Hidden Molecular Shield Lets Lung Cancer Cells Dodge Copper-Driven Cell Death

Scientists have uncovered a three-part molecular circuit that helps non-small cell lung cancer (NSCLC) cells survive a recently discovered form of cell death driven by copper, and the finding points to new vulnerabilities that could be exploited for therapy. In a study published in Molecular Genetics and Genomics, Lin Wang, Jiansheng Li and Hongxia Li describe how an enzyme called USP11 protects tumor cells from cuproptosis by stabilizing a protein that, in turn, keeps copper locked safely out of harm’s way. The work dissects, step by step, how a chain running from USP11 through the RNA-binding protein IGF2BP2 to the copper chaperone ATOX1 quietly disarms one of the body’s most dramatic anticancer mechanisms.

Cuproptosis burst onto the scene in 2022, when researchers showed that excess copper does not simply poison cells in the way that other metals do. Instead, copper binds directly to lipoylated proteins inside mitochondria, the cell’s energy factories, causing these lipid-modified components of the tricarboxylic acid cycle to clump together. The resulting protein aggregation is lethal, and cells die in a manner that looks distinct from apoptosis, necrosis or even ferroptosis, the iron-driven cell death that preceded it in the scientific lexicon. Because the process depends on mitochondrial respiration, it offers an appealing strategy against tumors that have reprogrammed their metabolism, including many lung cancers, the leading cause of cancer death worldwide.

The catch is that cancer cells, like healthy ones, deploy elaborate machinery to keep free copper under control. Central among these defenses is ATOX1, the antioxidant 1 copper chaperone, which ferries copper ions through the cell while binding them tightly so they cannot drift toward mitochondria. Previous work had established that ATOX1 can suppress cuproptosis and support NSCLC proliferation, but the upstream controls that determine how much ATOX1 a tumor makes remained murky. The new study set out to find those controls, reasoning that any molecule keeping ATOX1 abundant might itself be a promising drug target for unlocking copper-mediated death in lung tumors.

The investigators began with IGF2BP2, also known as IMP3, a member of the insulin-like growth factor 2 mRNA-binding protein family. IGF2BP2 is a reader of N6-methyladenosine, or m6A, the most common chemical mark on messenger RNAs in mammalian cells. The m6A tag, deposited on adenosine bases by writer enzymes, alters the fate of the mRNA carrying it, influencing how long the transcript survives before being chewed up by cellular recycling machinery. Reader proteins such as IGF2BP2 recognize the mark and often shield the transcript from degradation, boosting production of the encoded protein. Using RNA immunoprecipitation, the team showed that IGF2BP2 binds directly to the coding sequence of the ATOX1 mRNA, and they pinpointed a specific m6A site at position 261 within that coding region as the anchor point.

The binding is not casual. When the researchers chased ATOX1 mRNA decay after blocking new transcription with actinomycin D, transcripts associated with IGF2BP2 persisted far longer than they did in the protein’s absence, translating into more ATOX1 protein and, critically, more copper-sequestering capacity. To prove the interaction depended on the physical architecture of the reader, the team engineered mutant versions of IGF2BP2 lacking its KH domains, the helix-loop structures that grip RNA. Rescue experiments showed that the KH3 and KH4 domains in particular were indispensable: without them, IGF2BP2 could no longer stabilize the ATOX1 message, ATOX1 levels fell, and the cells became far more susceptible to cuproptosis triggered by elesclomol, a copper ionophore that ferries the metal into cells.

Functional assays tied the molecular details to cancer behavior. When IGF2BP2 was abundant, NSCLC cells proliferated robustly in cell-counting, colony-formation and Transwell assays that measure growth, long-term reproductive capacity and invasive migration, and they shrugged off elesclomol-copper treatment. When IGF2BP2 was depleted, or when its RNA-binding domains were disabled, copper levels inside the cells rose, mitochondrial stress mounted, and the malignant phenotypes collapsed. In short, IGF2BP2 was acting as a survival factor precisely because it kept the copper chaperone ATOX1 in plentiful supply, denying copper access to its mitochondrial killing targets.

