Gender comparisons in human lung cancer: analysis of p53 mutations, anti-p53 serum antibodies and C-erbB-2 expression

Gender differences in naphthalene metabolism and naphthalene-induced acute lung injury

Humans are widely exposed to polycyclic aromatic hydrocarbons, commonly found in cigarette smoke and diesel exhaust. These can undergo site- and cell-specific metabolism to cytotoxic intermediates. Metabolism of naphthalene and Clara cell cytotoxicity have been extensively studied in male animals. To address whether male and female mice are equally susceptible to naphthalene, mice were injected with naphthalene, and lungs were examined 1, 2, 3, 6, and 24 h after treatment. By analysis of acute injury using differential permeability to fluorescent nuclear dyes and high-resolution histopathology, injury in female mice was found to be more extensive, occur earlier, and include permeable cells in proximal airways, including airway bifurcations. HPLC analysis of the products of cytochrome P-450 (CYP)-mediated metabolism in microdissected airways indicated that although both genders produced a predominance of products from CYP2F2, female mice produced more naphthalene dihydrodiol in distal airways, the primary sites of injury. We conclude that there are clear gender differences in susceptibility to naphthalene-induced injury and that differences in metabolism of naphthalene may play a role in elevated susceptibility in female mice.

ErbB2 expression is correlated with increased survival of patients with osteosarcoma

BACKGROUND

Elevated ErbB2 expression and gene amplification have been shown to be associated with poor prognosis in many cancers. Recently, it has been demonstrated that overexpression of ErbB2 protein in osteosarcoma is associated with the presence of pulmonary metastasis and decreased survival. By contrast, a previous study showed that the expression of ErbB2 declines in individual osteosarcomas as they become metastatic. In the current study, the authors determined the relation between ErbB2 status and outcome in a large number of selected patients with high-grade osteosarcoma.

METHODS

ErbB2 status was determined immunohistochemically in biopsy specimens of osteosarcoma of the extremities from 81 patients who were treated with surgery and chemotherapy. None of the patients had metastatic disease at presentation (Stage II), and all were followed-up for at least five years. The ErbB2 status was analyzed in relation to the lengths of event-free and overall survival.

RESULTS

Of the 81 tumors examined, 51 (61%) demonstrated high levels of ErbB2 expression. The presence of increased levels of ErbB2 in osteosarcoma was significantly associated with the increased probability of event-free (72.2% v. 45.6% at 5 years, P = 0.03) and overall survival (79.7% v. 58.2% at 5 years, P = 0.03). Cox multivariate analysis showed that the risk of adverse events and death was increased substantially (rate ratio: 2.24 and 2.54; 95% confidence interval, 1.07-4.72 and 1.09-5.67, respectively) among patients with decreased levels of ErbB2 protein in tumor cells, as compared with patients who had increased levels of ErbB2 in tumor cells.

CONCLUSIONS

In patients with high-grade osteosarcoma without metastatic disease at presentation and treated with surgery and chemotherapy, the presence of increased levels of ErbB2 in tumor cells is associated with a significantly increased probability of event-free and overall survival. Further data are needed before this marker can be used in making clinical decisions.

Tumor suppressor genes: at the crossroads of molecular carcinogenesis, molecular epidemiology and human risk assessment

The p53 tumor suppressor gene is mutated in about half of all human cancer cases. The p53 protein modulates multiple cellular functions, such as gene transcription, DNA synthesis and repair, cell cycle arrest, senescence, and apoptosis. Mutations in the p53 gene can abrogate these functions and may lead to genetic instability and progress to cancer. The molecular archeology of the p53 mutation spectrum generates hypotheses concerning the etiology and molecular pathogenesis of cancer. The spectrum of somatic mutations in the p53 gene implicates environmental carcinogens and endogenous processes in the etiology of human cancer. The presence of a characteristic p53 mutation also can manifest a molecular link between exposure to a particular carcinogen and a specific type of human cancer, e.g. aflatoxin B1 (AFB1) exposure and codon 249ser mutations in hepatocellular carcinoma, ultraviolet (UV) exposure and CC to TT tandem mutations in skin cancer, and cigarette smoke and the prevalence of G to T transversions in lung cancer. Although several different exogenous carcinogens have been shown to selectively target p53, evidence supporting the endogenous insult of p53 from oxyradical and nitrogen-oxyradicals is accumulating. p53 mutations can be a biomarker of carcinogen effect. Determining the characteristic p53 mutation load in nontumorous tissue, with a highly sensitive mutation assay, can indicate a specific carcinogen exposure and also may help in identifying individuals at an increased risk of cancer.

Environment, genome and cancer

Cancer is one of the most serious diseases that threaten human being today. To some degree, it is a genetic disease but environmental and other nongenetic factors clearly play a role in many stages of neoplastic process. Genetic factors by themselves are thought to explain only about 5% of all cancer. The remainder can be attributed to external, 'environment' factors that act in conjunction with both genetic and acquired susceptibility. Of note, part of the susceptibility is owing to the variety of human genome. So, environment, human genome and cancer have much to do with each other. Combining all of the information from epidemiology and from research works in laboratory with policy-making and clinical works, purifying the environment, giving special protection to the high risk population, the mortality of cancer may decrease gradually in the future.

