Researchers say they have come up with new blood test that has the capability to identify cancer cells in their first onset.
At the earliest clinical drug testing, researchers from Stanford University administered a drug identified as DNA minicircles to mice and discovered mice having tumors produce a substance that mice without tumors didn’t and its presence was easily detected in the blood 48 hours later.
The technique “represents an alternative paradigm for improved cancer detection,” said the paper published in the U.S. journal Proceedings of the National Academy of Sciences. “If proven safe and effective, (it) eventually may have potential as a powerful cancer-screening tool for the general population.”
“The hunt for cancer “biomarkers” in the blood, or substances that indicate a probable tumor, is nothing new, but various tumor types naturally secrete characteristic substances with each requiring its own separate test”, said Prof. Sanjiv Gambhir, the study’s senior author, chair of radiology and director of the Canary Center at Stanford for Cancer Early Detection.
“Complicating matters, these substances are also quite often made in healthy tissues, so a positive test result doesn’t absolutely mean a person actually has cancer. In addition, a tumor, especially a small one, simply may not secrete enough of the trademark substance to be detectable”, Gambhir explained.
Gambhir and colleagues found a system that will induce any of the several types of tumor to release biomarkers whose blood presence will definitely indicate the presence of cancer, since rodent’s’ tissues would normally be producing it.
“This biomarker is a protein called secreted embryonic alkaline phosphatase (SEAP),” they said in a statement. “SEAP is naturally produced in human embryos as they form and develop, but it’s not present in adults.”.
In order for cancer cells to produce SEAP and emitting it to the blood circulation, Gambhir and his associates utilized a DNA minicircle, a tiny, artificial, single3 celled DNJA ring which is approximately 4,000 nucleotides in circumference or around one-millionth the length of the DNA strand. It’s similar to stretching all 23 chromosomes of the human genome from one end to another,
.They constructed the DNA minicircle so that it can be stimulated only by a specific promoter, s short sequence that only responds to cancer cells. When stimulated, a reporter gene on the DNA minicircle will produce the SEAP protein which can easily detected in the blood.
The researchers injected DNA minicircles intravenously to the mice which is inoculated with human melanoma metastases and mice without tumor and the SEAP levels were measured in the blood successively on the first, third, seventh, eleventh and fourteenth day later.
In the span of 48 hours, SEAP was already detected in the mice’s blood with tumor but absent in the tumor-free mice. The presence began to wane after 72 hours after injection, fading completely after two weeks or more.
“Its maximum strength varied with the total tumor volume in a mouse’s lungs, suggesting that the test may be sensitive not only to the presence of cancer but also to its extent,” they said.
The medium of choice in this research was using intravenous injection, but the researchers say that a pill fed orally will be a distinct possibility, Gambhir said.
“We haven’t got it down to a pill yet, but the oral delivery part of this is likely a solvable problem — only a few years off, not five or 10 years off,” he said, noting it will take much more time than that to prove that the approach is safe to use in humans.