Biology subjects

Giordano, S.

Publications and source records attributed to Giordano, S..

7 recordsLinked to original sources

bioRxiv2026

A multilayered in silico analysis links UHRF1, DNA methylation and developmental chromatin memory to lineage-dependent prognosis in gastric, renal and adrenal cancers

Aberrant DNA methylation is a hallmark of cancer, but its clinical interpretation remains debated. UHRF1, a key epigenetic adaptor for DNA methylation maintenance and chromatin bivalency regulation in embryonic stem cells, is frequently overexpressed yet shows context-dependent prognostic behaviour. By integrating bulk and single-cell transcriptomics, CpG-resolution methylation, developmental chromatin states, immune profiling and clinical outcomes across gastric (STAD), clear-cell renal (KIRC) and adrenal (ACC) carcinomas, we identified a four-class UHRF1-embryonic morphogenesis (UHRF1-EM) framework resolving this paradox. This axis revealed an inverse prognostic pattern: whilst across all three tumours EM-low and EM-high states mark better or worse prognosis, respectively, UHRF1-high levels associate with favourable outcome in STAD (UH-EML), and unfavourable in KIRC and ACC (UH-EMH). The classification proved reproducible and independently prognostic after adjustment for stage and molecular subtypes, outperforming existing classifiers and exceeding pathological stage in KIRC and ACC. Multivariable models incorporating UHRF1-EM yielded uniformly positive {Delta}C-indices. Hypermethylation associated with the UHRF1-EM axis was enriched at ESC bivalent developmental loci (EM and oncofoetal genes), but not at housekeeping cell-cycle sites. In STAD, this pattern was related to oncofoetal gene downregulation and best prognosis, whereas in KIRC and ACC it matched with gene-body/enhancer methylation, higher EM expression, immunosuppressive microenvironments and worst prognosis. Together, these findings establish the UHRF1-EM axis as a clinically robust molecular classifier and support a mechanistic model in which tumour-specific epigenetic engagement of developmental loci may contribute to the prognostic inversion, providing a foundation for further mechanistic experimental validation.

cancer biology↗

bioRxiv2024

Heat shock factor 2 positively regulates oncogenic herpesvirus gene expression by remodeling the chromatin landscape

Human gamma-herpesviruses, Kaposis sarcoma herpesvirus (KSHV) and Epstein-Barr virus (EBV) are causally associated to a wide range of cancers. While the default infection program for these viruses is latent, sporadic lytic reactivation supports virus dissemination and oncogenesis. Despite its relevance, the repertoire of host factors governing the transition from latent to lytic phase is not yet complete, leaving much of this complex process unresolved. Here, we show that heat shock factor 2 (HSF2), a transcription factor involved in regulation of acute stress responses and specific cell differentiation processes, promotes gamma-herpesvirus lytic gene expression. In lymphatic endothelial cells infected with KSHV and gastric cancer cells positive for EBV, ectopic HSF2 enhances the expression of lytic genes, while knocking down HSF2 significantly decreases their expression. Mechanistically, HSF2 overexpression results in decreased levels of repressive chromatin histone marks, at the promoters of the master regulators of the oncogenic lytic cascade, KSHV ORF50 and EBV BZLF1. Our results demonstrate that endogenous HSF2 binds to the ORF50 promoter in latent cells and sustains a transcriptionally permissive state. In contrast, in lytic cells, HSF2 occupancy at the ORF50 promoter is lost in conjunction with its proteasomal degradation. These findings establish HSF2 as a conserved regulator of gamma-herpesvirus lytic gene expression in latency and offer new functional insights on the cellular role of HSF2 at target promoters.