Prognostic significance of p53 and bcl-2 abnormalities in operable nonsmall cell lung cancer

The association of p53 abnormalities and bcl-2 protein expression with clinical data and prognosis in 102 patients with resected nonsmall cell lung cancer (NSCLC) was investigated. Deoxyribonucleic acid analysis of exons 5-8 of the p53 gene showed mutations (p53-M) in 47% of resected NSCLC, serum p53 antibodies (p53-Abs) were detected in 25%, p53 protein overexpression (p53-PE) in 54%, and bcl-2 protein overexpression (bcl-2-PE) in 48%. A statistically significant association was found between p53-PE, serum p53-Abs and the presence of a p53 gene alteration. No significant associations were found between results of the p53-M, p53-Abs, bcl-2-PE tests and clinicopathological parameters. In the case of the p53-PE test there were significantly fewer positive results for adenocarcinoma than for squamous cell carcinoma and large cell carcinoma. Survival analysis showed that both p53 abnormalities and negative staining for bcl-2, when analysed separately, were associated with poor overall survival. In a multivariate analysis, only the positive result of the p53-M test remained an independent, statistically significant, unfavourable prognostic factor for survival. When the p53 mutation test was removed from the model, positive results of the p53-PE test and the p53-Abs test became statistically significant, unfavourable prognostic factors. To conclude, among p53 and bcl-2 abnormalities, only p53 gene mutations seem to have a strong and independent effect on prognosis. When deoxyribonucleic acid sequence information is not available, p53 protein expression and the presence of p53 antibodies in serum may be used to obtain important prognostic information.

p53 tumor suppressor gene: at the crossroads of molecular carcinogenesis, molecular epidemiology, and human risk assessment

The molecular archaeology of the mutation spectra of tumor suppressor genes generates hypotheses concerning the etiology and molecular pathogenesis of human cancer. The spectrum of somatic mutations in the p53 gene implicates environmental carcinogens and both endogenous agents and processes in the etiology of human cancer.

Gender difference in DNA adduct levels among nonsmoking lung cancer patients

Lung cancer is the leading cause of cancer mortality in Taiwanese women. Cigarette smoking cannot explain the high lung cancer mortality in this population because less than 10% of women in Taiwan are smokers. Therefore, environmental factors other than smoking may play an important role in lung cancer development in female nonsmokers. The purpose of this study was to elucidate the role of environmental carcinogen exposure in lung cancer development in Taiwanese female nonsmokers, based on DNA adduct formation. We collected nontumorous lung tissues resected from 62 nonsmoking lung cancer patients and 20 noncancer controls to investigate whether differences in susceptibility to DNA adduct formation exist between men and women. (32)P-postlabeling and ELISA (enzyme-linked immunosorbent assay) with polyclonal antibody against BPDE (7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene)-DNA adduct were used to evaluate DNA adduct levels in lung tissues of study subjects. Our data showed that the DNA adduct levels of lung cancer patients determined by both assays were significantly higher than those of noncancer controls (P = 0.0001 for (32)P-postlabeling; P = 0.01 for ELISA). Moreover, DNA adduct levels in females were markedly greater than those in males (P = 0.014 for (32)P-postlabeling; P = 0.001 for ELISA). The difference in DNA adduct levels could not be explained by genetic polymorphisms of cytochrome P-4501A1 (CYP1A1) or glutathione S-transferase (GSTM1), as determined by polymerase chain reaction and restriction fragment length polymorphism. These results demonstrate that lung cancer patients have a higher susceptibility to DNA damage than that of noncancer controls. In addition, differences in susceptibility to DNA damage derived from environmental carcinogen exposure were observed between male and female nonsmokers. In conclusion, high susceptibility to DNA damage in females may partially explain the high mortality rate of lung cancer in nonsmoking Taiwanese women.

Women subjects in NIH-funded clinical research literature: lack of progress in both representation and analysis by sex

The National Institutes of Health (NIH) issued guidelines in 1990 requiring the inclusion of women and minorities in all NIH-sponsored clinical research and revised these guidelines in 1994 to require analysis of clinical trial outcomes by sex of the subjects. To ascertain whether these guidelines are yet reflected in the scientific literature, we performed a survey of research articles published in major medical journals. All original research articles in the New England Journal of Medicine, the Journal of the American Medical Association, the Journal of the National Cancer Institute, and Circulation from the years 1993, 1995, 1997, and 1998 were examined. Articles were assessed for use of human subjects, source of funding, type of study (clinical trial or not), sex-relatedness of the disease or condition, inclusion of women as study subjects, and analysis of outcomes by sex of the subjects. Among NIH-funded, non-sex-specific studies, approximately one fifth of the studies published each year failed to include women as research subjects. This number did not improve significantly over the 5-year period analyzed. Only one quarter to one third of the studies that included women analyzed data by sex of the subjects, with no significant change over the time period studied. Although most clinical trials included women as study subjects, in only a small percentage of the trials were results analyzed by sex of the subjects, with no significant improvement over time. These data clearly show the need for increased awareness and monitoring of recruitment and retention of women in clinical research and for analysis of data by sex of the subjects to be carried out consistently.

Molecular epidemiology: on the path to prevention?

