One of the most common carcinogen asbestos develops mesothelioma. Asbestos acts as a carcinogen in the growth of both pleural and peritoneal mesothelioma which occurs in subsiquent stages of triggering and growth. Asbestos fibres are thought to exert their carcinogenic effects via direct physical interactions with the cells of the mesothelium in conjunction with indirect effects following interaction with inflammatory cells such as macrophages.

Asbestos has also been shown to aid the entry of foreign DNA into healthy cells. This foreign DNA can insert itself into the human genome, causing mutations by one of the following mechanisms:

• Activation of oncogenes
• Activation of proto-oncogenes due to incorporation of foreign DNA containing a promoter region
• Prevention of apoptosis
• Inactivation of tumor suppressor genes
• Activation of DNA repair enzymes

Different types of asbestos fibers were studied in rats and mice, showed that long, thin fibres caused a higher incidence of mesothelioma than did short fibres and that cells will actually phagocytose longer fibres more effectively than shorter fibres. Interactive analysis between asbestos fibres and DNA has shown that phagocytosed fibres are able to make contact with chromosomes, often adhering to the chromatin fibres or gets entangled within the chromosome. This direct contact between the asbestos fibre and the chromosomes or structural proteins of the spindle apparatus can induce complex abnormalities. The most common abnormality is monosomy of chromosome 22. Other frequent abnormalities include structural rearrangement of 1p, 3p, 9p and 6q chromosome arms. Common gene abnormalities in pleural and peritoneal mesothelioma cell lines include deletion of the tumor suppressor genes.

Following asbestos phagocytosis, macrophages generate increased amounts of hydroxyl radicals. However, these free radicals are also known clastogenic and membrane-active agents thought to promote asbestos carcinogenicity. These oxidants can participate in the oncogenic process by directly and indirectly interacting with DNA, modifying membrane-associated cellular events, including oncogene activation and perturbation of cellular antioxidant defences. Asbestos also may possess immunosuppressive properties.

Tags: Asbestos Mesothelioma Cancer, Mesothelioma, Mesothelioma Cancer, Mesothelioma Information

This entry was posted on Wednesday, October 14th, 2009 at 10:38 am and is filed under Asbestos Cancer Mesothelioma, Cancer Mesothelioma, Mesothelioma, Mesothelioma Asbestos, Mesothelioma Information. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.