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Grimaldi, M.

Publications and source records attributed to Grimaldi, M..

13 recordsLinked to original sources
bioRxiv2026

The Pregnane X Receptor (PXR) contributes to phenotypic plasticity and modulates the sensitivity to targeted therapies in melanoma

The challenge in treating advanced metastatic melanoma lies in the development of therapeutic resistance and the risk of recurrence. Understanding the mechanisms underlying tumor adaptation to treatment is therefore crucial, as they can directly influence therapeutic efficacy. Tolerance to targeted therapies may be influenced by drug transport and metabolism within tumors, processes regulated by numerous genes under the transcriptional control of the nuclear receptor PXR (Pregnane X Receptor, NR1I2). We revealed, for the first time, significant and heterogeneous expression of PXR in human melanoma samples. We previously showed that PXR can be activated by BRAF inhibitors (BRAFi), but not by MEK inhibitors (MEKi), which are currently used in combination for the treatment of BRAF-V600E-mutated melanoma. Here, we investigated whether PXR expression influences melanoma cell sensitivity to MAPK pathway inhibitors. Using BRAF-mutated human melanoma cell lines, we showed that stable PXR expression sensitizes cells to combined BRAFi/MEKi treatment. Transcriptomic analysis further revealed that PXR expression is associated with the upregulation of several phenotypic markers, with MITF identified as a major regulator in untreated PXR-overexpressing cells. These findings suggest that PXR promotes a shift toward a melanocytic phenotype, which is associated with increased sensitivity to BRAFi/MEKi treatment. Characterization of the PXR-associated transcriptional signature in melanoma may therefore have translational value for identifying patients more likely to benefit from targeted therapies and support the development of PXR as a predictive biomarker of therapeutic response.

cancer biology↗
bioRxiv2026

The protective effect of NGF mutant CHF6467 in SH SY5Y cells exposed to Aβ(1-42): a pharmacometabolomic approach

Nerve Growth Factor (NGF) supports neuronal survival, plasticity, and growth by binding to p75NTR and TrkA receptors. There is a strong link between NGF and the cholinergic hippocampus, and changes in NGF pathways are observed in Alzheimer's disease (AD). Research shows NGF's neuroprotective and regenerative effects on cholinergic neurons, with positive results in AD models and clinical studies. However, NGF therapy faces challenges: limited blood-brain barrier crossing and dose-dependent pain. To address pain, a mutated NGF called CHF6467 was developed. Thanks to the R100E mutation, it prevents binding to p75NTR while maintaining TrkA affinity, which helps reduce pain side effects. Understanding CHF6467's mechanism remains a challenge. In this context, untargeted metabolomics is effective for uncovering unforeseen responses, making it suitable for assessing CHF6467's overall effects. Building on our previous research and recognizing the importance of amyloid-{beta} peptide as a critical pathological marker of AD, we used NMR-metabolomics to study the effect of CHF6467 on SH-SY5Y cells. The study examined metabolomic profiles of cells treated with CHF6467, with and without A{beta}(1-42), using NMR. Results show CHF6467 influences the metabolic changes caused by A{beta}(1-42), inducing biochemical effects consistent with the promotion of phospholipid precursors, reduced glutamate excitotoxicity, and restored energy metabolism.

cell biology↗
bioRxiv2026

Neuroblastoma-derived small extracellular vesicles retaincellular identity and adrenergic/mesenchymal state signatures

Neuroblastoma is a heterogeneous pediatric malignancy characterized by distinct genomic subgroups and cell-state plasticity between adrenergic (ADRN) and mesenchymal (MES) phenotypes. While small extracellular vesicles (sEVs) mediate pre-metastatic niche priming, the degree to which sEV proteomes reflect parental genomic and phenotypic identity remains unresolved. Here, we isolated sEVs from six neuroblastoma cell models (IMR-5/75, BE(2)-C, GI-ME-N, CLB-GA, LAN-6, and SK-N-FI) representing three genomic subgroups (MYCN-amplified, TERT-rearranged, and unaltered) using OptiPrep density gradient centrifugation followed by size exclusion chromatography and ultrafiltration. High-resolution mass spectrometry of sEV proteomes revealed that sEVs carry highly reproducible protein signatures that tightly correlate with the parental genomic subgroups. Analyzing paired cell/sEV samples, we demonstrate cell-to-EV concordance of lineage-specific markers: ADRN sEVs selectively enriched L1CAM and dopamine {beta}-hydroxylase (DBH), whereas MES sEVs enriched SERPINE1 and type III collagen (COL3A1). These findings indicate that neuroblastoma-derived sEVs systematically preserve both the genomic landscape and the lineage transdifferentiation states of their cells of origin. This study establishes a robust molecular foundation for utilizing sEV-based proteomics as a surrogate to track cellular plasticity and for studying sEV-mediated microenvironmental remodeling.