Cancer prevention has been the stated goal of molecular cancer epidemiology for the past 17 years. In this review, progress toward that goal is evaluated by using as examples well-studied environmental exposures-i.e., tobacco smoke, polycyclic aromatic hydrocarbons, aflatoxin B(1), benzene, and hepatitis B virus-and their roles in lung, breast, and liver cancers and leukemia. The contributions of molecular epidemiology discussed here include providing evidence that environmental agents pose carcinogenic risks, helping establish the causal roles of environmental factors in cancer, identifying environment-susceptibility interactions and populations at greatest risk, and developing new intervention strategies. Molecular epidemiologic and other data indicate that assessment of carcinogenic risks should address both the range of risk across the population and the risk to subgroups who may be at high risk because of genetic or acquired susceptibilities, including young children. However, for the most part, research results have not yet been effectively translated into risk assessments and preventive health policies. An infrastructure linking scientists, policy makers, and other constituencies is needed to facilitate this process. To extend our knowledge, the second generation of molecular epidemiologic research should include large-scale, collaborative studies incorporating validated biomarkers and automated technologies. An incentive to make the necessary investment is the recognition that prevention of only 20% of cancer in the United States would result in 200000 fewer new cases diagnosed each year and an annual savings of $21.4 billion in direct costs alone.

p53 gene mutation, tumor p53 protein overexpression, and serum p53 autoantibody generation in patients with breast cancer

OBJECTIVES

Autoantibodies against the p53 tumor suppressor protein have been detected in the serum of a proportion of patients with various cancers. The generation of such antibodies has been proposed to be due to either tumor p53 protein accumulation or to the type of p53 gene mutation. These hypotheses are examined in the present study.

DESIGN AND METHODS

Using immunofluorometric assays, we studied 195 patients with primary breast cancer for the presence of p53 antibodies in serum and p53 protein accumulation in the corresponding tumor. Seventeen patients (9%) were p53 antibody-positive and 77 (40%) overexpressed p53. Ten of the 17 p53 antibody-positive patients had tumor p53 accumulation and 7 were negative for p53. Statistical analysis revealed a weak association between the presence of p53 antibodies and p53 protein accumulation (p = 0.05). Direct DNA sequencing of exons 1-11 of the p53 gene was performed for 16 p53 antibody-positive and 16 p53 antibody-negative patients.

RESULTS

Five of the seropositive and eight of the seronegative patients had a p53 gene mutation. Four of the five mutations in the p53 antibody-positive patients affected a Tyr residue, whereas none of the gene abnormalities in the seronegative patients had such an effect.

CONCLUSIONS

We conclude that p53 antibodies tend to develop in patients with tumor p53 accumulation, but p53 accumulation is neither sufficient nor necessary for the generation of the immune response. Further, p53 antibody-positive patients do not have higher frequency of p53 gene mutations than p53 antibody-negative patients, but the former patient group is associated with a Tyr substitution in the protein product.

[Serum p53 antibody assay: evaluation in colorectal cancer]

INTRODUCTION

Alterations of the tumor suppressor gene p53 and its protein synthesis is the most commonly observed genetic feature in human cancers. Direct diagnosis of the gene mutation using sequencing is the gold standard method. However, it requires advanced technology and is only performed in specialized research units.

CURRENT KNOWLEDGE AND KEY POINTS

Demonstration of intratumoral p53 protein accumulation using immunohistochemistry is a routine diagnostic technique. Serum detection of p53 antibodies using ELISA has been recently developed. It is an easily feasible and reproducible method for the diagnosis of p53 alterations due to self-immunization in some patients in response to intratumoral p53 protein overexpression. This phenomenon is inconstant (about one-third of the patients with a p53 gene mutation produce antibodies) and its mechanism is unclear. p53 Antibodies are found in 25% of the patients with colorectal cancer, independently of traditional tumor markers (carcinoembryonic antigen and carbohydrate antigen 19.9). The presence of these antibodies is not linked to the tumor stage. Since their ratios vary during the treatment, they might constitute a new tumor marker.

FUTURE PROSPECTS AND PROJECTS

Early appearance of p53 serum antibodies during tumor development should make them useful for the detection of malignant transformation in patients with preneoplastic disease such as ulcerous colititis. Whether the presence of p53 antibodies in colorectal cancer patients has a prognostic significance requires further assessment.

Prognostic significance of serum p53 antibodies in patients with limited-stage small cell lung cancer

p53 tumour suppressor gene alterations are one of the most frequent genetic events in lung cancer. A subset of patients with p53 mutation and cancer exhibited circulating serum anti-p53 self-antibodies (p53-Ab). The prevalence of these antibodies in lung cancer is currently being analysed in a multicentric study. In a group of homogeneous SCLC patients, p53-Ab were detected in 20/97 (20.6%) individuals. In this group of patients, Cox's multivariate analysis identified disease extent (p = 0.022), WHO initial performance status greater than 0 (p = 0.005), and the absence of a complete response after 6 months of treatment (p < 0.0001) as independent prognostic variables, with p53-Ab being of borderline significance (p = 0.051). In the subset of limited-stage SCLC patients, Cox's multivariate analysis found p53-Ab (p = 0.033), WHO initial performance status greater than 0 (p = 0.028), and absence of a complete response (p < 0.001) to be independent prognostic variables. Thus, actuarial analysis showed that patients with limited-stage SCLC and p53-Ab had a median survival time of 10 months, whereas limited-stage SCLC patients without p53-Ab had a 17-month median survival time (p = 0.014).Therefore, serum assay of p53-Ab could help to identify a population of SCLC patients with an especially poor prognosis. This population could represent patients with tumours harboring aggressive p53 mutations.

