Loss of heterozygosity is related to p53 mutations and smoking in lung cancer.

Carcinogenesis results from an accumulation of several genetic alterations. Mutations in the p53 gene are frequent and occur at an early stage of lung carcinogenesis. Loss of multiple chromosomal regions is another genetic alteration frequently found in lung tumours. We have examined the association between p53 mutations, loss of heterozygosity (LOH) at frequently deleted loci in lung cancer, and tobacco exposure in 165 tumours from non-small cell lung cancer (NSCLC) patients. A highly significant association between p53 mutations and deletions on 3p, 5q, 9p, 11p and 17p was found. There was also a significant correlation between deletions at these loci. 86% of the tumours with concordant deletion in the 4 most involved loci (3p21, 5q11-13, 9p21 and 17p13) had p53 mutations as compared to only 8% of the tumours without deletions at the corresponding loci (P< 0.0001). Data were also examined in relation to smoking status of the patients and histology of the tumours. The frequency of deletions was significantly higher among smokers as compared to non-smokers. This difference was significant for the 3p21.3 (hMLH1 locus), 3p14.2 (FHIT locus), 5q11-13 (hMSH3 locus) and 9p21 (D9S157 locus). Tumours with deletions at the hMLH1 locus had higher levels of hydrophobic DNA adducts. Deletions were more common in squamous cell carcinomas than in adenocarcinomas. Covariate analysis revealed that histological type and p53 mutations were significant and independent parameters for predicting LOH status at several loci. In the pathogenesis of NSCLC exposure to tobacco carcinogens in addition to clonal selection may be the driving force in these alterations.

p53 mutations in defined structural and functional domains are related to poor clinical outcome in non-small cell lung cancer patients.

The prognostic value of p53 status in non-small cell lung cancer has been investigated in 148 patients with clinical stage I-IIIB disease. Tumor tissues were examined for mutations in exons 4-9, with emphasis on defined structural and functional domains. Eighty-four mutations were detected in 83 (54%) of the patients. Eighty-eight percent of the mutations were within exons 5-8, and 12% of the mutations were within exons 4 and 9. Missense mutations occurred in 67% of the tumors, and 30% were null mutations (10% stop mutations, 15% frameshift mutations, and 5% splice site mutations). Patients with mutations in p53 had a significantly higher risk for lung cancer-related death and for death from all causes than those with wild-type p53 [hazard ratio (HR) = 2.09 and 95% confidence interval (CI) = 1.20-3.64 and HR = 1.69 and 95% CI = 1.06-2.70, respectively]. Mutations in p53 related to even still poorer lung cancer-related prognosis were found at the following locations: (a) exon 8 (HR = 3.5; 95% CI, 1.59-7.71)]; (b) the structural domains L2 + L3 (HR = 2.36; 95% CI, 1.18-4.74), and (c) codons involved in zinc binding (HR = 11.7; 95% CI, 3.56-38.69). Together, the biologically functional group of severe flexible mutants (codons 172, 173, 175, 176, 179, 181, 238, 245, and 267) and severe contact mutants (248, 282) were significantly related to shorter lung cancer-related survival (HR = 4.16; 95% CI, 1.93-8.97). Squamous cell carcinoma was the dominant histological type in tumors involved in poor prognosis in exon 8 (HR = 3.19; 95% CI, 1.07-9.45). These results indicate that mutations in defined structural and functional domains of p53 may be useful molecular biological markers for prognosis and treatment strategy in non-small cell lung cancer patients.

Gene-environment interactions in human lung cancer.

Gene-environment interactions are thought to be critical for several diseases such as cancer, diabetes, heart disease and asthma. Cancer is a result of multiple gene-environment interactions occurring over several decades. During tumor development the cell accumulates multiple genetic changes, which generate the transformed phenotype, i.e. a cell with increased genetic instability. Lung cancer is a useful model for the study of the interplay between genetic factors and environmental exposure since the primary etiology is well established. Several polymorphic enzymes that may be important determinants of susceptibility have been demonstrated. Data also provide evidence for sex differences in lung cancer susceptibility. Furthermore, certain chemical carcinogens may contribute to the carcinogenic process in the lung epithelial cells by inducing genomic instability either directly or indirectly through inflammatory processes.

