), stomach carcinoma tissue samples (χ² = 23.750, P = 0.000), and thyroid gland tissue samples (χ² = 10.999, P = 0.004). The intensity of signals was also different in different carcinoma tissue samples and paracancerous tissue samples.

CONCLUSION: Over-expression of the Tp53, CCND1, and C-myc genes appears to play a role in development of human cancer by regulating the expression of mRNA. Tp53, CCND1 and C-myc genes are significantly correlated with the development of different carcinomas.

The p53 network: p53 and its downstream genes

The tumor-suppressor gene p53 and its downstream genes consist of a complicated gene network. p53 is a key molecular node in the network, which is activated in response to several cellular signals resulting in the maintenance of genetic stability. Several cellular signals may activate the p53 network. When the expression of P53 is elevated, P53-MDM2 module and the ubiquitin system can accurately regulate the expression level of P53. P53 can bind to specific DNA sequence, activate its downstream genes expression, and control cell-cycle arrest, DNA repair, and apoptosis. Elucidating the function of p53 gene network will help understand the interaction mechanisms of p53 and its downstream genes.

Angiostatin antagonizes the action of VEGF-A in human endothelial cells via two distinct pathways

Angiostatin consisting of the first four-kringle domains of the plasminogen potently inhibits angiogenesis in vitro and in vivo. However, the molecular mechanism of action whereby angiostatin mediates its inhibitory effect on proliferating endothelial cells remains elusive. We therefore used the proliferating cultured human umbilical vein endothelial cells (HUVECs) promoted by vascular endothelial growth factor A to identify the endogenous signaling elements that mediate the antiangiogenic effect of angiostatin. Treatment of HUVEC with angiostatin at a concentration known to inhibit cell proliferation and induce apoptosis resulted in induction of p53-, Bax-, and tBid-mediated release of cytochrome c into the cytosol. In addition, angiostatin also activated the Fas-mediated apoptotic pathway in part via up-regulation of FasL mRNA, down-regulation of c-Flip, and activation of caspase 3. These results suggest that the anti-angiogenic action of angiostatin is likely mediated by two distinct signaling pathways, one intrinsic mediated by p53 while the other extrinsic involved in FasL engagement and mitochondria dysfunction.

Significant correlation between expression of heat shock proteins 27, 70 and lymphocyte infiltration in esophageal squamous cell carcinoma

The objective of this study was to clarify the clinicopathologic and prognostic significance of heat shock proteins (HSP) 27 and 70 expression in esophageal squamous cell carcinoma (SCC). Immunohistochemical staining for HSPs 27 and 70 was performed on surgical specimens obtained from 62 patients with esophageal SCC. The expression of both HSPs 27 and 70 correlated inversely with depth of invasion (P<0.05) and pathologic stage (P<0.05), and correlated positively with lymphocyte infiltration (P<0.05). Reduction of HSP 70 expression was significantly correlated with poor prognosis (P<0.05). Patients with HSP 27-negative tumors tended to have a poor prognosis compared with patients with HSP 27-positive tumors. The present findings suggest that HSPs 27 and 70 are significant prognostic factors for esophageal SCC.

After portal branch ligation in the rat, cellular proliferation is associated with selective induction of c-Ha-ras, p53, cyclin E, and Cdk2

BACKGROUND

In liver regeneration after portal branch ligation we previously showed that early cellular changes are observed in both the proliferating and atrophying liver lobes. They are therefore not indicative of future proliferative response. In this study we attempted to define precisely, in the same model, the time at which the cellular processes diverge between the lobes by measuring various parameters associated with cellular proliferation. We also investigated the possible role of inhibitors of cell proliferation in the absence of progression towards the S phase in the atrophying lobes.

AIMS

Expression of p53, c-Ha-ras, cyclin E, cyclin dependent kinase (Cdk2), transforming growth factor (TGF)-beta, and interleukin (IL)-1alpha and IL-1beta were assessed in relation to their potential role in proliferating and atrophying cellular phenomenons.

METHODS

Immunohistochemistry, northern blotting, western blotting, and reverse transcription-polymerase chain reaction were performed, mainly at time points corresponding to mid-G1/S phase progression (8-24 hours after surgery).

RESULTS

The common and thus most likely non-specific response was still evident 5-8 hours after surgery and included an increase in IL-1 mRNA as well as p53 and cyclin E proteins. From 12 hours onwards, p53, c-Ha-ras, cyclin E, and Cdk2 were selectively induced in proliferating lobes whereas IL-1beta was predominantly activated in atrophying lobes. No changes in TGF-beta or IL-1alpha expression were observed at the same time points in any of the liver lobes.

CONCLUSIONS

The initial response to portal branch ligation and thus probably to partial hepatectomy seems to be non-specific for at least eight hours. Thereafter, p53, c-Ha-ras, cyclin E, and Cdk2 seem to drive cellular proliferation while IL-1beta is associated with cellular atrophy. In contrast, TGF-beta and IL-1alpha do not seem to play a role in determining the commitment of cells towards atrophy or proliferation.

