Australian researchers have discovered a protein in lung fluid that could help them determine if a patient has mesothelioma months or potentially even years before the tumor has grown large enough to be visible in scans.

Proteins as Mesothelioma Biomarkers

Proteins are found naturally in the body. They are what different parts of our bodies use to communicate with one another. But sometimes things go wrong, and the messages the proteins send can help cancerous cells grow and thrive. In those situations, some proteins can be used as biomarkers.

This means pathologists (doctors who study disease) can look for these proteins to determine whether or not a person has or potentially has mesothelioma or some other disease.

Recently, researchers at Flinders University in Adelaide, South Australia, decided to study the proteome (protein profile) in pleural effusions—the fluid build-up in patients’ lungs that is often the first pleural mesothelioma symptom. The scientists were hoping to see if any of the proteins associated with mesothelioma would be in the fluid in unusual amounts. They found several.

In the article, Reuben White, the lead investigator, wrote: “We identified several proteins that may be possible targets and warrant further investigation.” Some of the proteins that were upregulated—there were more of them than usual—were S100 proteins, cytokeratin 5/6, serum amyloid protein-2 and vascular endothelial growth factor (VEGF).

The VEGF Protein

VEGF is a signal protein that helps the body both form new blood vessels and ensure their survival. This process is called angiogenesis. However, while this is a vital process, when it comes to tumors, new and sustained blood vessels also promote the growth of cancer cells. Tumors need a blood supply for oxygen and nutrients that help it grow. Cancer cells trick VEGF into creating new blood vessels by giving off the chemicals that encourage angiogenesis.

White and his team explains that “Due to the predominance of [up-regulated] proteins involved in VEGF [signaling] in [pleural mesothelioma], we [analyzed] VEGFA levels in effusions and found a strong correlation between VEGFA levels and survival in [pleural mesothelioma].”

Unfortunately, that correlation is patients who have higher levels of VEGF in their pleural effusions tend to have poorer prognoses and do not live as long as others with lower levels of VEGF.

Mesothelioma Biomarkers for Detection and Treatment

While the correlation between VEGF and pleural mesothelioma survival rates sounds bleak, it is essential for researchers to learn about. Once they have determined whether or not the proteins they singled out for further research are mesothelioma biomarkers, they can turn to use them to improve diagnosis and treatment methods.

One reason for this is because fluid build-up in the lungs is one of the earliest symptoms of mesothelioma. Therefore, once a patient has fluid in their lungs, a pathologist can draw fluid from the lungs to look for any biomarkers.

If high VEGF levels in a pleural effusion is a mesothelioma biomarker, then pathologists can see if there is more VEGF than usual in order to accurately determine whether or not a patient has mesothelioma.

Furthermore, because the pathologist did not have to wait for a tissue biopsy, this diagnosis can happen much sooner, mainly because the tumor must be visible for doctors to be able to remove part of it.

VEGF may also be an excellent protein to target for therapy. Another study that was focusing on a different protein that stimulates angiogenesis—brain-derived neurotrophic factor (BDNF)—discovered that there might be a link between VEGF and BDNF. So those researchers are looking into ways to block the messages these proteins are sending to prevent the cancer from growing.

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Sources
  1. National Cancer Institute. “Angiogenesis Inhibitors.” Retrieved from: https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/angiogenesis-inhibitors-fact-sheet. Accessed November 1, 2018.
  2. National Cancer Institute. “Biomarkers.” Retrieved from: https://epi.grants.cancer.gov/biomarkers/. Accessed November 1, 2018.
  3. White, R. et al. (2018). “Quantitative mass spectrometry to identify protein markers for diagnosis of malignant pleural mesothelioma.” Journal of Proteomics. Epub ahead of print. Retrieved from: https://doi.org/10.1016/j.jprot.2018.09.018. Accessed November 1, 2018.

Last modified: November 16, 2018