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PubMed1998

Mortality in beagles irradiated during prenatal and postnatal development. II. Contribution of benign and malignant neoplasia.

To evaluate the lifetime carcinogenic hazards of exposure to ionizing radiation during development, 1,680 beagles received whole-body exposures to 60Co gamma rays or sham exposures. Eight groups of 120 dogs each received mean doses of 15.6-17.5 or 80.8-88.3 cGy in early, mid- or late gestation, at 8, 28 or 55 days postcoitus or at 2 days after birth. Another group of 120 dogs received a mean dose of 82.6 cGy as 70-day-old juveniles and one group of 240 dogs received a mean dose of 81.2 cGy as 365-day-old young adults. Sham irradiations were given to 360 controls. Sexes were equally represented. In 1,343 dogs allowed to live out their life span, neoplasia was a major disease, contributing to mortality in 40% of the dogs. There was a significant increase in benign and malignant neoplasms occurring in young dogs (<4 years old), including fatal malignancies, after irradiation in the perinatal (late fetal and neonatal) periods. The lifetime incidence of fatal neoplasms was also increased in dogs irradiated perinatally. Three malignancies-lymphomas, hemangiosarcomas and mammary carcinomas-accounted for 51% of all fatal tumors. There was an apparent lifetime increase and earlier onset of lymphomas in dogs exposed as fetuses. Fatal hemangiosarcomas were increased in dogs irradiated early and late in gestation. Fatal mammary carcinomas were not increased by irradiation, although non-fatal carcinomas were increased after perinatal exposure. Myeloproliferative disorders and central nervous system astrocytomas appeared to be increased in perinatally irradiated dogs. These data suggest that irradiation in both the fetal and neonatal periods is associated with increased early onset and lifetime cancer risk.

Animals↗
PubMed2005

Tumorigenesis in p27/p53- and p18/p53-double null mice: functional collaboration between the pRb and p53 pathways.

Mice lacking both p18(Ink4c) and p27(Kip1) develop a tumor spectrum similar to pRb(+/-) mice, and loss of p53 function accelerates tumorigenesis in pRb(+/-) mice. We hypothesized that codeletion of either p18 or p27 in conjunction with p53 deletion will also accelerate tumorigenesis. Mice lacking both p18 and p53 develop several tumors not reported in either single null genotype, including hepatocellular carcinoma, testicular choriocarcinoma, hemangiosarcoma, leiomyosarcoma, fibrosarcoma, and osteosarcoma. Mice lacking both p27 and p53 exhibit a decreased lifespan and develop unique tumors, including papillary carcinoma of the colon, hemangiosarcoma, and leiomyosarcoma. In both p18/p53 and p27/p53 double null genotypes, the incidence and spectra of tissues that develop lymphoma are also increased, as compared to the single null genotypes. The development of p27/p53 double null colon tumors correlates with secondary changes in cell-cycle protein expression and CDK (cyclin-dependent kinase) activity, perhaps contributing to the progression of colorectal cancer. We concluded that p18 and p27 can, not only functionally collaborate with one another, but also can independently collaborate with p53 to modulate the cell cycle and suppress tumorigenesis in a tissue-specific manner.

Animals↗
PubMed1995

Hepatocarcinogenesis in p53-deficient mice.

To determine whether a constitutive p53 deficiency would enhance the rate of development of chemically induced hepatocellular carcinoma, we treated groups of wild-type, p53-heterozygous (+/-), and null (-/-) male mice with a single dose of diethylnitrosamine at 12 d of age. Although the null mice had to be killed very early, at 15 wk of age because of the development of nonliver tumors, hemangiosarcoma of the liver had already developed in two of seven mice. More detailed analysis of the wild-type and heterozygous mice showed no difference in the number, size, or growth rate of early microscopic lesions or in the number or apparent malignancy of hepatocellular adenomas or carcinomas at later time points. Thus, germline p53 deficiency does not enhance the rate of development of diethylnitrosamine-induced hepatocellular adenoma or carcinoma but may instead favor development of hepatic hemangiosarcoma.

