Carcinogenesis in experimental animals

Exposure to arsenic has been associated with different types of human cancers such as respiratory cancers and epidermoid carcinomas of the skin, as well as precancerous dermal keratosis. The epidemiological evidence of human carcinogenicity is supported by carcinogenesis in experimental animals (Deknudt et al. 1986). 

Sphingolipids are ubiquitous constituents of the cell membrane and are highly bioactive. The hydrolyzed products of sphingolipids are used by cells to regulate growth, differentiation and apoptosis. There is evidence that sphingolipids inhibit colon carcinogenesis in experimental animals at a human diet-equivalent... 

Chronic inhalation exposures to indium compounds can induce pulmonary toxicity and carcinogenesis in experimental animals. Indium (III) phosphide (IP) was chosen by the National Toxicology Program (NTP) for chronic toxicity studies due to its widespread use in the microelectronics industry and its potential for chronic exposure to workers (NTP 2001). Inhalation exposures of rats to IP at doses of 0, 1, 3,... 

As mentioned pievionsly, eaidnogen metabolism has been one of the drivers for the P450 field. There is strong evidenee that the P450 composition can strongly inflnence chemical carcinogenesis in experimental animal models [2762], reinforced with transgenie monse models [1441]. 

Carcinogenesis research has demonstrated the tumorigenic activities of a large number of chemical substances in experimental animals. These include molecules of diverse chemical classes, organic and inorganic, and natural products as well as compounds synthesized in the laboratory or produced by industry. 

Preconceptual and transplacental carcinogenesis are special types of developmental toxicity and can result when either parent is exposed prior to mating. Both male-mediated and female-mediated effects have been demonstrated in experimental animals for a variety of chemicals and several types of radiation (Anderson, 2000). Transplacental carcinogenesis is recognized in the female, but carcinogenesis mediated through the male germ cells is not as well appreciated or understood. 

Although cancer is known to occur in many groups of animals, the primary interest and the focus of most research is in human cancer. Nevertheless, much of the mechanistic research and the hazard assessment is carried out in experimental animals. A consideration of the general aspects of human carcinogenesis follows. 

In addition to the regression of established tumors, a number of retinoids show apparent inhibition of the chemical induction of the bladder and other epithelial tumors in experimental animals. The effect is not in fact inhibition of carcinogenesis, but rather a lengthening of the latent period between the initiation step of carcinogenesis and the development of mmors. Although perhaps not as exciting as compounds that prevent the development of cancers, such a delaying action may be usefitl. If the results can be scaled from... 

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