Biology subjects

Spitz, F.

Publications and source records attributed to Spitz, F..

11 recordsLinked to original sources

bioRxiv2026

TIM3+ Tumor Associated M2 Macrophages Impair Antitumor T Cell Immunity and Promote Gastric Cancer Progression and Peritoneal Metastasis

Peritoneal metastases (PM) are the leading cause of cancer-related death in gastric cancer (GC) patients with survival typically < 9 months. Here, we demonstrate that TIM3 and its ligands are increased along the GC continuum and associated with poor survival. Integrated omics analyses and functional studies revealed highly enriched TIM3 in CD163+ tumor associated M2 immunosuppressive macrophages significantly promote tumor cell invasion and tumor growth in vivo, while TIM3 depletion in macrophages reduced tumor cell malignant attributes and increased T cell immunity from PBMCs or CD45+ immune cells of malignant ascites in co-culture system. By cytokine and kinase arrays, we discovered that depletion of TIM3 in macrophages reduced the production of notable secretome of cytokines/chemokines from M2 macrophages; and the protumor function of TIM3+ macrophages rely on the p90RSK1/2/CCL20 axis. Finally, we reveal that TIM3 blockage or genetic KO had superior antitumor activity in combination with anti-PD1 immunotherapy and mitomycin C (MMC) chemotherapy. Together, this study uncovers an important role for TIM3 in tumor associated M2 macrophages and underscores the potential of TIM3 blockage in GC patients with PM. Statement of significanceIn this study, we show TIM3 increases along GC continuum, and highly enriched on tumor associated M2 macrophages that fuel tumor growth; and suppress T cell function via p90RSK1/2/CCL20 axis. TIM3 depletion restores T-cell immunity and curbs tumor growth. TIM3 blockade combined with anti-PD1 and mitomycin C provide a novel therapeutic strategy for GC patients with PM.

immunology↗

bioRxiv2025

YAP1 Depletion Enhances TAZ and its Complexation with TEAD4 and AP-1 Heterodimer C-JUN/FOSB to Promote Gastric Cancer Progression and Metastases

BackgroundDysregulation of the Hippo signaling pathway, characterized by aberrant activation of the transcriptional coactivators YAP1 and TAZ, drives tumour progression, immunosuppression and metastasis. Hippo pathway components are emerging therapeutic targets in several solid tumours, however, the expression profiles of Hippo coactivators YAP1, TAZ and their transcriptional factors TEAD1-4 in gastric cancer peritoneal metastases (GCPMs) and their therapeutic value are unknown. ObjectiveTo determine expression status of YAP1, TAZ and TEAD1-4 in GCPMs; and to evaluate whether dual targeting of YAP1 and TAZ provides superior antitumour activity compared with inhibition of either coactivator alone. DesignExpression of YAP1, TAZ and TEAD1-4 was examined in GCPMs by single-cell RNA sequencing and co-immunofluorescent staining. Functional studies using genetic knockout and antisense oligonucleotide (ASO) inhibition of YAP1 or TAZ were performed to assess antineoplastic effects in vitro and in vivo. Co-immunoprecipitation and luciferase reporter assays were used to characterize YAP1/TAZ interactions with TEADs and AP-1 components (JUN and FOSB) and to quantify transcriptional activity. Antitumour efficacy was validated in patient-derived xenograft (PDX) and KP-Luc2 syngeneic models. ResultsYAP1, TAZ, and TEADs1- 4 were highly coexpressed in GCPMs and correlated with poor survival. YAP1 inhibition alone elicited compensatory upregulation of TAZ, while combined inhibition of both coactivators maximally repressed cell proliferation and invasion in vitro, and tumor growth in vivo. Increased TAZ complexation with TEAD4 and AP-1 (c-JUN and FOSB) heterodimer was observed following YAP1 knockdown or pharmacological ASO inhibition. Dual inhibition of YAP1 and TAZ was required to maximally suppress YAP1/TAZ expression and reduce their nuclear accumulation, transactivation of TEAD, and activation of downstream genes. ConclusionsThese findings show that combined YAP1 and TAZ inhibition holds promise for the treatment of GCPMs, a highly lethal disease with an urgent need for novel treatment options. WHAT IS ALREADY KNOWN ON THIS TOPICO_LIGastric cancer with peritoneal metastasis (GCPM), occurring in > 45% of gastric cancer (GC) patients, is a highly lethal malignancy with limited therapeutic options. C_LIO_LIThe Hippo pathway mediator Yes-associated protein 1 (YAP1) is intimately involved in chemoresistance, cancer stemness properties, and the epithelial-to-mesenchymal transition in gastric and other cancers. C_LIO_LIWhile YAP1 represents a promising therapeutic target, clinical trial of YAP1 antisense oligonucleotides has been disappointing. C_LI WHAT THIS STUDY ADDSO_LIHippo coactivators YAP1, TAZ and their main transcription factors TEAD1-4 are markedly upregulated in GCPMs and associated with poor prognosis. C_LIO_LIAntisense targeting of YAP1 results in compensatory upregulation of its paralog TAZ. C_LIO_LIUpon YAP1 depletion, TAZ forms transcriptional complexes with TEAD4 and the AP-1 heterodimer (JUN and FOSB). C_LIO_LIDual targeting of YAP1 and TAZ, by oligonucleotides, achieves maximal suppression of tumour growth in vitro and in vivo. C_LI HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICYO_LIThese findings provide a strong mechanistic rationale for co-targeting YAP1 and TAZ as a therapeutic approach in metastatic gastric cancer. C_LIO_LIDual Hippo coactivator inhibition could inform the design of future clinical trials aimed at improving outcomes for patients with GCPMs. C_LI