Neurobehavioral performance in aluminum welders.

METHODS: Twenty aluminum welders (mean age 33 years; range 21-52), who had been exposed to aluminum for an average of 8.1 years (range 2-21), were tested for tremor and reaction time and screened for neuropsychiatric symptoms in a cross-sectional study. The welders' median urinary aluminum concentration was 1.5 micromol/L (range 0. 7-4.8). Aluminum in air, measured inside the respiratory protection, was 0.9 mg/m(3) (range 0.6-3.8). The welders were compared with twenty construction workers matched for age. RESULTS: Welders reported more symptoms than referents did (median 2 vs. 1; P=0.047). Although the welders as a group performed better than the referents on a tremor test, years of exposure, but not age, was predictive of poorer performance. The welders' reaction times were rapid by clinical standards (mean simple reaction time (SRT): 221 milliseconds; mean continuous performance test (CPT): 364 milliseconds). Although, as a group, they performed better than the referents, there was a statistically significant relation between longer reaction times and aluminum in air (air-Al). CONCLUSIONS: The relations between hand steadiness and years exposed, and between reaction time and air-Al, could indicate slight effects from exposure to aluminum. The possibility of selection of workers with high manual skills into welding work and a possible job-related training effect, might partly serve to explain the good performance among the welders.

Genotypes of glutathione transferase M1 and P1 and their significance for lung DNA adduct levels and cancer risk.

The A-G polymorphism at codon 104 in the glutathione S-transferase P1 (GSTP1) gene was examined in 138 male lung cancer patients and 297 healthy controls. The patients had significantly higher frequency of the GG genotype (15.9%) and a lower frequency of AA (38.4%) than the controls (9.1% and 51.5%, respectively). The level of hydrophobic DNA-adducts were determined in lung tissue from 70 current smokers. Patients with the GG genotype had a significantly higher adduct level than patients with AA (15.5 +/- 10.2 vs 7.9 +/- 5.1 per 10(8) nucleotides, P = 0.006). We also analyzed the deletion polymorphism in the GSTM1 gene in 135 male patients and 342 controls. The patients were stratified according to histology, smoking dose, age, adduct level and mutational types found in the tumors (Ki-ras and p53 genes). The results consistently indicated that the GSTM1 null genotype was associated with a slightly increased lung cancer risk. When the combined GST M1 and P1 genotypes were examined, patients with the combination null and AG or GG had significantly higher adduct levels than all other genotype combinations (P = 0.011). The distribution of combined genotypes was also significantly different in cases and controls, mainly due to increased frequency of the combination GSTM1 null and GSTP1 AG or GG among patients.

p53 mutations in lung tumours: relationship to gender and lung DNA adduct levels.

Human lung cancer exhibits a high frequency of transversion mutations at G:C base pairs of the p53 gene, possibly the result of DNA damage by cigarette smoke constituents, most notably benzo[a]pyrene. We have investigated gender differences in the p53 mutational spectrum and levels of hydrophobic DNA adducts. Tumour tissue was obtained from 115 non-small cell lung cancer tumours and examined for mutational alterations in the p53 gene (exons 4-9) using PCR and single-strand conformational polymorphism analysis. We have previously examined exons 5-8 in lung cancer. Sequence analysis of exons 4 and 9 revealed that almost 20% of the mutations were located in exons 4 and 9. The levels of hydrophobic DNA adducts in non-tumorous lung tissue of 55 of the patients were analyzed by the 32P-postlabelling assay. There were both a higher frequency of G:C-->T:A mutations and a higher average hydrophobic DNA adduct level in females than in male patients, even though the level of exposure to carcinogens from cigarette smoking was lower among the females than among the males. Frameshift mutations were more common in women than in men (30 versus 15%). These preliminary findings lend support to epidemiological evidence that women may be at greater risk than men of contracting tobacco-induced lung cancer.

Fatal accident resulting from methyl bromide poisoning after fumigation of a neighbouring house; leakage through sewage pipes.