Sex-specific expression of gastrin-releasing peptide receptor: relationship to smoking history and risk of lung cancer

BACKGROUND

Activation of gastrin-releasing peptide receptor (GRPR) in human airways has been associated with a proliferative response of bronchial cells to gastrin-releasing peptide and with long-term tobacco use. The GRPR gene is located on the X chromosome and escapes X-chromosome inactivation, which occurs in females. Increasing evidence demonstrates that women are more susceptible than men to tobacco carcinogenesis. We hypothesized that the susceptibility of women to the effects of tobacco may be associated with airway expression of GRPR.

METHODS

We analyzed GRPR messenger RNA (mRNA) expression in lung tissues and cultured airway cells from 78 individuals (40 males and 38 females) and in lung fibroblasts exposed to nicotine in vitro. Nicotinic acetylcholine receptors in airway cells were assayed by use of radioactively labeled nicotine and nicotine antagonists. A polymorphism in exon 2 of the GRPR gene was used to detect allele-specific GRPR mRNA expression in some individuals. Statistical tests were two-sided.

RESULTS

GRPR mRNA expression was detected in airway cells and tissues of more female than male nonsmokers (55% versus 0%) and short-term smokers (1-25 pack-years [pack-years = number of packs of cigarettes smoked per day multiplied by the number of years of smoking]) (75% versus 20%) (P =.018 for nonsmoking and short-term smoking females versus nonsmoking and short-term smoking males). Female smokers exhibited expression of GRPR mRNA at a lower mean pack-year exposure than male smokers (37.4 pack-years versus 56.3 pack-years; P =.037). Lung fibroblasts and bronchial epithelial cells exhibited high-affinity, saturable nicotinic acetylcholine-binding sites. Expression of GRPR mRNA in lung fibroblasts was elevated following exposure to nicotine.

CONCLUSIONS

Our results suggest that the GRPR gene is expressed more frequently in women than in men in the absence of smoking and that expression of this gene is activated earlier in women in response to tobacco exposure. The presence of two expressed copies of the GRPR gene in females may be a factor in the increased susceptibility of women to tobacco-induced lung cancer.

p53 tumor suppressor gene mutations in transformed cutaneous T-cell lymphoma: a study of 12 cases

The transformation of cutaneous T-cell lymphoma (t-CTCL) is an uncommon phenomenon that is associated with histopathologic changes and follows an aggressive course. The factors contributing to this transformation are poorly understood. The aim of this study was to analyze the p53 status in t-CTCL and to correlate it with disease outcome. The p53 status was investigated by immunohistochemistry, single-strand conformation polymorphism (SSCP) and DNA sequencing in 12 patients with t-CTCL. Eight mutations were detected; including four in exon 5, one in exon 6 and three in exon 7. Five were point mutations and three were deletions. Paired samples from nontransformed patch and plaque lesions showed no p53 over-expression. Eight disease-related deaths were reported, six to 23 months after transformation, all of which had p53 mutations. Three other patients with wild phenotype (WT-p53) were last reported alive with the disease 19-33 months after transformation (p < 0.0002). One other case had a p53 mutation but a short period of follow-up. Our results suggest that phenotypic changes of t-CTCL are frequently associated with genotype alterations in the p53 gene. Because 70% of the mutations detected were either G to C transversions or deletions, nucleotide-pairing mismatch and not DNA damage by UVB represents a likely mechanism for mutagenesis. Furthermore, the data may help in the design of gene transfer therapies that target the p53 molecule.

Gender differences in risk of renal cell carcinoma and occupational exposures to chlorinated aliphatic hydrocarbons

BACKGROUND

Organic solvents have been associated with renal cell cancer; however, the risk by gender and type of solvents is nuclear.

METHODS

We evaluated the risk of renal cell carcinoma among men and women exposed to all organic solvents-combined, all chlorinated aliphatic hydrocarbons (CAHC)-combined, and nine individual CAHC using a priori job exposure matrices developed by NCI in a population-based case-control study in Minnesota, U.S. We interviewed 438 renal cell cancer cases (273 men and 165 women) and 687 controls (462 men and 225 women).

RESULTS

Overall, 34% of male cases and 21% of female cases were exposed to organic solvents in general. The risk of renal cell carcinoma was significantly elevated among women exposed to all organic solvents combined (OR = 2.3; 95% CI = 1.3-4.2), to CAHC combined (OR = 2.1; 95% CI = 1.1-3.9), and to trichloroethylene (TCE) (OR = 2.0; 95% CI = 1.0-4.0). Among men, no significant excess risk was observed among men exposed to any of these nine individual CAHCs, all CAHCs-combined, or all organic solvents-combined.

DISCUSSION

These observed gender differences in risk of renal cell carcinoma in relation to exposure to organic solvents may be explained by chance based on small numbers, or by the differences in body fat content, metabolic activity, the rate of elimination of xenobiotics from the body, or by differences in the level of exposure between men and women, even though they have the same job title.

Correlations between p53-protein accumulation, serum antibodies and gene mutation in colorectal cancer

Only half of colorectal-cancer patients elicit serum antibodies in response to intratumoral p53-gene mutations. Our study was designed to compare cellular events (p53-protein accumulation and gene mutations) with the presence of circulating anti-p53 antibodies (p53-Ab). Thirty-five colorectal-cancer patients were studied for their intratumoral p53-protein accumulation and circulating p53-Ab. Tumour DNA was analyzed for genomic mutations in a sub-set of 28 patients. In all, 18 tumours (51.4%) were positive by immunohistochemistry, and 17 tumour extracts were shown to contain "mutant" conformation p53 protein, 16 of them being were concordant by both methods. Of the 28 tumours tested by DGGE, 16 contained alterations in p53 exons 5 to 8 (57.1%). Of 12 tumours without detectable mutations, 10 were "mutant"-conformation-negative by immunohistochemistry and ELISA. Paradiploid tumors presented more frequently wild-type p53 genes and were significantly less frequently immunohistochemistry- or p53-Ab-positive than polyploid tumors. Circulating p53-Ab were detected in the serum of 11 patients (31%). In 9/11 cases, a gene mutation was found in the corresponding tumour. Three of four mutations in exon 8 and 3/3 mutations in exons 5-6 were associated with p53-Ab, in contrast with only 3/9 mutations in exon 7. We found good agreement in the detection of p53-gene alterations by different methods. However, our data suggest that all gene mutations may not be equivalent in term of immunogenicity.