Histopathological analysis of non-malignant and malignant epithelium in achalasia of the esophagus

We studied the premalignant nature of achalasia using anti-Ki-67 and anti-p53 monoclonal antibodies immunohistochemically. In this study, four patients with esophageal carcinoma and achalasia were investigated. Three tumors were pT4 (UICC pTNM) and one tumor was pT1. The majority of non-malignant esophageal epithelium showed esophagitis and/or dysplasia histologically. Esophageal epithelial cells in the lesions of esophagitis and/or dysplasia had a higher number of Ki-67-positive cells than normal epithelial cells. p53 protein was expressed in two tumors and it was not expressed in non-malignant epithelium. From these results, we found that esophageal epithelium in achalasia lesions is changed to varying degrees of esophagitis and/or dysplasia by stagnation of intake foods, and these abnormal epithelial cells showed a high proliferative state compared with the normal cells without the p53 gene mutation. We suggest that the distinct proliferative status is a cause of carcinogenesis.

Blast crisis of Ph-positive chronic myeloid leukemia with isochromosome 17q: report of 12 cases and review of the literature

Isochromosome 17q [i(17q)] is frequently observed in the blast crisis (BC) of chronic myelogenous leukemia (CML). It has been suggested that this chromosome abnormality is associated with special hematological characteristics of the BC, but the information on this subject is scarce. The clinical, hematological and cytogenetic features of patients with i(17q) were analyzed in a series of 121 patients with BC of Ph-positive CML. Twelve patients (10%) displayed an i(17q), representing the third commonest cytogenetic abnormality, after trisomy 8 and Ph chromosome duplication. In seven of the 12 patients the BC was preceded by an accelerated phase, and 10 had more than 10% blood basophils at BC diagnosis. The blast cells had a myeloid phenotype in the 12 patients. Five patients exhibited cytogenetic abnormalities in addition to i(17q), with trisomy 8 and duplication of the Ph chromosome being the alterations most frequently observed. Median survival of patients with i(17q) was 22 weeks, which was not significantly different from the survival of patients with myeloid BC in the overall series. These results are similar to the findings in 181 patients with i(17q) from 12 series of the literature, and confirm the special hematologic profile of BC of CML with this cytogenetic abnormality.

Urothelial lesions in Chinese-herb nephropathy

Rapidly progressive renal fibrosis after a slimming regimen including Chinese herbs containing aristolochic acid (AA) has been identified as Chinese-herb nephropathy (CHN). We reported urothelial atypia in three patients with CHN, with the subsequent development in one patient of overt transitional cell carcinoma (TCC). Therefore, it was decided to remove the native kidneys, as well as the ureters, in all patients with CHN. Nineteen kidneys and ureters removed during and/or after renal transplantation from 10 patients were studied to assess critically urothelial lesions and to characterize the cellular expression of p53, a tumor-suppressor gene overexpressed in several types of malignancies. Multifocal high-grade flat TCC in situ (carcinoma in situ; CiS) was observed, mainly in the upper urinary tract, in four patients, a prevalence of 40%. In one of those patients, a superficially invasive flat TCC of the right upper ureter, as well as two additional foci of noninvasive papillary TCC, were found in the right pelvis and left lower ureter, respectively. This patient also presented recurrent noninvasive papillary TCC of the bladder. Furthermore, in all cases, multifocal, overall moderate atypia was found in the medullary collecting ducts, pelvis, and ureter. All CiS and papillary TCC, as well as urothelial atypia, overexpressed p53. These results show that the intake of Chinese herbs containing AA has a dramatic carcinogenic effect. Carcinogenesis is associated with the overexpression of p53, which suggests a role for a p53 gene mutation. The relationship of this mutation with the reported presence of AA DNA adducts in the kidney remains to be explored.

Alterations of p53 gene and Ha-ras gene are independent events in solar keratosis and squamous cell carcinoma

In order to clarity the multiple-step progression from solar keratosis to squamous cell carcinoma, aberrations of the p53 gene (exons 2-11) and ras genes (exons 1 and 2) in solar keratosis and squamous cell carcinoma were investigated by polymerase chain reaction and single-strand conformation polymorphism analysis. In a series of Japanese patients, eight of 27 (30%) samples of solar keratosis and three of six (50%) samples of squamous cell carcinoma showed structural abnormalities in the p53 gene. Only one solar keratosis (4%) showed a point mutation in the Ha-ras gene but not in the p53 gene. Among these cases, no mutation of ras genes could be detected in squamous cell carcinoma. Simultaneous mutation of ras genes and the p53 gene was not detected in any cases of either solar keratosis or squamous cell carcinoma. It is concluded that aberrations of the p53 gene and ras genes are induced through independent processes of ultraviolet irradiation in the course of carcinogenic change from solar keratosis to squamous cell carcinoma.

Primary small cell carcinoma of the esophagus: flow cytometric analysis and immunohistochemical staining for the p53 protein and proliferating cell nuclear antigen

BACKGROUND AND OBJECTIVES

The purpose of this study was to determine the clinical course and effects of histopathologic characteristics of specific tumors including DNA contents and immunohistochemical aspects in patients with small cell carcinoma of the esophagus.

