Researchers have discovered a protein encoded by the glypican-1 (GPC1) gene present on cancer exomes that may be used as part of a potential noninvasive diagnostic and screening tool to detect early pancreatic cancer.
In the study, published in Nature, Raghu Kalluri, MD, PhD, chair of the department of cancer biology at the University of Texas MD Anderson Cancer Center, and colleagues isolated and observed GPC1-enriched circulating exosomes, which they called GPC1+ crExos, using flow cytometry from the blood of patients with pancreatic cancer.
The researchers found that GPC1+ crExos were present in the blood of patients with pancreatic cancer with absolute specificity and sensitivity, clearly distinguishing these patients from healthy patients or those with benign pancreatic disease.
In addition, the study showed that levels of GPC1+ crExos were significantly lower in patients after surgical resection of the tumor.
“GPC1+ crExos can be detected and isolated in blood samples that were stored in freezers almost 30 years ago, unlike circulating tumor cells (CTCs) that require large amounts of fresh blood,” said Kalluri in a prepared statement. “DNA, RNA, and proteins can be isolated from cancer exosomes isolated from stored specimen for further genetic and biological analyses. Therefore, cancer exosomes are not just a biomarker but isolating them provides a trove of cancer-specific information.”
The researchers also conducted studies in mice to determine the value of GPC1+ crExos as a screening biomarker. They found that the presence of GPC1+ crExos reliably detected pancreatic intraepithelial lesions in mice despite negative results for pancreatic disease found with MRI screening.
“Routine screening of the general population for pancreatic cancer using MRIs or CTs would be prohibitively expensive with the likelihood for many false positives,” said David Piwnica-Worms, MD, PhD, chair of the department of cancer systems imaging at MD Anderson Cancer Center, in a prepared statement. “Our study suggests the potential for GPC1+ crExos as a detection and monitoring tool for pancreatic cancer in combination with imaging, with an emphasis on its application in early detection.”