cancer biology↗

bioRxiv2025

Pyrimethamine inhibits mutant NRF2 as a molecular glue

Esophageal squamous cell carcinoma (ESCC) is a deadly disease and one of the most aggressive cancers of the gastrointestinal tract. As a master transcription factor regulating the stress response, nuclear factor erythroid 2-related factor 2 (NRF2) is often mutated, loses negative regulation by Kelch-like ECH-associated protein 1 (KEAP1), becomes hyperactive, and thus causes chemo-radioresistance and poor survival in human ESCC. Our previous research identified pyrimethamine (PYR) as an NRF2 inhibitor and demonstrated that inhibition of dihydrofolate reductase (DHFR) is the major mechanism of its action. Based on these findings, PYR has advanced into a Phase I window-of-opportunity clinical trial. In this study, using isogenic ESCC cell lines, we aimed to investigate the phenotypic consequences of NRF2 activation in ESCC cells and further elucidate the mechanism of action of PYR. While overexpression of wild-type NRF2 (NRF2WT) promoted squamous differentiation and suppressed proliferation, expression of mutant NRF2 (NRF2Mut) produced mixed effects on differentiation markers and promoted proliferation. NRF2 activation reduced sensitivity to chemotherapy and radiation, whereas PYR treatment restored chemosensitivity and radiosensitivity in NRF2Mut ESCC cells. Co-immunoprecipitation and proximity ligation assays revealed that PYR selectively enhanced the interaction between NRF2W24C and KEAP1, but not between NRF2WT and KEAP1. Isothermal titration calorimetry (ITC) confirmed the direct binding of PYR to KEAP1 and surface plasmon resonance (SPR) showed that PYR modestly facilitated the interaction between a DLGW24C peptide and the Kelch fragment. Molecular docking suggested that PYR bound to a pocket within the Kelch domain near Arg415. In summary, NRF2 activation promotes cell proliferation and therapy resistance in ESCC in a context-dependent manner. PYR functions as a modest molecular glue that selectively restores KEAP1 binding to NRF2W24C, providing a potential therapeutic strategy for NRF2Mut ESCC.

