High Incidence Of Lung Tumors Research Articles

Carcinogenicity and DNA adduct formation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and enantiomers of its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in F-344 rats.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is metabolized to enantiomers of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), found in the urine of virtually all people exposed to tobacco products. We assessed the carcinogenicity in male F-344 rats of (R)-NNAL (5 ppm in drinking water), (S)-NNAL (5 ppm), NNK (5 ppm) and racemic NNAL (10 ppm) and analyzed DNA adduct formation in lung and pancreas of these rats after 10, 30, 50 and 70 weeks of treatment. All test compounds induced a high incidence of lung tumors, both adenomas and carcinomas. NNK and racemic NNAL were most potent; (R)-NNAL and (S)-NNAL had equivalent activity. Metastasis was observed from primary pulmonary carcinomas to the pancreas, particularly in the racemic NNAL group. DNA adducts analyzed were O (2)-[4-(3-pyridyl)-4-oxobut-1-yl]thymidine (O (2)-POB-dThd), 7-[4-(3-pyridyl)-4-oxobut-1-yl]guanine(7-POB-Gua),O (6)-[4-(3-pyridyl)-4-oxobut-1-yl]deoxyguanosine(O (6)-POB-dGuo),the 4-(3-pyridyl)-4-hydroxybut-1-yl(PHB)adductsO (2)-PHB-dThd and 7-PHB-Gua, O (6)-methylguanine (O (6)-Me-Gua) and 4-hydroxy-1-(3-pyridyl)-1-butanone (HPB)-releasing adducts. Adduct levels significantly decreased with time in the lungs of rats treated with NNK. Pulmonary POB-DNA adducts and O (6)-Me-Gua were similar in rats treated with NNK and (S)-NNAL; both were significantly greater than in the (R)-NNAL rats. In contrast, pulmonary PHB-DNA adduct levels were greatest in the rats treated with (R)-NNAL. Total pulmonary DNA adduct levels were similar in (S)-NNAL and (R)-NNAL rats. Similar trends were observed for DNA adducts in the pancreas, but adduct levels were significantly lower than in the lung. The results of this study clearly demonstrate the potent pulmonary carcinogenicity of both enantiomers of NNAL in rats and provide important new information regarding DNA damage by these compounds in lung and pancreas.

Strain‐specific induction of murine lung tumors following in utero exposure to 3‐methylcholanthrene

Fetal mice are more sensitive to chemical carcinogens than are adults. We previously demonstrated that resistant offspring of a DBA/2 x (C57BL/6 x DBA2) backcross exhibited a high incidence of lung tumors 12-13 mo after transplacental exposure to 3-methylcholanthrene (MC). We compared the effects of in utero treatment with MC on lung tumor incidence in the offspring of intermediately susceptible BALB/c (C), resistant C57BL/6 (B6), and reciprocal crosses between these strains. Pregnant mice were treated with 45 mg/kg of MC on day 17 of gestation and tumor incidence, multiplicity, and the Ki-ras mutational spectrum determined in the offspring 12-18 mo after birth. Tumor incidences in C mice and reciprocal crosses were 86% and 100%, respectively, while B6 mice demonstrated resistance to tumorigenesis, with a tumor incidence of 11%. Tumor multiplicities in C, B6C, CB6, and B6 mice were 3.3 +/- 3.2, 5.8 +/- 3.2, 5.0 +/- 2.7, and <0.1, respectively. Ki-ras mutations, which occurred chiefly in the K(s) allele (96%), were found in 79-81% of reciprocally crossed F1 mice, 64% of C mice, and 50% of B6 mice, with the Val(12), Asp(12), and Arg(13) mutations associated with more aggressive tumors. A subset of these mice was used to demonstrate the utility of computer tomography (CT) for the visualization and measurement of lung tumors in the submillimeter range in vivo. Based on known genetic differences in murine strains for lung cancer, our results suggest the presence of a previously unidentified genetic factor(s) which appears to specifically influence lung tumorigenesis following exposure to carcinogens during fetal development.

