Biology subjects

Pastor, J.

Publications and source records attributed to Pastor, J..

5 recordsLinked to original sources

bioRxiv2025

The tyrosine kinase inhibitor GNF-7 targets senescent cells through allosteric activation of GCN2.

The one-two-punch approach refers to the sequential administration of two different chemotherapies, the second of which targets cancer cells that resisted the initial treatment. To find such a second punch, we performed a chemical screen to find drugs that are preferentially toxic for cells with an activated DNA damage response (DDR). This screen identified the tyrosine kinase inhibitor GNF-7 as a top hit. Subsequent work revealed that GNF-7 is a potent senolytic, even when senescence is triggered by therapies that do not activate the DDR. Consistently, GNF-7 is highly efficacious to kill cancer cells previously treated with CDK4/6 inhibitors, including in patient-derived organoids and mouse xenografts. Surprisingly, the senolytic effect of GNF-7 is not mediated by the inhibition of a tyrosine kinase (TK), but rather by the activation of GCN2, an effect previously reported for other TK inhibitors. Together, our study reports the discovery of a novel senolytic agent that strongly synergizes with CDK4/6 inhibitors when applied sequentially and expands our understanding of the mechanisms behind the anticancer effects of TK inhibitors.

cancer biology↗

bioRxiv2024

SETD8 inhibition targets cancer cells with increased rates of ribosome biogenesis

SETD8 is a methyltransferase that is overexpressed in several cancers, which monomethylates H4K20 as well as other non-histone targets such as PCNA or p53. We here report novel SETD8 inhibitors, which were discovered while trying to identify chemicals that prevent 53BP1 foci formation, an event mediated by H4K20 methylation. Consistent with previous reports, SETD8 inhibitors induce p53 expression, although they are equally toxic for p53-deficient cells. Thermal stability proteomics revealed that the compounds had a particular impact on nucleoli, which was confirmed by fluorescent and electron microscopy. Similarly, Setd8 deletion generated nucleolar stress and impaired ribosome biogenesis, confirming that this was an on-target effect of SETD8 inhibitors. Furthermore, a genome-wide CRISPR screen identified an enrichment of nucleolar factors among those modulating the toxicity of SETD8 inhibitors. Accordingly, the toxicity of SETD8 inhibitors correlated with MYC or mTOR activity, key regulators of ribosome biogenesis. Together, our study provides a new class of SETD8 inhibitors and a novel biomarker to identify tumors most likely to respond to this therapy.

cancer biology↗

bioRxiv2024

Identification of novel and distinct FGF23 signaling in a Klotho-dependent and -independent manner

Fibroblast growth factor 23 (FGF23) levels are highly elevated in patients with chronic kidney disease (CKD); however, whether it serves merely as a biomarker or actively contributes to kidney inflammation remains unclear. Full-length FGF23 is cleaved into C-terminal FGF23 (cFGF23), which acts as a natural antagonist of FGF23 by inhibiting its binding to the FGF receptor (FGFR) and the co-receptor Klotho. Here, we show that chronically elevated FGF23 levels in a mouse model Hyp-Duk cause sustained-ERK signaling and an inflammatory and immune responses in the kidney. cFGF23, delivered via adeno-associated virus (AAV) gene therapy, successfully mitigated renal sustained-ERK signaling and inflammatory and immune responses in Hyp-Duk mice. On the other hand, acute physiological FGF23 levels in vitro elicited transient-ERK signaling with the expression of canonical early-ERK targets (EGR1, JUNB, FOSB). Consistent with in vivo findings, prolonged pathological FGF23 treatment in-vitro revealed sustained-ERK signaling with upregulation of late-ERK targets (ETV4/5, SPRED1/2, SPRY2/4) and unique inflammatory and immune gene signatures. These effects were significantly mitigated by FGFR and ERK inhibitors, as well as by recombinant cFGF23 treatment. In summary, chronically high levels of FGF23 induce kidney inflammation through the FGFR-Klotho complex and sustained-ERK activation, which are successfully mitigated by cFGF23 gene therapy. TRANSLATIONAL STATEMENTChronically elevated circulating levels of Fibroblast Growth Factor 23 (FGF23) are strongly associated with inflammation and adverse outcomes in chronic kidney disease, but the underlying mechanisms remain poorly understood. Our study identifies sustained activation of the ERK signaling pathway as a key mechanism by which chronic FGF23 elevation induces inflammatory transcriptional programs in the kidney. Importantly, gene therapy using the C-terminal fragment of FGF23 (cFGF23) mitigates these effects, highlighting a potential therapeutic strategy to counteract the excessive FGF23 signaling.

physiology↗

bioRxiv2020

A drug-screening platform based on organotypic cultures identifies vulnerabilities to prevent local relapse and treat established brain metastasis

Exclusion of brain metastases from clinical trials is a major cause of the limited therapeutic options for this growing population of cancer patients. Here, we report a medium-throughput drug-screening platform (METPlatform) based on organotypic cultures that allows to evaluate inhibitors against metastases growing in situ. By applying this approach to brain metastasis, we identified several hits from a library of FDA approved inhibitors and others being tested in clinical trials. A blood-brain barrier permeable HSP90 inhibitor showed high potency against mouse and human brain metastases at clinically relevant stages of the disease, including a novel model of local relapse after neurosurgery. Furthermore, in situ proteomic analysis applied to organotypic cultures with metastases treated with the chaperone inhibitor revealed novel biomarkers in human brain metastasis and actionable mechanisms of resistance. Our work validates METPlatform as a potent resource for metastasis research integrating drug-screening and unbiased omic approaches that is fully compatible with human samples. We envision that METPlatform could be established as a clinically relevant strategy to personalize the management of metastatic disease in the brain and elsewhere. SummarySystemic spread of cancer continues to be the key aspect associated with lethality. In this publication, Zhu et al. describes a drug-screening platform specifically designed to study vulnerabilities of metastasis when colonizing secondary organs and demonstrates its value in difficult-to-treat brain metastasis using new models and patient-derived samples.

cancer biology↗

bioRxiv2019

Age-linked heterogeneity among oligodendrocyte precursor cells in the cerebral cortex of mice and human

Oligodendrocyte precursor cells (OPCs) are responsible for spontaneous remyelination after a demyelinating lesion. They are present in large parts of the mouse and human central nervous system, both during development and in adulthood, yet how their physiological behaviour is modified throughout life remains largely unknown. Moreover, the activity of adult human OPCs is still not fully understood. Significantly, most of the molecules involved in OPC-mediated remyelination are also involved in their development, a phenomenon that may be clinically relevant. In this article, we have systematically analyzed the intrinsic properties of OPCs isolated from the cerebral cortex of neonatal, postnatal and adult mice, as well as those recovered from neurosurgical adult human cerebral cortex tissue. We also analyze the response of these cells to two molecules that have known effects on OPC biology during development and that are overexpressed in individuals with Multiple Sclerosis (MS): FGF2 and anosmin-1. By analyzing intact OPCs for the first time with H-1 HR-MAS NMR spectroscopy, we show that these cells behave distinctly and that they have different metabolic patterns in function of their stage of maturity. Moreover, their response to FGF-2 and anosmin-1 differs in relation to their developmental stage and in function of the species. Our data reveal that the behaviour of adult human and mouse OPCs differs in a very dynamic way that should be considered when testing drugs and for the proper design of effective pharmacological and/or cell therapies for MS.

neuroscience↗