METHODS

Medical records of 4 patients who presented with small cell carcinoma of the esophagus were retrospectively reviewed.

RESULTS

DNA aneuploidy was observed in 2 cases. Staining for the p53 product was positive in all cases. The average proliferating cell nuclear antigen (PCNA) labeling rate (LR) was 77.6% (64.0-90.8%). The estimated median survival was 42 days for all patients. Distant metastases were observed in 2 of the 4 patients.

CONCLUSIONS

Higher PCNA LR of small cell carcinoma may be an unfavorable characteristic of biological behavior. Patients with disseminated disease should have symptomatically palliative operation combined with chemotherapy.

Serum- and polypeptide growth factor-inducible gene expression in mouse fibroblasts

Complex cellular processes such as proliferation, differentiation, and apoptosis are regulated in part by extracellular signaling molecules: for example, polypeptide growth factors, cytokines, and peptide hormones. Many polypeptide growth factors exert their mitogenic effects by binding to specific cell surface receptor protein tyrosine kinases. This interaction triggers numerous biochemical responses, including changes in phospholipid metabolism, the activation of a protein phosphorylation cascade, and the enhanced expression of specific immediate-early, delayed-early, or late response genes. In this review, I summarize the major findings obtained from studies investigating the effects of serum or individual polypeptide growth factors on gene expression in murine fibroblasts. Several experimental approaches, including differential hybridization screening of cDNA libraries and differential display, have been employed to identify mRNA species that are expressed at elevated levels in serum- or polypeptide growth factor-stimulated cells. These studies have demonstrated that serum- and growth factor-inducible genes encode a diverse family of proteins, including DNA-binding transcription factors, cytoskeletal and extracellular matrix proteins, metabolic enzymes, secreted chemokines, and serine-threonine kinases. Some of these gene products act as effectors of specific cell cycle functions (e.g., enzymes involved in nucleotide and DNA synthesis), others are required to successfully convert a metabolically inactive cell to a metabolically active cell that will eventually increase in size and then divide (e.g., glucose-metabolizing enzymes), and some actually function as positive or negative regulators of cell cycle progression. In conclusion, research conducted during the past 15 years on serum- and growth factor-regulated gene expression in murine fibroblasts has provided significant insight into mitogenic signal transduction and cell growth control.

Association between p53 overexpression, cell proliferation, tumor necrosis and extent of apoptosis in operated pancreatic adenocarcinoma

In this study we investigated the immunohistochemical expression of the p53 protein in 44 ductal pancreatic adenocarcinomas and its relation to cell proliferation, apoptosis and necrosis, three factors affecting tumor growth. The results were evaluated against survival and other clinical parameters of the patients. p53-positivity was found in 18/44 (41%) of the tumors. A positive p53 status was significantly associated with a high extent of necrosis (> or = 10% of tumor tissue)(p = 0.04, Fisher's exact test), with a high immunohistochemical expression of PCNA (p = 0.04, Fisher's exact test) and with a high mitotic count (p = 0.05, two-tailed t test). No statistically significant association was found between p53-positivity and high or low extent of apoptosis as evaluated by in situ labeling of the 3'-ends of the DNA fragments (p = 0.34, Fisher's exact test). Patient survival was not associated with the p53 expression of the tumors or separately with tumor cell proliferation, apoptosis or necrosis. The results suggest that an altered p53 function, as reflected by p53 overexpression, affects tumor growth by promoting cell proliferation and necrosis, but does not show a significant association with the extent of apoptosis in operated pancreatic adenocarcinoma.

Significance of p53 overexpression in urinary bladder transitional cell carcinoma in situ before and after bacillus Calmette-Guérin treatment

OBJECTIVES

Overexpression of p53, normally secondary to gene mutation, in invasive uroepithelial neoplasms (transitional cell carcinoma) and a high percentage of transitional cell carcinoma in situ (CIS) has been described; however, the role of p53 before and after bacillus Calmette-Guérin (BCG) treatment of CIS needs to be defined.

METHODS

Immunohistochemical reaction for p53 overexpression was performed on 12 patients with CIS before and after BCG treatment. Thirty cystectomy specimens with invasive TCC were also evaluated for the presence of CIS, hyperplasia, and dysplasia.

RESULTS

Twenty-three cases of CIS were identified. Approximately 90% of CIS cases (21 of 23) were positive for p53 overexpression, whereas transitional cell hyperplasia was uniformly negative. Less than 5% of the cells in morphologically dysplastic lesions were positively stained. Ten of 12 CIS patients displayed p53 overexpression before BCG treatment. After BCG treatment, 4 patients displayed residual CIS with p53 overexpression, and 8 patients showed no residual CIS or p53 overexpression. Three of the 4 patients with residual CIS and overexpression rapidly developed invasive transitional cell carcinoma requiring cystectomy. The 1 remaining patient was treated with a second course of BCG; further biopsies displayed the development of grade 1 papillary transitional cell carcinoma without invasion, and the patient is currently being followed

CONCLUSIONS

Our data suggest that follow-up biopsy procedures are essential in all patients with CIS treated with BCG. The biopsy specimens should be evaluated for p53 overexpression, because our data indicate that persistent p53 overexpression in uroepithelial lesions after BCG treatment is an ominous finding for probable tumor progression.

