The screen might offer a better safety test for new chemicals, It’s estimated that there are approximately 80,000 industrial chemicals currently in use, in products such as clothing, cleaning solutions, carpets, and furniture. For the vast majority of these chemicals, scientists have little or no information about their potential to cause cancer.
The detection of DNA damage in cells can predict whether cancer will develop, but tests for this kind of damage have limited sensitivity.
The research lab is now working on further validating the test, which makes use of human liver-like cells that metabolize chemicals very similarly to real human liver cells and produce a distinctive signal when DNA damage occurs.
Currently, tests for the cancer-causing potential of chemicals involve exposing mice to the chemical and then waiting to see whether they develop cancer, which takes about two years.
Researchers have spent much of her career developing ways to detect DNA damage in cells, which can eventually lead to cancer. One of these devices, the CometChip, reveals DNA damage by placing the DNA in an array of microwells on a slab of polymer gel and then exposing it to an electric field. DNA strands that have broken travel farther, producing a comet-shaped tail.
While the CometChip is good at detecting breaks in DNA, as well as DNA damage that is readily converted into breaks, it can’t pick up another type of damage known as a bulky lesion.
To capture those broken strands, the researchers treated cells with two compounds that prevent them from synthesizing new DNA. This halts the repair process and generates unrepaired single-stranded DNA that the Comet test can detect.
The researchers also wanted to make sure that their test, which is called HepaCometChip, would detect chemicals that only become hazardous after modified in the liver through a process called bioactivation.
In the liver, you have a lot of metabolizing enzymes, which change the chemicals so that they become more easily excreted by the body. But this process sometimes produces intermediates that can turn out to be more toxic than the original chemical.
To detect those chemicals, the researchers had to perform their tests in liver cells. Human liver cells are notoriously difficult to grow outside the body, but the research team was able to incorporate a type of liver-like cell called HepaRG, developed by a company in France, into the new test.
These cells produce many of the same metabolic enzymes found in normal human liver cells, and like human liver cells, they can generate potentially harmful intermediates that create bulky lesions.
The whole process takes between two days and a week, offering a significantly faster turnaround than studies in mice.
Researcher says the HepaCometChip could be useful not only for manufacturers of new chemical products but also for drug companies, which are required to test new drugs for cancer-causing potential. The new test could offer a much easier and faster way to perform those screens.