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