cancer biology↗

bioRxiv2025

CDK9 degradation Inhibits Gastroesophageal Cancer growth and Overcomes Radiation Resistance by Increasing Chromatin Accessibility and Downregulating YAP1/TEAD signaling

BackgroundGastroesophageal cancer (GEAC) remains a major health burden and urgently needs novel therapeutic targets. The inhibition of CDK9s activity holds the potential to be a highly effective anti-cancer therapeutic. However, the functional role of CDK9, and its potential targeting in GEAC, remain largely unknown. ObjectiveWe aim to evaluate the potential of degradation CDK9 in GEAC treatment and explore its mechanisms. DesignWe evaluated the expression and distribution of CDK9 in GEAC tissue. We designed and synthesized novel CDK9 degraders using proteolysis targeting chimeras (PROTACs) strategy and selected the promising one for further anti-tumor activity evaluation both in vitro and in vivo. We evaluated the effects of CDK9 degradation on epigenetic reactivation, gene expression and chromatin accessibility. We evaluated the co-targeting of CDK9 and YAP/Tead signaling for GEAC treatment, especially for radiation-resistant tumor treatment. ResultsWe demonstrated significantly elevated CDK9 expression in primary GEAC tumor tissues compared to normal tissues, in association with poor survival. We developed a novel CDK9 degrader, YX0597, reducing RNA Pol II Serine 2 phosphorylation, and inhibition MCL-1; this was accompanied by potent inhibition of GEAC cell growth, especially in radiation-resistant tumor cells. Mechanistically, YX0597 strongly enhanced chromatin accessibility, activating epigenetically silenced genes; and dramatically inhibited YAP/TEAD signaling. CDK9 closely interacts with YAP/TEAD signaling, and co-targeting these two mediators could be a novel treatment strategy for the treatment of GEAC. ConclusionOur studies reveal a new avenue for targeting CDK9-hyperactivated GEAC tumors, especially in combination with YAP1/TEAD inhibition in radiation-resistant GEAC tumors. What is already known on this subject?Gastroesophageal cancer (GEAC), the third-leading cause of global cancer death and urgently needs novel targeted therapies. Targeted protein degradation has emerged as an attractive strategy to fight cancer, complementing the activity of traditional small-molecule inhibitors. Cyclin-dependent kinase 9 (CDK9) has been implicated in various cancers. Recently, CDK9 degraders have now been developed for future clinical benefit in targeting tumors with highly activated CDK9. What are the new findings?In this study, we show that CDK9 expression was significantly elevated in primary GEAC tumor tissues including PDXs compared to normal tissues, in association with poor survival. We developed a novel CDK9 degrader XY0597 and proved that it inhibits the progression of GEAC by increasing chromatin accessibility and down-regulating YAP/Tead signaling. We also proved a strong connection between CDK9 and YAP/TEAD signaling and Co-targeting them synergistically inhibits GEAC tumor cell growth, especially in tumors with high YAP signaling activity, such as radiation-resistant cancer. How might it impact on clinical practice in the foreseeable future?Our data suggests that CDK9 is a viable anticancer target in GEAC. We demonstrate that a novel CDK9 degrader, YX0597, has high potential clinical application for GEAC treatment, especially in radiation-resistant cancer. We reveal the crosstalk of CDK9 and YAP/TEAD signaling, and that co-targeting these two mediators could be a new avenue for targeting CDK9-hyperactivated GEAC primary and radiation-resistant tumors.

