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UCLA study uncovers key new insights into how cells are wired to survive radiation therapy

MicroRNA molecules were discovered only relatively recently in humans, but have been shown to play a pivotal role in how a cell responds to injury or stress, such as radiation therapy. With radiation treatment currently used in over two-thirds of cancer patients, there remains a critical need for researchers and clinicians to better understand the genetics behind the radiation response and develop more personalized therapies for patients.

A UCLA-led study has for the first time shown that microRNAs, specifically the microRNA known as miR-34, can sit silently in an inactive state in a cell waiting for a signal to turn it on. The discovery turns on its head the long-held notion that a microRNA when made is always already activated and ready to work, and shows for the first time that microRNAs can be controlled in a way similar to proteins, waiting for stress signals to turn them on.

The study is published online in the journal Nature Communications.

Dr. Joanne Weidhaas, the study’s lead author and a UCLA Jonsson Comprehensive Cancer Center member, investigated numerous human cell lines. Her team found that there was an abundance of miR-34 in cells before radiation treatment, but that these molecules were inactive, or not functioning. It was only after radiation that the miR-34 sitting in the cells was activated, they discovered, and that a major radiation response protein called ATM was responsible.

DNA damage, as caused by radiation, changes microRNAs to activate them
The investigators discovered that DNA damage, as caused by radiation, changes microRNAs to activate them
Image Credit: UCLA Jonsson Comprehensive Cancer Center