p53 protein expression in ductal carcinoma in situ (DCIS) of the breast

Abnormalities in p53 gene expression have been implicated in many inherited and sporadic forms of malignancies in humans. Immunohistochemical staining using monoclonal antibody D0-7 for the p53 protein expression was performed in 81 cases of pure DCIS, 14 benign breast lesions and 2 cases with normal breast tissue. Expression of p53 protein was detected in 15 (18.5%) cases of pure DCIS. Thirteen (25%) of the 52 comedo type DCIS showed p53 protein expression compared with 2 (6.9%) of the 29 non-comedo types (P < 0.02). p53 protein expression was also associated with high nuclear grade (P < 0.001) and high mitotic index (P < 0.05). The pattern of p53 protein staining was diffuse in one comedo type DCIS, regional in 6 comedo types, and focal in the remaining 8 cases (6 comedo type and 2 micropapillary type DCIS). The patient with comedo type DCIS showing diffuse staining has a family history of breast cancer in the first and second degree relatives (sister and maternal aunt). Clinical follow-up data was available in 52 cases. Follow-up period ranged from 9 to 55 months. Three patients, who were primarily treated by local excision, have had a documented local recurrence in the form of residual tumor within a short interval of 5 to 11 months. In all these three patients both the original and the recurrent tumors are negative for p53 protein expression. The difference in the local recurrence rate between p53 positive (0/15) and p53 negative (3/37) cased does not reach statistical significance (p > 0.05). We interpret that the local tumor recurrence in these three cases within a short period after primary excision is due to the presence of residual tumor at the excision site and is independent of the p53 gene alteration. It is concluded that p53 protein expression in DCIS is associated with comedo subtype, high nuclear grade, and high mitotic index, and is a promising new parameter to evaluate the cellular biology and prognosis of DCIS.

Expression of wild-type p53 tumor suppressor gene and its possible involvement in the apoptosis of thyroid tumors

A good prognosis is often achieved in patients who have undergone treatment for human papillary carcinoma of the thyroid. On the assumption that this may be partly attributable to an apoptotic tendency of this special type of tumor, we measured DNA fragmentation, cell death by enzyme-linked immunosorbent assay (ELISA), and the expression of apoptosis-related genes. DNA fragmentation occurred more extensively in malignant tumor cells than in benign thyroid tumors or normal thyroid tissue, as examined by agarose gel electrophoresis and confirmed by the quantitative method using an ELISA kit. Although only expression of the tumor suppressor gene, p53, was increased in the tumor tissue, no expression of other genes, such as Fas, TNF, c-myc, c-fos or bcl-2, was observed in the normal, benign, or malignant tumor tissues, indicating that the roles of these gene functions, if any, were minimal in these tissues. Since p53 is closely related to cellular apoptosis and no point mutation was observed in the transcripts expressed by malignant cells, apoptosis and/or the production of an angiogenesis inhibitor induced by wild-type p53 molecules may be related to the favorable prognosis of patients treated for papillary carcinoma of the thyroid.

p53 expression in hepatocellular carcinoma in Greece. Correlation with epidemiological and histopathological data

Localization of p53 oncoprotein was investigated in 60 hepatocellular carcinomas (HCCs) from patients resident in the Northwest and Central Greece. The streptavidin-biotin complex immunoperoxidase method was performed in archival formalin-fixed, paraffin-embedded material, using the monoclonal antibody DO-1. The aim of our study was to correlate p53 expression with histological and epidemiological data. p53 overexpression in patients with serological hepatitis B or C was greater (47%) as compared to that observed in patients without these markers (p < 0.01). Morphologically normal liver tissue (NLT) and liver cell dysplasia (LCD) was recognized adjacent to HCC developing on non-alcoholic cirrhotic livers in patients with "NonA, NonB hepatitis" from between 1975-1986. NLT and LCD and p53 oncoprotein was expressed in 10% of the cases. No relationship was observed between p53 expression and tumor histological grade, patients' age and sex. These results suggest that in Northwest and Central Greece, p53 oncosupressor gene may be involved in some HCCs; it may be associated with viral chronic infection disease (HBV or HCV), and as yet with uncharacterized viruses which remain to be determined.

p53 antisense oligonucleotide inhibits growth of human colon tumor and normal cell lines

We examined the relationship between the expression of mutant p53 proteins and tumor cell growth using a p53 antisense oligonucleotide (5'-CCCTGCTCCCCCCTGGCTCC-3'). The oligonucleotide inhibited the growth of three human colon tumor cell lines (DLD-a, SW620 and WiDr), which produce only mutant p53 proteins with different mutation sites. Treatment of DLD-1 cells with the p53 antisense oligonucleotide caused a decrease in the level of p53 mutant protein. Synthesis of DNA in DLD-1 and SW620 cells was inhibited more potently than that of RNA or protein after antisense treatment. Furthermore, these cells were accumulated in the S phase when DNA synthesis was inhibited. Meanwhile, the antisense oligonucleotide also inhibited the growth of three human normal cell lines (WI-38, TIG-1 and Intestine 407). While treatment of WI-38 and TIG-1 cells with the antisense oligonucleotide inhibited synthesis of DNA more potently than that of RNA or protein, these normal cells were accumulated in the G0/G1 phase. These results suggest that p53 proteins, either with or without mutation, play a pivotal role in the growth of tumor and normal cells, but that mutant and wild-type p53 proteins may function differently in cell growth.

