Some surprising research findings suggest that a simple blood test could be developed to detect gene mutations associated with cancer and thus guide treatment. Such a test might also facilitate the early diagnosis of pancreatic cancer and other cancers that often are asymptomatic until they become advanced and difficult to treat.
“At the present time, there is no single blood test that can screen for all cancer-related DNA defects,” said Raghu Kalluri, M.D., Ph.D., a professor in and chair of the Department of Cancer Biology at The University of Texas MD Anderson Cancer Center.
As the first step toward developing such a test, Dr. Kalluri and his research team investigated exosomes, which are tiny vesicles shed into the serum by many types of cells—including cancer cells. It was known that exosomes play a role in intercellular signaling and that they carry single-strand DNA fragments. Dr. Kalluri’s team hypothesized that exosomes also contain double-stranded genomic DNA, which could reveal cancer-related gene mutations.
To test their hypothesis, the researchers performed polymerase chain reaction analyses and whole-genome sequencing on exosomes from two human pancreatic cancer cell lines and from blood samples from patients with pancreatic cancer and healthy volunteers. The two cancer cell lines, Panc-1 and T3M4, both are known to harbor KRAS and TP53 mutations.
The researchers found KRAS and TP53 mutations in the exosomes from cancer cells and from pancreatic cancer patients’ blood samples. The mutations were not found in the exosomes from healthy volunteers’ blood samples.
“Because different forms of cancer are associated with different chromosomal mutations, we believe analysis of exosome DNA taken from blood samples may not only help determine the presence of a cancerous tumor somewhere in the body but also identify mutations without the need for a tumor sample,” Dr. Kalluri said.
The research was reported in the Journal of Biological Chemistry.
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OncoLog, June 2014, Volume 59, Issue 6