Biology subjects

Gotorbe, C.

Publications and source records attributed to Gotorbe, C..

3 recordsLinked to original sources

bioRxiv2025

Glucocorticoids Modulate mRNA Translation Fate Through P-Body Dynamics

Processing bodies (P-bodies) are cytoplasmic, membraneless organelles that play a key role in regulating RNA translation. To identify new pathways controlling their formation, we conducted a Food and Drug Administration (FDA)-approved drug screen. We found that glucocorticoids, among the most prescribed medicines, significantly increase P-body numbers across diverse epithelial cell types. This effect was fully reversible after glucocorticoid withdrawal, illustrating the adaptive dynamics of P-bodies. Using genetic invalidation and rescue approaches, we demonstrated that this accumulation requires the Glucocorticoid Receptor alpha isoform. P-body accumulation was associated with the sequestration of P-body-specific-targeted mRNAs, altering their translation yield. Notably, this translational regulation depends on transcript sequence features rather than abundance, with AU-rich mRNA transcripts being sequestered and GC-rich mRNAs preferentially translated under glucocorticoid treatment. Furthermore, we linked the decrease of LSM14B, a negative regulator of P-bodies, under glucocorticoid treatment to P-body reshaping. Our results reveal that, beyond their known transcriptional activity, prolonged exposure to glucocorticoids influences mRNA post-transcription and translation through a nucleotide composition-based mechanism.

cell biology↗

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↗

bioRxiv2023

Integrin-alpha V beta 3 is a fundamental factor in medulloblastoma tumorigenicity and radioresistance: A new game for an old player

Medulloblastoma (MB) is the most frequent solid tumor in children, localized in the brains posterior fossa. Its standard of care comprises maximal resection surgery followed by craniospinal irradiation and chemotherapy. Despite a long-term survival rate of 70%, wide disparities among patients have been observed. Relevant targets for naive and recurrent MB are urgently needed. Primary and recurrent MBs are characterized by aggressive invasion into surrounding brain tissue, active angiogenesis, and radioresistance. Integrin-v{beta}3 was a major driver of these features in glioblastoma. Nevertheless, such observations have not yet been reported in MB. Integrin-v{beta}3 was found to be expressed in a subset of MB patients. We investigated the role of integrin-v{beta}3 using MB-derived cell lines with {beta}3-subunit depletion or overexpression both in vitro and in vivo. Radioresistant MB cell lines were generated and showed increased integrin-v{beta}3 expression, which correlated with increased susceptibility to pharmacological integrin-v{beta}3 inhibition with cilengitide, a competitive ligand mimetic. Finally, we conducted single-photon emission computed tomography (SPECT)/magnetic resonance imaging (MRI) studies on orthotopic models using a radiolabeled integrin-v{beta}3 ligand (99mTc-RAFT-RGD). This approach offers the prospect of a novel predictive imaging modality in MB. Altogether, our data pave the way for SPECT/MRI-based selection of a subpopulation of MB patients eligible for integrin-v{beta}3-directed therapies. SIGNIFICANCEThis study demonstrates integrin-v{beta}3s fundamental role in MB tumorigenicity and radioresistance and the effect of its expression on cilengitide functional activity.

cancer biology↗