Acceleration of proliferative activity of esophageal squamous cell carcinoma with invasion beyond the mucosa: immunohistochemical analysis of Ki-67 and p53 antigen in relation to histopathologic findings

BACKGROUND

The authors observed patients with superficial esophageal squamous cell carcinoma (s-ESC). Those with cancer invasion beyond the muscularis mucosae (SM-carcinoma) had an extremely poor prognosis, compared with those with intramucosal carcinoma (M-carcinoma). Therefore, we surveyed cell proliferative activities in relation to pathologic findings of the s-ESC.

METHODS

p53 protein expression and Ki-67 labeling index (LI) were surveyed with detailed pathologic examinations of 75 s-ESC lesions from 70 patients who underwent esophagectomy. The results were compared by statistical analysis using the chi-square test and unpaired Student's t-test.

RESULTS

p53 protein expression was observed in 57.3% of the patients with s-ESC. The frequency and intensity of its accumulation correlated with the depth of cancer invasion and was markedly elevated in invasion beyond the muscularis mucosae. The LI of Ki-67 positive nuclei was also increased with cancer invasion. The values in the intraepithelial carcinoma and in carcinoma with invasion to the muscularis mucosae were 48.5 +/- 13.7% [mean +/- standard deviation (SD)] and 66.6 +/- 12.9%, respectively, and the difference is significant, P < 0.01. In the SM-carcinomas, the LIs of Ki-67, with or without lymph node metastasis, were 73.5 +/- 10.0% and 64.4 +/- 11.3%, respectively, and the former was higher than the latter with a significant difference, P < 0.05.

CONCLUSIONS

Cancer cell proliferative activities were markedly accelerated in s-ESC cases with cancer invasion beyond the muscularis mucosae and lymph nodal involvement, which was associated with a poorer prognosis of the SM-carcinoma compared with the M-carcinoma, and must be one of the important indices to decide the indication of local resection for s-ESC.

The relationship between the gene mutation of p53 and the protein expression of p53 and Ki-67 in non-Hodgkin's lymphomas

The relationship between the mutation of the p53 gene and the expression of the p53 protein and the Ki-67 antigen has been investigated in 115 cases with non-Hodgkin's lymphoma, using the immunohistochemical double staining technique, single-strand conformational polymorphism and DNA sequencing methods. Eighteen cases showed more than 10% of p53+ cells and the others showed a few p53+ cells presented sporadically. Alterations in the p53 gene were detected in six cases with B cell type, consisting of five cases with point mutation and one case with point mutation and 15 base pairs deletion. These six cases showed a high percentage of p53+ cells and five cases revealed that the percentage of p53+ cells was higher than that of Ki-67+ cells (p53+ cells > Ki-67+ cells). Excluding the six cases with mutation of the p53 gene, all cases revealed that the percentage of p53+ cells was less than that of Ki-67+ cells (p53+ cells < Ki-67+ cells). Moreover, there was a positive correlation between expression of the p53 protein and of the Ki-67 antigen in histologic types of B cell lymphomas and of T cell lymphomas, respectively, except in small non-cleaved (Burkitt's) and lymphoblastic types. Therefore, sporadic cases showing p53+ cells > Ki-67+ cells revealed alteration of the p53 gene, and expressed abnormal p53 protein (mutant form). Most cases showing p53+ cells < Ki-67+ cells expressed normal p53 protein (wild type), and may reflect the rapid proliferation rate.

Intracellular immunization against HIV-1 infection of human T lymphocytes: utility of anti-rev single-chain variable fragments

Genetic therapy offers a potentially promising approach with which to combat human immunodeficiency virus type 1 (HIV-1) infections. Several modalities, using protein- and RNA-based systems, have recently been shown to inhibit HIV-1 replication. A single-chain variable fragment (SFv), constructed from the cDNA of a monoclonal antibody to the HIV-1 regulatory protein Rev, has been demonstrated to potently inhibit HIV-1 replication, when expressed intracellularly in an epithelial cell-line (HeLa-CD4). Murine retroviral shuttle vectors, which express the anti-Rev SFv moiety, have now been constructed. HIV-1 infection was dramatically inhibited in human T-lymphocytic cell-lines, CEM and Sup-T1, transduced with these anti-Rev SFv-expressing vectors. This resistance to high levels of HIV-1 expression was demonstrated in both mixed populations and clones of these cells. Of further potential clinical significance, HIV-1 infection was also potently inhibited in human peripheral blood mononuclear cells (PBMC), transduced with retroviral vectors expressing the anti-Rev SFv molecule. These data suggest that intracellular expression of anti-Rev SFvs, or related approaches, may be utilized as genetic therapy, or intracellular immunization, for HIV-1 infections in vivo.

Prognostic value of immunohistochemically detected p53 expression in vulvar carcinoma

BACKGROUND

Overexpression of the p53 protein has been reported to correlate with poor prognosis in several types of tumors. To the authors' knowledge, there are no studies concerning the prognostic value of p53 protein overexpression in squamous cell vulvar carcinoma.

METHODS

Twenty-five cases of squamous cell carcinoma of the vulva with International Federation of Gynecology and Obstetrics (FIGO) Stage I-II were examined for p53 protein overexpression using immunohistochemistry. The correlation of p53 protein overexpression with clinical stage, histologic grade, and overall survival was investigated. Follow-up ranged from 36 to 120 months.

RESULTS

Clinical stage and histologic grade did not correlate with p53 protein overexpression. p53 protein overexpression was associated with poorer overall survival (log rank: P < 0.05).

CONCLUSION

Immunohistochemically detected p53 protein overexpression is significantly correlated with a reduced overall survival rate for patients with vulvar carcinoma.

Small peptides activate the latent sequence-specific DNA binding function of p53

Normal cells contain p53 protein in a latent state that can be activated for sequence-specific transcription by low levels of UV radiation without an increase in protein levels. Microinjection of cells with an antibody specific to the C-terminal negative regulatory domain can activate the function of p53 as a specific transcription factor in the absence of irradiation damage, suggesting that posttranslational modification of a negative regulatory domain in vivo is a rate-limiting step for p53 activation. Small peptides derived from the negative regulatory domain of p53 have been used as biochemical tools to distinguish between allosteric and steric mechanisms of negative regulation of p53 tetramer activity. Presented is the development of a highly specific peptide activation system that is consistent with an allosteric mechanism of negative regulation and that forms a precedent for the synthesis of novel low molecular mass modifiers of the p53 response.

Radiation induced G1-block and p53 status in six human cell lines

Considerable attention has recently been focused on the fact that the tumor suppressor protein p53 is involved in the cellular response to radiation. In its wild-type form the protein appears to control a cell cycle checkpoint, preventing entry into S-phase following DNA damage. A number of authors observed a radiation induced G1-block in cells expressing wild-type p53, but not in p53 mutant cells. We obtained similar results with four human tumour cell lines as well as two strains of human fibroblasts, whose p53 status was ascertained at the protein as well as DNA levels. In addition to cell cycle delays in exponentially growing cell cultures, we have studied the possible role of the p53 in the transition from quiescence to active proliferation. Cells were irradiated after 6 days of serum-starvation and labelled with BrdU at different times after addition of fresh medium. Entry into S-phase was found to be delayed by several hours in the p53 wild-type cells, but no such effect was observed in the p53 mutants. Where a delay occurred, it was roughly proportional to the X-ray dose. Although it remains to be clarified, whether the cells were delayed only in G1 or also in G0, it is interesting to note that entry into S-phase can be delayed by irradiation in a quiescent state immediately before serum-stimulation, provided the cells are wild-type with respect to p53. Certain differences in the cell cycle response of transformed and untransformed cells were noted.

The developmental pattern of Brca1 expression implies a role in differentiation of the breast and other tissues

We have examined the developmental expression of the murine breast and ovarian cancer susceptibility gene, Brca1, to investigate its role in the control of cell growth and differentiation. Specifically, we have analysed Brca1 expression during embryonic development, in adult tissues, and during postnatal mammary gland development, particularly in response to ovarian hormones. Our results suggest that Brca1 is expressed in rapidly proliferating cell types undergoing differentiation. In the mammary gland, Brca1 expression is induced during puberty, pregnancy, and following treatment of ovariectomized animals with 17 beta-estradiol and progesterone. These observations imply that Brca1 is involved in the processes of proliferation and differentiation in multiple tissues, notably in the mammary gland in response to ovarian hormones.

p53 and Sp1 interact and cooperate in the tumor necrosis factor-induced transcriptional activation of the HIV-1 long terminal repeat

Tumor necrosis factor alpha (TNF) is a potent activator of transcription directed by the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR). We have recently reported that the p53 tumor suppressor gene product binds to a site within the Sp1 binding region of the HIV-1 LTR and contributes to the TNF induction of this promoter. In this study we show that the transcription factor Sp1 cooperates with p53 in the transcriptional activation directed by the HIV-1 LTR. The presence of Sp1 increased p53 binding to its recognition sequence in the HIV-1 LTR, and experiments in Drosophila cells show that Sp1 is necessary for full transactivation by mutant p53. Importantly, TNF induced the association between p53 and Sp1 in Jurkat T cells. These data demonstrate a synergistic role for these proteins in the mechanism of TNF induction of HIV-1 LTR-mediated transcription and suggest that Sp1 may play an important role in modulating certain functions of p53.