Incidence and Risk Factors of Development of Lung Tumors After Liver Transplantation

Introduction Lung tumors have been related to tobacco and alcohol. The incidence increases after orthotopic liver transplantation (OLT) especially when it is performed because of alcoholic cirrhosis. Patients and Methods We analyzed the incidence and risk factors for de novo lung tumors among 701 patients who underwent OLT between April 1986 and July 2004, after exclusion of pediatric recipients and adults who died within 2 months after OLT. Results The incidence of de novo lung tumors was 15 patients (2.1%), including 12 (4.3%) who underwent OLT for alcoholic cirrhosis and 3 (0.7%) for nonalcoholic diseases. There were 14 men and 1 woman of mean age at OLT of 50.8 ± 9.6 years. Mean time from OLT to lung tumor was 83 ± 43 months (range, 10–184 months). Thirteen patients (86.6%) were heavy smokers before OLT and 8 (61.5%) continued after OLT; 12 patients (80%) were heavy drinkers before OLT. Ten patients were immunosuppressed with CyA and 5 with tacrolimus. Acute rejection episodes before tumor diagnosis occurred in 6 patients (40%). Two patients underwent thoracotomy, but only one was resected. The remaining 13 patients were unresectable because of locally advanced tumor or metastatic disease. Two unresectable patients received palliative chemotherapy. All patients died with a mean survival from tumor diagnosis, of 5.3 months (range, 3 days to 33 months). Conclusion A significantly higher incidence of lung tumors was observed among patients who underwent OLT for alcoholic cirrhosis, usually diagnosed in advanced stages of poor prognosis and low survival.

Induction of a high incidence of lung tumors in C57BL/6 mice with multiple ethyl carbamate injections.

Murine pulmonary adenomas progress to malignancy with many similarities to human pulmonary adenocarcinoma, the most common form of lung cancer. Inbred mice vary in their susceptibility to lung tumor development, and induced genetic modifications are a powerful tool for understanding this susceptibility. Many transgenic and null mutations relevant to lung cancer pathogenesis were derived on the highly resistant C57BL/B6 (B6) background. Since the inability to reliably induce lung tumors in B6 mice limits these studies, we systematically examined several carcinogenesis protocols in B6 mice. Ten weekly ethyl carbamate (EC) doses caused a nearly 100% lung tumor incidence with a tumor multiplicity >2; multiple EC dosing is thus an alternative to the time-consuming transfer of transgenes and null mutations to susceptible backgrounds.

Lung tumors in mice expressing an antisense RARβ2 transgene

Retinoic acid has been shown to be an anticancer agent, and a growing literature suggests that it is the nuclear retinoic acid receptor beta2 (RARbeta2) that is primarily responsible for mediating this effect, at least in some systems. To determine whether partial inactivation of RARbeta2 would predispose to lung cancer in mice, we generated three transgenic lines expressing antisense sequences. When killed at 13-3/4-18 months of age, 21/36 animals had a total of 43 pulmonary tumors superficially visible upon necropsy, whereas among 23 nontransgenic mice, only 1 had a single visible lung tumor. A twofold higher incidence of lung tumors was seen in homozygous vs. hemizygous antisense mice. The endogenous RARbeta2 message level was reduced in transgenic lung tissue and further reduced in the tumors. RARbeta4, a truncated isoform derived from the same transcript as RARbeta2, does not carry the sequence identified by the antisense construct and its message was not as strongly affected. Immunofluorescence studies showed that RARbeta was virtually undetectable in the tumors, but present in normal tissue. We conclude that RARbeta2, but probably not RARbeta4, plays an important role in suppression of murine lung tumorigenesis.

Transplacental initiation of liver, lung, neurogenic, and connective tissue tumors by N-nitroso compounds in mice

Epidemiological studies have implicated nitroso compounds as possible causative agents for human childhood cancers, including those of neurogenic orgin. Published evidence from animal models, which is reviewed in this report, indicates that capacity for metabolic activation of nitrosamines is limited in rodent fetuses and that nitrosamines are correspondingly weak transplacental carcinogens. The C3H mouse fetus, however, has both moderate capability for activation of N-nitrosodimethylamine (NDMA) and proven susceptibility to transplacental causation of neurogenic tumors by a nitrosourea. We tested whether NDMA could act as a transplacental carcinogen in the C3H mouse, and whether it or N-nitrosodiethylamine (NDEA) would initiate neurogenic tumors. N-Nitrosoethylurea (NEU) served as positive control. C3H HeNCr MTV − pregnant mice were treated ip on Gestation Day 16 or 19 with NDMA (0.1 mmol, 7.4 mg/kg, maximum nonfetotoxic dose), NDEA (0.5 mmol, 51 mg/kg), or NEU (0.4 mmol, 47 mg/kg). NDMA had significant transplacental carcinogenic effects, resulting in an increase in percentage female offspring with hepatocellular carcinomas and in average number of liver tumors after treatment on either gestational day, compared with controls. In the males there was a significant increase in numbers of liver tumors and carcinomas following Day 19 exposure. An increase in incidence of histiocytic and undifferentiated sarcomas was also of statistical significance. There was no change in number of pulmonary tumors. One intracranial schwannoma resulted. NDEA had no effect when given on Gestation Day 16, but caused a significant increase in liver and lung tumor numbers in both sexes when treatment was on Day 19. NEU induced the expected high incidence of lung tumors, significantly increased liver tumor incidence in females (Day 19 exposure), and produced schwannomas in 14 and 35% of the offspring after Days 16 or 19 treatment, respectively. The results show that NDMA at even a low dose had significant transplacental carcinogenic effects, including one schwannoma, which was most unlikely to have occurred spontaneously. However, this single neurogenic tumor contrasts with the absence of similar neoplasms in mice exposed transplacentally to NDEA, in view of the generally greater efficiency of ethylating agents as carcinogens for the nervous system in rodents. These data thus neither conclusively support nor refute the hypothesis that nitrosamines may initiate neurogenic tumors in fetuses.

Transplacental Initiation of Liver, Lung, Neurogenic, and Connective Tissue Tumors by N-Nitroso Compounds in Mice

Transplacental Initiation of Liver, Lung, Neurogenic, and Connective Tissue Tumors by N-Nitroso Compounds in Mice. ANDERSON, L. M., HAGIWARA, A., KOVATCH, R. M., REHM, S., AND RICE, J. M. (1989). Fundam. Appl Toxicol. 12, 604–620. Epidemiological studies have implicated nitroso compounds as possible causative agents for human childhood cancers, including those of neurogenic origin. Published evidence from animal models, which is reviewed in this report, indicates that capacity for metabolic activation of nitrosamines is limited in rodent fetuses and that nitrosamines are correspondingly weak transplacental carcinogens. The C3H mouse fetus, however, has both moderate capability for activation of N-nitrosodimethylamine (NDMA) and proven susceptibility to transplacental causation of neurogenic tumors by a nitrosourea. We tested whether NDMA could act as a transplacental carcinogen in the C3H mouse, and whether it or N-nitrosodiethylamine (NDEA) would initiate neurogenic tumors. N-Nitrosoethylurea (NEU) served as positive control. C3H/HeNCr MTV− pregnant mice were treated ip on Gestation Day 16 or 19 with NDMA (0.1 mmol, 7.4 mg/kg, maximum nonfetotoxic dose), NDEA (0.5 mmol, 51 mg/kg), or NEU (0.4 mmol, 47 mg/kg). NDMA had significant transplacental carcinogenic effects, resulting in an increase in percentage female offspring with hepatocellular carcinomas and in average number of liver tumors after treatment on either gestational day, compared with controls. In the males there was a significant increase in numbers of liver tumors and carcinomas following Day 19 exposure. An increase in incidence of histiocytic and undifferentiated sarcomas was also of statistical significance. There was no change in num ber of pulmonary tumors. One intracranial schwannoma resulted. NDEA had no effect when given on Gestation Day 16, but caused a significant increase in liver and lung tumor numbers in both sexes when treatment was on Day 19. NELl induced the expected high incidence of lung tumors, significantly increased liver tumor incidence in females (Day 19 exposure), and produced schwannomas in 14 and 35% of the offspring after Days 16 or 19 treatment, respectively. The results show that NDMA at even a low dose had significant transplacental carcino genic effects, including one schwannoma, which was most unlikely to have occurred spontaneously. However, this single neurogenic tumor contrasts with the absence of similar neoplasms in mice exposed transplacentally to NDEA, in view of the generally greater efficiency of ethylat ing agents as carcinogens for the nervous system in rodents. These data thus neither conclusively support nor refute the hypothesis that nitrosamines may initiate neurogenic tumors in fetuses.