cancer biology↗

bioRxiv2023

HYENA detects non-coding genes activated by distal enhancers in cancer

Somatic structural variations (SVs) in cancer can shuffle DNA content in the genome, relocate regulatory elements, and alter genome organization. Enhancer hijacking occurs when SVs relocate distal enhancers to activate proto-oncogenes. However, most enhancer hijacking studies have only focused on protein-coding genes. Here, we develop a computational algorithm "HYENA" to identify candidate oncogenes (both protein-coding and non-coding) activated by enhancer hijacking based on tumor whole-genome and transcriptome sequencing data. HYENA detects genes whose elevated expression is associated with somatic SVs by using a rank-based regression model. We systematically analyze 1,146 tumors across 25 types of adult tumors and identify a total of 108 candidate oncogenes including many non-coding genes. A long non-coding RNA TOB1-AS1 is activated by various types of SVs in 10% of pancreatic cancers through altered 3-dimensional genome structure. We find that high expression of TOB1-AS1 can promote cell invasion and metastasis. Our study highlights the contribution of genetic alterations in non-coding regions to tumorigenesis and tumor progression.

cancer biology↗

bioRxiv2022

TATTOO-seq delineates spatial and cell type-specific regulatory programs during limb patterning

The coordinated differentiation of progenitor cells into specialized cell types and their spatial organization into distinct domains is central to embryogenesis. Here, we applied a new unbiased spatially resolved single-cell transcriptomics method to identify the genetic programs that underlie the emergence of specialized cell types during limb development and their integration in space. We uncovered combinations of transcription factors whose expression patterns are predominantly associated with cell type specification or spatial position, enabling the deconvolution of cell fate and position identity. We demonstrate that the embryonic limb undergoes a complex multi-scale re-organization upon perturbation of one of its spatial organizing centers, including the loss of specific cell populations, specific alterations in the molecular identities of other pre-existing cell states and changes in their relative spatial distribution. Altogether, our study shows how multi-dimensional single-cell and spatially resolved molecular atlases could reveal the interconnected genetic networks that regulate the intricacies of organogenesis and its reorganization upon genetic alterations.

systems biology↗

bioRxiv2020

Dissection of the Fgf8 regulatory landscape by in vivo CRISPR-editing reveals extensive inter- and intra-enhancer redundancy

Developmental genes are often regulated by multiple elements with overlapping activity. Yet, in most cases, the relative function of those elements and their contribution to endogenous gene expression remain uncharacterized. Illustrating this situation, distinct sets of enhancers have been proposed to direct Fgf8 in the limb apical ectodermal ridge (AER) and the midbrain-hindbrain boundary (MHB). Using in vivo CRISPR/Cas9 genome engineering, we functionally dissect this complex regulatory ensemble and demonstrate two distinct regulatory logics. In the AER, the control of Fgf8 expression appears extremely distributed between different enhancers. In contrast, in the MHB, one of the three active enhancers is essential while the other two are dispensable. Further dissection of the essential MHB enhancer revealed another layer of redundancy and identified two sub-parts required independently for Fgf8 expression and formation of midbrain and cerebellar structures. Interestingly, cross-species transgenic analysis of this enhancer suggests changes of the organisation of this essential regulatory node in the vertebrate lineage.

developmental biology↗

bioRxiv2020

Local retinoic acid directs emergence of the extraocular muscle functional unit

Coordinated development of muscles, tendons, and their attachment sites ensures emergence of functional musculoskeletal units that are adapted to diverse anatomical demands among different species. How these different tissues are patterned and functionally assembled during embryogenesis is poorly understood. Here, we investigated the morphogenesis of extraocular muscles (EOMs), an evolutionary conserved cranial muscle group that is crucial for the coordinated movement of the eyeballs and for visual acuity. By means of lineage analysis, we redefined the cellular origins of periocular connective tissues interacting with the EOMs, which do not arise exclusively from neural crest mesenchyme as previously thought. Using 3D imaging approaches, we established an integrative blueprint for the EOM functional unit. By doing so, we identified a developmental time window where individual EOMs emerge from a unique muscle anlage and establish insertions in the sclera, which sets these muscles apart from classical muscle-to-bone type of insertions. Further, we demonstrate that the eyeballs are a source of diffusible retinoic acid that allow their targeting by the EOMs in a temporal and dose dependent manner. Using genetically modified mice and inhibitor treatments, we find that endogenous local variations in the concentration of retinoids contribute to the establishment of tendon condensations and attachment sites that precede the initiation of muscle patterning. Collectively, our results highlight how global and site-specific programs are deployed for the assembly of muscle functional units with precise definition of muscle shapes and topographical wiring of their tendon attachments.