microbiology↗

bioRxiv2024

The "very moment" when UDG recognizes aflipped-out uracil base in dsDNA

Uracil-DNA glycosylase (UDG) is the first enzyme in the base-excision repair (BER) pathway, acting on uracil bases in DNA. How UDG finds its targets has not been conclusively resolved yet. Based on available structural and other experimental evidence, two possible pathways are under discussion. In one, the action of UDG on the DNA bases is believed to follow a pinch-push-pull model, in which UDG generates the base-flip in an active manner. A second scenario is based on the exploitation of bases flipping out thermally from the DNA. Recent molecular dynamics (MD) studies of DNA in trinucleosome arrays have shown that base-flipping can be readily induced by the action of mechanical forces on DNA alone. This alternative mechanism could possibly enhance the probability for the second scnenario of UDG-uracil interaction via the formation of a recognition complex of UDG with flipped-out base. In this work we describe DNA structures with flipped-out uracil bases generated by MD simulations which we then subject to docking simulations with the UDG enzyme. Our results for the UDG-uracil recognition complex support the view that base-flipping induced by DNA mechanics can be a relevant mechanism of uracil base recognition by the UDG glycosylase in chromatin.

bioinformatics↗

bioRxiv2023

High clonal diversity and spatial genetic admixture in early prostate cancer and surrounding normal tissue

Somatic copy number alterations (SCNAs) are pervasive in advanced human cancers, but their prevalence and spatial distribution in early-stage, localized tumors and their surrounding normal tissues are poorly characterized. Here, we performed multi-region, single-cell DNA sequencing to characterize the SCNA landscape across multiple tumor-rich and normal tissue regions ([~]125 mm3 tissue cubes) obtained from prostatectomy performed in two patients with localized prostate cancer. We identified two distinct populations of cells with abnormal karyotypes, one marked by sparse deletions or amplifications ( pseudo-diploid cells) and the second characterized by genome-wide copy number changes reminiscent of monster cells previously described in colorectal cancer. Pseudo-diploid cells formed numerous small-sized subclones ranging from highly spatially localized to broadly spread subclones mainly featuring (sub-)chromosomal arm deletions. In contrast, monster cells harbored whole-chromosome gains and losses and were mostly singular events detected throughout the prostate, including normal tissue regions. Targeted deep sequencing of cancer-associated genes revealed a more confined pattern of mutations overlapping with tumor-rich regions, although we also detected mutations in regions deemed normal based on morphological assessment and bulk RNA-seq. Highly localized pseudo-diploid subclones were confined within tumor-rich regions and typically carried deletions involving chromosome (chr) 6 and 13, resulting in simultaneous loss of multiple tumor-suppressor genes, including FOXO1 and FOXO3 encoding two transcription factors belonging to the Forkhead family previously implicated in prostate carcinogenesis. Tumor-rich regions also contained mutations in genes frequently mutated in prostate cancer, including FOXA1, LRP1B, SPOP, and SPTA1. Our study reveals that SCNAs are widespread in both normal and tumor regions across the prostate gland of patients with localized prostate cancer and suggests that a subset of pseudo-diploid cells harboring chromosomal deletions that result in the loss of specific tumor-suppressor genes drive tumorigenesis in the aging prostate.

cancer biology↗

bioRxiv2022

Structure of the Inmazeb cocktail and resistance to escape against Ebola virus

Monoclonal antibodies can provide important pre- or post-exposure protection against disease for those not yet vaccinated or in individuals that fail to mount a protective immune response after vaccination. A key concern in use of monotherapy monoclonal antibody products lies in the high risk of mutagenic escape. Inmazeb (REGN-EB3), a three-antibody cocktail against Ebola virus, demonstrated efficacy in lessening disease course and improving survival in a randomized, controlled trial. Here we present the cryoEM structure at 3.1 [A] of the Ebola virus glycoprotein, determined without symmetry averaging, in a simultaneous complex with eight Fab fragments of antibodies in the Inmazeb cocktail. This structure allows modeling of previously disordered portions of the glycan cap, maps the non-overlapping epitopes of Inmazeb, and illuminates the basis for complementary activities, as well as residues that are critical for resistance to escape by each component of this cocktail and other clinically relevant antibodies. We also provide direct evidence that, unlike monotherapy treatments, including those targeting conserved epitopes, the Inmazeb protects against the rapid emergence of EBOV escape mutants and supports the benefit of the combination approach.

biophysics↗

bioRxiv2021

In vitro and in vivo preclinical studies predict REGEN-COV protection against emergence of viral escape in humans