That raised the question of what keeps IGF2BP2 itself alive. Proteins marked with ubiquitin chains are typically dragged to the proteasome for destruction, and the study found that IGF2BP2 carries such ubiquitin tags. Enter USP11, a deubiquitinating enzyme previously implicated in several cancers for stabilizing other pro-growth proteins. Through co-immunoprecipitation experiments, the researchers demonstrated that USP11 physically associates with IGF2BP2 and snips off its ubiquitin marks, dramatically extending the protein’s half-life, a result confirmed by treating cells with cycloheximide to halt new protein synthesis and watching how fast existing IGF2BP2 disappeared. Immunofluorescence microscopy showed the two proteins co-localizing within cells, consistent with a genuine partnership rather than a biochemical accident.

The consequences of this stabilization were decisive. In NSCLC cells with high USP11, IGF2BP2 accumulated, ATOX1 mRNA and protein climbed, intracellular free copper dropped, and cuproptosis induced by elesclomol was blunted, fueling unchecked proliferation. Silencing USP11 reversed every one of those effects, restoring the cells’ sensitivity to copper-driven death. To see whether the axis mattered beyond the dish, the team established a subcutaneous xenograft model, implanting human NSCLC cells into mice. Tumors expressing the intact USP11-IGF2BP2-ATOX1 circuit grew aggressively, while disrupting the axis suppressed tumor growth, findings the authors interpret as evidence that the pathway promotes NSCLC progression in living tissue by suppressing cuproptosis.

The study joins a rapidly expanding literature linking RNA modifications to copper biology. Other groups have shown that m6A marks on the mRNA encoding the lipoyltransferase FDX1, another key player in cuproptosis, can determine whether gastric cancer cells succumb to copper stress, and that cuproptosis-related genes can serve as prognostic markers in lung cancer patients. What distinguishes the new work is the completeness of the regulatory chain it documents: a deubiquitinase that stabilizes an m6A reader that stabilizes a copper chaperone that neutralizes the very metal that would otherwise kill the cell. Each link is a potential intervention point, and the authors highlight USP11 as especially attractive, since inhibiting it would collapse the entire protective cascade at its source.

Cautions remain before the discovery reaches the clinic. Deubiquitinating enzymes participate in many cellular processes, and USP11 has been reported to stabilize other proteins in different cancers, so any inhibitor would need careful calibration to avoid collateral damage. Nor is it yet clear how the USP11-IGF2BP2-ATOX1 axis is dysregulated in human NSCLC specimens, how it interacts with established treatments such as EGFR inhibitors and immunotherapy, or whether copper-based nanomedicines and cuproptosis inducers now in preclinical development would synergize with USP11 blockade. Nevertheless, by revealing how lung cancer cells quietly metabolize away a whole category of cell death, the study gives researchers a detailed map of the enemy’s defenses and a tantalizing strategy for tearing them down.

Subject of Research: Regulation of cuproptosis by the USP11-IGF2BP2-ATOX1 axis in non-small cell lung cancer

Article Title: USP11 inhibits cuproptosis in non-small cell lung cancer by deubiquitinating IGF2BP2 to enhance the stability of m6A-modified ATOX1 mRNA

Article References: USP11 inhibits cuproptosis in non-small cell lung cancer by deubiquitinating IGF2BP2 to enhance the stability of m6A-modified ATOX1 mRNA. (n.d.). https://doi.org/10.1007/s00438-026-02531-y

Image Credits: AI Generated

DOI: 10.1007/s00438-026-02531-y

Keywords: cuproptosis, non-small cell lung cancer, USP11, IGF2BP2, ATOX1, m6A, deubiquitination, copper metabolism, RNA-binding protein, mRNA stability, cancer therapy, elesclomol