MYC is one of the most researched genes when it comes to cancer, and it’s easy to see why. It gets messed up in almost every type of human tumor, promotes uncontrolled cell growth, and is often linked to chemotherapy resistance and poor survival rates for patients. For years, scientists have mainly viewed MYC as a master switch that ramps up gene activity, making cells divide way faster than they’re supposed to.
A study from 2026 that came out in Genes & Development revealed something pretty surprising: MYC works as a DNA repair agent too! It actually moves to areas where DNA is broken and helps run the repair process. Even more interesting is that researchers found a single chemical tweak to the MYC protein determines whether this repair feature kicks in. If you block that tweak, cancer cells become a lot more sensitive to treatments that damage DNA.
This discovery changes our understanding of MYC and could lead to new cancer treatments.
To get why this finding is so important, it helps to know what MYC usually does and why it’s such a big deal in cancer. In healthy cells, MYC is a key regulator that turns on genes involved in growth, energy, and cell division. Its activity is kept in check because MYC doesn’t last long, only about 15 to 30 minutes in normal conditions, so its effects on gene activation are quick and balanced.
In the context of cancer, the regulatory control mechanisms become compromised. MYC, a key oncogene, becomes excessively active, remaining perpetually activated and concurrently amplifying the expression of numerous downstream genes. This heightened transcriptional activity places substantial stress on DNA, leading to physical conflicts between the transcriptional machinery and the replication apparatus. The consequence of this overload is DNA damage, specifically double-strand breaks (DSBs) in the DNA double helix.
A longstanding paradox that has intrigued researchers is that MYC induces DNA damage while simultaneously enabling cancer cells to withstand it. Observations indicate that cancer cells with high MYC activity exhibit not only increased DNA damage signatures but also enhanced DNA repair mechanisms.
This study posits that MYC is not merely a contributor to DNA damage; rather, it plays a pivotal role in resolving these challenges.
MYC Shows Up Where DNA Is Broken
The research team, based at Oregon Health and Science University and collaborating with teams in Toronto, London, and Würzburg, employed a highly sensitive technique, the DI-PLA (DNA damage in situ proximity ligation assay), to directly visualize the physical association of MYC with DNA double-strand breaks in living cells.
The results were unequivocal. After artificially inducing DNA breaks using either the precision gene-editing tool CRISPR-Cas9 or a drug that stalls the DNA replication machinery, the researchers observed that MYC rapidly accumulated at the sites of damage. This finding was consistent across four different cell lines, including those derived from pancreatic cancer.
Furthermore, once at the break site, MYC was found in proximity to two essential repair proteins in the cell: BRCA1 and RAD51. These proteins are critical participants in a DNA repair process known as homologous recombination (HR), a high-fidelity mechanism that cells use to mend broken DNA by using an intact copy as a template. Mutations in BRCA1 and RAD51 are well-documented for significantly increasing cancer risk, particularly for breast and ovarian cancers, as their loss severely impairs this vital repair process.
The revelation that MYC physically interacts with BRCA1 and RAD51 at the damage sites, and interacts with RAD51 in a manner not previously described in the literature, suggests that MYC is not merely a passive observer at the break site. Instead, it may actively coordinate the repair response.
The Chemical Tag That Controls Everything
Not all MYC proteins in the cell are the same. MYC can be chemically modified at different locations along its structure, through phosphorylation, in which a phosphate group is attached to a specific amino acid. Two phosphorylation sites have long been known to regulate MYC stability: one at a position called serine 62 (S62) and one at threonine 58 (T58).
Phosphorylation at S62 stabilises MYC, keeping the protein active and functional. Phosphorylation at T58, which follows shortly after, triggers MYC’s destruction through the cell’s protein disposal system.
The key question the researchers asked was: Does the phosphorylation status of MYC affect its ability to associate with DNA breaks and repair them?