P53 tumor suppressor gene in chronic myelogenous leukemia: a sequential study

Loss of the p53 gene alleles was investigated in 26 patients with Ph+, BCR/ABL+ chronic myeloid leukemia (CML) by means of the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis using the restriction enzyme AccII. In all cases, peripheral blood and/or bone marrow samples were obtained at different times during the chronic phase of the disease and at blast crisis, and in some of them also at the accelerated phase. Of the 12 cases considered informative, 11 evolved into myeloid type blast crisis and one into a lymphoid blast crisis, whereas only two showed an i(17q) chromosome at cytogenetic study. In four of the 12 informative cases, a loss of one p53 gene allele was observed, in all cases coincident with the development of the accelerated phase or blast crisis. One patient with a deleted p53 gene allele, in whom it was possible to analyze the gene structure in the three CML evolutive phases (chronic and accelerated phases and blast crisis), showed loss of the p53 gene allele in both the accelerated and the blastic phase, but not during the chronic phase. On the other hand, one of the two cases with an i(17q) chromosome exhibited one allelic deletion of the p53 gene. Thus, the relatively frequent monoallelic deletion of the p53 gene coincident with the appearance of the blast crisis registered in the present study would support a possible role of the p53 gene alterations in the evolution of CML to its final stages.

Immunohistochemical analysis of p53 in colorectal cancer regarding clinicopathological correlation and prognostic significance

The overexpression of the tumor suppressor gene p53 was investigated immunohistochemically in 144 cases of primary colorectal cancer and in 8 cases with cancer in the corresponding metastatic lymph nodes. Abnormalities in p53 expression were found in 36 cases (25%) of the 144 primary cancer cases. In addition, p53-positive tumors were found to metastasize frequently to the lymph nodes, as compared to p53-negative tumors (61.1% vs. 41.7%, P = 0.0428). p53 staining was identical in 7 of 8 (87.5%) cases in primary and metastatic lesions. When the DNA content of the tumor was determined by flow cytometry, the DNA index (mean +/- SD) was significantly higher in p53-positive tumors than in p53-negative tumors (1.57 +/- 0.38 vs. 1.39 +/- 0.37, P = 0.012). Therefore, the immunohistochemical data of p53 in colorectal cancer may help in potentially predicting metastatic spread to the lymph nodes.

Tumor suppressor p53 mutations and breast cancer: a critical analysis

Alterations in the tumor suppressor gene p53 are the most commonly identified changes in cancer, including neoplasia of the breast. The activity of p53 is regulated post-translationally. Phosphorylation state, subcellular localization, and interaction with any of a number of cellular proteins are likely to influence the function of p53. The exact effect of p53-mediated growth suppression seems to be cell-type specific but appears to be directly related to the ability of p53 to act as a specific transcriptional activator. The role that transcriptional repression plays in the function of WT p53 is less clear. It is also possible that p53 has a more direct activity in DNA replication and repair. Most documented p53 mutations result in single amino acid substitutions which may confer one or more of a spectrum of transforming abilities on the protein. Mutation may lead to nuclear accumulation of p53 protein; however, inactivation of p53 by nuclear exclusion and interaction with the mdm2 protein also appear to be important in tumorigenesis. Used in conjunction with other established factors, accumulation of cellular p53 may be a useful prognostic indicator in breast cancer. A syngeneic mouse model system yielded evidence that p53 mutations are important in the early, preneoplastic stages of mammary tumorigenesis. This murine system may provide the ability to investigate the functions of p53 in the early stages of breast cancer which are technically difficult to examine in the human system.

Molecular and virological effects of intracellular anti-Rev single-chain variable fragments on the expression of various human immunodeficiency virus-1 strains

A variety of genetic therapies or intracellular immunization techniques hold promise as modalities to inhibit human immunodeficiency virus type 1 (HIV-1) replication in vivo. We have recently demonstrated that a single-chain variable fragment (SFv) construct, derived from a monoclonal antibody that binds to the HIV-1 regulatory protein Rev, can be expressed intracellularly and potently inhibits HIV-1 replication. This single-chain intracellular antibody, which avidly binds to the effector domain of Rev, is now demonstrated to dramatically inhibit various diverse laboratory and primary clinical strains of HIV-1. Potent suppression of HIV-1 replication by this modality is maintained over several months in long-term cultures. As well, the intracellular expression of anti-Rev SFv is shown to alter HIV-1 replication by specifically affecting Rev function. Importantly, no alterations in HIV-1 internalization, reverse transcription, or initial transcription of multiply spliced viral mRNAs are demonstrated in SFv-immunized cells, as compared to controls. Thus, these studies extend the understanding of the molecular mechanisms involved in the inhibition of lentivirus replication, by these intracellular antibody constructs.

