p53 protein is absent from the serum of patients with lung cancer

A highly sensitive particle agglutination assay for the detection of P53 autoantibodies in patients with lung cancer

BACKGROUND

Numerous assays have been described for the detection of p53 autoantibodies. These assays are highly specific with low sensitivity. In this report, the authors describe a highly sensitive and simple particle agglutination immunoassay using superparamagnetic particles for capturing p5 autoantibodies, p53 protein, and p53 protein-antibody complexes from large volumes of serum samples (2 mL).

METHODS

Superparamagnetic particles were coated with different peptides spanning the entire p53 protein. These particles were incubated with serum samples from healthy blood donors (n=180), from patients without malignancies (n=27), and from patients with various forms of lung cancer (n=166). The particles were washed and placed into the reaction chamber of a gel card. After centrifugation, agglutination results were read visually. Positive reactions were defined by a layer of particles on top of the gel or agglutinated particles dispersed through the gel matrix.

RESULTS

Depending on the peptide used, p53 autoantibodies were detected in from 17.5% to 35% of the investigated patients with lung cancer. By using a commercially available enzyme-linked immunoadsorbent assay (ELISA) kit, p53 autoantibodies were detected in only 3% of those patients. P53 protein and p53 protein-antibody complexes were not detected in patients with lung cancer (n=20).

CONCLUSIONS

The newly developed assay was easy to perform and had sensitivity superior to that of the currently available p53 ELISAs.

Oncogene and tumor-suppressor gene products as serum biomarkers in occupational-derived lung cancer

Since lung cancer is the most frequent occupational cancer and one of the leading causes of cancer mortality in the world, it is one of the biggest challenges for research. In the literature, there are inconsistent results regarding the utility of the serum biomarkers p53, anti-p53 antibodies, EGF receptor or Ras. Based on the published results, routine use of these biomarkers for detection of occupationally derived lung carcinomas is not currently recommended. In this review, we summarize the literature and discuss the relevance of these oncogene and tumor-suppressor gene products as serum biomarkers in occupational-derived lung cancer.

Air pollution by carcinogenic PAHs and plasma levels of p53 and p21(WAF1) proteins

We analyzed the effect of exposure to carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) in ambient air on the plasma levels of p53 and p21(WAF1) proteins among city policemen, bus drivers and controls in three European cities: Prague (Czech Republic), Kosice (Slovakia) and Sofia (Bulgaria). p53 and p21(WAF1) proteins are key regulators of the cell cycle and are accepted as universal markers of genotoxic stress and DNA damage. In total 204 exposed subjects (100 smokers, 104 nonsmokers) and 152 controls (54 smokers, 98 nonsmokers) were analyzed. Personal exposure to c-PAHs was evaluated using personal samplers during the working shift. The levels of p53 and p21(WAF1) proteins were assessed by ELISA assay. There were no differences between the levels of either protein between exposed and controls, or smokers and nonsmokers, in any city. However, we observed significant differences in p53 plasma levels in all subjects regardless of the exposure status between the individual cities (median values: 5, 31, 234pg/ml, p<0.001, for Prague, Kosice and Sofia, respectively). The levels correspond to the differences in exposure levels to c-PAHs and benzo[a]pyrene (B[a]P) in the individual cities. A multiple linear regression analysis confirmed that c-PAHs exposure is a variable significantly affecting levels of both proteins in all locations. When all subjects were divided into the group exposed to below-median levels of c-PAHs and the group exposed to above-median levels of c-PAHs we found significantly higher p53, as well as p21(WAF1) levels in the above-median exposure group (p53, 167pg/ml versus 25pg/ml, p<0.001; p21(WAF1), 2690pg/ml versus 2600pg/ml, p<0.05). Among all subjects p53 plasma levels were positively correlated with p21(WAF1) levels, exposure to B[a]P, c-PAHs and levels of total DNA adducts; for p21(WAF1) levels we observed the positive correlation with cotinine, c-PAHs exposure, total and B[a]P-like DNA adduct levels. In conclusion our results suggest that p53 and p21(WAF1) proteins plasma levels may be useful biomarkers of c-PAHs environmental exposure.

Plasma Mutant-p53 Protein and Anti-p53 Antibody as a Marker: An Experience in Vinyl Chloride Workers in Italy

OBJECTIVE

The objective of this study was to examine the presence of mutant-p53 protein (p53Ag) and antibodies to p53 protein (p53Ab) in a population of workers exposed to vinyl chloride (VC).

