Heavy Metal Bioaccumulation in an Atypical Primitive Neuroectodermal Tumor of the Abdominal Wall.

Heavy metals are able to interfere with the function of vital cellular components. Besides in trace heavy metals, which are essential at low concentration for humans, there are heavy metals with a well-known toxic and oncogenic potential. In this study, for the first time in literature, we report the unique adulthood case of an atypical primitive neuroectodermal tumor of the abdominal wall, diagnosed by histology and immunohistochemistry, with the molecular hybridization support. The neoplasia occurred in a patient chronically exposed to a transdermal delivery of heavy metal salts (aluminum and bismuth), whose intracellular bioaccumulation has been revealed by elemental microanalysis.

Increased oncogenicity of subclones of SV40 large T-induced neuroectodermal tumor cell lines after loss of large T expression and concomitant mutation in p53.

A model for medulloblastoma-like primitive neuroectodermal tumors was established in rat using retrovirally transduced SV40 large T antigen (LT) as an inducing agent (O. D. Wiestler et al., Brain Pathol., 2: 47-59, 1992). A cell line isolated from such a tumor and clonal derivatives thereof were biologically and molecularly characterized. In the parental tumor cell line, TZ870, which had been selected for G418 resistance, virtually all cells expressed LT and wild-type p53, which were complexed to each other. When plated in soft agar, these cells grew relatively slowly and formed disperse colonies. However, when grown without selection pressure, these cells reproducibly gave rise to LT-negative and G418-sensitive derivatives, LT-0 cells. Surprisingly, these latter cells exhibited a higher degree of malignancy both in vitro, growing readily to large colonies in soft agar, and in vivo, where they gave rise to a rapidly growing malignant tumor. Clonal selection from TZ870 cells revealed two types of clones: in one type, LT expression was stably maintained, even without selection pressure, whereas the other type lost the LT coding sequences. All LT-negative clones exhibited the same phenotype as the LT-0 cells. Reexpression of LT had no effect. However, LT no longer formed complexes with p53, and p53 was metabolically stable, suggesting that it had been mutated. Sequence analyses and diagnostic restriction digests of the p53 gene revealed that (a) both the parental LT-transformed cells and their derivatives contained only one complete p53 allele and (b) all LT-positive clones expressed wild-type p53, whereas all LT-negative clones expressed a mutant allele with a common mutation at Cys-174-->Tyr, indicating their clonal origin. We assume that the loss of LT coding sequences is the consequence of the p53 mutation, perhaps by inducing genomic instability, and that both the p53 mutation and additional genetic alterations that accompany the loss of LT coding sequences might contribute to enhanced malignancy.

A study of tobacco carcinogenesis XLVIII. Carcinogenicity of N'-nitrosonornicotine in mink (Mustela vison).

During tobacco processing and smoking, nicotine and nornicotine give rise to N'-nitrosonornicotine (NNN), a highly abundant, strong carcinogen. NNN is known to exert carcinogenic activity in mice, rats and hamsters. Major target organs for NNN carcinogenicity in the rat are the esophagus and the nasal mucosa, and in the Syrian golden hamster trachea and nasal mucosa. In comparison with the rat, the mink (Mustela vison) has a markedly expanded nasal mucosa. Therefore, we explored in this study whether the mink could serve as a non-rodent model for nasal carcinogenesis using NNN as the carcinogen. Twenty random-bred mink, beginning at the age of 3 weeks, received twice weekly s.c. injections of NNN, a total dose of 11.9 mM per animal over a 38 week period. All of the 19 mink at risk developed malignant tumors of both the respiratory and the olfactory region of the nose within 3.5 years. In most animals the malignant tumors, primarily esthesioneuroepithelioma, invaded the brain. Remarkably, NNN induced no other tumors in the mink. None of the control animals developed nasal tumors nor tumors at other sites during the 3.5 years of the assay. The historical data from the farm did not reveal any spontaneous occurrence of nasal tumors in mink at any age. This study supports the concept that NNN is a proven carcinogen for multiple species of mammals and that the mink can serve as a non-rodent, non-inbred animal model for nasal carcinogenesis, especially since NNN induces only tumors in the nasal cavity in this species and not at other sites, as it does in mice, rats and hamsters.

Chemically induced esthesioneuroepithelioma: ultrastructural findings.

Tumors of the olfactory epithelium of rats were induced with two different nitrosamines: 2,6-dimethylnitrosomorpholine and N-nitrosopiperidine. Both carcinogens yielded identical tumors consisting of small, undifferentiated, neuroblastic cell elements without specialized cell contact. Cell processes contained microtubuli, centrioles, and neurosecretory granules. Two kinds of rosettes were encountered frequently: neuroblastic Homer Wright rosettes consisted of undifferentiated cells, surrounding a minute lumen filled with amorphous material; and Flexner rosettes showed a higher degree of maturation. Inside their central lumen, cell processes with characteristic features of olfactory sensory cells (basal bodies, cilia, centrioles, microtubuli) could be demonstrated. The stem cell of this tumor is most likely the undifferentiated light basal cell inside the olfactory epithelium, since its ultrastructural appearance and its cytoskeleton are alike. At least under neoplastic conditions, this stem cell may likewise differentiate into epithelial cells, since transition to squamous cell carcinomas has been observed. In view of their overwhelming similarity to their human counterpart, the induced tumors are most likely to represent esthesioneuroepitheliomas.