Flow cytometric quantitation of C-myc and P53 proteins in bovine papillomavirus type 1-transformed primary mouse fibroblasts

Bovine papillomavirus type 1 (BPV-1)-transformed mouse fibroblast cell lines were analyzed via flow cytometry (FCM) for expression of p53 and c-myc proteins along with their DNA content. In comparison to the nontransformed control cell line, significantly elevated levels of both the p53 and the c-myc protein were present in some but not all of the transformed cell lines. Quantitation of p53 and c-myc proteins in cell lines containing BPV-1 DNA revealed that the tumorigenic cell lines expressed higher levels of both the p53 (P = 0.0034; Mann-Whitney U test) and the c-myc protein (P = 0.0039; Mann-Whitney U test) as compared to the nontumorigenic cell lines. On average, at least 9,000-10,000 p53 or c-myc protein molecules per cell were detected in the transformed tumorigenic cell lines. These results show that quantitative FCM can be reliably used to detect very low levels (3,000 molecules per cell) of specific protein, and FCM is a useful tool to study the virus-induced changes in the levels of nuclear proteins within a cell population and in tumorigenesis.

p53 protein expression and prognosis in squamous cell carcinoma of the esophagus

BACKGROUND

The p53 gene product is known to regulate cell growth and proliferation. Whereas the wild-type p53 protein suppresses cell growth, the mutated p53 protein acts as an oncogene. Mutations in the p53 gene usually result in p53 protein stabilization and accumulation; so that the gene product can be detected by immunohistochemistry. Recently, the immunohistochemical detection of the p53 protein was associated with prognosis in breast, colorectal, and other types of cancer. However, its prognostic role in esophageal cancer remains to be elucidated.

METHODS

p53 expression in formalin fixed, paraffin embedded samples of 204 patients with primary squamous cell carcinoma of the esophagus, who underwent esophageal resection, were analyzed immunohistochemically with DO-1, a monoclonal antibody that detects wild-type and mutant forms of p53. The relationship between p53 immunoreactivity and prognostic factors was determined by the Chi-square test, and the prognostic impact of p53 protein expression was analyzed using univariate and multivariate survival analyses.

RESULTS

In 137 of 204 tumors (67.2%), nuclear immunoreactivity for the p53 protein was detected. There was no correlation with sex, age, pathologic tumor (pT) category, pathologic lymph node (pN) category, metastasis (M) category, residual cancer (R) category, histologic grade, or preoperative radiation therapy. In contrast to clinicopathologic parameters, p53 expression was not correlated with prognosis in univariate and multivariate survival analyses.

CONCLUSIONS

The p53 protein can be detected by immunohistochemistry in a high percentage of squamous cell carcinomas of the esophagus. However, the overexpression of the p53 gene product has no impact on the prognosis.

Human non-small cell lung cancer: p53 protein accumulation is an early event and persists during metastatic progression

Mutations in the p53 tumour suppressor gene, with consequent accumulation of the p53 protein, are frequently observed in non-small cell lung cancer (NSCLC). Little is known, however, about the timing of their appearance or their maintenance through cancer progression and metastatic spread. We have examined the normal epithelium and a panel of bronchial lesions, including dysplastic, neoplastic, and metastatic lesions, for p53 immunoreactivity and for expression of proliferating cell nuclear antigen (PCNA). No p53 immunoreactivity was found in normal and hyperplastic epithelium, nor in squamous metaplastic lesions. Twenty out of 30 invasive tumours and 13 out of 17 in situ carcinomas adjacent to an invasive tumour showed p53 immunoreactivity. There was a strict correlation between the level of p53 expression in the non-invasive and the invasive components of the tumours. Five out of eight pairs of primary tumours and matching metastases expressed p53, at identical levels in both compartments. These data indicate that p53 overexpression can occur in the earliest recognized phase of NSCLC and that the alteration is maintained during progression from in situ to invasive carcinoma and metastatic spread. PCNA expression increased from early to advanced phases of NSCLC. High PCNA immunoreactivity was observed in tumours expressing high p53 levels. A significant association was observed for PCNA expression between preinvasive and invasive lesions.

Immunohistochemical Detection of p53 and c-erbB-2 Proteins: Prognostic Significance in Operable Breast Cancer

We examined the associations of p53 expression and/or c-erbB-2 expression with Ag-NOR counts and clinicopathologic variables in 111 breast cancer patients, and assessed whether expression of either p53or c-erbB-2 would be useful prognostic indicators. There was no significant association between p53 expression and c-erbB-2 expression, but p53 expression and c-erbB-2 expression, especially in combination, were shown to be significantly associated with Ag-NOR counts and axillary lymph node metastasis. Although p53 expression and c-erbB-2 expression were significant prognostic factors by univariate analysis, they did not appear to be independent prognostic factors by multivariate analysis, in which nodal status was introduced using the Cox model. When nodal status was excluded from the model, however, concurrent p53 and c-erbB-2 expression did have a significant prognostic value. Therefore, it was suggested that concurrent p53 and c-erbB-2 expression provides valuable prognostic information for breast cancer patients in whom axillary lymph node dissection has not been performed.

The relationship of p53 protein and lymph node metastases in invasive breast cancer

The p53 expression in invasive breast cancers from 106 patients was correlated with clinicopathological variables to ascertain its usefulness for estimating prognosis. The p53 expression was significantly associated with the number of axillary lymph node metastases and the presence of internal mammary lymph node metastases; however, it was not associated with age, menopausal status, histologic type, or tumor size. Although p53 expression was a significant prognostic factor according to univariate analysis, it did not appear to be an independent prognostic factor according to multivariate analysis. Thus, the prognostic power of p53 expression is likely to be weak and therefore probably of limited clinical value. Nevertheless, the number of patients in our study was small, and we believe that an investigation of a larger series of patients is indicated.