Animals↗
PubMed2002

The hepatic endothelial carcinogen riddelliine induces endothelial apoptosis, mitosis, S phase, and p53 and hepatocytic vascular endothelial growth factor expression after short-term exposure.

Riddelliineis a naturally occurring pyrrolizidine alkaloid found in certain poisonous rangeland plants of the western United States. In National Toxicology Program 2-year studies, riddelliine induced high incidences of hemangiosarcoma in the liver of F344/N rats (both sexes) and B6C3F1 mice (males). To understand this pathogenesis, we tested short-term effects of riddelliine. Three groups (control; 1.0 mg/kg/day, high dose used in the 2-year study; and 2.5 mg/kg/day) of seven male F344/N rats per group were terminated after 8 consecutive doses and 30 doses (6 weeks, excluding weekends). Serum vascular endothelial growth factor (VEGF), histological, immunohistochemical [factor VIII-related antigen/von Willebrand factor (fVIII-ra/vWf)], VEGF, VEGF receptor-2 (VEGFR2), glutathione S-transferase-pi, S-phase (BrdU), p53, apoptosis, and ultrastructural evaluations were performed on the liver. Following 8 doses of 1.0 and 2.5 mg/kg/day, increased numbers of apoptotic and S-phase nuclei appeared in hepatocytes and endothelial cells. Following 30 doses of 1.0 and 2.5 mg/kg/day, hepatocytes exhibited reduced mitosis, fewer S-phase nuclei, increased hypertrophy, and fatty degeneration, while endothelial cells showed karyomegaly, cytomegaly, decreased apoptosis, more S-phase nuclei, and p53 positivity. Hepatocytes of treated animals expressed higher VEGF immunopositivity. That altered endothelial cells were fVIII-ra/vWf and VEGFR2 positive confirmed their identity. These changes may have promoted hemangiosarcoma development upon long-term exposure through endothelial adduct formation, apoptosis, proliferation of endothelial cells having undamaged and/or damaged DNA, and mutation. Endothelial proliferation may also have been promoted through endothelial arrest at S phase, which was associated with endothelial karyo- and cytomegaly, resulting in hepatocytic hypoxia, triggering VEGF induction.

Administration, Oral↗
PubMed1984

Carcinogenesis in F-344 rats by nitrosobis(2-oxopropyl)amine and related compounds administered in drinking water.

Three asymmetric nitrosamines related to nitrosobis-(2-oxopropyl)-amine (BOP) were given to female F344 rats in drinking water to assess the significance of other alkyl groups on the carcinogenic expression by the 2-oxopropyl group. Nitroso-oxopropylethanolamine (OPE) was weakly carcinogenic, leading to little life-shortening and to induction of tumors (most of them liver neoplasms) in less than half of the treated animals. BOP under these conditions induced a high incidence of hepatocellular carcinomas and hemangiosarcomas of the liver together with lung adenomas in most animals. At the same dose rate nitrosohydroxypropyl-oxopropylamine (HPOP) induced hepatocellular carcinomas, lung carcinomas, and carcinomas of the esophagus with a high incidence; life-shortening was greater with HPOP than with BOP. At a higher dose rate HPOP again induced a high incidence of esophageal carcinomas, and of liver neoplasms, but more animals had hemangiosarcomas than hepatocellular carcinomas. Nitrosodihydroxypropyl-oxopropylamine (DHPOP) increased the mortality rate due to tumors by much more than the other three compounds, but induced mainly tumors of the upper gastrointestinal tract and no neoplasms in the liver. These results do not support the concept that BOP acts through reduction to HPOP, but suggest rather that the nature of the substituents other than 2-oxopropyl in the analogs of BOP has a profound influence on the potency and organ-specificity of the carcinogen. It is probable that pharmacokinetics and the specificity of activation of the particular molecular structures play an important role.

Animals↗
PubMed2003

Toxicity and carcinogenicity of Elmiron in F344/N rats and B6C3F1 mice following 2 years of gavage administration.