An intoxication after using methyl bromide (CH3Br) in fumigation is reported. The accident resulted in the death of a newborn infant within 12-13 h after exposure, as well as clinical intoxication of the infant's parents. The concentration of bromide ion in the infant's blood was 170 mg l-1 and in the parents blood it was 130 and 110 mg l-1. Autopsy showed that the cause of death was acute pneumonia due to aspiration, most likely resulting from vomiting and aspiration after inhalation of CH3Br. The clinical symptoms of the parents are reported, as well as a brief survey on the kinetics and CH3Br toxicity in animals and humans. Reconstruction of the events prior to the intoxication revealed that the sewage pipes serving the two houses had been sucked empty only 1-2 h prior to the start of fumigation, resulting in an open sewage connection between the houses and permitting CH3Br to leak from the treated house into the house of the affected family.

Fertility in mice after prenatal exposure to benzo[a]pyrene and inorganic lead.

Experimental evidence suggests that inorganic lead and benzo[a]pyrene (BaP) suppress the development of primordial oocytes during fetal life. We examined the single and combined effects of prenatal exposure to BaP and moderate doses of lead. The fertility and ovarian morphology of F1 female NMRI mice in four treatment groups (nine mice per group) were investigated: control; lead (F0 given 1 g PbCl2/L in drinking water until mating); BaP (10 mg/kg body weight daily by oral intubation on days 7-16 of F0 pregnancy); and combined lead and BaP. F1 groups exposed prenatally to BaP either alone or in combination with inorganic lead showed markedly reduced fertility with few ovarian follicles compared to controls, whereas the group exposed to lead only had measures comparable to the controls. Mice exposed to both lead and BaP had a significantly longer gestation period (days to litter) compared to mice exposed only to BaP, lead, or controls. There is a nonsignificant indication that the compounds together further reduce number of offspring, number of litters, and litter size. These results suggest that lead and BaP have synergistic effects on impairment of fertility. The possibility of synergism may be of human relevance as inorganic lead and BaP are ubiquitous environmental pollutants.

p53 mutations in lung tumors: relationship to putative susceptibility markers for cancer.

We have screened 108 non-small cell lung tumors for mutational alterations in the p53 gene (exons 5 through 8) using polymerase chain reaction and denaturing gel electrophoresis techniques. Thirty-four cases (32%) had aberrant band migrations. The following DNA-sequencing step confirmed the mutations in all these samples. Seventy-six % of the mutations were found at G:C base pairs. Of all the mutations found, 29% were GC to AT, 29% GC to TA, 15% AT to GC, 12% GC to CG, and 3% AT to CG. The other mutations (12%) were deletions or insertions of one base pair. The frequency of p53 mutations among heavy smokers was higher than in nonsmokers (P = 0.047; odds ratio, 6.75; 95% confidence interval, 0.80-57). We examined p53 mutations in relation to genotypes of GSTmu1 and H-ras1. Our data showed that nearly all heavy smokers with transversion mutations were homozygous for the GSTmu1 null allele (10 of 11). The frequency of such mutations was significantly higher for patients with two null alleles (10 of 25) than for those with at least one allele intact (1 of 18) (P = 0.011; odds ratio, 11.33; 95% confidence interval, 1.29-99.3). This study indicated that rare alleles at the variable number of tandem repeats region flanking the H-ras protooncogene are negatively associated to the presence of p53 mutations in the tumors (P = 0.009).

Karyotypic changes in the preclinical and subsequent stages of malignant mesothelioma: a case report.

The karyotypic evolution was evaluated in cells from recurring pleural effusions in a patient previously exposed to asbestos. Pleural malignant mesothelioma (MM) was diagnosed 4 years after the first cytogenetic examination. The primary cytogenetic changes consisted of loss of chromosomes 1p,14,21, Y, both 22, and derivative chromosomes involving 1, 2, and 14. The modal chromosome number was 44. Sixty-seven percent of the cells had a normal karyotype. After 4 years of spontaneous remission, only 6% of the cells had a normal karyotype, 42% had the same karyotypic changes as found previously, whereas 52% had additional derivative chromosomes involving chromosomes 1, 3, 5, 7, 8, and 12, trisomy 7, 7p, and 11, and partial or whole monosomy 3, 8, and 9. The chromosomal changes are in agreement with the main findings in previous reports. The karyotype remained quite stable for 7 months in vitro. After 23 months in culture, all the cells were near-triploid. Cells established in culture were cytokeratin positive. All derivative and marker chromosomes identified in the cultured cells had previously been observed in direct preparations from the pleural effusions. We conclude that chromosomes 1, 14, 21, and 22 may be involved in the preclinical stage of development of asbestos-induced mesothelioma, whereas the later chromosomal changes may be related to progression of the tumor.