METHOD

We have investigated the presence of two cancer markers in the plasma of 151 subjects exposed to varying concentrations of VC (4-2823 ppm). The investigation took place in two sessions: in 1999, the analysis was limited to p53Ab, and in 2000, the analysis was repeated and extended to include also the mutant-p53Ag. The available information on the subjects in this study includes age, total years of employment in the VC polymerization industry, exposure concentration, results of abdominal ultrasonogram, hepatitis status, smoking and alcohol drinking status, and clinical records. Logistic regression analyses were performed to calculate the association between prevalence of positivity for p53Ab or mutant-p53Ag and cumulative VC exposure concentration after adjustment for confounding factors. t test and chi analyses were performed to test significant differences among groups.

RESULTS

Three (1.9%) of the 151 workers exposed to VC resulted seropositive for the mutant-p53Ag and five (3.3%) for the p53Ab. All seropositive subjects are distributed in the highest exposure classes (>1000 ppm). No seropositivity was found among controls. The stratified relationship between seropositivity and exposure appeared statistically significant (chi = 23.65 for mutant-p53Ag and 30.35 for p53Ab).

CONCLUSIONS

revealing its presence in subjects having a history of VC exposure greater than 1000 ppm. On the basis of this study, and the clinical experience of the authors, the presence of a minimum threshold for the carcinogenic effects of VC is hypothesized.

Comparison of p53 levels in lymphocytes and in blood plasma of nuclear power plant workers

p53 levels were assessed in lymphocytes and in blood plasma of workers from two Czech nuclear power plants (NPP): 114 subjects working in Temelin and 108 subjects working in Dukovany. Ionizing radiation (IR) exposure data were available for 64 and 59 subjects working in the monitored zones from the NPP in Temelin and Dukovany, respectively. The short-term doses of IR for these subjects were 0.01 and 0.12 mSv, and the long-term doses were 0.46 and 5.68 mSv, in the Temelin and Dukovany NPP, respectively. As a control group, 46 subjects living in Ceske Budejovice, a city nearby the Temelin NPP, were analyzed. The concentration of p53 in lymphocytes was significantly higher in workers from the monitored zone in the Dukovany NPP (median value 6.4 pg/microg protein, P <0.001) than in workers from the Temelin NPP (3.2 pg/microg) as well as in the control group (3.5 pg/microg). In contrast, plasma levels of p53 were comparable in the control group (median value 116 pg/ml plasma) and workers from the monitored zone of Dukovany NPP (102 pg/ml), but lower in workers from Temelin NPP (5 pg/ml). Other factors affecting p53 levels were studied. Smoking resulted in increased p53 lymphocyte levels. The effect of polymorphisms in metabolic and DNA repair genes on p53 levels was analyzed. The correlation was found between p53 levels in lymphocytes and p53 codon 72 polymorphism in subjects working in NPPs, but not in the control group. The results of measurement p53 levels in lymphocytes suggest that this biomarker could reflect the short-term as well as long-term effects of low doses IR. Its impact on human health should be further explored.

Molecular epidemiology of plasma oncoproteins in vinyl chloride monomer workers in Taiwan

AIMS

To determine the presence of Asp13-p21-ki-ras oncoprotein and p53 oncoprotein in the plasma of vinyl chloride monomer (VCM)-workers in Taiwan.

METHODS

We used enhanced chemiluminescence (ECL) western blotting to detect Asp13-p21-ki-ras and ELISA to detect mutant p53 protein (p53-Ag) and anti-p53 antibodies (p53-Ab) in the plasma of VCM-exposed workers.

RESULTS

Twenty-five out of 251 (10%) VCM-workers were positive for Asp13-p21-ki-ras in plasma, but 0 out of 36 controls were positive. There were 15 out of 95 (15.8%) plasma-positives among the more highly exposed (> 480 ppm-month) workers and 10 out of 156 (6.4%) plasma-positives among the lesser exposed (< or = 480 ppm-month). Compared to the unexposed controls, age and drinking adjusted odds ratios (95% CI) were 1.2 (0.1, 9.8) in the lower exposed workers, and 4.8 (0.8, 28) in the higher exposed workers, and there was a significant linear trend between exposure and plasma positivity (P=0.001). Thirty-three out of 251 (13.2%) VCM-workers were positive for the p53 over-expression (10% with positive p53-Ag and 2.8% with positive p53-Ab). There was a significant association between cumulative VCM exposure concentration and positive p53 expression (P=0.032) among VCM-workers after adjusting for age, hepatitis, drinking and smoking status.

CONCLUSIONS

Asp13-p21-ki-ras oncoprotein and p53 over-expression (p53-Ag or p53-Ab) can be found in the plasma of VCM-workers in Taiwan, and a significant dose-response relationship exists between plasma oncoproteins expression and VCM exposure.