Elmiron (sodium pentosan polysulfate) is used for the relief of urinary bladder pain associated with interstitial cystitis. The National Toxicology Program (NTP) tested this compound because of its orphan drug status and lack of information about its chronic toxicity and carcinogenicity. Groups of 50 male and 50 female F344/N rats were given Elmiron in de-ionized water by gavage at doses of 0, 14, 42, or 126 mg/kg to males and 0, 28, 84, or 252 mg/kg to females once daily, 5 days per week, for up to 2 years. The same numbers of male and female B6C3F1 mice were dosed similarly with 0, 56, 168, or 504 mg/kg. Elmiron administration produced no effect on the body weight of rats, male mice, or low- and mid-dose groups of female mice. The body weights of the high-dose female mice were significantly decreased relative to those of controls. Pairwise comparison showed that survival of all dosed groups of rats and mice was similar to that of the controls. Elmiron was not carcinogenic in F344/N rats. An increased incidence of liver hemangiosarcoma provided evidence of some carcinogenic activity for Elmiron in male B6C3F1 mice. Increased incidences of liver hemangiosarcoma, hepatocellular neoplasms (predominantly adenomas), and malignant lymphomas revealed carcinogenic activity of Elmiron in female B6C3F1 mice. Elmiron administration produced elevated occurrences of nonneoplastic lesions, such as vacuolated histiocytes in the rectum, lung, spleen (males only), and mesenteric lymph node in rats and liver, rectum, mesenteric lymph node, and spleen in mice. Myxomatous change, chronic inflammation, and squamous metaplasia (mice only) were observed in the large intestine, and lymphohistiocytic hyperplasia was found to be increased in the spleen of rats of both sexes treated with the highest dose. In the latter lesion, the histiocytes contained pale, finely granular cytoplasm and were not considered to represent the same change as the vacuolated histiocytes seen in the mesenteric lymph node and rectum. Under the conditions of these 2-year studies, Elmiron was carcinogenic to mice but not rats.

Animals↗
PubMed1981

Comparative carcinogenesis by some aliphatic nitrosamines in Fischer rats.

The carcinogenic effectiveness of 5 simple aliphatic nitrosamines was compared by feeding to groups of 20 Fischer rats in drinking water. Nitrosodi-isobutylamine was by far the weakest carcinogen, giving rise after comparatively high doses to tumors of the nasal cavity and trachea. Nitrosodimethylamine (NDMA) induced almost exclusively hemangiosarcomas of the liver, whereas nitrosodiethylamine (NDEA) gave rise to a high incidence of hepatocellular carcinomas, after administration of approximately the equivalent dose; all of the animals also developed tumors of the esophagus. Nitrosomethylethylamine (NMEA) induced both hemangiosarcomas and hepatocellular carcinomas, together with some esophageal tumors, but must be considered a weaker carcinogen than the dimethyl or diethyl analogs, since a much higher dose was needed to achieve a comparable effect. Nitrosodi-n-propylamine (NDPA) was of comparable potency with NDMA and NDEA, but gave rise under these conditions only to tumors of the esophagus and forestomach, and induced no liver tumors.

Animals↗
PubMed1988

Carcinogenesis by nitroso-2-hydroxyethylurea in splenectomized hamsters.

Several nitrosoalkylureas tested for carcinogenic activity in Syrian hamsters have as their main effect the induction of hemangiosarcomas of the spleen, many of which appear to metastasize to the liver. To investigate whether any of these lesions in the liver might not be metastases, a group of female Syrian hamsters was surgically splenectomized and treated with nitroso-2-hydroxyethylurea (NHEU) dissolved in corn oil/ethyl acetate once a week for 22 weeks. The animals survived much longer (median 45 weeks) than a comparable group of unsplenectomized female hamsters given identical treatment (median 24 weeks). The absence of hemangiosarcomas of the liver in the splenectomized hamsters showed that the presumed metastases seen in intact animals were, in fact, just that. A second interesting conclusion is that the compound did not produce a concomitant increase in tumors of other types.

Animals↗
PubMed1999

Enhancement of urinary bladder carcinogenesis in nullizygous p53-deficient mice by N-butyl-N-(4-hydroxybutyl)nitrosamine.