Allele diversity of the H-ras-1 variable number of tandem repeats in Norwegian lung cancer patients.

We have examined restriction fragment length polymorphisms of the H-ras-1 gene in germ-line DNA from 214 lung cancer patients and 309 unaffected controls. When DNA samples were digested with MspI/HpaII, Southern blot analysis revealed at least 22 different alleles, grouped according to their frequencies as common, intermediate, and rare. The frequency of rare alleles in lung cancer patients (16/428) is significantly different (p = 0.002) from that in the control group (5/618). Individuals with rare alleles were found to be at 4.7-fold greater risk of lung cancer than those with no rare alleles.

Human CYP1A1 (cytochrome P(1)450) gene: lack of association between the Msp I restriction fragment length polymorphism and incidence of lung cancer in a Norwegian population.

In this study of 221 lung cancer patients and 212 controls, no association between a Msp I polymorphism in the CYP1A1 gene and an increased risk of lung cancer was found. Histological type, smoking habits and family history were also examined. No associations between the Msp I restriction fragment length polymorphism in the CYP1A1 gene and any of these parameters were found. These results are in contrast to a previous report by a Japanese group (Kawajiri et al., 1990) who found an association between the less common allele and an increased susceptibility to lung cancer in their population. The frequency of the less common Msp I 1.9 kb fragment allele (C2) appears to be three times greater in the Japanese population than in the Norwegian population and a Caucasian population of North America. It is possible that in the Asian population this Msp I polymorphism is in linkage disequilibrium with another mutation important for CYP1A1 gene expression, whereas in the Caucasian population these mutations are in equilibrium.

Ha-ras-1 alleles in Norwegian lung cancer patients.

We have examined DNA restriction fragment length polymorphisms (RFLP) of the Ha-ras-1 gene in DNA from 118 lung cancer patients and 123 unaffected controls. When DNA samples were digested with MspI/HpaII restriction endonucleases. Southern blot analysis demonstrated 4 common, 4 intermediate and 7 different rare alleles in the combined population after hybridization to the pGDa1 probe. Six of the rare alleles were unique for the lung cancer group and 1 rare allele for the control group. The frequency of rare alleles in lung cancer patients (10/236) was significantly different (P less than 0.01) from the control group (1/246). The lung cancer group also had a significantly lower frequency of the common 2.57 kb fragment than the controls (P less than 0.02). The results thus indicate that Ha-ras genotyping may be of value in lung cancer risk assessment.

Subacute inhalation toxicity of mineral oils, C15-C20 alkylbenzenes, and polybutene in male rats.

Male Wistar rats were exposed to mist and vapor of two mineral oils, two C15-C20 alkylbenzenes, and one polybutene at aerosol concentrations of 70 mg.m-3 and 700 mg.m-3 for 2 weeks. Of oil mist particles, 82-97 wt% were respirable (less than 4.7 microns). High-level exposure to polybutene was lethal to three of four animals, due to pulmonary edema. Elevated numbers of pulmonary macrophages and increased macrophage vacuolization were observed after exposure to the polybutene, both mineral oils, and one alkylbenzene. The same alkylbenzene produced body weight loss. Deposition analysis was performed for one mineral oil. No oil was detected in brain tissue, while retroperitoneal fat tissue contained 541 (401-702) micrograms oil/g tissue, half of this still present after an exposure-free period of 2 weeks. It is concluded that inhalation of the polybutene and one of the mineral cable oils tested here produces toxic effects in lung.

Gas supersaturation tolerances in amoeboid cells before and after ingestion of bubble-promoting particles.

