A new report suggests that it may be possible to verify that a case of lung cancer or malignant mesothelioma was caused by exposure to asbestos. The key may lie in tiny cellular structures called microRNAs.
The Molecular “Fingerprint” of Mesothelioma?
MicroRNAs (miRNAs) are small non-coding molecules of RNA that play a key role in the regulation of gene expression in cells. When these miRNAs are out of balance or “overexpressed”, the result can be cancer.
By examining the miRNAs of mesothelioma patients, lung cancer patients, and healthy subjects, researchers at Marche Polytechnic University in Ancona, Italy are working to develop a miRNA “signature” profile that is unique to people with asbestos-related lung malignancies.
If certain miRNAs are consistently overexpressed in asbestos-exposed people, they could theoretically be used to help identify which patients have asbestos-related cancers and which do not.
Mesothelioma, Lung Cancer, and Asbestos
Pleural mesothelioma is a deadly lung-related cancer wherein tumors grow and spread across the thin tissue that surrounds the lungs. Once it takes hold, mesothelioma is extremely difficult to treat and rarely responds to conventional cancer therapies.
In most cases, the cause of mesothelioma is exposure to asbestos at work. Occupational asbestos exposure has also been implicated in cases of non-small cell lung cancer.
In some cases, a legal case against a negligent employer can hinge on a person’s ability to show that their illness was, in fact, triggered by asbestos.
The Search for MiRNAs Behind Mesothelioma
In an effort to determine which miRNAs are mostly likely to be involved in the development of asbestos-related cancer, the Italian team recruited four sets of test subjects — one group with asbestos-related lung cancer, one with non-asbestos related lung cancer, one with malignant pleural mesothelioma, and one group of healthy subjects.
“Four serum miRNAs (miR-126, miR-205, miR-222, and miR-520g) were found to be implicated in asbestos-related malignant diseases,” writes Dr Marco Tomasetti, a biochemist in the Department of Clinical and Molecular Sciences. “Notably, increased expression of miR-126 and miR-222 were found in asbestos-exposed subjects, and both miRNAs are involved in major pathways linked to cancer development.”
In other words, the researchers identified the “signature” of asbestos-related cancerous changes at the molecular level in mesothelioma patients and patients with asbestos-related lung cancer.
Potential Impact on Mesothelioma Patients and Families
The new study, published in Cancer Epidemiology, Biomarkers, and Prevention, is potentially important for mesothelioma patients and their families for several reasons.
First, by identifying the molecular mechanisms behind the development of mesothelioma, the study opens the door to new mesothelioma treatments that directly target these mechanisms. Previous studies have suggested that focusing on microRNAs has the potential to improve mesothelioma immunotherapy.
Second, a “signature” miRNA profile could be used to screen asbestos-exposed people to identify those at highest risk for developing cancer and may make it easier to diagnose cases of pleural mesothelioma earlier.
Finally, the asbestos-related miRNA profile could potentially be used in legal cases to provide further evidence that asbestos was the likely cause of a particular case of malignant mesothelioma or non-small cell lung cancer.
Santarelli, L, et al “Four-miRNA signature to identify asbestos-related lung malignancies”, September 26, 2018, Cancer Epidemiology, Biomarkers, and Prevention, Epub ahead of print