We recently reported p53 mutations to be frequent in mouse invasive urinary bladder carcinomas, with and without metastasis. However, the role of p53 dysfunctions during carcinogenesis remains unclear. In the present study, heterozygous and nullizygous p53-deficient mice and their littermates were treated with the urinary bladder carcinogen, N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN), at a concentration of 0.01% in the drinking water throughout the experiment. This markedly accelerated urinary bladder carcinogenesis but not development of other tumors in the nullizygous p53-deficient mice. Thus the appearance of neoplastic urothelial lesions in nullizygotes (at day 60 of the experiment) was earlier than in wild-type mice and heterozygotes (at day 125). Moreover, malignant vascular tumors (hemangiosarcomas (HS)) were found in all four nullizygotes killed later than day 108. Mutational inactivation of the wild-type allele was not apparent in either the single transitional cell carcinoma observed in a wild-type mouse and a hemangiosarcoma in a heterozygote. Overall, it can be concluded that the number of normal p53 alleles is a significant determining factor in the susceptibility of urothelial cells to carcinogens. The role of the p53 defect in mouse urinary bladder carcinogenesis may thus be to diminish the threshold for occurrence of additional genetic alterations.

Animals↗
PubMed1998

The role of gastric Helicobacter and N-methyl-N'-nitro- N-nitrosoguanidine in carcinogenesis of mice.

BACKGROUND: The aim of this study was to determine whether gastric epithelial proliferation due to gastric Helicobacter infection in mice represents a preneoplastic lesion. MATERIALS AND METHODS: Helicobacter heilmannii infected and uninfected mice were treated with 150 microg/ml N-methyl-N'-nitro-N-nitrosoguanidine in drinking water for either 20 or 38 weeks. Mice were killed 12 or 18 months after bacterial inoculation. RESULTS: All infected mice developed lymphoplasmocytic gastritis and epithelial hyperplasia. Proliferative gastric lesions were characterised by nodular hypertrophy of the glandular mucosa, multifocal epithelial hyperplasia, and elevated BrdU labeling index. Intestinal metaplasia and true atrophy were not present but proliferative glands were poorly differentiated, lined by mucus-type epithelial cells with no parietal, chief or other specialized cell types. Neoplasms developed only in MNNG-treated mice. of the 180 treated mice the following neoplasms developed: 14 squamous cell carcinomas of mouth and forestomach; 37 hemangiosarcomas of the intestinal serosa; and 15 splenic lymphomas. No tumors were present in the glandular gastric mucosa, and infection did not affect tumor incidence. p53 overexpression occurred in 79% of hemangiosarcomas and 71% of squamous cell carcinomas but not in normal or proliferative gastric glandular mucosa. CONCLUSIONS: Gastric proliferative lesions in Helicobacter-infected mice are not preneoplastic, and the combination of an alkylating agent and non-neoplastic proliferation does not result in gastric carcinogenesis in mice.

Animals↗
PubMed1995

Life-span, T-cell responses, and incidence of lymphomas in congenic mice.

Survival, T-cell functions, and postmortem histopathology were studied in H-2 congenic strains of mice bearing H-2b, H-2k, and H-2d haplotypes. Males lived longer than females in all homozygous and heterozygous combinations except for H-2d homozygotes, which showed no differences between males and females. Association of heterozygosity with longer survival was observed only with H-2b/H-2b and H-2b/H-2d mice. Analysis using classification and regression trees (CART) showed that both males and females of H-2b homozygous and H-2k/H-2b mice had the shortest life-span of the strains studied. In histopathological analyses, lymphomas were noted to be more frequent in females, while hemangiosarcomas and hepatomas were more frequent in males. Lymphomas appeared earlier than hepatomas or hemangiosarcomas. The incidence of lymphomas was associated with the H-2 haplotype--e.g., H-2b homozygous mice had more lymphomas than did mice of the H-2d haplotype. More vigorous T-cell function was maintained with age (27 months) in H-2d, H-2b/H-2d, and H-2d/H-2k mice as compared with H-2b, H-2k, and H-2b/H-2k mice, which showed a decline of T-cell responses with age.

Animals↗
PubMed1999

Inhalation toxicity and carcinogenicity studies of cobalt sulfate.