developmental biology↗

bioRxiv2018

Condensin II inactivation in interphase does not affect chromatin folding or gene expression

Condensin complexes have been proposed to play a prominent role in interphase chromatin organization and control of gene expression. Here, we report that the deletion of the central condensin II kleisin subunit Ncaph2 in differentiated mouse hepatocytes does not lead to significant changes in chromosome organization or in gene expression. Both observations challenge current views that implicate condensin in interphase chromosomal domain formation and in enhancer-promoter interactions. Instead, we suggest that the previously reported effects of condensin perturbation may result from their structural role during mitosis, which might indirectly impact the re-establishment of interphase chromosomal architecture after cell division.

genomics↗

bioRxiv2017

Cnidarian cell type diversity revealed by whole-organism single-cell RNA-seq analysis

A hallmark of animal evolution is the emergence and diversification of cell type-specific transcriptional states. But systematic and unbiased characterization of differentiated gene regulatory programs was so far limited to specific tissues in a few model species. Here, we perform whole-organism single cell transcriptomics to map cell types in the cnidarian Nematostella vectensis, a non-bilaterian animal that display complex tissue-level bodyplan organization. We uncover high diversity of transcriptional states in Nematostella, demonstrating cell type-specific expression for 35% of the genes and 51% of the transcription factors (TFs) detected. We identify eight broad cell clusters corresponding to cell classes such as neurons, muscles, cnidocytes, or digestive cells. These clusters comprise multiple cell modules expressing diverse and specific markers, uncovering in particular a rich repertoire of cells associated with neuronal markers. TF expression and sequence analysis defines the combinatorial code that underlies this cell-specific expression. It also reveals the existence of a complex regulatory lexicon of TF binding motifs encoded at both enhancer and promoters of Nematostella tissue-specific genes. Whole organism single cell RNA-seq is thereby established as a tool for comprehensive study of genome regulation and cell type evolution.

genomics↗

bioRxiv2016

Two independent modes of chromosome organization are revealed by cohesin removal

The three-dimensional organization of chromosomes is tightly related to their biological function 1. Both imaging and chromosome conformation capture studies have revealed several layers of organization 2-4: segregation into active and inactive compartments at the megabase scale 5, and partitioning into domains (TADs) 6,7 and associated loops 8 at the sub-megabase scale. Yet, it remains unclear how these layers of genome organization form, interact with one another, and contribute to or result from genome activities. TADs seem to have critical roles in regulating gene expression by promoting or preventing interactions between promoters and distant cis-acting regulatory elements 9-14, and different architectural proteins, including cohesin, have been proposed to play central roles in their formation 15,16. However, experimental depletions of these proteins have resulted in marginal changes in chromosome organization 17-19. Here, we show that deletion of the cohesin-loading factor, Nipbl, leads to loss of chromosome-associated cohesin and results in dramatic genome reorganization. TADs and associated loops vanish globally, even in the absence of transcriptional changes. In contrast, segregation into compartments is preserved and even reinforced. Strikingly, the disappearance of TADs unmasks a finer compartment structure that accurately reflects the underlying epigenetic landscape. These observations demonstrate that the 3D organization of the genome results from the independent action of two distinct mechanisms: 1) cohesin-independent segregation of the genome into fine-scale compartment regions, defined by the underlying chromatin state; and 2) cohes-dependent formation of TADs possibly by the recently proposed loop extrusion mechanism 20,21, enabling long-range and target-specific activity of promiscuous enhancers. The interplay between these mechanisms creates an architecture that is more complex than a simple hierarchy of layers and can be central to guiding normal development.

genomics↗