Lung cancer and past occupational exposure to asbestos. Role of p53 and K-ras mutations

Studies on somatic mutations in lung cancers associated with cigarette smoking and asbestos exposure are few. We investigated prevalence of mutations in the p53 and K-ras genes in lung tumors from smokers with and without asbestos exposure at work. For K-ras mutations, the study was an extension of an earlier analysis. Nearly all of the 105 consecutive patients examined were smokers and had non-small-cell carcinoma of the lung with squamous-cell carcinoma or adenocarcinoma histology. Exposure to asbestos was estimated by pulmonary fiber counts and occupational histories. A pulmonary burden of >/= 1 x 10(6) asbestos fibers per gram of lung tissue, indicating work-related exposure, was found in 32% of the patients for whom fiber-analysis data were available (33 of 102 patients, all men). The statistical analysis showed pulmonary fiber count as the only significant predictor of adenocarcinoma histology, in contrast to squamous-cell carcinoma (smoking-adjusted odds ratio [OR] 3.0, 95% confidence interval [CI] 1.1 to 8.5). The frequency of p53 mutations was 39% (13 of 33) among the asbestos-exposed cases, as compared with 54% (29 of 54) among the nonexposed cases; the difference was not significant, however. In male ever-smokers, a long duration of smoking was associated with p53 mutation (OR 3.2, 95% CI 1.2 to 8.8). In adenocarcinoma, p53 mutations were less prevalent (10 of 30, 33%) as compared with squamous-cell carcinoma (28 of 46, 61%; P = 0.02), whereas a strong and significant association was found between adenocarcinoma and K-ras mutation (OR 37, 95% CI 5.8 to 232, adjusted for smoking and asbestos exposure). Asbestos exposure alone was not significantly associated with increased occurrence of K-ras mutations. In conclusion, the results may primarily reflect the observed excess of adenocarcinoma in the asbestos- exposed patients, and hence the decrease in p53 mutations and increase in K-ras mutations.

p53, c-erbB2, and PCNA status in benign, proliferative and malignant ovarian surface epithelial neoplasms: a study of 75 cases

Low malignant potential tumors of the ovary are believed to behave in a manner intermediate to their benign and malignant counterparts. However, recent evidence suggests these lesions are in fact benign and better classified as proliferative. Based on our previous work and evaluating p53, c-erbB2, and PCNA status in a full spectrum of ovarian surface epithelial tumors, with emphasis on low malignant potential tumors, we tested this hypothesis. Immunohistochemical stains with monoclonal antibodies were used on 75 archival ovarian neoplasms. The results demonstrated anti-p53 reactivity in 30 carcinomas (40%), 2 of which were proliferative, and no reactivity in the benign tumors. Overexpression of c-erbB2 was seen in 31 malignant neoplasms (64.5%), 4 of which were proliferative (22.1%), and none in benign tumors. The PCNA proliferative index showed means of 42.8%, 22.8%, and 14.9% with benign, low malignant potential, and malignant tumors, respectively. Predicting immunoreactivity in carcinomas for anti-PCNA (Student t test), anti-p53, and anti-c-erbB2 (Pearson chi2 test) versus a lack of immunoreactivity in proliferative tumors indicate P values of .001, <.001, and <.001, respectively. These data show significant differences in the expression of these markers in ovarian tumors and suggest a possible role for these oncogenes as supplemental tools in diagnostic pathology. Further, our findings also support the designation of proliferative as opposed to the current nomenclature of low malignant potential tumors.

Gender-specific frequency of background somatic mutations at the hypoxanthine phosphoribosyltransferase locus in cord blood T lymphocytes from preterm newborns

Limited information is available regarding the frequency, spectrum, and clinical relevance of somatic mutations in the developing fetus. The goal of this study was to determine somatic mutant frequencies (Mfs) at the hypoxanthine phosphoribosyltransferase (HPRT) reporter gene in cord blood T lymphocytes from preterm infants to gain insight into in utero mutational events. Mf determinations were made by using the HPRT T cell cloning assay on cord blood samples from 52 preterm infants. Natural logarithm Mfs (lnMfs) from preterm infants were compared with results from our database for full-term infants. Our analysis revealed higher lnMfs in cord blood T lymphocytes from preterm compared with full-term infants (P = 0.008). In addition, preterm females had significantly higher lnMfs compared with full-term females (P < 0.001), whereas preterm males were found to have significantly lower lnMfs than preterm females (P = 0.005). Regression analyses also demonstrate a significant relationship between lnMf and gestational age for preterm females that does not exist for preterm males. These results demonstrate the gender-specific association between Mf and age in humans.