Cobalt sulfate is a water-soluble cobalt salt with a variety of industrial and agricultural uses. Several cobalt compounds have induced sarcomas at injection sites in animals, and reports have suggested that exposure to cobalt-containing materials may cause lung cancer in humans. The present studies were done because no adequate rodent carcinogenicity studies had been performed with a soluble cobalt salt using a route relevant to occupational exposures. Groups of 50 male and 50 female F344/N rats and B6C3F1 mice were exposed to aerosols containing 0, 0.3, 1.0, or 3.0 mg/m3 cobalt sulfate hexahydrate, 6 h/day, 5 days/week, for 104 weeks. Survival and body weights of exposed rats and mice were generally unaffected by the exposures. In rats, proteinosis, alveolar epithelial metaplasia, granulomatous alveolar inflammation, and interstitial fibrosis were observed in the lung in all exposed groups. Nonneoplastic lesions of the nose and larynx were also attributed to exposure to all concentrations of cobalt sulfate. In 3.0 mg/m3 male rats and in female rats exposed to 1.0 or 3.0 mg/m3, the incidences of alveolar/bronchiolar neoplasms were increased over those in the control groups. Lung tumors occurred with significant positive trends in both sexes. The incidences of adrenal pheochromocytoma in 1.0 mg/m3 male rats and in 3.0 mg/m3 female rats were increased. Nonneoplastic lesions of the respiratory tract were less severe in mice than in rats. In mice, alveolar/bronchiolar neoplasms in 3.0 mg/m3 males and females were greater than those in the controls, and lung tumors occurred with significantly positive trends. Male mice had liver lesions consistent with a Helicobacter hepaticus infection. Incidences of liver hemangiosarcomas were increased in exposed groups of male mice; however, because of the infection, no conclusion could be reached concerning an association between liver hemangiosarcomas and cobalt sulfate. In summary, exposure to cobalt sulfate by inhalation resulted in increased incidence of alveolar/bronchiolar neoplasms and a spectrum of inflammatory, fibrotic, and proliferative lesions in the respiratory tracts of male and female rats and mice. Adrenal pheochromocytomas were increased in female rats, and possibly in male rats.

Administration, Inhalation↗
PubMed1995

Sarcomas in organ allograft recipients.

In a review of 8724 de novo malignancies that occurred in 8191 organ allograft recipients sarcomas were 7.4% of cancers. Kaposi's sarcoma (KS) made up 5.7%, and other sarcomas (OS) 1.7% a much higher proportion than in the general population. KS was most common in Arab, black, Italian, Jewish, or Greek patients. In 60% of patients with KS the lesions were confined to the skin and/or oropharynx while 40% involved internal organs and/or lymph nodes. Complete remissions following various treatments occurred in 53% of the former group and 27% of the latter. In both groups 32% and 60% of remissions, respectively, occurred when the only treatment was reduction or cessation of immunosuppressive therapy. However, this treatment caused impaired function or allograft loss from rejection in 22 of 34 kidney recipients. Recurrent KS occurred in 5% of patients in remission when immunosuppressive therapy was resumed. Nine of 114 patients (8%) tested for human immunodeficiency virus were positive. Most OS arose in internal organs or soft tissues. The major types were fibrous histiocytoma (20 patients), leiomyosarcoma (15), fibrosarcoma (12), rhabdomyosarcoma (9), hemangiosarcoma (8), undifferentiated sarcoma (7) and mesothelioma (6). Several unusual features were noted. Remarkably, 10 of 105 (10%) sarcomas occurred adjacent to or in a renal (6) or hepatic (4) allograft. Leiomyosarcomas are rare in children, yet 5 of 15 (33%) occurred in pediatric patients. Three hemangiosarcomas occurred in forearms at sites of arteriovenous fistulas used for pretransplant hemodialysis access. One leiomyosarcoma and one fibrosarcoma occurred in previously irradiated areas. One patient with mesothelioma had a history of asbestos exposure and two others had possible exposure.

Humans↗
PubMed1984

Fine needle aspiration cytology and histologic correlation in canine tumors.