cancer biology↗
bioRxiv2025

Analyzing nicotine action against amyloid toxicity by NMR-pharmacometabolomics: an exploratory study.

Alzheimers disease (AD) is the primary neurodegenerative disease spread worldwide. One of the main histopathological hallmarks of AD is amyloid plaque deposition in the brain. Despite some epidemiological studies demonstrating that cigarette smoke is a factor in predisposing people to AD, nicotine, the principal alkaloid of Nicotiana Tobacco, has been widely studied for its ability to improve cognitive performance, both in animal models and in human studies. Several hypotheses have been proposed to explain the mechanism of action underlying the beneficial effect of Nicotine in AD; however, this is still questioned. To have new insights into the molecular mechanism underlying the neuroprotective action of Nicotine in Alzheimers disease, we performed an NMR metabolomic analysis of SH-SY5Y neuroblastoma cells treated with A{beta} (1-42) in the presence of nicotine. Our data show that the neuroprotective action of nicotine resides in its ability to restore the systemic unbalanced metabolism associated with AD. In particular, nicotine reverses most A{beta} (1-42)-induced metabolic impairments, including those related to amino acid metabolism, especially those involved in neurotransmission, as well as alterations in energy metabolism and membrane phospholipid metabolism.

cell biology↗
bioRxiv2025

Distinct 2-phenyl-imidazo pyridine derivatives drive ER degradation and selectively impair proliferation of ER+ breast cancer cells via the aryl hydrocarbon receptor

X15695 is a 2-phenyl-imidazo[1, 2] pyridine derivative identified as an orally active, selective oestrogen receptor (ER) degrader that inhibits the proliferation of ER+ breast cancer cells. Here, we show that X15695 is an aryl hydrocarbon receptor (AHR) ligand that stabilises the AHR more efficiently than its classical ligand, indirubin. X15695 enables AHR to form a complex with the ER, promoting its proteasomal degradation. In the presence of oestradiol, X15695 outperforms the standard of care drug fulvestrant in suppressing the growth of ER+ breast cancer cells, either expressing the wild-type or clinically relevant ER mutant forms (Y537S and D538G), and of patient-derived xenograft organoids established from ER+ tumours. Using computational techniques, we discovered that a low pKa value resulting from electron-withdrawing substituents in the 2-phenyl-imidazo[1, 2] pyridine compounds is a key feature that identify them as potent AHR ligands, leading to the potential discovery of additional derivatives for future therapeutic development.

cancer biology↗
bioRxiv2025

RNase H1 counteracts DNA damage and ameliorates SMN-dependent phenotypes in a Drosophila model of Spinal Muscular Atrophy

Spinal Muscular Atrophy (SMA) is caused by a deficiency of the Survival Motor Neuron (SMN) protein. Mutations in SMN disrupt mRNA splicing and translation, leading to maladaptive changes in transcriptomes, proteomes, neuroinflammation, and metabolism, which drive motor neuron degeneration in SMA patients. Using a Drosophila SMA model, we found that systemic depletion of Smn leads to accumulation of RNA:DNA hybrids (R-loops), increased DNA damage, dysregulation of amino acids and sugar metabolism and activation of the innate immune response, recapitulating key pathological features reported in mammalian models and severe SMA patients. Persistent DNA damage in Smn-deficient flies alters cell proliferation rates in larval brains and induces extensive cell death in the developing eye. Importantly here, we show that stimulating the resolution of RNA:DNA hybrids with transgenic human RNAse H1 prevents the accumulation of DNA damage and attenuates the transcriptome and amino acid alterations induced by Smn depletion, mitigating the Smn-dependent cellular and developmental abnormalities, in Smn-deficient flies. Our data suggest that depletion of Smn causes an accumulation of aberrant transcripts and chronic DNA damage, which--along with the altered metabolomic profiles associated with Smn deficiency--trigger systemic inflammatory responses, ultimately affecting neuronal function and survival.

