Protein Circulating in Blood Could Be Key to Early Diagnosis Pancreatic Cancer
Certain proteins that circulate in the blood may help identify patients with this disease, for which there’s currently no reliable screening. These findings were published in the journal Nature.
Pancreatic cancer is one of the deadliest forms of cancer. Each year, close to 44,000 people are diagnosed with pancreatic cancer in the United States and more than 37,000 die from the disease. The disease is often diagnosed at an advanced stage, and treatment of advanced disease remains challenging.
Currently, there are no screening tests that are able to accurately identify pancreatic cancer at an early, more-treatable stage and reduce a patient’s risk of dying from the disease. This is an active area of research, however, and could eventually improve pancreatic cancer outcomes.
One current area of study in pancreatic cancer screening involves genomic testing, the study of genes and their function. Specifically, this approach examines a portion of the gene known as an exome. Exomes are the part of the gene that provides the information for protein synthesis, or the process by which the genetic code puts together proteins in the cell.
All types of cells, including cancer cells, excrete exomes, which are then circulated in the bloodstream. There is currently no way, however, to find exomes from cancer cells in the blood stream.
Researchers recently used a chemistry technique called mass spectrometry analyses to look for a type of protein called glypican-1 (GPC1), known to be present on exomes from cancer cells. They used a technique called flow cytometry that allowed them identify and isolate exomes from cancer cells in the blood of patients and mice with pancreatic cancer.
The researchers were able to accurately find cancer exomes in the blood of patients who had pancreatic cancer. The test could also tell the difference between cells in the blood of healthy individuals, cells from people with noncancerous pancreatic disease, and cells from people with early and more advanced pancreatic cancer.
Importantly, the researchers found that patients with higher levels of GPC1 had more extensive disease as well as a lower rate of survival before and after surgery. They also found that GPC1 exomes from patients and mice with pancreatic carried mutations in the KRAS gene—a mutation associated with the development of many cancers. In mice, researchers were able to use these KRAS mutations to accurately identify pancreatic tumors, even in cases where they didn’t find tumors on MRI.
The possibility that GPC1 exomes circulating in the blood can be reliable used to detect pancreatic cancer could be a very important finding in pancreatic research. This approach would offer a noninvasive way to diagnose and screen for pancreatic cancer and, as a result, improve a patient’s chances of early, effective treatment.
Reference: Melo SA, Luecke LB, Kahlert C, et al. Glypican-1 identifies cancer exosomes and detects early pancreatic cancer. Nature. 2015 July 9;523(7559):177-82. doi: 10.1038/nature14581.
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