Fine needle aspiration biopsy was performed on 147 skin tumors in 119 dogs over a 4-year period. Both air-dried smears (Wright's stain) and wet-fixed smears (Papanicolaou's stain) were prepared from the aspirates from each tumor and the cytological diagnosis was correlated with histology. In 105 tumors, the cytological and histological interpretations agreed. Histologically, there were 36 stromal tumors, including 19 fibrosarcomas and nine hemangiosarcomas. Cytologically, 12 of the fibrosarcomas and five of the hemangiosarcomas were interpreted correctly as malignant tumors. All 11 melanomas and all 37 mast cell tumors were identified correctly cytologically, while nine of the 11 squamous cell carcinomas, 15 of 21 adenocarcinomas and eight of 19 mammary carcinomas were interpreted as malignant using aspiration biopsy. The fine-needle technique also identified 16 dogs with metastases to the regional lymph nodes before surgical biopsies were undertaken. Benign tumors were incorrectly described as malignancies in only three cases.

Journal Article↗
PubMedDate not supplied

Neoplasia in zebrafish (Danio rerio) treated with N-methyl-N'-nitro-N-nitrosoguanidine by three exposure routes at different developmental stages.

We exposed embryos (83 hours postfertilizaton) and fry (3 weeks posthatch) to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) by immersion in aqueous solutions of 0-10 ppm for 1 hour (embryo) or 0-2 ppm for 24 hours (fry). Zebrafish embryos were microinjected with MNNG at levels of 0 or 96 ng/egg. Diets containing 0-2,000 ppm MNNG were fed to juvenile zebrafish for 3 months beginning at 2 months posthatch. Fish were sampled for histopathologic study at 6-12 months after initiation of carcinogen exposure. Embryos and fry were both quite responsive to MNNG; however, juvenile zebrafish were remarkably refractory to MNNG-induced neoplasia. Principal target organs in zebrafish treated as embryos with MNNG were liver and testis, with hepatocellular adenoma the most prevalent hepatic neoplasm. A variety of mesenchymal neoplasms occurred in zebrafish following embryo exposure to MNNG, including chondroma, hemangioma, hemangiosarcoma, leiomyosarcoma, and rhabdomyosarcoma. Testis and blood vessels were primary target organs for MNNG following fry exposure, with seminoma, hemangioma, hemangiosarcoma, and various other epithelial and mesenchymal neoplasms occurring. The zebrafish is a responsive, cost-effective lower vertebrate model system in which to study mechanisms of carcinogenesis.

Animals↗
PubMedDate not supplied

Pathological features of spontaneous and induced tumors in transgenic mice carrying a human prototype c-Ha-ras gene used for six-month carcinogenicity studies.

To validate the transgenic (Tg) mouse carrying a human prototype c-Ha-ras gene (rasH2 mouse) as a model for short or medium-term carcinogenicity testing, 6-mo carcinogenicity studies using more than 30 chemicals, including carcinogens and noncarcinogens, have been performed. The results obtained so far indicate that rasH2 mice are generally much more susceptible to both mutagenic and nonmutagenic carcinogens than are non-Tg mice, pointing to advantageous application for detection of carcinogenic potential. In this review, histopathological features and diagnostic criteria for spontaneous and induced-tumors observed in our 6-mo carcinogenicity studies are described. Incidences of spontaneous tumors were generally low in rasH2 mice during the 6-mo studies, although values for lung adenomas and splenic hemangiosarcomas were higher than those in the control non-Tg mice. A few forestomach papillomas and skin papillomas were also observed in the control rasH2 mice. The target organs in rasH2 mice treated with known carcinogens were not always identical to those in the treated B6C3F1 mice in 2-yr carcinogenicity bioassays, with forestomach squamous cell tumors, lung alveolar epithelial tumors and/or hemangiosarcomas in the spleen observed in addition to some but not all of the lesions in target organs observed in non-Tg mice in long-term carcinogenicity bioassays. The results of the present histological study suggest that the lung, spleen and/or forestomach, where tumors are induced in rasH2 mice treated with known carcinogens, should be regarded as informative target organs in addition to the target organs reported in previous long-term carcinogenicity bioassays in rats and mice.

Animals↗
PubMedDate not supplied

Point mutations of the c-H-ras gene in spontaneous liver tumors of transgenic mice carrying the human c-H-ras gene.