Fetal mouse susceptibility to transplacental lung and liver carcinogenesis by 3-methylcholanthrene: positive correlation with responsiveness to inducers of aromatic hydrocarbon metabolism.

The role of metabolic activation of carcinogens in fetal tissue as a determinant of sensitivity in transplacental carcinogenesis was investigated in a pharmacogenetic experiment utilizing backcrosses of C57BL/6 (AhbAhb, responsive to induction of aromatic hydrocarbon metabolism) and DBA/2 (AhdAhd, non-responsive) mice. Responsive (C57BL/6 X DBA/2)F1 and non-responsive DBA mothers, all carrying both responsive (AhbAhd) and non-responsive (AhdAhd) fetuses, were given i.p. doses of the carcinogen 3-methylcholanthrene (MC) ranging from 5 to 175 mg/kg on gestation day 17. At 10 months of age the metabolic phenotype of each offspring was determined, and correlated with number of lung and liver tumors. Both male and female AhbAhd (responsive) offspring in most dose groups presented a consistent two- to three-fold higher incidence of lung tumors than did non-responsive AhdAhd littermates. The difference held for offspring of both (C57BL/6 X DBA)F1 and DBA mothers and it was of statistical significance for one or both sexes at most dosage levels. Hepatocellular tumors were also significantly more frequent in responsive male AhbAhd progeny of (C57BL/6 X DBA/2)F1 mothers than in non-responsive AhdAhd littermates. Progeny of the DBA mothers exhibited significantly more liver and lung tumors than did those of the (C57BL/6 X DBA/2)F1 mothers receiving the same dose. These results suggest that in this model system both maternal and fetal genotype for responsiveness to induction of aromatic hydrocarbon metabolism are important factors modulating fetal carcinogenic risk.

Histocompatibility genes (theH-2 complex) and susceptibility to spontaneous lung tumors in mice

The incidence of spontaneous lung tumors in relation toH-2, the major histocompatibility complex, was studied in congenic strains of mice on the B10-, A-, and C3H-backgrounds. The most relevant results were obtained with congenic strains on the B10-background. The strains could be divided into two groups: one with a low frequency of spontaneous lung tumors carrying the haplotypesH-2 b ,H-2 h4 ,H-2 d ,H-2 i H-2 r and one with a higher incidence of lung tumors carrying the haplotypesH-2 f ,H-2 m ,H-2 h2 ,H-2 a . The differences between these two groups were highly significant. Analysis of the results obtained with the recombinant strains indicated that genes in theIB region determined the susceptibility to the development of spontaneous lung tumors. The comparison of the results in the B10, B10.A and A strain has shown that the incidence in the B10.A strain carrying the haplotypeH-2 a derived from the highly susceptible strain A (H-2 a ) on the resistant background strain B10 (H-2 b ) is intermediate between these two strains. This shows, that other genes of the background are also involved. The lung tumor incidence in (B10.A × B10)F1 hybrids was intermediate between the two parental strains. The results obtained in the strains C3H with the haplotypeH-2 k , C3H.B10 with the haplotypeH-2 b and C3H.NB with the haplotypeH-2 p , were inconclusive because of the early mortality which occurred among the animals of these strains. The strains A (H-2a) and A.SW (H-H-2 s ) were both equally susceptible.

PRIMARY LUNG TUMORS IN MICE FOLLOWING THE CUTANEOUS APPLICATION OF COAL TAR

The external application of tar to a number of separated areas on the surface of mice, in such fashion that no single area is irritated sufficiently long to cause lesions of the skin, has resulted in a very high incidence of lung tumors. This incidence ranged from 60.0 per cent in one experiment to 78.3 per cent in another. Control mice from the same stock but from 3 to 6 months older, and for that reason the more liable to spontaneous lung tumors, failed to show a single instance of such growths. Even in a stock in which spontaneous lung tumors had been frequent, the incidence for corresponding age periods has never been above 5.5 per cent while the average has been between 1 and 2 per cent over a period of years. The tumors in the tar-painted animals occur as small white nodules, either single or multiple. They are typical epithelial neoplasms, identical histologically with those described by previous authors as occurring spontaneously in mice. Some possible factors in the causation of the tumors are briefly discussed.