genetics↗
bioRxiv2024

Exploring Breast Cancer-Related Biochemical Changes in Circulating Extracellular Vesicles Using Raman Spectroscopy

Extracellular vesicles (EVs) are a subgroup of the circulating particles, released by cells in both normal and diseased states, carrying active biomolecules. They have gained significant attention as potential cancer biomarkers, particularly in breast cancer (BC). Previous research showed variations in EVs content and quantity between BC patients and healthy controls (HC). However, studying EVs biochemical profile remains challenging due to their low abundance and complex composition. Additionally, EVs may interact with other plasma components, like lipoproteins (LPs), forming a so called "biomolecular corona" that further complicates their analysis. Here, Raman spectroscopy (RS) is proposed as a fast tool to obtain the biochemical profile of circulating EVs in the context of BC. RS was employed to differentiate various extracellular particles (EPs) in blood, including LPs and EVs. The study also evaluated RSs capability to quantify major classes of biomolecules and compared these results with those obtained by traditional biochemical assays. Finally, compositional differences in large EVs (lEVs) and small EVs (sEVs) were assessed between 30 HC and 34 BC patients. RS revealed the existence of distinct biochemical signatures associated with BC, highlighting increased levels of nucleic acids and lipids in the BC group.

biophysics↗
bioRxiv2022

2,4-Di-tert-butylphenol Induces Adipogenesis in Human Mesenchymal Stem Cells by Activating Retinoid X Receptors

2,4-di-tert-butylphenol (2,4-DTBP) is an important commercial antioxidant and a toxic natural secondary metabolite that has been detected in humans. However, there is scant information regarding its toxicological effects. Here we asked whether 2,4-DTBP is a potential obesogen. Using a human mesenchymal stem cell (MSC) adipogenesis assay, we found that exposure to 2,4-DTBP led to increased lipid accumulation and expression of adipogenic marker genes. Antagonist assays revealed that 2,4-DTBP increased lipid accumulation by activating the peroxisome proliferator-activated receptor {gamma} (PPAR{gamma})-retinoid X receptor (RXR) heterodimer. 2,4-DTBP likely activated the PPAR{gamma}/RXR heterodimer by activating RXR but not directly binding to PPAR{gamma}. We confirmed that 2,4-DTBP directly bound to RXR by solving the crystal structure of this complex, then predicted and demonstrated that related compounds could also activate RXR. Our study demonstrated that 2,4-DTBP and related chemicals could act as obesogens and endocrine disruptors via RXR. These data showed that 2,4-DTBP belongs to a family of compounds whose endocrine-disrupting and obesogenic effects can be strongly modulated by their chemical composition and that structure-activity studies such as the present one could help guide the rational development of safer antioxidants. SYNOPSISLittle research exists on the effects of commercially valuable antioxidants on biological systems. This study reports that di- and tri-tert-butylphenols can act as endocrine disruptors and potential obesogens by activating nuclear hormone receptors.

pharmacology and toxicology↗
bioRxiv2022

Cryo-EM structure of the agonist-bound Hsp90-XAP2-AHR complex

SummaryLiving organisms have developed protein sensors helping them to adapt to their environment1. The aryl hydrocarbon receptor (AHR) is an emblematic member of this class of proteins, and a ligand-dependent transcription factor that mediates a broad spectrum of (patho)physiological processes in response to numerous substances including pollutants, natural products and metabolites2. However, in the absence of high-resolution structural data, a molecular understanding of how AHR is activated by such diverse compounds is lacking. Here we present a 2.85 [A] cryo-electron microscopy structure of the cytosolic complex comprising AHR bound to the ligand indirubin, the chaperone Hsp90 and the co-chaperone XAP2. The structure reveals a closed Hsp90 dimer with AHR threaded through its lumen. XAP2 directly interacts with Hsp90 and the AHR ligand-binding domain, thereby acting as a brace stabilizing the entire complex. Importantly, we provide the first experimental visualization of the AHR PAS-B domain bound to a ligand, revealing a unique organization of the ligand-binding pocket and the structural determinants of ligand-binding specificity and promiscuity of the receptor. By providing unprecedented structural details of the molecular initiating event leading to AHR activation, our study rationalizes prior biochemical data and provides a framework for future mechanistic studies and structure-guided drug design.