Detection of serum p53 protein in patients with different gastrointestinal cancers

Overexpression of p53 has been found in many types of human malignancy. The present study aimed to detect preoperative serum p53 among 158 patients with different gastrointestinal cancers using ELISA technique based on mouse anti-p53 DO-7 monoclonal antibody and anti-p53 rabbit polyclonal antibody. A single band of 53kDa was detected in nuclear protein tissue extracts of selected cancer patients and in 96% of the corresponding sera using Western blot assay. The ELISA technique revealed that the serum p53 was detected in 100% of patients with cholangiocarcinoma, 76% of pancreatic carcinoma, 75% of hepatocellular carcinoma, 70% of colon cancer, 60% of esophagus carcinoma, and 35% of gastric carcinoma. The serum p53 concentrations of the positive patients were highly elevated (P<0.001) compared with healthy individuals. These results suggest that immunodetection of serum p53 could be valuable for post-operative monitoring during follow up in preoperatively positive patients with gastrointestinal cancers.

Serum and tissue c-erb B2, bcl-2, and mutant p53 oncoprotein levels in nasopharyngeal cancer

To date there are no prognostic factors that can account for the biology and disease behavior in nasopharyngeal cancer. Therefore, identification of new factors that can help in predicting the behavior of the disease and characterizing the subgroup with more aggressive tumors more likely to benefitfrom chemotherapy is important. In this study, c-erb B2, bcl-2, and mutant p53 protein levels were investigated in sera and tumor tissue of patients with nasopharyngeal cancer. Serum c-erb B2 levels were significantly higher in the patients than in the healthy subjects. No meaningful difference was observed between the serum and tissue levels of the mutant p53 protein. Tissue bcl-2 concentrations were considerably high. Our results suggest that serum c-erb B2 levels may aid in identifying a subgroup of patients with a poorer response rate to first-line treatment.

Humoral response to p53 in human colorectal tumors: a prospective study of 1,209 patients

p53 Antibodies (p53-Abs) have been detected in the serum of a proportion of colorectal cancer (CRC) patients. It is not yet known at which stage during colorectal tumor progression p53-Abs appear in the serum. The utility of these antibodies as markers for CRC prognosis remains to be clarified. Using a quantitative enzyme-linked immunosorbent assay, we analyzed serum samples from 998 CRC patients and from 211 patients with polyp. Levels of p53-Abs were defined as negative (<10 U/microL), low (10-76 U/microL) and high (>76 U/microL). Overall, 13.0% of CRC patients and less than 1% of polyp patients had increased serum p53-Ab levels. High p53-Ab levels were only seen in patients with invasive carcinomas. The parameters that were significantly and independently associated with a greater frequency of high p53-Ab levels were the left colon (odds ratio [OR] = 3.4; 95% CI = 1.1-10.5), the rectum (OR = 2.9; 95% CI, 1.0-8.8) and advanced lymph node metastasis (OR = 4.6; 95% CI, 2.2-9.6). In univariate analysis, patients with high p53-Ab levels had a shorter survival times than did those without (p = 0.007). However, the significant effect disappeared in a Cox regression model adjusting for sex, age, tumor location, carcinoembryonic antigen levels, gross findings, histologic grade, mucin production and TNM stage. Thus, autoantibodies against p53 occur with tumor progression in multistep colorectal carcinogenesis and increase with advanced node metastasis. Furthermore, the seemingly adverse effect of high p53-Ab levels on the survival of CRC patients may be explained by other prognostic factors.

Serum levels of pantropic p53 protein and EGF-receptor, and detection of anti-p53 antibodies in former uranium miners (SDAG Wismut)

BACKGROUND

The oncogene product EGF-receptor (EGF-R), the tumor suppressor gene product p53, and anti-p53 antibodies are detectable in serum of certain cancer patients. Increased levels of some of these products were reported in lung cancer patients after occupational asbestos exposure, after exposure to polycyclic aromatic hydrocarbons or vinyl chloride. This molecular epidemiological study investigated the use of serum EGF-R, p53-protein, and anti-p53 antibodies as biomarkers for detection of effects of radon and its decay products.

METHODS

Serum EGF-R, p53-protein, and anti-53 antibodies were measured using ELISA in former uranium miners of SDAG Wismut without lung disease (n=106) and miners with Schneeberg lung cancer (n=22). They were compared with healthy subjects (n=23), patients with lung cancer not due to ionizing radiation (n=88), and patients with non-malignant lung or pleural diseases (n=50).

RESULTS

No significantly elevated or decreased serum values for p53 protein, EGF-R, or anti-p53 antibodies could be found. There was no correlation of these with Working Level Months (WLM).

