Human cells used to determine carcinogenicity of substances.
Researchers at the Massachusetts Institute of Technology have come up with a new screening method that is faster, easier and more accurate than existing tests, can determine if a particular substance can cause cancer. An article by scientists was published in the journal Nucleic Acids Research.
At present, according to researchers, about 80 thousand chemicals are used in industry. For the vast majority of them, there is very little or no information about carcinogenicity — the ability to cause cancer.
Today, to determine carcinogenic activity, scientists apply chemicals to mice, and then monitor whether they have cancer. This method takes about two years. But a new test, developed by American scientists, can speed up and simplify this process.
The device created earlier by researchers was called CometChip. It detects DNA damage, which can be used to judge the occurrence of cancer. To do this, the DNA is placed in an array of trace elements on a plate of a polymer gel, and then subjected to an electric field. DNA strands that have been damaged go towards one of the poles of the electric field, creating a comet-like tail.
Although CometChip is good at detecting DNA breaks, as well as damage that can easily be converted to breaks, it cannot detect another type of damage. They are formed when chemicals combine with a DNA strand and distort the structure of the double helix, inhibiting gene expression and cell division.
This kind of damage is caused by some chemicals. For example, aflatoxin, which is produced by mushrooms and can be found in peanuts and other crops, as well as benzo [a] pyrene, which can form during cooking at high temperatures.
In their new work, scientists decided to try to adapt CometChip so that it could catch this type of DNA damage. To do this, the authors performed cell DNA repair to generate strand breaks. Usually, when a cell detects the attachment of foreign chemicals and the subsequent distortion of the DNA structure, it tries to repair it by cutting out the damage and then replacing it with a new piece of DNA.
To capture these broken strands, the researchers processed the cells with two compounds that prevent them from synthesizing new DNA. This stops the recovery process and causes the synthesis of unrepaired single-stranded DNA that the test can detect. Scientists called the modified device HepaCometChip and tested it on human liver cells.
First, they irradiated hepatocytes with ultraviolet radiation, which is guaranteed to cause DNA damage, leading to the development of cancer. After that, HepaCometChip was able to find these changes. Then the scientists checked how different chemicals act on the DNA of the cells. It turned out that they all coincide with the data obtained previously by laboratory methods. The next goal of scientists is to test for carcinogenicity of a wide group of chemical compounds that were previously tested by standard methods.