The answer was striking. Using cells engineered to express three different versions of MYC, normal MYC, an S62-blocked mutant (S62A), and a T58-blocked mutant (T58A), the team showed that the S62-phosphorylated form is essential for MYC’s recruitment to DNA break sites. When S62 phosphorylation was blocked, MYC failed to accumulate at breaks. It also failed to interact with BRCA1 and RAD51, and neither protein was efficiently recruited to the sites of damage.
The downstream consequences were severe. Cells expressing the S62-blocked MYC mutant showed impaired ability to repair DNA breaks via homologous recombination, accumulated more unresolved DNA damage after stress, and critically formed significantly fewer colonies and grew more poorly after exposure to DNA-damaging treatment, compared to cells with normal or T58A-mutant MYC.
In other words, removing S62 phosphorylation, and MYC loses its repair function. Cancer cells become less able to fix their broken DNA and more likely to die under genotoxic stress.
Why This Matters for Pancreatic Cancer
The researchers specifically investigated this mechanism in pancreatic ductal adenocarcinoma (PDAC), one of the most treatment-resistant and deadly cancers, with a five-year survival rate that remains below 15%.
In a patient-derived PDAC cell line, MYC again showed increased proximity to DNA breaks after bleomycin treatment, a DNA-damaging chemotherapy agent. Critically, when the researchers used a drug called DT061, which activates an enzyme (PP2A) that removes the S62 phosphate tag from MYC, MYC’s association with DNA breaks was significantly reduced.
Looking at gene expression data from 289 primary and metastatic PDAC patient tumours, the team found that high MYC activity correlated strongly with both a replication stress signature and the hallmark DNA repair pathway, despite only 4% of genes being shared between the two gene sets. In tumour microarray data from 34 patients, the phosphorylated form of MYC (pS62-MYC) was consistently co-expressed with RAD51, BRCA1, and other DNA damage markers at the single-cell level. Patients with high MYC activity showed worse survival, regardless of whether their tumour also carried known DNA repair gene mutations, suggesting that MYC’s repair function helps cancer cells tolerate DNA damage that would otherwise kill them.
What This Means for Therapy
This discovery adds a new dimension to the already compelling case for targeting MYC therapeutically, something the cancer research community has long pursued but has found technically difficult, since MYC was, for many years, considered “undruggable.”
The finding that S62 phosphorylation is the key switch controlling MYC’s repair function opens a more specific target: rather than eliminating MYC, blocking this particular modification might selectively turn off the repair function without destroying the protein wholesale. DT061, the PP2A activator used in this study, is an example of an existing drug class that has been shown to reduce S62 phosphorylation in cancer cells.
The broader implication is also significant. If MYC’s repair function is what allows cancer cells to tolerate the DNA stress caused by their own rampant growth, then disrupting it could sensitise tumours to chemotherapy and radiation treatments that kill cells specifically by inducing DNA damage. Cancers that are currently resistant to these treatments because of high MYC activity might become vulnerable if that repair pathway is cut off.
This is still early-stage, mechanistic science. The findings are based on cell line experiments and patient tumour data, not clinical trials. But what they reveal about MYC is genuinely new: that this notorious oncogene is not simply a driver of genomic chaos, but also an active participant in maintaining the very genomic stability it so frequently undermines.
It turns out MYC starts fires and then quietly helps put them out.
Reference
Cohn, G. M., Daniel, C. J., Eng, J. R., MacDonald, A. S., St-Germain, J., Pieper, N. M., Kannan, T., Sun, X.-X., Pelz, C., Ali, A., Chin, K., Smith, A., Lopez, C. D., Brody, J. R., Raught, B., Penn, L. Z., Eilers, M., Dai, M., & Sears, R. C. (2026). MYC serine 62 phosphorylation promotes its association with DNA double-strand breaks to facilitate repair and cell survival under genotoxic stress. Genes & Development. https://doi.org/10.1101/gad.352832.125