Nanomaterials Of Carbon Origin And Mesothelioma Research
Another interesting study is called, Induction of mesothelioma in p53 mouse by intraperitoneal
application of multi-wall carbon nanotube by Atsuya Takagi, Akihiko Hirose, Tetsuji Nishimura, Nobutaka Fukumori, Akio Ogata, Norio Ohashi, Satoshi Kitajima and Jun Kanno - The Journal of Toxicological Sciences Vol. 33 (2008) , No. 1 February 105-116. Here is an excerpt: ABSTRACT- Nanomaterials of carbon origin tend to form various shapes of particles in micrometer dimensions. Among them, multi-wall carbon nanotubes (MWCNT) form fibrous or rod-shaped particles of length around 10 to 20 micrometers with an aspect ratio of more than three. Fibrous particles of this dimension including asbestos and some man-made fibers are reported to be carcinogenic, typically inducing mesothelioma. Here we report that MWCNT induces mesothelioma along with a positive control, crocidolite (blue asbestos), when administered intraperitoneally to p53 heterozygous mice that have been reported to be sensitive to asbestos. Our results point out the possibility that carbon-made fibrous or rod-shaped micrometer particles may share the carcinogenic mechanisms postulated for asbestos. To maintain sound activity of industrialization of nanomaterials, it would be prudent to implement strategies to keep good control of exposure to fibrous or rod-shaped carbon materials both in the workplace and in the future market until the biological/ carcinogenic properties, especially of their long-term biodurability, are fully assessed.
One interesting study is called, Inactivation of p16INK4a expression in malignant mesothelioma by methylation. By Wong L, Zhou J, Anderson D, Kratzke RA. - Research Service, Minneapolis VA Medical Center, Minneapolis, MN, USA - Lung Cancer. 2002 Nov;38(2):131-6. Here is an excerpt: Abstract - The molecular mechanisms of oncogenesis in mesothelioma involve the loss of negative regulators of cell growth including p16(INK4a). Absence of expression of the p16(INK4a) gene product is exhibited in virtually all mesothelioma tumors and cell lines examined to date. Loss of p16(INK4a) expression has also been frequently observed in more common neoplasms such as lung cancer as well. In a wide variety of these malignancies, including lung cancer, p16(INK4a) expression is known to be inactivated by hypermethylation of the first exon. In a survey of ten mesothelioma cell lines, one cell line (NCI-H2596) was identified as possessing loss of p16(INK4a) gene product following gene methylation. This methylation in these mesothelioma cells could be reversed, resulting in re-expression of p16(INK4a) protein, following the treatment of the cells with cytidine analogs, which are known inhibitors of DNA methylation. In previous clinical trials in mesothelioma, the cytidine analog dihydro-5-azacytidine (DHAC) has been found to induce clinical responses in approximately 17% of patients with mesothelioma treated with this drug, including prolonged complete responses. In addition, we identified evidence for methylation of p16(INK4a) in three of 11 resected mesothelioma tumor samples. When both cell lines and tumors are combined, inactivation of p16(INK4a) gene product expression following DNA hypermethylation was found in four of 21 samples (19%). We are further exploring the clinical significance of inhibition of methylation in mesothelioma by cytidine analogs. This may provide a potential treatment target in some mesothelioma tumors by inhibition of methylation.
One interesting study is called, Immunohistochemistry in the distinction between malignant mesothelioma and pulmonary adenocarcinoma: a critical evaluation of new antibodies by A S Abutaily, B J Addis, W R Roche - J Clin Pathol 2002;55:662-668 Here is an excerpt: Abstract - Aim: The value of immunohistochemical staining in differentiating between malignant mesothelioma and pulmonary adenocarcinoma was re-examined using newly available commercial antibodies, with the aim of increasing the sensitivity and specificity of diagnosis, and simplifying the antibody panel required.
Methods: Forty one malignant mesotheliomas and 35 lung adenocarcinomas were studied. Commercial antibodies to calretinin, E-cadherin, N-cadherin, surfactant apoprotein A (SP-A), thyroid transcription factor 1 (TTF-1), thrombomodulin, and cytokeratin 5/6 were applied using the streptavidinbiotinperoxidase complex procedure on formalin fixed, paraffin wax embedded tissue. Results: E-cadherin was expressed in all adenocarcinomas and in 22% of the mesotheliomas. TTF-1 expression was detected in 69% of the adenocarcinomas and none of the mesotheliomas. Positive staining with polyclonal anticalretinin was detected in 80% of the mesotheliomas and 6% of the adenocarcinomas. N-cadherin was expressed in 78% of mesotheliomas and 26% of adenocarcinomas. Thrombomodulin was expressed in 6% of the adenocarcinomas and in 53% of the mesotheliomas. Cytokeratin 5/6 expression was detected in 6% of the adenocarcinomas and 63% of the mesotheliomas. The results were compared with the standard laboratory panel for mesothelioma diagnosis: anticarcinoembryonic antigen (anti-CEA), LeuM1, BerEP4, and HBME-1.
Conclusion: Of the antibodies used in this study, E-cadherin was 100% sensitive for pulmonary adenocarcinoma and TTF-1 was 100% specific for pulmonary adenocarcinoma. The application of these two antibodies alone was adequate for the diagnosis of 69% of adenocarcinomas and 78% of mesotheliomas. Where TTF-1 is negative and E-cadherin is positive, a secondary panel of antibodies, including BerEP4 and LeuM1 (CD15) and antibodies directed against CEA, calretinin, cytokeratin 5/6, thrombomodulin, and N-cadherin, is required for differentiation between malignant mesothelioma and pulmonary adenocarcinoma.
We all owe a debt of gratitude to these fine researchers. If you found any of these excerpts interesting, please read the studies in their entirety.
by: Mont Wrobleski
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