Macrophages and other cells are capable of ingesting a variety of solids from their external environment. When such phagocytic processes occur in animals, they can lead to phagocytosis from the respiratory or the digestive tract of particles containing minute air emobli that may serve as bubble nuclei upon exposure of the animal to conditions of gas supersaturation. To test whether this is possible, gas supersaturation tolerances were determined for murine macrophages and macrophage-like tumor cells, and for cells of the slime mold Dictyostelium discoideum, before and after phagocytosis of particles that were effective in inducing bubble formation in nitrogen-supersaturated aqueous suspensions. After phagocytosis, the ability of the particles to induce bubble formation was completely abolished. All three cell types essentially retained their normal high resistance to bubble formation; even nitrogen supersaturations in excess of 150 atm (1.55 x 10(7) Pa) did not lead to internal bubbles. Alterations of the particle surfaces and unique properties of the intracellular fluid appear to be the underlying cause of the extremely high gas supersaturation tolerances observed.

[Health damage caused by asbestos and other mineral fibers]. / Helseskader av asbest og andre mineralfibrer.

Occupational exposure to asbestos is associated with malignant tumors in the lung and malignant mesothelioma in the pleura and peritoneum. Tumors at other sites have also been reported. The benign asbestos-related disorders are asbestosis and pleural fibrosis, effusion and plaques. Chronic bronchitis may be associated with previous asbestos exposure. Fiber dimensions and durability are main factors for carcinogenicity. For practical reasons, long and thin fibers like asbestos should be considered carcinogenic. The diagnosis of asbestos-related disease is based upon information on occupational exposure. Analysis of lung fiber burden supports information given by the occupational history and gives valuable information on dose-response and dose-effect relationships. Building materials with good maintainance of the surfaces do not release asbestos fibers, whereas materials subject to mechanical stress should be replaced by nonasbestos-containing materials to avoid the stipulated very low increase in cancer risk.

[Cancer--occupational exposure and genetics]. / Kreft--yrkeseksponeringer og genetiske faktorer.

Carcinogenesis involves a complex interplay of environment and heredity. Several steps are involved in carcinogenesis. Oncogenes and anti-oncogenes influence carcinogenesis by becoming respectively activated or inactivated/lost in somatic cells. Damage to DNA in considered as the initial step in carcinogenesis. Metabolic activation of procarcinogen to an electrophilic intermediate may damage cellular DNA (via adduct formation) priming the process of cancer induction, which after promotion may result in cancer. Advances in our understanding of the mechanisms of chemical carcinogens are now being applied to improve assessment of human risk. In the past epidemiologic studies of the workplace have served to identify important human chemical carcinogens. However, molecular methods are now emerging which will serve in the prospective monitoring of genotoxic effects in the tissues of exposed individuals. Predisposing host factors to chemical toxicity and cancer probably exist. Advances in genetics may make it possible to evaluate human susceptibility factors and genes involved in malignant transformation of human cells. Only epidemiological studies can demonstrate that a chemical is a human carcinogen. For numerous chemicals, data relating to human carcinogenicity are insufficient. It is therefore reasonable for practical purposes to regard chemicals for which there is sufficient evidence of carcinogenicity in animals as presenting a carcinogenic risk to humans. Since hazard from chemical carcinogens depends upon how they are used, one should aim at a better education and information to the public about dangerous chemicals.

Relation between pathological grading and lung fibre concentration in a patient with asbestosis.

The fibre concentration and extent and severity of fibrosis have been analysed in 48 specimens from the left lung of a patient with asbestosis. Two different methods of fibre analysis were used. The results obtained by transmission electron microscopy were 2-2.5 times higher than those obtained by scanning electron microscopy. Low temperature ashed samples showed on average twice the number of fibres obtained after wet digestion of the samples. The transmission electron microscope detected considerably shorter fibres than the scanning electron microscope. Low temperature ashing produced also shorter fibres compared with the wet digestion procedure. A statistically significant correlation between fibre concentration and the grade of fibrosis was found only for low temperature ashed samples analysed in the transmission electron microscope. When dividing the lung into nine anatomical compartments and pooling the grade of fibrosis and the fibre concentration data within each compartment, an even better correlation was obtained.