Biology subjects

Giaccia, A. J.

Publications and source records attributed to Giaccia, A. J..

9 recordsLinked to original sources

bioRxiv2025

Targeting C5aR1 Reveals Protective Macrophage Maturation States in Intestinal Injury

Inflammatory intestinal injury, which may occur following cytotoxic cancer treatments such as radiotherapy, compromises homeostasis when intestinal stem cells undergo apoptosis and regeneration programmes are not effectively engaged. Recent evidence indicates the importance of macrophages in regulating stem regeneration following injury, but how to therapeutically promote specific macrophage subtypes which may tip the balance away from apoptosis and towards regeneration is still unclear. Here we show that targeting complement C5a receptor 1 (C5aR1) reduces radiation-induced intestinal injury by promoting macrophage phenotypes which reduce intestinal stem cell apoptosis. Specifically, C5aR1 signalling attenuates a macrophage maturation response characterised by increased IL10 and CX3CR1 expression. Our data indicate that increased IL10 signalling, and macrophage maturation induced following C5aR1 targeting are important for regulating crypt cell loss via radiotherapy-induced apoptosis. Interestingly, IL10-signalling is also critical for the improved tumour radiation response observed following C5aR1 targeting.

immunology↗

bioRxiv2023

The colocatome as a spatial -omic reveals shared microenvironment features between tumour-stroma assembloids and lung cancer specimens

Computational frameworks to quantify and compare microenvironment spatial features of in-vitro patient-derived models and clinical specimens are needed. