New study frames altered protein modifications as cancer drivers

Cancer has often been explained through mutations in deoxyribonucleic acid (DNA) or changes in ribonucleic acid (RNA), but these layers do not fully explain why tumors with similar genetic profiles can behave differently. Proteins are the working machinery of cells, and PTMs can rapidly change protein activity, stability, location, and interactions. In cancer, these modifications are frequently rewired, reshaping signaling, metabolism, chromatin organization, immune escape, and drug resistance. Many studies still focus on one modification, enzyme, or pathway at a time, leaving the broader regulatory system unclear. Based on these challenges, an in-depth investigation of PTM systems as integrated cancer regulatory networks is needed.

In a review published (DOI: 10.1093/pcmedi/pbag014) on May 1, 2026, in Precision Clinical Medicine, researchers from the National Clinical Research Center for Geriatrics and Department of Laboratory Medicine, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, and the Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, summarized current evidence linking dysregulated PTM systems to cancer biomarkers and therapeutic targets. The review, titled "Protein modification systems as cancer biomarkers and therapeutic targets," frames PTMs as dynamic protein-control systems that connect cancer mechanisms with clinical decision-making.

The review highlights two major layers of PTM dysregulation in cancer. First, individual PTMs can directly drive tumor initiation, metastasis, immune evasion, and therapeutic resistance by altering key proteins and pathways. Phosphorylation can amplify cancer-promoting signaling; acetylation and methylation can reshape chromatin and transcription; ubiquitination and SUMOylation can control protein stability; and glycosylation can influence membrane signaling, immune recognition, and circulating biomarkers. Emerging PTMs, including lactylation, palmitoylation, β-hydroxybutyrylation, citrullination, and malonylation, further expand this regulatory landscape. Second, the authors emphasize PTM crosstalk, in which different modifications cooperate or compete on the same protein or pathway. This network-level rewiring can stabilize malignant signaling, weaken tumor-suppressive programs, reprogram metabolism, remodel chromatin, and support immune checkpoint activity involving programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1). Such combined PTM signatures may explain patient heterogeneity better than single molecular markers.

The authors said the central message is that cancer should be viewed not only as a disease of altered genes, but also as a disease of altered protein regulation. They said PTMs provide a dynamic and functional view of tumor cell state, complementing genomic and transcriptomic information and, in some contexts, offering improved association with treatment response and immune regulation. By analyzing PTM writers, erasers, readers, substrates, and modification sites as an integrated regulatory network, researchers may improve the discovery of candidate biomarkers and reveal signaling dependencies or potentially targetable vulnerabilities associated with tumor progression.

The clinical implications are broad. PTM-based biomarkers may improve early detection, molecular subtyping, prognosis, and prediction of therapy response, especially when combined with quantitative proteomics, spatial profiling, low-input workflows, and machine learning. Examples reviewed include glycosylated alpha-fetoprotein (AFP), phosphorylated extracellular signal-regulated kinase (ERK), exosomal PD-L1, phosphorylated SHP2 (p-SHP2), and deglycosylated PD-L1. Therapeutically, PTM-related strategies are already represented by kinase inhibitors, histone deacetylase (HDAC) inhibitors, bromodomain and extraterminal (BET) inhibitors, ubiquitin-proteasome system modulators, and epigenetic therapies. The review concludes that precision oncology may increasingly move from single-marker testing toward system-level PTM maps that show how tumors adapt—and where they can be stopped.