Spontaneous proliferative liver lesions were found in 15 (13 males and 2 females) of 244 (122 of each sex) transgenic (Tg) mice carrying the human prototype c-H-ras gene (rasH2). The liver lesions included 3 foci of cellular alteration, 1 hepatocellular adenoma, 5 hepatocellular carcinomas, and 4 hepatic hemangiosarcomas in the males and 1 focus of cellular alteration and 1 hepatocellular carcinoma in the females. The mutation patterns of the human and endogenous mouse c-H-ras codon 61 in these proliferative liver lesions were analyzed by DNA amplification using polymerase chain reaction, single-strand conformation polymorphism (PCR-SSCP), and oligonucleotide dot blot hybridization. The hepatocellular carcinomas in 4 males and 1 female contained a point mutation in the mouse c-H-ras gene: 3, 1, and 1 carcinomas had a CAA to AAA transversion at the first base of codon 61, a CAA to CTA transversions, and a CAA to CGA transition at the second base of codon 61, respectively. No point mutations in the human c-H-ras transgene were detected in any hepatocellular carcinoma. All 4 hepatic hemangiosarcomas had a CAG to CTG transversion at codon 61 of the human c-H-ras gene, but no point mutations were detected in codon 61 of the mouse c-H-ras gene. No mutations in human or mouse c-H-ras codon 61 were detected in altered cell foci or hepatocellular adenoma. These results indicate that spontaneous liver tumors in rasH2 Tg mice contain different mutation patterns depending on the histologic type or cell origin of the tumors (i.e., hepatocellular carcinomas or hepatic hemangiosacomas). The absence of similar mutations in foci of cellular alteration and the hepatocellular adenoma suggests that the occurrence of codon 61 point mutations is a late event in the progression of hepatocellular neoplasia in rasH2 Tg mice.

Animals↗
PubMed1992

A morphologic and immunocytochemical study of hepatic neoplasms in cats.

A retrospective study was done of 47 neoplasms of the hepatic and biliary systems from 47 cats brought to The Animal Medical Center over a period of 10 years (1980 to 1989). Histologic examination of specimens taken at necropsy revealed that 87% (41/47) of the hepatic neoplasms were epithelial and 13% (6/47) were nonepithelial. Of the epithelial tumors, 25/47 (53%) were of intrahepatic bile duct origin, 9/47 (19%) were of hepatocellular origin, 5/47 (11%) involved the extrahepatic bile ducts, and 2/47 (4%) were adenocarcinomas of the gall bladder. Of the nonepithelial neoplasms, hemangiosarcomas were more common, 5/47 (11%), than leiomyosarcomas, 1/47 (2%). Multiple liver lobes were involved in 21/34 (62%) of the epithelial and all six of the nonepithelial intrahepatic neoplasms. Most of the bile duct adenocarcinomas (6/9) were predominantly characterized by acinar structures with mucin production, diffuse necrosis, and little desmoplasia. The hepatocellular carcinomas were characterized by three patterns-trabecular (five tumors), pseudoglandular pattern (two tumors), and anaplastic (one tumor). The hepatic carcinoid was characterized by various-sized groups of acinar and rosettelike structures, some with lumens, separated by thin fibrovascular stroma. The extrahepatic bile duct adenocarcinomas (4/4) were acinopapillary with moderate desmosplasia, whereas the adenocarcinomas of the gall bladder had elongated tubular structures lined by anaplastic cells and a severe desmoplastic reaction. The neuroendocrine carcinoma of the extrahepatic bile duct, the hemangiosarcomas, and the leiomyosarcoma had morphologic features characteristic of these neoplasms. Two of the 16 (13%) bile duct adenomas had anaplastic and precancerous changes. Residual benign components were seen in 10/15 (67%) of the biliary adenocarcinomas, 4/9 (44%) of the intrahepatic bile duct adenocarcinomas, and all of the extrahepatic bile duct adenocarcinomas and gall bladder adenocarcinomas. Results of immunohistochemical studies of the biliary neoplasms were similar to those described in studies of biliary neoplasms in human beings. Results of this study revealed that the frequency of different types of hepatic neoplasms in cats varied from that seen in dogs and human beings, but the morphologic features were comparable.

Animals↗