Long Carbon Nanotubes Could Have Carcinogenic Effect Similar to Asbestos

Nanotechnology, the science of creating materials possessing very tiny fibers, is having an increasing influence on everyday life. Currently, researchers have demonstrated for the first time in mice that long and thin nanomaterials known as carbon nanotubes could possibly have the same carcinogenic effect as asbestos: they can trigger the development of mesothelioma.

The findings were noticed in 10%-25% of the 32 animals included in the research, which has not yet been simulated in humans. The paper has been published in the November 6 issue of Current Biology.

Long carbon nanotubes are a subtype of nanotubes used in the creation of incredibly robust, yet lightweight materials that are progressively being used in numerous industrial and consumer products including aircrafts, bicycles, sports cars, sports equipment such as helmets, and computer motherboards.

Unlike previously reported short-term studies, this is the first time the effects of long and thin carbon nanotubes, leading to mesothelioma, have been monitored in mice over many months

Marion MacFarlane, Professor at the Medical Research Council (MRC) Toxicology Unit in Leicester, UK

"Importantly, not all nanofibers pose a hazard," she adds. "We want our research to inform manufacturers and regulators about safer options when a nanofiber is being selected for the production of nanomaterials for emerging technologies"

"The outcomes seen in this paper will thus help contribute to a 'Safe by Design' approach," says first author Tatyana Chernova, a senior staff scientist at MRC.

In the animal experiments, the researchers positioned long carbon nanotubes in the pleura, the area around the lungs where mesothelioma forms in humans. "In that way, we followed changes in the pleura throughout disease development, observing stages of chronic inflammation, activation of pro-oncogenic signaling pathways, and eventually inactivation and/or loss of genes that are the gatekeepers of cancer development," MacFarlane says. The mesothelioma caused by long carbon nanotubes placed mice was in many ways comparable to tumor samples from patients.

The researchers emphasize that the risk is posed only by types of nanomaterials that are long, thin, and biopersistent - meaning that they do not break down inside the body:

These long, thin nanotubes are very similar to asbestos in their structural and physical characteristics, the immune system does a good job of recognizing nanotubes that are shorter, thicker, or tangled up. They can be phagocytized by macrophages and cleared out of the body.

Marion MacFarlane, Professor at the Medical Research Council (MRC) Toxicology Unit in Leicester, UK

Another crucial set of findings was revealed through this research: the team learned new details about what takes place during the very long latency of mesothelioma formation and provided new information on the mechanism by which mesothelioma forms. Observations in the mice revealed that chronic inflammation caused by long nanotubes caused inactivation of the same genes seen to be disturbed in people diagnosed with mesothelioma. The researchers found that hypermethylation and silencing of the Cdkn2a locus eventually resulted in the loss of the tumor suppressor proteins p16 and p19.

Because mesothelioma is diagnosed when it's quite advanced, we don't know much about the early mechanisms by which it forms, this research could help us find biomarkers for early detection, as well as provide information for developing targeted therapies for this devastating disease.

Tatyana Chernova, a senior staff scientist at MRC

Source: http://www.cellpress.com

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