Mutant p53 suppresses antitumor immunity through RNA splicing

Mutant p53 suppresses antitumor immunity not only by depriving cells of one of their major safeguards against cancer. A new Nature Communications study points to a more active role: certain TP53 mutations can help tumor cells silence an internal danger signal that would otherwise alert the immune system.

At the center of the mechanism is RBM28, a protein involved in RNA processing. The authors found that mutations in the DNA-binding domain of p53 can give the mutant protein an acquired regulatory function, increasing RBM28 expression. This creates a direct molecular link between mutant p53 and innate antitumor immunity.

How a tumor removes a viral-like alarm

The human genome contains large numbers of transposable elements, DNA sequences that originated from mobile genetic elements. Most are no longer active, but some can still be transcribed into RNA. Certain transcripts from these elements can form double-stranded RNA.

To a cell, double-stranded RNA is suspicious because it resembles a molecular feature of many viral infections. Cellular sensors can therefore recognize it as a danger signal and trigger type I interferon signaling. That innate immune response can help make a tumor cell more visible to the immune system. In cancer biology, this kind of response is often described as viral mimicry: the tumor's own RNA activates antiviral programs even when no virus is present.

RBM28 changes this balance. In the study, elevated RBM28 increased the splicing of transcripts derived from transposable elements. In simple terms, the RNA was processed more extensively, reducing the formation of double-stranded RNA. The result was less dsRNA, weaker type I interferon signaling, and reduced downstream antitumor immune activity.

In this model, mutant p53 therefore does more than lose its normal tumor-suppressive function. It gains an additional ability to help the tumor erase a molecular signal that would otherwise resemble a viral infection.

From cells to tumors

The study combined several layers of evidence. The mechanism was examined in esophageal cancer cells, including genetic disruption of RBM28 followed by RNA-expression analysis. In the deposited RNA-seq experiment, three biological replicates of RBM28-knockout KYSE30 cells were compared with three control replicates.

The authors also used mouse tumorigenesis models and analyzed human tissues representing different stages of esophageal cancer development. Together, these data supported the same axis: mutant p53 was associated with increased RBM28 activity, reduced double-stranded RNA signaling, and weaker interferon responses as tumors developed.

The researchers then extended the analysis across multiple cancer types. Their pan-cancer analysis suggested that this pathway may also be linked to resistance to immune checkpoint blockade beyond esophageal cancer. That does not mean every TP53 mutation behaves identically, but it raises the possibility that the mechanism is relevant across a broader set of tumors.

Why this matters for immunotherapy

Immune checkpoint inhibitors work by releasing inhibitory signals that restrain T cells. But removing those brakes is not always enough: the tumor still needs to generate immune signals that allow it to be recognized.

The authors tested two experimental strategies in preclinical models. One aimed to restore a more normal conformation of mutant p53; the other inhibited RNA splicing. Both increased antitumor immune activity and improved the efficacy of immune checkpoint blockade in the models used.

This is not yet a new treatment for patients with TP53-mutant cancer. The therapeutic experiments were preclinical, while the human data support the biological pathway rather than proving clinical benefit. Different TP53 mutations can also have different molecular consequences, so the findings should not be generalized automatically to every TP53-mutant tumor.

The broader conclusion is mechanistic. A TP53 mutation can potentially help a tumor in two ways at once: by removing normal p53 tumor-suppressive activity and by acquiring a new ability to dampen innate immune sensing. The p53–RBM28–double-stranded RNA–interferon pathway provides a concrete route by which a genetic alteration can be converted into immune escape—and potentially into resistance to immunotherapy.