Molecular epidemiology of human cancer risk: gene-environment interactions and p53 mutation spectrum in human lung cancer

The p53 tumour suppressor gene is at the crossroads of a network of cellular pathways including cell cycle checkpoints, DNA repair, chromosomal segregation, and apoptosis. These pathways have evolved to maintain the stability of the genome during cellular stress from DNA damage, hypoxia, and activated oncogenes. The high frequency of p53 mutations in human cancer is a reflection of the importance of p53 involvement in this network of pathways during human carcinogenesis. An electronic database containing p53 mutations from more than 9000 cancers (http:/(/)www.iarc.fr/p53/homepage.html) can be used to generate hypotheses for further clinical, epidemiological, and laboratory investigations. For example, one can hypothesize that (a) p53 mutations vary in their pathobiological significance; (b) cellular content influences the selection of p53 mutations in clonally derived cancers; (c) the location and type of mutation within the p53 gene provide clues to functional domains in the gene product; and (d) the p53 mutation spectrum can be a molecular link between aetiological agents and human cancer. This review will focus on the role of p53 and cancer susceptibility genes in the molecular pathogenesis and epidemiology of human lung cancer.

Prognostic value of serum p53 antibodies in patients with resected non-small cell lung cancer

BACKGROUND

Serum antibodies against p53 protein (p53-Abs) have been detected in some cancer patients. The significance and use of p53-Abs as a marker of the clinical behavior of lung cancer is currently under investigation.

PURPOSE

In this study, we measured the serum p53-Abs in 84 patients with operable non-small cell lung cancer (NSCLC) and evaluated potential association between the presence of these antibodies and prognosis.

METHODS

Enzyme-linked immunosorbent assay (ELISA) was used to detect p53-Abs in serum. Survival and disease-free survival curves related to initial p53-Abs status were estimated using the Kaplan-Meier method.

RESULTS

At the time of diagnosis 19 (22.6%) of 84 analyzed patients had positive result from the serum p53 antibodies (p53-Abs) test. No association was found between p53-Abs, histological types of tumors and clinical stage of disease. We found that patients with a positive result from the p53-Abs test had lower probability of overall and disease-free survival. The unfavorable effect was significant both in the univariate analysis, as well as in the multivariate analysis (after adjustment for sex, histopathological type of tumor. TNM stage).

CONCLUSION

The results of the present study indicate that serum p53 antibodies may be an independent prognostic factor in NSCLC, especially in the squamous cell carcinoma (SqCC) patients and may be useful in identifying resected lung cancer patients at high risk for treatment failure.

A specific spectrum of p53 mutations in lung cancer from smokers: review of mutations compiled in the IARC p53 database

Mutations in the p53 gene are common in lung cancer. Using data from the the International Agency for Research on Cancer p53 mutation database (R1), we have analyzed the distribution and nature of p53 mutations in 876 lung tumors described in the literature. These analyses confirm that G to T transitions are the predominant type of p53 mutation in lung cancer from smokers. The most frequently mutated codons include 157, 158, 179, 248, 249, and 273, and several of them (157, 248, and 273) have been shown to correspond to sites of in vitro DNA adduct formation by metabolites of polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene. Furthermore, most of the base changes at codons 248, 249, and 273 in lung cancer differ from those commonly observed at these codons in other cancers reported in the database. Thus, lung cancer from smokers shows a distinct, unique p53 mutation spectrum that is not observed in lung cancer from nonsmokers. These results further strengthen the association between active smoking, exposure to PAHs, and lung cancer. They also indicate that a different pattern of mutations occurs in nonsmokers, and this observation may help to identify other agents causally involved in lung cancer in nonsmokers.

Anti-p53 antibodies in patients with Barrett's esophagus or esophageal carcinoma can predate cancer diagnosis

BACKGROUND & AIMS

We previously discovered anti-p53 antibodies predating a cancer diagnosis in subjects at increased risk for liver, lung, breast, and prostate cancer. Recently, we reported a significant correlation (P < 0.017) between p53 antibodies and p53 mutations in patients with late-stage esophageal carcinoma. Because others have reported p53 mutations and overexpression of p53 protein in Barrett's esophagus, we studied p53 antibodies in plasma of 88 serially endoscoped patients: 36 with Barrett's metaplasia, 23 with esophageal squamous cell carcinoma, 10 with esophageal adenocarcinoma, and 19 with esophagitis or normal esophagus.

METHODS

We used enzyme immunoassay, immunoblotting, and immunoprecipitation assays for p53 antibodies; polymerase chain reaction, denaturant gradient gel electrophoresis, and sequencing for p53 mutations; and immunohistochemistry for p53 protein.

RESULTS

p53 antibodies were detected in 4 patients with Barrett's esophagus, including 1 with dysplasia that later progressed to adenocarcinoma, and in 10 cancer patients (P = 0.002) (8 squamous and 2 adenocarcinoma), 2 of whom (1 squamous, 1 adenocarcinoma) had antibodies before cancer was diagnosed. Other patient groups were too small for informative statistical analysis. Six antibody-positive cancer patients had p53 mutations, whereas 2 patients with cancer and 1 with Barrett's esophagus with antibodies had p53 protein overexpressed in esophageal tissues.

CONCLUSIONS

Patients with Barrett's esophagus and esophageal cancer can develop p53 antibodies that may predate the clinical diagnosis of malignancy.

