Frank Slack, PhD, Named Fellow of the American Association for the Advancement of Science
BIDMC Researcher and Molecular Biologist Named AAAS Fellow
BOSTON — For decades, scientists wrote off roughly 98 percent of the human genome as evolutionary clutter — literally called junk DNA. Through his pioneering research, Frank Slack, PhD, has helped reveal what that so-called junk is actually doing: acting as the genome's control system, the knobs that dial critical genes up or down. Understanding and harnessing these controls could lead to new therapies and novel ways to approach aging.
"Science moves forward because people build on each other's discoveries,” Slack said. “Twenty-five years ago, when we first identified let-7, the idea that these molecules could be used to treat cancer or influence how we age was barely imaginable. We're still figuring out exactly how microRNAs do everything they do, but what we've learned so far has real implications for how we treat cancer and how we think about aging. To be recognized by your peers for that journey — it's a great honor."
Slack, a molecular biologist at Beth Israel Deaconess Medical Center (BIDMC), has been named a fellow of the American Association for the Advancement of Science (AAAS). He is among only 500 scientists nationwide named to the 2025 fellows' class.
Slack holds the Shields Warren-Mallinckrodt Professorship of Medical Research at Harvard Medical School and directs both the Harvard Initiative for RNA Medicine and the Cancer Research Institute at BIDMC.
MicroRNAs are small but powerful regulatory molecules. They don't encode proteins themselves; they control the genes that do. Because they govern so many biological processes — aging, immunity, metabolism, and more — they represent compelling targets for a new generation of treatments: dialing the right switch may allow novel interventions.
As a postdoctoral fellow in the laboratory of Gary Ruvkun at Harvard Medical School — who was awarded the 2024 Nobel Prize in Physiology or Medicine for the discovery of microRNA — Slack co-discovered let-7, only the second microRNA ever identified and the first ever found in humans. His lab then demonstrated that let-7 acts as a tumor suppressor, keeping dangerous cancer-driving genes (including RAS, MYC, and LIN28) under control. When let-7 is lost or silenced, those genes can accelerate cancer growth. The implications rippled across oncology.
In a landmark 2005 paper in Science, Slack's lab showed for the first time that microRNAs regulate lifespan. By manipulating a single microRNA in C. elegans — a microscopic worm whose short life and surprisingly human-like cellular machinery have made it one of biology's most powerful research tools — his team could shorten or extend how long the worm lived. It was the first direct evidence that these regulatory molecules played a role in governing aging.
Subsequent work from his lab, published in Current Biology in 2010, revealed that multiple microRNAs influence aging, some promoting longevity and others working against it, through the same pathways that govern insulin signaling and the body's response to cellular damage. The implications for human aging research are profound: if microRNAs are dials on the aging process, they may one day be targets for interventions that help people live not just longer, but healthier.
"Dr. Slack’s work represents exactly what basic science is: the essential first step in every treatment we offer patients,” said Gyongyi Szabo, MD, PhD, Chief Academic Officer, Beth Israel Lahey Health and Beth Israel Deaconess Medical Center. “Every cancer therapy, every diagnostic tool, every intervention we have today began with a scientist asking a fundamental question about how life works. Frank has spent his career asking those questions at the highest level, and BIDMC is a better place because of it."
That basic science is now moving toward the clinic. Slack's lab has been instrumental in developing microRNAs as cancer therapeutics, work that has advanced from laboratory discovery to human trials. Among the most promising: miR-34, a microRNA his lab helped identify as a tumor suppressor, which has entered Phase I clinical trials as a novel cancer treatment. It is among the first microRNA-based therapies ever tested in humans, a direct line from the junk DNA dismissed by a previous generation of scientists to a potential new class of medicine.
The new fellows will be celebrated at a forum in Washington, D.C., on May 29, 2026.
About Beth Israel Deaconess Medical Center
Beth Israel Deaconess Medical Center is a leading academic medical center, where extraordinary care is supported by high-quality education and research. BIDMC is a teaching affiliate of Harvard Medical School, and consistently ranks as a national leader among independent hospitals in National Institutes of Health funding. BIDMC is the official hospital of the Boston Red Sox.
Beth Israel Deaconess Medical Center is a part of Beth Israel Lahey Health, a healthcare system that brings together academic medical centers and teaching hospitals, community and specialty hospitals, more than 4,700 physicians and 39,000 employees in a shared mission to expand access to great care and advance the science and practice of medicine through groundbreaking research and education.
