By DANIEL NIEMANN, MARIA CHENG and MIKE CORDER

STOCKHOLM (AP) — Two Massachusetts scientists won the Nobel Prize in Physiology or Medicine on Monday for their discovery of microRNA, small pieces of genetic material that serve as on and off switches in cells that help determine what the cells do and when they do it .

If scientists can better understand how they work and how to manipulate them, it could one day lead to powerful treatments for diseases like cancer.

The work of Americans Victor Ambros and Gary Ruvkun appears to be “fundamentally important for the way organisms develop and function,” according to a panel that presented the prize in Stockholm.

Dr. Ambros is from the University of Massachusetts Medical School; Dr. Ruvkun is an investigator at Massachusetts General Hospital (MGH) and Harvard Medical School.

Ambros and Ruvkun were initially interested in genes that determine the timing of various genetic developments and ensure that cell types develop at the right time.

Their discovery ultimately revealed “a new dimension of gene regulation, essential for all complex life forms,” the panel said.

What is the Nobel Prize for?

RNA is best known for carrying instructions for making proteins from DNA in the cell’s nucleus to tiny cellular factories that actually build the proteins. MicroRNA doesn’t make proteins, but it helps control what cells do, including turning on and off crucial genes that make proteins.

Last year’s Nobel Prize in Medicine went to scientists who discovered how to manipulate one of those types of RNA, known as messenger RNA or mRNA, that is now being used to make vaccines for COVID-19.

Ambros and Ruvkun’s revolutionary discovery was initially made in worms; they tried to determine why some types of cells failed to develop in two mutant strains of worms commonly used as research models in science.

“Their groundbreaking discovery revealed a completely new principle of gene regulation that proved to be essential for multicellular organisms, including humans,” says the citation explaining the importance of their work.

That mechanism has been working for hundreds of millions of years and has made the evolution of complex organisms possible, the report said.

Ambros, currently a professor of natural sciences at the University of Massachusetts Medical School, conducted the research at Harvard University. Ruvkun’s research was conducted at Massachusetts General Hospital and Harvard Medical School, where he is a professor of genetics.

Why is microRNA important?

The study of microRNA has opened up new approaches to treating diseases such as cancer because it helps regulate the way genes work in our cells, said Dr Claire Fletcher, lecturer in molecular oncology at Imperial College London.

Fletcher said there are two main areas where microRNA could be useful: in developing drugs to treat diseases and in serving as possible indicators of disease, by monitoring microRNA levels in the body.

“If we take the example of cancer, we see that a certain gene is working overtime. It could be mutated and working in overdrive,” says Fletcher. She said scientists may one day be able to use microRNA to stop such effects.