Implications of p53 alterations and anti-p53 antibody response in head and neck squamous cell carcinomas

Point mutations at the tumour suppressor gene p53 are one of the most frequent genetic alterations in squamous cell carcinoma of the head and neck (SCCHN), which lead to the nuclear accumulation and overexpression of inactive p53 protein. The overexpression of mutant p53 protein can induce a specific humoral response in cancer patients. p53 protein was studied in 112 SCCHN. Biopsies and sera samples were collected before initiation of treatment. 74 patients received neoadjuvant chemotherapy (5-fluorouracil-cisplatin-folinic acid). p53 protein expression was evaluated by immunohistochemistry (IHC) on paraffin-embedded sections. The analysis of mutations was assessed by PCR-SSCP of exons 5-10 on DNA from 28 representative cases. Antibodies specific for p53 protein were analysed in sera of 74 patients by an ELISA procedure. Overexpression (> 20% positive cells) of p53 protein was frequent (56%: 63/112) and was correlated with localisation of the primary tumour and tumour stage. p53 mutations were detected in 57% (16/28) of studied cases. The prevalence of p53 antibodies in sera was high (44% 32/74) and among this population, 68% (20/29) had a positive immunophenotype and 67% (6/9) a p53 mutation in the tumour. In addition, the presence of anti-p53 antibodies was slightly associated with complete response to neoadjuvant chemotherapy. If the humoral response seems to be an indicator of the p53 protein status, the detection of anti-p53 antibodies could be a good approach in the early detection of the presence of p53 alterations in SCCHN and recurrent tumours or the appearance of second primary cancer.

Molecular markers of carcinogenesis

The protein products of oncogenes and tumor suppressor genes play critical roles in the development of many cancers. The expression of a number of these proteins can be detected in extracellular fluids such as blood. This article reviews the literature on the application of methods for the detection of the proteins of oncogenes and tumor suppressor genes in the blood of humans with cancer or at risk for the development of cancer. The detection of these proteins in blood may be useful molecular markers of carcinogenesis that could play an important part in cancer diagnosis, prognosis, and prevention.

P53 expression in stage I squamous cell lung cancer

P53 expression was studied using immunohistochemistry in patients (n=94) with pathologic stage I squamous cell lung cancer treated surgically between 1991-1992. The overall p53 positivity ratio was 48/94. 83 of the cases proved to be suitable for follow-up analysis carried out in November, 1995. 46/83 were p53 positive, and 25/46 patients were alive at the time of analysis. The patients who died (21/46) had a mean survival time of 17.5 months. In p53 negative cases (37/83), however, 29/37 patients were still alive at the time of follow-up, and 8/37 had died with a mean survival time of 23.1 months. A significant correlation could be found between p53 immunopositivity and reduced survival time (p=0.0125). Interestingly, out of 83 cases analyzed histologic evidence of tuberculous scar tissue was present in 9 tumors with a p53 positivity ratio of only 1/9. When flow cytometry was used to examine tumor samples from all subgroups mentioned above (n=32), no correlation was found between the p53 immunopositivity or the prognosis and the DNA content of tumor tissues. Our results suggest that in the early stage of squamous cell lung cancer the p53 positivity may be an indicator of a more aggressive tumor behavior and a shortened survival time.

Very low incidence of p53 antibodies in adult non-Hodgkin's lymphoma and multiple myeloma

In several types of solid tumours, circulating antibodies to p53 are seen in about a third of cases with a p53 mutation, but are absent in cases without p53 mutation. Therefore detection of those antibodies has relatively low sensitivity but high specificity in the detection of p53 mutations. We looked for circulating p53 antibodies by ELISA in 56 adult non-Hodgkin's lymphoma (NHL) and 80 multiple myeloma cases. A certain or highly probable p53 mutation was found by SSCP analysis, immunocyto- or immunohistochemistry in 8/35 (23%) NHL cases and 2/19 (10%) MM cases analysed by these techniques. None of the 80 MM cases and only one of the 56 cases of NHL had circulating p53 antibodies. The positive case had Burkitt's lymphoma and a p53 missense mutation at codon 273. Thus, very few MM and NHL patients with a p53 mutation develop p53 antibodies and this test does not appear to be useful in haematological malignancies.

Bcl-2 immunohistochemistry in a surgical series of non-small cell lung cancer patients

The bcl-2 gene is implicated in oncogenesis by its ability to prolong cell survival through the inhibition of apoptosis, without increasing cell proliferation. An association between immunohistochemical staining for bcl-2 protein and the histological type and prognosis of non-small cell carcinoma was hypothesized by Pezzella et al. (N Engl J Med 329:690-694, 1993). In a case series, we stained formalin-fixed, paraffin-embedded tumor tissue from 106 surgical non-small cell lung cancer patients with an antibody to bcl-2 protein (DAKO clone 124, Carpinteria, CA). The resulting bcl-2 staining data were evaluated for associations with demographic, histological, immunohistochemical, and genetic features, including p53 mutations. Bcl-2 staining was observed in tumors from 29 of 106 (27%) of subjects, but was significantly less frequent in subjects' adenocarcinoma histology (8 of 55, 14.6%) (P = .007). This finding persisted after adjustment for age, gender, stage, grade, smoking history, and disease-free survival. In univariate analyses, no association was seen with age, weight, body mass index, gender, or pack-years smoking; tumor grade, stage, or patient performance status; p53 or c-erbB2 immunohistochemical staining, or p53 mutations. These data agree with earlier reports that bcl-2 staining is less common in adenocarcinomas; however, our data do not support the hypothesis that bcl-2 staining confers a better prognosis overall, in squamous cell carcinoma, or in an older patient population.