Chemically induced esthesioneuroepithelioma: a cytogenetic, cell culture and biochemical investigation with implications for tumor histogenesis.

Chemically induced esthesioneuroepitheliomas (ENE) in rats were subjected to tissue culture experiments, biochemical evaluations for catecholamines and chromosomal analyses. The most conspicuous cytogenetic finding was a C1 marker chromosome in addition to numerical and structural chromosomal aberrations. Regarding the overwhelming similarity between human ENE and experimentally induced ENE, similar cytogenetic aberrations in its human counterpart are postulated. Biochemically, no catecholamines or their metabolic precursors could be identified, thus distinguishing ENE from sympathetic neuroblastomas. No keratin-positive cells could be found in the primary tumor or in the cell cultures studied, thus showing that immunohistology can be a valuable tool for differentiating ENE from anaplastic carcinomas.

Investigation into the pharmacodynamics of the carcinogen N-nitrodimethylamine.

N-Nitrodimethylamine (NTDMA) was found to be a carcinogen of the nasal mucosa leading to aesthesioneuroepitheliomas in BDVI rats. N-Nitromethylamine (NTMA), a product of the oxidative metabolism of NTDMA, was also carcinogenic, leading to neurogenic tumours of the lumbar region of the spine. The 100,000 X g supernatant of both liver and nasal mucosa contains an enzyme capable of reducing NTDMA to N-nitrosodimethylamine (NDMA). In the microsomal fraction of both organs, NTDMA is oxidized to formaldehyde. The fractions from nasal mucosa have a higher capacity than the corresponding liver fractions to both oxidize and reduce NTDMA. NDMA was detected in blood and urine from rats treated with NTDMA. The elimination of NTDMA from blood occurs biphasically, with an initial half-life of 3.5 min.

Chemically induced tumors of rat olfactory epithelium: a model for human esthesioneuroepithelioma.

N-Nitrosopiperidine (CAS: 100-75-4) and 2,6-dimethylnitrosomorpholine induced tumors of the olfactory epithelium in white Wistar rats. Some tumors were serially transplanted to NMRI nude mice (nu/nu) and passaged up to 16 times in a 1-year period. Tumor tissues from rats and mice were analyzed by conventional pathological stains, by electron microscopy, and by immunofluorescence microscopy with the use of antibodies specific for different intermediate filaments. Both carcinogens induced tumors built of undifferentiated small, round cells in which neuroblastic (Homer-Wright) rosettes and ependymal (Flexner) rosettes were visible. In some tumors areas of squamous cell metaplasia could be observed, which sometimes differentiated toward squamous cell carcinoma. Electron microscopy showed neurosecretory granules in some tumor cells, and biochemical studies of plasma showed in some instances elevated ACTH and calcitonin levels. Intermediate filament typing showed that in general the undifferentiated tumor cells lack intermediate filaments, although in 6 of 29 tumors a few cells that stained positively for neurofilaments were found. Flexner rosettes, the areas showing squamous cell differentiation, and occasional single tumor cells were positive with keratin antibodies. Neurofilament expression was observed in a minor population of tumor cells placed in tissue culture. These findings are used to argue that the chemically induced rat tumors are a model for human esthesioneuroepithelioma and furthermore that the light basal cells of the epithelium may be the stem cells of the rat tumors as well as of its rare counterparts in humans.

Intraocular neoplasms induced by methylazoxymethanol acetate in Japanese medaka (Oryzias latipes).

Intraocular neoplasms developed in the Japanese medaka, a small fish species, following a single brief exposure to methylazoxymethanol acetate [(MAM-Ac) CAS: 592-62-1]. Specimens 6-10 days old were exposed to doses of MAM-Ac up to 100 mg/liter for 2 hours and then transferred to carcinogen-free water for "grow-out." Of 218 exposed fish examined, 98 (45%) had neoplastic lesions in various stages of development. Of those exposed to 30 mg/liter or more, 57% had the lesions. No lesions were found in eyes or other tissues of 95 control specimens. Early and advanced neoplastic lesions were recognized. Early lesions were characterized by complexes of neoplastic retinal epithelium and tubes that consisted of cells of the sensory retina. Areas of mitotically active, heterogeneous cells associated with such complexes gave rise to advanced neoplasms. We considered the advanced neoplasms to be medulloepitheliomas, which differentiated into three principal cellular patterns: 1) solid masses of unpigmented cells, which frequently showed photoreceptor differentiation as well as ductular formation; 2) heavily pigmented cuboidal to columnar cells resembling retinal epithelium that formed adenomatous patterns; and 3) teratoid medulloepitheliomas. Teratoid medulloepitheliomas, which we considered the most advanced and malignant lesions, consisted of heterogeneous, highly mitotic, invasive cells and contained heteroplastic elements including striated muscle, undifferentiated mesenchymal tissues, and hyaline cartilage. We suggest that MAM-Ac induces hyperplasia of retinal cells followed by establishment of aberrant growth zones containing miscoded cells that give rise to medulloepitheliomas.

