Biology subjects

Rodriguez-Berriguete, G.

Publications and source records attributed to Rodriguez-Berriguete, G..

4 recordsLinked to original sources

bioRxiv2025

SHLD2 loss is a synthetic vulnerability to Polθ inhibition combined with radiotherapy

DNA polymerase theta (Pol{theta}) plays a crucial role in the repair of DNA double-strand breaks (DSBs) by microhomology-mediated end joining (MMEJ). We previously demonstrated that Pol{theta} inhibition (Pol{theta}i) is an effective and well-tolerated approach to sensitise tumours to radiotherapy (RT). Here, we profiled 54 cancer cell lines and found that Pol{theta}i induces significant radiosensitisation in most models, though with marked variability not explained by indicators of Pol{theta} activity. To pinpoint molecular determinants of radiosensitisation by Pol{theta}i, we performed a CRISPR knockout screen which revealed loss of the TP53BP1/Shieldin pathway component SHLD2 (FAM35A) as a vulnerability to Pol{theta}i combined with RT. We demonstrated that SHLD2 loss not only increases sensitivity to RT alone, but also enhances the radiosensitising effect of Pol{theta}i, both in vitro and in vivo. Importantly, we found that SHLD2 is deleted in a subset of human prostate cancers, often co-occurring with PTEN loss, an adverse prognostic factor. Furthermore, we show that SHLD2-deficient cancer cells are more reliant on Pol{theta} to prevent DSB accumulation and chromosomal instability. In summary, we discovered SHLD2 loss as a novel collateral vulnerability that can be exploited through combined treatment with Pol{theta}i and RT.

cancer biology↗

bioRxiv2024

UPR-induced intracellular C5aR1 promotes adaptation to the hypoxic tumour microenvironment by regulating tumour cell fate

Dysregulation of the C5a-C5a receptor 1 (C5aR1) signalling axis underlies inflammation and immune-driven pathology. C5aR1 was traditionally thought to be primarily expressed on the cell membrane, although recent reports indicate the importance of intracellular C5aR1 expression for the inflammatory effector functions of various cell types. However, the mechanisms regulating C5aR1 expression and localisation remain unclear. In tumours with an immunosuppressive microenvironment, we recently found robust C5aR1 expression on malignant epithelial cells, highlighting potential tumour cell-specific functions. Here, we show that hypoxia, a hallmark of immunosuppressive microenvironments, induces C5aR1 expression in an unfolded protein response (UPR)-dependent manner via enhanced endoplasmic reticulum stress. Furthermore, hypoxia drives endocytosis, relocating C5aR1 from the cell membrane to the intracellular compartment. By genetically and pharmacologically targeting the C5a/C5aR1 axis, we show that C5aR1 mediates cellular adaptation to hypoxia by regulating processes associated with cell fate, including autophagy and apoptosis. In line with hypoxia-induced intracellular C5aR1 pools, pharmacological inhibition of C5aR1, particularly with cell-permeable small molecule inhibitors, significantly reduces tumour cell survival. These results suggest that the dysregulated C5a/C5aR1 axis and the hypoxia-induced shift in C5aR1 localisation, support tumour cell survival and provide new insights into therapeutic strategies for targeting the C5a/C5aR1 axis.

cancer biology↗

bioRxiv2022

Small-molecule Polθ inhibitors provide safe and effective tumor radiosensitization in preclinical models

DNA polymerase theta (Pol{theta}) is a DNA repair enzyme critical for microhomology mediated end joining (MMEJ). Pol{theta} has limited expression in normal tissues but is frequently overexpressed in cancer cells and, therefore, represents an ideal target for tumor-specific radiosensitization. Here, we show that ART558 and ART899, two novel and specific allosteric inhibitors of the Pol{theta} DNA polymerase domain, potently radiosensitize tumor cells, particularly when combined with fractionated radiation. Importantly, normal fibroblasts are not radiosensitized by Pol{theta} inhibition. Mechanistically, we show that the radiosensitization caused by Pol{theta} inhibition is most effective in replicating cells and is due to impaired DNA damage repair. We also show that radiosensitization is still effective under hypoxia, suggesting that these inhibitors may help overcome hypoxia-induced radioresistance. In addition, we describe for the first time ART899 and characterize it as a potent and specific Pol{theta} inhibitor with improved metabolic stability. In vivo, the combination of Pol{theta} inhibition using ART899 with fractionated radiation is well tolerated and results in a significant reduction in tumor growth compared to radiation alone. These results pave the way for future clinical trials of Pol{theta} inhibitors in combination with radiotherapy.

cancer biology↗

bioRxiv2020

SPRTN protease and SUMOylation coordinate DNA-protein crosslink repair to prevent genome instability

DNA-protein crosslinks (DPCs) are a specific type of DNA lesions where proteins are covalently attached to DNA. Unrepaired DPCs lead to genomic instability, cancer, neurodegeneration and accelerated ageing. DPC proteolysis was recently discovered as a specialised pathway for DPC repair. The DNA-dependent SPRTN protease and 26S proteasome emerged as as two independent proteolytic systems for DPC repair. DPCs are also repaired by homologous recombination (HR), a canonical DNA repair pathway. While studying the role of ubiquitin and SUMO in DPC repair, we identified mutually exclusive signalling mechanisms associated with DPC repair pathway choice. DPC modification by SUMO-1 favours SPRTN proteolysis as the preferred pathway for DPC repair. DPC SUMOylation counteracts DPC ubiquitination, which promotes DNA breaks and the switch to HR. We propose that modification of DPCs by SUMO-1 promotes SPRTN proteolysis, which is essential for DPC removal to prevent DNA replication defects, chromosomal recombination and genomic instability.

cell biology↗