Biology subjects

Casanova, A.

Publications and source records attributed to Casanova, A..

5 recordsLinked to original sources

bioRxiv2026

Persistent TOP1 cleavage complexes in drug-tolerant cells drive adaptive resistance to EGFR-targeted therapies in lung cancer

Resistance to targeted cancer therapies often arises from drug-tolerant cells (DTCs), which survive treatment by entering a non-proliferative state. Over time, DTCs can acquire mutations that contribute to cell reproliferation, but how non-proliferating DTCs accumulate such mutations remains unclear. Here, we show that EGFR inhibition in EGFR-mutated lung cancer transiently downregulates tyrosyl-DNA phosphodiesterase 1 (TDP1), a repair enzyme that resolves abortive topoisomerase I cleavage complexes (TOP1ccs). In DTCs, elevated reactive oxygen species promote TOP1cc trapping, while TDP1 downregulation impairs their repair, driving TOP1cc accumulation, resistance mutation acquisition, and cell reproliferation. We further find that TDP1 expression is absent in approximately 25% of EGFR-mutated lung cancers. In TDP1-deficient cells, combining EGFR inhibition with a sublethal concentration of topotecan, which further increases TOP1ccs, abolishes cell reproliferation. Together, these findings establish persistent TOP1cc accumulation as a driver of therapy-induced mutagenesis linking drug tolerance to adaptive resistance, and reveal TDP1 loss as a targetable vulnerability in EGFR-mutated lung cancers. TeaserA drug-tolerant state that fuels mutagenesis and resistance also creates a transient vulnerability.

molecular biology↗

bioRxiv2026

Potassium-Selective Nanoelectrode Arrays for Single-Cell Profiling of human iPSC-Derived Cardiomyocytes

Potassium ion (K) dynamics are central to cardiac electrophysiology, with early disruptions in K flux often preceding arrhythmia and contractile dysfunction. However, current sensing technologies, such as patch-clamp, Microelectrode arrays (MEAs), and fluorescent indicators, either lack chemical specificity for K or are unsuitable for long-term, single-cell analysis. Conventional ion-selective electrodes (ISEs), while more selective, are limited by bulk-phase design and poor spatial resolution. To address these limitations, we present KINESIS (K-Ion Nano-Electrode Selective Interface System), a nanofabricated, cell-compliant platform that enables direct, label-free potentiometric measurement of K gradients with subcellular precision. KINESIS features high-aspect-ratio nanopillars coated with a valinomycin-based K recognition membrane, forming a stable, non-invasive interface with human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). This architecture allows localized, Nernstian sensing of K efflux or depletion without disrupting cell membranes. Pharmacological validation shows distinct potential shifts in response to caffeine and ouabain. KINESIS thus offers a highly selective, spatially resolved approach for studying K handling in cardiotoxicity screening and patient-specific disease modeling.

pharmacology and toxicology↗

bioRxiv2022

Farnesyltransferase inhibition overcomes the adaptive resistance to osimertinib in EGFR-mutant NSCLC

Drug-tolerant "dormant" cells (DTC) have emerged as one of the major non-genetic mechanisms driving resistance to targeted therapy in lung cancer, although the sequence of events leading to entry and exit from dormancy remain poorly described. Here, we performed real-time monitoring of the cell cycle dynamics during the adaptive response to Epidermal Growth Factor Receptor tyrosine kinase inhibitors (EGFR-TKi) in a panel of EGFR-mutated lung cancer cell lines. We identified a rare population of S/G2 cycling cells (referred to as early escapers) that emerged in the first hours of treatment amongst stably arrested and progressively dying G1 cells. We determined that early escapers evolved from a non-proliferative differentiated alveolar type 1 (AT1) phenotype which was invariably associated with cytoskeletal remodeling through Rho/ROCK pathway activation. Using a panel of Rho-pathway inhibitors, we found that the farnesyltransferase inhibitor tipifarnib induced a complete clearance of EGFR-TKi-induced DTC thus fully preventing relapse in vitro. Using a xenograft model and a PDX model of EGFRL858R/T790M lung cancer, co-treatment with tipifarnib prevented relapse to osimertinib for up to 6 months with no evidence of toxicity. Among the farnesylated proteins regulated during osimertinib treatment, concomitant inhibition of RHOE and LaminB1 was sufficient to recapitulated FTIs effect. Osimertinib and tipifarnib co-treatment completely suppressed the emergence of AT1 phenotype, prevented mitosis of S/G2-treated cells and increased the apoptotic response through activation of ATF4-CHOP-dependent Integrated Stress Response (ISR) pathway. Our data strongly support the use of tipifarnib in combination with osimertinib in patients to effectively and durably prevent relapse.