Influence of ethyl alcohol on carcinogenesis with N-nitrosodimethylamine.

This paper presents the results of an experiment on the combined action of nitrosodimethylamine and ethyl alcohol in C57BL mice. As shown, alcohol can act to change the target organ of that liver carcinogen by favouring development of olfactory neuroepitheliomas, which infiltrate the frontal lobe of the brain.

Chronic oral administration of 1-nitrosopiperazine at high doses to MRC rats.

1-Nitrosopiperazine was fed to two groups of rats as drinking water solutions containing 400 mg/liter (3.5 millimolar) and 800 mg/liter (7.0 millimolar), respectively. The treatment was 20 ml per rat per day, 5 days per week for life. In both groups many animals died with olfactory tumors (mostly esthesioneuroblastomas), the first at 36 weeks in the higher dose group, the first at 64 weeks in the lower dose group. There was also a small number of liver tumors in both groups. None of these tumors was seen in the untreated controls. The similarity of this tumor distribution to that produced by 1,4-dinitrosopiperazine suggests that the observed carcinogenicity of 1-nitrosopiperazine may be entirely due to its disproportionation in the acidic medium of the rat stomach. Chemical data supporting this interpretation are presented.

Chemically induced esthesioneuroblastomas in rats.

Malignant tumours of the nasal cavity were induced in 19 of 56 (34%) female MRC-Wistar rats by 1-nitrosopiperazine administered orally for life. These tumours were of neurogenic origin, according to classical histologic criteria.

Carcinogenic action of quinoxaline 1,4-dioxide in rats.

Quinoxaline 1,4-dioxide was fed to 400 rats at levels of 10 mg or 1 mg/kg body weight for 18 months. It produced a high incidence of nasal and liver tumors only in the group fed 10 mg/kg. Of diverse histologies, the nasal tumors included anaplastic carcinomas, adenocarcinomas, squamous cell carcinomas, neuroepitheliomas, basal cell carcinomas, and a single fibrosarcoma. The nasal epithelium not involved in the neoplastic process showed dysplasia and hyperplasia.

Inhalation carcinogenicity of alpha halo ethers. I. The acute inhalation toxicity of chloromethyl methyl ether and bis(chloromethyl)ether.

A range of acute studies were performed with chloromethyl methyl either (CMME) and bis(chloromethyl)ether (BCME), including 14-day LC50's following single seven-hour inhalation exposures. The LC50's for CMME were 55 ppm for rats and 65 ppm for hamsters. The LC50's for BCME were 7 ppm for both species. All animals showed characteristic changes of acute irritation of the respiratory tract manifested by congestion, edema, and hemorrhage. Severe shortening of life span was seen in 30-day exposures of rats to CMME and in all studies with BCME. Incidences of mucosal changes, including atypia, were generally increased in a dose-related manner in both species. The carcinogenicity of BCME in these range finding experiments was demonstrated by a skin cancer in a rat after three exposures and a nasal tumor in a hamster after one exposure to 1 ppm BCME.

Inhalation carcinogenicity of alpha halo ethers. II. Chronic inhalation studies with chloromethyl methyl ether.

Rats and hamsters were exposed to 1 ppm of chloromethyl methyl ether six hours per day, five days per week, throughout their lifetime. Mortality and weight gain of the exposed animals paralleled that of the control animals. Malignant tumors of the respiratory tract were found in two rats. These were a squamous cell carcinoma of the lung with blood vessel invasion and an esthesloneuroepithelioma originating in the olfactory epithelium and invading the forebrain. One hamster was found to have an adenocarcinoma of the lung and another, a squamous papilloma of the trachea. A single exposed rat had a pituitary tumor of primitive cell type that may well have been coincidental.

Inhalation carcinogenicity of alpha halo ethers. III. Lifetime and limited period inhalation studies with bis(chloromethyl)ether at 0.1 ppm.

Rats and hamsters were exposed to 0.1 ppm bis(chloromethyl)ether (BCME) six hours per day, five days per week throughout their lifetime. Additional groups of rats were given 10, 20, 40, 60, 80, and 100 exposures to 0.1 ppm BCME and then held until death. Forty cancers originating in the respiratory tract were found in the 200 rats involved in these studies. These included 14 cancers of the lung and 26 cancers of the nasal cavity. They occurred in dose-related fashion. A single undifferentiated carcinoma of the lung was seen in a hamster.