DNA-protein crosslinks (DPCs) are one of the most complex and deleterious forms of DNA damage. DPCs arise from the stabilization of covalent enzyme-DNA intermediates, such as topoisomerase cleavage complexes, or from exposure to bifunctional crosslinking agents, and they differ in protein identity, DNA context and chemical linkage. Because of their bulky nature, DPCs obstruct essential chromatin processes such as DNA replication and transcription, making their timely removal by dedicated DPC repair pathways crucial for genome stability and cellular homeostasis. In this Review, we discuss the origin and properties of the major classes of DPCs. We also describe key enzymes involved in DPC repair, with a particular focus on the proteasome and the specialized DPC protease SPRTN. Next, we synthesize recent advances in the understanding of proteolytic DPC repair across replication-coupled, transcription-coupled and global genome repair pathways and explain how these pathways converge on ubiquitylation of the crosslinked protein to license proteolysis by the proteasome or SPRTN. Finally, we discuss how defective DPC proteolysis contributes to genome instability, premature ageing and cancer predisposition.

The systemic treatment landscape of unresectable hepatocellular carcinoma has been transformed by immune-checkpoint inhibitor (ICI)-based regimens. These advances have led to efforts to combine ICIs with locoregional therapies (LRTs), particularly transarterial chemoembolization, transarterial radioembolization and external beam radiotherapy, in an attempt to improve tumour control and extend the benefits of ICIs to patients with intermediate-stage disease. The rationale for this combination approach is provided by the ability of LRTs to induce immunogenic cell death and tumour antigen release and to reprogramme the immunosuppressive tumour microenvironment. Five phase III trials have thus far shown improvements in progression-free survival and objective response rates with regimens combining ICIs with transarterial chemoembolization. Early-phase and real-world data also support the combination of ICIs with transarterial radioembolization or external beam radiotherapy, particularly in selected patients with focal disease unsuitable for embolization or portal vein tumour thrombosis. However, various challenges remain, including patient selection and therapy sequencing, response assessment, and the growing difficulties in demonstrating survival advantages in the context of widespread post-progression crossover and effective subsequent therapies. In this Review, we describe the biological rationale, summarize the clinical evidence and discuss future directions for trial design, imaging and biomarker-driven patient selection in the integration of LRTs with immune-based regimens for patients with unresectable hepatocellular carcinoma.

Cytotoxic CD8[+] T cells induce target-cell death by producing effector proteases called granzymes. Most granzymes, as exemplified by granzyme B, induce apoptosis by cleaving intracellular substrates after delivery to target cells via the immunological synapse. By contrast, it was recently shown that granzyme K (GZMK), which is selectively expressed by a unique population of CD8[+] T cells, activates the complement cascade instead of executing direct cytotoxicity. In this Perspective, we summarize recent data on complement activation by CD8[+] T cell-derived GZMK that points to a novel lymphocyte-mediated pathway of complement activation. We present evidence that GZMK-expressing CD8[+] T cells have distinct pro-inflammatory effects in tissues and discuss their involvement in an array of chronic and inflammatory diseases. Furthermore, we propose the concept of 'tissue histotoxicity' as a core feature of GZMK-expressing CD8[+] T cells. We suggest this as a defence strategy that enables the immune system to act on a tissue neighbourhood instead of targeting one cell at a time. Finally, we discuss the possibility of GZMK expression being a heritable trait in subsets of memory T cells.