Australian researchers believe they have identified what amounts to a microRNA signature for mesothelioma in pleural effusion.
Pleural effusion is the name for excess lung fluid. Up to 90 percent of pleural mesothelioma patients develop a pleural effusion.
Researchers at the University of Western Australia say this fluid contains a wealth of information that could improve mesothelioma diagnosis. They have recently identified a trio of RNA molecules in fluid samples that could serve as a microRNA signature for mesothelioma. This “signature” could help doctors distinguish mesothelioma from other types of cancer.
The Challenge of Mesothelioma Diagnosis
Pleural mesothelioma is notoriously hard to diagnose. The early symptoms of mesothelioma are similar to the symptoms of many other lung conditions. They are also similar to lung cancer.
One of the symptoms of mesothelioma is pleural effusion. Lung cancer and several other types of cancer can also cause pleural effusion. As lung fluid builds up, it gets harder for patients to breathe. Often, doctors drain this fluid to help with symptoms.
Under a microscope, this fluid can help show if a patient has cancer. But it is difficult to tell if the cancer cells floating in the fluid came from a mesothelioma tumor or another kind of cancer.
That is where having a clear microRNA signature for mesothelioma could be useful. If a sample contained that unique set of markers, it could be an indication that the patient probably has mesothelioma.
In Search of a MicroRNA Signature for Mesothelioma
MicroRNAs are tiny non-coding bits of RNA. They play an important role in regulating gene expression inside cells, including mesothelioma cells.
MicroRNAs are well-known signposts or “biomarkers” for several types of cancer. Biomarkers offer a simple, inexpensive, and minimally invasive way to look for cancer.
But there are hundreds of microRNAs. If doctors do not know exactly which ones are linked to mesothelioma, they cannot use them to diagnose it. This is why the Australian team set out to identify a microRNA signature for mesothelioma.
Three Key MicroRNAs
The Australian team started with lung fluid samples from 26 cases of malignant pleural mesothelioma and 21 other diseases that also cause pleural effusion. They used a test called an array to analyze more than 700 microRNAs in the fluid.
They found three microRNAs in a high percentage of the pleural mesothelioma PE samples. These three RNA molecules are miR-143, miR-210, and miR-200c.
Together, they form a unique microRNA signature for mesothelioma. Few non-mesothelioma samples contained this same set of microRNAs.
The research team says the three-microRNA signature also showed the difference between pleural mesothelioma and 40 adenocarcinomas. (Adenocarcinoma is a type of cancer that forms in the mucus glands.)
“These results suggest that the expression of miR-143, miR-210, and miR-200c in PE cells might provide a signature for diagnosing MPM,” they conclude.
Other studies suggest that microRNAs can also help show how a patients is responding to mesothelioma treatment.
Birnie, KA, et al, “MicroRNA Signatures in Malignant Pleural Mesothelioma Effusions”, July 2019, Disease Markers, https://www.hindawi.com/journals/dm/2019/8628612/