Trichlorethylene (TCE) is a widely used organic solvent and an important industrial material. It's easily released into the environment through manufacture, use and disposal process, so there is a wide range of occupationally and environmentally exposed population. Based on accumulated research data, International Agency for Research on Cancer (IARC) increased the carcinogenic rating of TCE from probable human carcinogen to certain human carcinogen in 2012. This paper is a review of the carcinogenic effects of TCE and its metabolites from the aspects of epidemiological data, experimental evidence on animals as well as the mechanisms of carcinogenesis.
Animals ; Carcinogens ; Humans ; Trichloroethylene

This study was undertaken to elucidate the short-term effect of iron on the hyperplastic lesions of experimental hepatocarcinogenesis. The Solt-Farber's resistant hepatocyte model was chosen for the experiment, and Sprague-Dawley rats wee divided into six groups: normal control, iron-rich diet administration with or without hydroxyquinoline. The iron content, microscopic changes, bromodeoxyuridine(BrdU) labelling index and the DNA polidy were studied. In the carcinogen administered group, oval cell proliferation and consecutive hyperplastic lesions of hepatocyte developed regardless of iron administration. The hepatic iron content was increased rimarkably by iron administration, but gradually decreased as the hyperplastic lesions developed in carcinogen administered groups. Although the administration of iron without carcinogen induced hepatic accumulation of stainable iron, the hyperplastic lesions appeared to be lack of it. BrdU labelling indices of the oval cells and the hyperplastic lesions of hepatocyte were very high and were not significantly altered by iron administration. Most liver cells had diploid or tetraploid DNA content, but there was an increase of diploidy as the development of hyperplastic lesions regardless of iron administration. The results indicate that the chemical carcinogen-induced hyperplastic lesions of hepatocyte do not accumulate iron, and that short-term iron administration does not affect the development of hyperplastic lesions and their proliferative activity and DNA ploidy.
Rats ; Animals ; Carcinogens

Carcinogens ; Occupational Exposure

Carcinogens ; Carcinogens, Environmental ; Retrospective Studies ; Threshold Limit Values

Chemically induced epiderml carcinogenesis is usually divided into two stages, the initiation and promotion. The initiation involves conversion of some epidermal cells into latent neoplastic cells and the promotion is proliferation of the transformed cells. As immunosurveillence is thought to be a host defense against tumors, Langerhans cells, being essential in initiation of local cutaneous immunologic reaction, is suggested to be important in the carcingenesis of the epidermis. This study is attempted to investigate the epidermal proliferative changes in mice induced by application of 12-0-tetradecanoy1-phorbol-13-acetate(TPA) on the skin initiated with 7, 12-dimethylbenzanthracene(DMBA) and its relationship with Langerhans cell. Ninty five male inbred BALB/c mice weighing 20~25 g were divided into five groups; the 33 week-group, the 21 week-group, the 12 week-group and the 4 week-group according to the duration of carcinogen application, and the control group. The carcingen was applied with a brush on the dorsal skin of mice after depilation. Ten days after application of 800 nmole DMBA in 0.4 cc acetone, 20 nmole TPA in 0.4 cc acetone was applied twice per week and the control group was applied with the same amount of acetone for 4 weeks. Animals were sacrificed 3 days after the last application of TPA. One hour before sacrifice, bromodeoxyuridine(BrdU) (1 mg/g) was injected via the tail artert for BrdU stain of S phase cells. A strip of dorsal skin was used for hematoxylineosin stain, immunohistochemical stain for BrdU and la antigen of Langerhans cell, and flow cytometry. The results are as follows: 1. Cellular proliferation, hyperkeratosis and dysplasia of the epidermis were increased in relation to duration of carcingen application. Papillomas were developed 12 weeks after application of the carcingen. 2. BrdU labelling and proliferative indices of the 20 weeks' application group were significantly higher than those of the 12 weeks' application group. The number of Langerhans cell was decreased markedly ater 4 week' application of the carcinogen. 3. All epiedrmal lesions including a case of squamous cell carcinoma were diploidy in flow cytometry. It is thought that disturbance of immunosurveillence, caused by depletion of Langerhans cell, may permit proliferation of epidermal cells. Although abnormal quantitative change of nuclear DNA has not occurred even when the epidermal proliferative activity and dysplastic change were increased markedly, it is thought that the occurrence of structural change of chromosome is remained to be clarified.
Male ; Humans ; Mice ; Animals ; Carcinogens

Carcinogens, Environmental ; Ecotoxicology ; Neoplasms ; etiology

No abstract available.
Carcinogens* ; Colon* ; Colonic Neoplasms* ; Humans*

The focus of this study was o aialyze the morphologic expression of p53, Pan-ras, c-erbB-2, and PCNA in preneoplastic and neoplastic liver lesions induced with NNM of rats. The development of hepatocellular tumors was investigated by histology and electron microscope in 65 Splague-Dawley rats administered with NNM in drinking water at low dose(5 mg/100 ml) and high dose(20 mg/100 ml). Three types of hepatocytic degeneration glycogenotic, eosinophilic and basophilic changes were followed by the appearance of hepatocellullar carcinoma. Hepatocellular carcinoma was increased in number and size according to NNM dosage and to duration of exposure. The histological classifications of hepatocelular carcinoma wer trabecular type, which was which was the most common, large eosinophilic, small cell, adenocarcinomatous and clear cell type. The expression of p53, Pan-ras, c-erbB-2 PCNA was examined by immunohistochemical stains. Eosinophilic degeneration revealed mild positivity at 18-26 weeks for expression of all oncogenic proteins studied and PCNA, whereas precancerous lesions showed variable expression from negative to moderate positivity on PCNA. Hepatocellular carcinoma lesions showed strong positivity for all stains and increased intensity during experimental period. These may indicate that chemical carcinogen produce hepatic eosinophilic degeneration and preCancerOus lesions by genetic mutation, resulting in hepatocellular carcinoma.
Rats ; Animals ; Carcinoma, Hepatocellular ; Carcinogens

Forty eight female Sprague-Dawley rats received a subcutaneous implant containing 12.5 mg estradiol ant the age of 3 weeks. Three rats were killed in 1, 2, 3, 4, 6 weeks and in every month during 2~12 months after implantation, and the breasts were examined by light microscope. In all rats, enlargement of terminal end buds was obseved in 1~2 weeks, maximum development of hyperplastic alveolar nodules in 3 weeks, and marked dilatation and secretion of alveoli or ducts in 1~12 months after implantation. Ductal epithelial hyperplasia was observed in 27 rats and carcinomas developed in 23 rats in 2~12 months after implantation. It was thought that the changes induced by estradiol are more similar to the human breast lesions, compared with changes induced by chemical carcinogens such as dimethylbenzanthracene(DMBA), because breast carcinomas developed in close relationship with ductal epithelial hyperplasia in both estradiol-treated rats and humans, but not in DMBA-treated rats.
Female ; Humans ; Rats ; Animals ; Carcinogens

Biomarkers ; Carcinogens ; Epigenesis, Genetic ; Humans