Researchers at N.C. State have successfully run computations inside of human cells using engineered DNA. Specific chemical structures inside the cells were used to identify a certain type of cancer – a targeting approach that could one day be used to direct treatment to selected cells in the body.
“The approach allows you to differentiate between cancerous cells and noncancerous cells,” said Alex Deiters, a chemistry professor at N.C. State.
The researchers were interested in identifying cancer cells using a cellular component called microRNA. These small molecules, similar in structure to DNA, are found inside cells and can modify the activity of different genes.
Different types of cells have different levels of these microRNAs, said James Hemphill, Deiters’ graduate student and the primary author of the study that appeared in the Journal of the American Chemical Society in June.
Using an engineered assembly of DNA molecules, the researchers were able to detect when two specific microRNAs were both present, a situation that can occur in a type of liver cancer cell.
When both microRNA of interest were simultaneously present in a cell, the researchers’ device would emit a fluorescent glow. This response is equivalent to what programmers call an “AND gate” – a computer code that activates when two conditions are met.
Instead of emitting a fluorescent signal, it could be changed to release a drug that could kill a cancer cell, Hemphill said.
DNA computation has been done before. Other researchers have used DNA to conduct simple programming operations, solve math problems and even play tic-tac-toe. But until now, this had mostly happened only in test tubes, outside of cells.
“Getting this to work in mammalian cells is a big step,” said Georg Seelig, a professor at the University of Washington and an expert in DNA computation. Seelig was unaffiliated with the N.C. State study. “The work is really cool,” he said.
Hemphill constructed the DNA computation device in a test tube and then introduced it into three types of cells: kidney cells, cancerous liver cells and cervical cancer cells.
“First of all, I didn’t think it would work,” Deiters said. But Hemphill insisted it would.
“I kind of put myself on the line with my boss,” the third-year Ph.D. student said.
Hemphill’s hard work paid off – the device was able to identify the cancerous liver cells out of the three types tested.
And while the approach is years away from medical use, the study’s success represents an important step forward for the development of more sophisticated DNA computation techniques. One day, DNA devices may be used to run diagnostics on a tissue sample or, if packaged on a delivery vehicle, could target treatment to specific cancer cells in the body.
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