CONCLUSIONS

p53 protein, EGF-R, or anti-p53 antibodies in serum are not useful as biomarkers for detection of lung cancer related to ionizing radiation (i.e., Schneeberg lung cancer).

p53 protein, EGF receptor, and anti-p53 antibodies in serum from patients with occupationally derived lung cancer

The oncogene product epidermal growth factor receptor (EGF-R), the tumour suppressor gene product p53 and anti-p53 antibodies are detectable in the serum of certain cancer patients. Increased levels of some of these products were reported in lung cancer patients after occupational asbestos exposure and after exposure to polycyclic aromatic hydrocarbons or vinylchloride. In the first step, this study investigated the possible diagnostic value of serum EGF-R, p53-protein and anti-p53 antibodies, measured by an enzyme-linked immunosorbent assay, in lung tumour patients. In addition to being investigated on a molecular epidemiological basis, these parameters were examined as biomarkers of carcinogenesis, especially with regard to asbestos incorporation effects or of radon-induced lung cancers. Also, a possible effect of cigarette smoking and age dependence were studied. A total of 116 male patients with lung or pleural tumours were examined. The histological classification was four small-cell cancers, six large-cell cancers, 32 adenocarcinomas, 47 squamous carcinomas, 12 mixed lung carcinomas, five diffuse malignant mesotheliomas and ten lung metastasis of extrapulmonary tumours. Twenty-two lung cancers and all mesotheliomas were related to asbestos, 22 lung cancers were related to ionizing radiation and 61 patients had cigarette smoke-related lung cancer. Besides these patients 50 male patients with non-malignant lung or pleural diseases were included; of the latter eight subjects suffered from asbestosis. Controls were 129 male subjects without any lung disease. No significantly elevated or decreased serum values for p53 protein, EGF-R, or anti-p53 antibodies as a function of histological tumour type, age, or degree and type of exposure (asbestos, smoking, ionizing radiation) could be found. The utility of p53-protein, EGF-R and anti-p53 antibodies as routine biomarkers for screening occupationally derived lung cancers is limited.

A study on p53 protein and anti-p53 antibodies in the sera of patients with oesophageal cancer

p53 protein levels were examined in sera of 15 oesophageal cancer patients using the p53 monoclonal antibody Pab 1801. Antibodies specific for p53 were also analyzed in 20 patients (including 15 patients used for p53 protein level study) and 20 healthy controls. Anti-p53 antibodies were present in 30% (6/20) patients while no antibodies were detected in sera of healthy controls. Comparative analysis of the two parameters, i.e., p53 protein levels and the corresponding antibodies in the patients revealed no correlation.

Gel fiberglass membranes for affinity chromatography columns and their application to cancer detection

The development of mechanical supports for biochemically active compounds serving as immunochemical sensors has been the goal of many studies. A new compound in the form of gel fiberglass (GFG) membranes was recently developed as an example of such supports. These membranes prepared from glass fibers covered with oxysilanes to create a matrix 'gel fiberglass' (R. Zusman, USA Patent #08/112,087, 1993) were used to prepare affinity chromatography columns for the isolation of soluble p53 protein from the serum of cancer patients. A thin layer of protein, trapped in gel glass during its preparation, was deposited on a lattice of glass fibers. Derivatization of the support eliminated nonspecific adsorption of proteins. Under such conditions, external agents percolating through a membrane may contact a maximum number of protein molecules trapped in the gel glass. The membranes are very stable, and can be stored in dry conditions for several months at room temperature. Affinity chromatography columns were prepared from the GFG membranes and used to isolate various proteins, including tumor-associated antigens (TAA). The capacity of the columns was calculated as the amount of protein (mg ml(-1)) isolated from TAA-containing solution, and amounted to up to 9 mg ml(-1) of serum in colon cancer patients. The cytoplasmic p53 protein was one of the main components of TAA isolated in our experiments. Its concentration was determined by HPLC. This protein was isolated from the serum of cancer patients in the highest concentration yet reported, up to 5 mg ml(-1). The described method allows an easy and highly effective isolation of TAA and can be used for important goals including cancer diagnosis.

Humoral immune response to p53 in malignant glioma

p53 immunoreactivity and humoral immune response to p53 were examined in 14 patients with malignant glioma, including 4 patients with leptomeningeal glioma cell dissemination. Twelve patients expressed p53 protein within the tumour tissue. p53 antibodies were detected in the serum in 2 of 14 patients but never in the cerebrospinal fluid (CSF). Soluble p53 protein was detected neither in serum nor in CSF of the glioma patients. CSF levels of the immunosuppressive cytokine, transforming growth factor (TGF)-beta, were elevated in the glioma patients, including those with a humoral response to p53. These preliminary findings raise the possibility of systemic humoral immune responses to antigens, including mutant p53, expressed by glioma cells in the central nervous system.