cancer biology↗

bioRxiv2020

Aberrant RNA methylation triggers recruitment of an alkylation repair complex

A critical question in genome stability is the nature of the chemical damage responsible for repair activation. We previously reported a novel pathway specifically activated during alkylation damage in human cells, where the E3 ubiquitin ligase RNF113A mediates the recruitment of the ASCC repair complex. Yet the mechanistic basis for the alkylation damage selectivity of this pathway remains unclear. Here, we demonstrate that RNA but not DNA alkylation is the initiating signal for this process. Aberrantly methylated RNA is sufficient to recruit ASCC, while an RNA dealkylase suppresses ASCC recruitment during chemical alkylation. This aberrant RNA methylation causes transcriptional repression in a manner dependent on the ASCC complex. We show that an alkylated pre-mRNA, or an RNA containing a single damaged base, is sufficient to activate RNF113A E3 activity in a phosphorylation-dependent manner. Together, our work identifies an unexpected role for RNA damage in eliciting a DNA repair response, and suggests that RNA may serve as the "canary in the coal mine" for sensing alkylation damage.

molecular biology↗

bioRxiv2018

A role for VPS35 in Brucella intracellular replication revealed by genome-wide siRNA screening

Brucella, the causing agent of brucellosis, is a major zoonotic pathogen with worldwide distribution. Brucella resides and replicates inside infected host cells in membrane-bound compartments called BCVs (Brucella-containing vacuoles). Following uptake, Brucella resides in eBCVs (endosomal BCVs) that gradually mature from early to late endosomal features. Through a poorly understood process that is key to the intracellular lifestyle of Brucella, the eBCV escapes fusion with lysosomes by transitioning to the rBCV (replicative BCV), a replicative niche directly connected to the endoplasmic reticulum (ER). Despite the notion that this complex intracellular lifestyle must depend on a multitude of host factors, a holistic view on which of these components control Brucella cell entry, trafficking and replication is still missing. Here we used a systematic cell-based siRNA knockdown screen in HeLa cells infected with Brucella abortus and identified 425 components of the human infectome for Brucella infection. These include multiple components of pathways involved in central processes such as cell cycle, actin cytoskeleton dynamics or vesicular trafficking. Using assays for pathogen entry, knockdown complementation and co-localization at single-cell resolution, we identified the requirement of the VPS retromer for Brucella to escape the lysosomal degradative pathway and to establish its intracellular replicative niche. We thus validated a component of the VPS retromer as novel host factor critical for Brucella intracellular trafficking. Further, our genome-wide data shed light on the interplay between central host processes and the biogenesis of the Brucella replicative niche.\n\nImportanceWith >300,000 new cases of human brucellosis annually, Brucella is regarded as one of the most important zoonotic bacterial pathogen worldwide. The causing agent of brucellosis resides inside host cells within vacuoles termed Brucella containing vacuoles (BCVs). Although few host components required to escape the degradative lysosomal pathway and to establish the ER-derived replicative BCV (rBCV) have already been identified, the global understanding of this highly coordinated process is still partial and many factors remain unknown. To gain a deeper insight into these fundamental questions we performed a genome-wide RNA interference (RNAi) screen aiming at discovering novel host factors involved in the Brucella intracellular cycle. We identified 425 host proteins that contribute to Brucella cellular entry, intracellular trafficking, and replication. Together, this study sheds light on previously unknown host pathways required for the Brucella infection cycle and highlights the VPS retromer components as critical factors for the establishment of the Brucella intracellular replicative niche.

microbiology↗