DNA rings may detect early cancer, researchers find

In a new study, researchers have shown that an innovative technique the use of DNA microcircles has the potential to detect a broad range of cancers in the earliest stages by forcing tumors to create a unique protein.

The proof-of-principal study from Stanford University Medical School used DNA microcircles, a customized genetic construct consisting of tiny rings of DNA. After injecting the microcircles into mice, researchers used a blood test to show that mice with tumors produced a substance that tumor-free mice did not.

With this approach, researchers are reversing the typical laboratory method of detecting cancer, senior study author Sanjiv Sam Gambhir, professor and chair of radiology and director of the Canary Center at Stanford for Cancer Early Detection, told FoxNews.com. With blood and urine tests, doctors must depend on detecting biomarkers that the tumor itself makes.

The challenge for those kinds of biomarkers is that theyre rarely very specific and often not made in sufficient quantities, Gambhir said.

For example, early detection of prostate cancer using prostate-specific antigen (PSA) is controversial because the biomarker is made even in normal prostate cells. Also, small tumors of any kind in the body may generate quantities of biomarkers that are too low to detect in blood or urine.

On the other hand, DNA minicircles work by forcing tumors to make something a protein that it otherwise wouldnt to detect the presence of cancer.

We flip the problem around. [Youre] no longer dependent on nature to make a molecule thats unique to cancer. Youre given a pill that forces cancer cells to make the molecule for you, Gambhir said.

For the purposes of their animal trial, Gambhir noted that a cancerous tumor one cubic millimeter in size, equal to about a grain of rice, would be detectable. For context, when a woman feels a mass in her breast, by the time shes able to feel it, its about a cubic centimeter in size. While researchers have yet to conduct trials with human participants, Gambhir said he hopes minicircles will be able to help detect early and stage 1 cancer.

The DNA minicircles, which are comprised of tiny rings of DNA, work by going into a cancer cell and turning on the cells machinery to make RNA. The RNA then makes protein, which in this case is secreted embryonic alkaline phosphatase (SEAP), which then serves as a cancer biomarker. While the microcircles infiltrate all cells in the body, healthy cells do not make SEAP because researchers added a switch, called a surviving promotor, that only activates in cancer cells. After minicircles are introduced to the body, the surviving promoter activates within about 48 hours to create SEAP. Eventually, the minicircles degrade and in about two weeks are no longer in the body.

Researchers say the minicircles are advantageous because they dont integrate with the host genome, which means they wont tamper with a healthy cells DNA.

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DNA rings may detect early cancer, researchers find