For decades, oncologists have viewed MYC primarily as an engine of cancer growth. This protein, which is abnormally active in the majority of human cancers, drives cells to divide rapidly and consume resources. However, new research from Oregon Health & Science University (OHSU) reveals a more insidious role: MYC acts as a shield, helping tumor cells survive the very treatments designed to destroy them.
The study, published in Genes & Development, identifies a mechanism by which MYC facilitates the repair of dangerous DNA breaks. By allowing cancer cells to recover from the cellular damage inflicted by chemotherapy and radiation, MYC contributes significantly to treatment resistance and poorer patient outcomes.
A New Role for an Old Villain
Scientists have long known that MYC resides in the cell nucleus, where it switches on genes to promote metabolism and growth. This “canonical” role explains why MYC-driven tumors grow so aggressively. But the OHSU team, led by senior author Dr. Rosalie Sears, discovered a “non-canonical” function that had remained largely hidden.
When DNA becomes damaged—whether due to the stress of rapid tumor replication or the intentional assault of cancer therapy—a modified version of MYC physically migrates to the site of the damage. There, it acts as a recruiter, gathering the specific proteins needed to stitch the DNA back together.
“Our work shows that MYC isn’t just helping cancer cells grow—it’s also helping them survive some of the very treatments designed to kill them,” explains Dr. Sears, Krista L. Lake Chair in Cancer Research at OHSU.
This finding shifts the understanding of MYC from a simple growth promoter to a survival facilitator. It suggests that the protein’s ability to manage cellular stress is just as critical to tumor persistence as its ability to drive proliferation.
Why DNA Repair Defeats Therapy
The effectiveness of many standard cancer treatments, including chemotherapy and radiation, relies on a simple principle: overwhelm the cancer cell with DNA damage until it can no longer repair itself and dies.
However, if a tumor possesses a highly efficient repair mechanism, this strategy fails. The OHSU researchers found that cells with active, modified MYC repaired DNA damage more efficiently than those without. Consequently, these cells were far more likely to survive the toxic effects of treatment and continue growing.
This dynamic is particularly devastating in pancreatic cancer, one of the deadliest forms of the disease. Pancreatic tumors often exhibit extremely high levels of MYC activity. These cells exist in a state of constant “replication stress” due to poor blood supply and rapid growth, yet they persist. The study suggests that MYC helps these cells cope with that extreme stress by actively promoting DNA repair, effectively neutralizing the therapeutic intent of chemotherapy.
The implications for patients are stark:
* High MYC activity correlates with increased DNA repair capacity.
* Increased repair capacity leads to higher rates of treatment resistance.
* Treatment resistance is associated with worse overall patient outcomes.
Turning “Undruggable” Into Targetable
Historically, MYC has been labeled an “undruggable” target. Its structure makes it difficult for traditional drugs to bind to it safely without disrupting essential functions in healthy cells. This has frustrated researchers for years, as MYC is one of the two most important oncogenes in human cancer.
However, the discovery of MYC’s specific role in DNA repair offers a new strategic angle. Instead of trying to shut down MYC entirely—which could be toxic to healthy tissues—therapists might focus on interfering specifically with its interaction with DNA repair machinery.
“If we can interfere with MYC’s role in DNA repair—without shutting down everything MYC does in healthy cells—we may be able to make cancer cells more vulnerable to treatment,” says Dr. Sears.
Clinical Trials Begin
This theoretical shift is already moving into clinical practice. OHSU researchers are investigating a first-in-class MYC inhibitor, OMO-103, in a “window of opportunity” trial.
In this short-term study, patients with advanced pancreatic cancer undergo biopsies before and after receiving the drug. The goal is to observe in real-time how blocking MYC alters the tumor’s biology, specifically looking for signs that the cancer’s ability to repair DNA is being compromised.
“Tumor cells in these cancers experience significant DNA damage and replication stress, yet they continue to survive and grow. Our work suggests that MYC helps these cells cope with that stress by actively promoting DNA repair,” notes Dr. Gabriel Cohn, the study’s first author, who conducted the research while at OHSU.
Conclusion
The discovery that MYC aids in DNA repair fundamentally changes how scientists view treatment resistance. It highlights that cancer is not just a disease of uncontrolled growth, but also of adaptive survival. By identifying this specific mechanism, researchers have opened a new pathway to sensitize aggressive tumors to existing therapies, potentially turning a resilient enemy into a vulnerable target.