biochemistry↗
bioRxiv2018

All in thirty milliseconds: EEG evidence of hierarchical and asymmetric phonological encoding of vowels

How the brain encodes the speech acoustic signal into phonological representations (distinctive features) is a fundamental question for the neurobiology of language. Whether this process is characterized by tonotopic maps in primary or secondary auditory areas, with bilateral or leftward activity, remains a long-standing challenge. Magnetoencephalographic and ECoG studies failed to show hierarchical and asymmetric hints for speech processing. We employed high-density electroencephalography to map the Salento Italian vowel system onto cortical sources using the N1 auditory evoked component. We found evidence that the N1 is characterized by hierarchical and asymmetric indexes structuring vowels representation. We identified them with two N1 subcomponents: the typical N1 (N1a) peaking at 125-135 ms and localized in the primary auditory cortex bilaterally with a tangential distribution and a late phase of the N1 (N1b) peaking at 145-155 ms and localized in the left superior temporal gyrus with a radial distribution. Notably, we showed that the processing of distinctive feature representations begins early in the primary auditory cortex and carries on in the superior temporal gyrus along lateral-medial, anterior-posterior and inferior-superior gradients. It is the dynamical interface of both auditory cortices and the interaction effects between different distinctive features that generate the categorical representations of vowels.

neuroscience↗
bioRxiv2017

The Phonetics-Phonology Relationship in the Neurobiology of Language

In this work, I address the connection of phonetic structure with phonological representations. This classical issue is discussed in the light of recent neurophysiological data which - thanks to direct measurements of temporal and spatial brain activation - provide new avenues to investigate the biological substrate of human language. After describing principal techniques and methods, I critically discuss magnetoencephalographic and electroencephalographic findings of speech processing based on event-related potentials and event-related oscillatory rhythms. The available data do not permit us to clearly disambiguate between neural evidence suggesting pure acoustic patterns and those indicating abstract phonological features. Starting from this evidence, which only at the surface represents a limit, I develop a preliminary proposal where discretization and phonological abstraction are the result of a continuous process that converts spectro-temporal (acoustic) states into neurophysiological states such that some properties of the former undergo changes interacting with the latter until a new equilibrium is reached. I assume that - at the end of the process - phonological segments (and the related categorical processes) take the form of continuous neural states represented by nested cortical oscillatory rhythms spatially distributed in the auditory cortex. Within this perspective, distinctive features (i.e., the relevant representational linguistic primitives) are represented by both spatially local and distributed neural selectivity. I suggest that this hypothesis is suitable to explain hierarchical layout of auditory cortex highly specialized in analyzing different aspects of the speech signal and to explain learning and memory processes during the acquisition of phonological systems.

neuroscience↗
bioRxiv2017

From brain noise to syntactic structures: A formal proposal within the oscillatory rhythms perspective

The neurobiology investigation of language seems limited by the impossibility to link directly linguistic computations with neural computations. To address this issue, we need to explore the hierarchical interconnections between the investigated fields trying to develop an inter-field theory. Considerable research has realized that event-related fluctuations in rhythmic, oscillatory EEG/MEG activity may provide a new window on the dynamics of functional neuronal networks involved in cognitive processing. Accordingly, this paper aims to outline a formal proposal on neuronal computation and representation of syntactic structures within the oscillatory neuronal dynamics. I briefly present the nature of event-related oscillations and how they work on the base of synchronization and de-synchronization processes. Then, I discuss some theoretical premises assuming that reentrant (hierarchical) properties of synchronized oscillatory rhythms constitute the biological endowment that allow the development of language in humans when exposed to appropriate inputs. The main rhythms involved in language and speech processing are examined: i.e. theta, alpha, beta, and gamma bands. A possible formal representation of the syntactic structures on the base of these oscillatory rhythms is discussed: in this model, the theta-gamma rhythms are cross-frequency coupled into the alpha-gamma-beta and into the gamma-beta-theta rhythms to generate the sentence along reentrant cortico-thalamic pathways through Merge, Label and Move operations. Finally, I present few conclusive remarks within an evolutionary perspective.\n\nO_QD\"...The whole burden of philosophy seems to consist in this, from the phenomena of motions to investigate the forces of nature, and from these forces to demonstrate the other phenomena.\" (Newton, 1687/1726)\n\nC_QD

neuroscience↗