Monoclonal antibodies against SARS-CoV-2 are a clinically validated therapeutic option against COVID-19. As rapidly emerging virus mutants are becoming the next major concern in the fight against the global pandemic, it is imperative that these therapeutic treatments provide coverage against circulating variants and do not contribute to development of treatment emergent resistance. To this end, we investigated the sequence diversity of the spike protein and monitored emergence of minor virus variants in SARS-COV-2 isolates found in COVID-19 patients or identified from preclinical in vitro and in vivo studies. This study demonstrates that a combination of non-competing antibodies, REGEN-COV, not only provides full coverage against current variants of concern/interest but also protects against emergence of new such variants and their potential seeding into the population in a clinical setting.

microbiology↗

bioRxiv2020

FGFR2 fusion protein-driven mouse models of intrahepatic cholangiocarcinoma unveil a necessary role for Erk signalling

Background and aimsAbout 15% of intrahepatic cholangiocarcinoma (iCCA) express fibroblast growth factor receptor 2 (FGFR2) fusion proteins (FFs), most often in concert with mutationally inactivated TP53, CDKN2A or BAP1. FFs span residues 1-768 of FGFR2 fused to sequences encoded by any of a long list (>60) of partner genes, a configuration sufficient to ignite oncogenic FF activation. In line, FGFR-specific tyrosine kinase inhibitors (F-TKI) were shown to provide clinical benefit in FF+ iCCA, although responses were partial and/or limited by resistance mechanisms, including the FF V565F gatekeeper mutation. Herein we present an FF-driven murine iCCA model and exploit its potential for pre-clinical studies on FF therapeutic targeting. MethodsFour iCCA FFs carrying different fusion sequences were expressed in Tp53-/- mouse liver organoids. Tumorigenic properties of genetically modified liver organoids were assessed by intrahepatic/subcutaneous transplantation in immuno-deficient mice. Cellular models derived from neoplastic lesions were exploited for pre-clinical studies. ResultsTumors diagnosed as CCA were obtained upon transplantation of FF-expressing liver organoids. The penetrance of this tumorigenic phenotype was influenced by FF identity. Tumor organoids and 2D cell lines derived from CCA lesions were addicted to FF signaling via Ras-Erk, regardless of FF identity or presence of V565F mutation. Double blockade of FF-Ras-Erk pathway by concomitant pharmacological inhibition of FFs and Mek1/2 provided greater therapeutic efficacy than single agent F-TKI in vitro and in vivo. ConclusionsFF-driven iCCA pathogenesis was successfully modelled in murine Tp53-/- background. This model revealed biological heterogeneity among structurally different FFs. Double blockade of FF-Erk signaling deserves consideration for improving precision-based approaches against human FF+ iCCA. Abbreviations used in this paper: ANOVA, analysis of variance; Bap1, BRCA1-Associated-Protein 1; Cdkn2a, cyclin-dependent kinase inhibitor 2A; Cftr, cystic fibrosis transmembrane conductance regulator; Ck19, cytokeratin 19; Cyp3A, cytochrome P450, family 3, subfamily A; EGF, Epidermal growth factor; EGFR, Epidermal growth factor receptor; EpCAM, epithelial cell adhesion molecule; Erk, extracellular signal-regulated kinase; FGFR2, fibroblast growth factor receptor 2; FRS2, fibroblast growth factor receptor substrate 2; GRB2, growth factor receptor-bound 2; GSEA, gene set enrichment analysis; GSVA, gene set variation analysis; H&E, hematoxylin and eosin; HepPar1, hepatocyte Paraffin 1; Hnf4-7, hepatocyte nuclear factor 4 alpha; Hprt, hypoxanthine-guanine phosphoribosyl transferase; LGR5, leucine-rich repeat-containing G-protein coupled receptor 5; NTRK, neurotrophic Tyrosine Kinase; Parp, Poly (ADP-ribose) polymerase; RECIST, response evaluation criteria in solid tumors; SHP2, Src homology phosphatase 2; Ttr, transthyretin.

cancer biology↗