Study Identifies Biomarker that Detects Early Pancreatic Cancer
September 15, 2015, by Amy E Blum, M.A.
Due to the lack of reliable biomarkers to screen for pancreatic cancer, as many as 80% of pancreatic cancers are metastatic when diagnosed, leading to very poor prognoses.
Researchers from the University of Texas MD Anderson Cancer Center have identified a protein marker that is found at much higher levels in exosomes that derive from cancer cells compared to healthy cells, a discovery that may improve the detection and treatment of pancreatic cancer.
The cell surface protein Glypican-1 (GPC1) is enriched in many cancers, and is released into the blood on the surface of membrane enclosed vesicles called exosomes. The researchers found that the enrichment of GPC1 on exosomes from pancreatic cancers accurately identified patients with pancreatic cancer in all 190 cases examined with 100% sensitivity and specificity. Unlike the current standard biomarker CA19-9, GPC1-enriched exosomes could reliably detect precursors to pancreatic cancer and distinguish between benign pancreatic disease and pancreatic cancer.
Levels of GPC1 also accurately tracked pancreatic cancer patients’ tumor development and response to therapy. GPC1 exosome enrichment correlated directly with the severity of the cancer, and a decrease in the ratio of GPC1-enriched exosomes after surgical resection corresponded to a more favorable prognosis.
Further, enriched GPC1 exosomes enabled access to the cancer genome. Mutant KRAS, a frequently mutated gene in pancreatic cancer, was detected in GPC1-enriched exosomes circulating in the blood of patients with these lesions. This suggests that the DNA and RNA contained within exosomes can reveal aberrations that are characteristic of cancer.
Screening for GPC1-enriched exosomes may act as a non-invasive diagnostic and prognostic tool with the potential to revolutionize the treatment and diagnosis of pancreatic cancer, and further research will determine whether the genomic content of cancer-derived exosomes can be used to monitor changes in the cancer genome during the course of clinical care.