Environment and cancer: who are susceptible?

Acting in concert with individual susceptibility, environmental factors such as smoking, diet, and pollutants play a role in most human cancer. However, new molecular evidence indicates that specific groups-characterized by predisposing genetic traits or ethnicity, the very young, and women-may have heightened risk from certain exposures. This is illustrated by molecular epidemiologic studies of environmental carcinogens such as polycyclic aromatic hydrocarbons and aromatic amines. Individual genetic screening for rare high-risk traits or for more common, low-penetrant susceptibility genes is problematic and not routinely recommended. However, knowledge of the full spectrum of both genetic and acquired susceptibility in the population will be instrumental in developing health and regulatory policies that increase protection of the more susceptible groups from risks of environmental carcinogens. This will necessitate revision of current risk assessment methodologies to explicitly account for individual variation in susceptibility to environmental carcinogens.

Detection of p53 autoantibodies in sera of gastric cancer patients and their prognostic relevance

BACKGROUND

Changes in the p53 gene product can be immunogenic and enable the formation of p53 serum antibodies (p53ab), detectable in patients with different cancer types. So far, there have been no reports describing the detectability of p53ab in gastric cancer patients.

METHODS

We investigated the presence of p53ab and their clinical relevance in a cohort of 74 gastric cancer patients, using an enzyme-linked immunosorbent assay system.

RESULTS

In our investigation 20.3% of all patients (15 of 74) and 46.9% of the patients with immunohistochemically (IHC) p53-positive tumors (15 of 32) showed detectable p53ab in serum. All p53ab-positive patients had IHC p53-positive tumors. We have found a significant correlation of p53ab with a higher tumor stage (P = 0.002) and also with a poor prognosis of survival (P = 0.04).

CONCLUSION

We have shown that in gastric cancer patients p53ab are also detectable and that p53ab positivity is a predictor of an unfavorable prognosis.

Clonal origin of multiple lung cancers: K-ras and p53 mutations determined by nonradioisotopic single-strand conformation polymorphism analysis

Disease stage is the most important factor in determining prognosis and treatment of lung cancer. Staging of lung cancer is complicated by presentation of multiple pulmonary malignant lesions with a similar histology. It is a dilemma to decide if these lesions are synchronous primaries arising from different malignant clones or metastases from a single clone. Lung cancer is associated with multiple genetic abnormalities including mutations of K-ras and p53, which are believed to occur prior to onset of metastasis. To determine the clonal origin of multiple pulmonary malginant nodules, we analyzed point-mutations of K-ras and p53 by microdissection, polymerase chain reactions (PCR), nonradioisotopic single-strand conformation polymorphism (SSCP) analysis, and DNA sequencing. Each pulmonary lesion was microdissected from paraffin slides. Genomic DNA was amplified by two sequential PCRs followed by electrophoresis in a minigel and silver staining. Deoxyribonucleic acid sequencing was performed if necessary to confirm a mutation found upon SSCP analysis. Applying this molecular approach, we were able to differentiate the clonal origins of multiple malignant nodules of the lung as exemplified by the two cases presented.

Mutations, tissue accumulations, and serum levels of p53 in patients with occupational cancers from asbestos and silica exposure

In order to determine the relationship between mutations, tissue accumulations, and serum levels of p53 in occupational cancers, we used denaturing gradient gel electrophoresis and DNA sequencing of exons 5-9 of the p53 gene, immunohistochemical analysis for tissue identification of mutant p53 protein, and enzyme-linked immunosorbent assay for serum levels of mutant p53 protein to examine for such alteration in a cohort of individuals with workplace exposure to asbestos or silica, and resultant lung cancers or mesotheliomas. DNA analysis detected mutations in 5 of 18 (28%) tumors, and tissue accumulations of protein were detected in 7 of 20 (35%) tumors; the agreement between mutational and immunohistochemical analyses was significant (kappa = 0.62, P = 0.002). Serum elevations of protein were detected in 4 of 11 (36%) cases with available serum samples; the agreement between tissue alterations and serum elevations was also significant (kappa = 0.71, P = 0.017). In addition, based on the analysis of banked samples, serum results tended to be consistent over time prior to the diagnosis of disease (positive predictive value = 0.67, negative predictive value = 0.83). These results suggest that serum levels of p53 are reasonably accurate in reflecting tissue alterations in p53 at the gene and/ or protein level and may be early biomarkers of disease risk.

Mutations in the p53 gene in pulmonary blastomas: immunohistochemical and molecular studies

Well-differentiated fetal adenocarcinomas and biphasic blastomas are types of lung cancer that contain glands that mimic the appearance of fetal lung. Biphasic blastomas also show a primitive embryonic stroma. Despite histological similarities leading these two tumors to be classified as pulmonary blastomas, they have distinct clinical and prognostic features. Little information is available on genetic changes in these tumors because they are rare; therefore, the authors studied nine biphasic blastomas and 12 well-differentiated fetal adenocarcinomas for the presence of mutations in the p53 gene. Mutations in the p53 gene are common in other lung cancers, and the type of mutation in the p53 gene can provide information about the original or inciting mutagens. The authors found five biphasic blastomas (42%) had mutations in the p53 gene by immunohistochemical and molecular analysis, whereas none of the well-differentiated fetal adenocarcinomas contained mutations. These results provide molecular support for the significance of distinguishing between well-differentiated fetal adenocarcinoma and biphasic blastoma histologically and identify several types of p53 gene mutations that occur in these tumors.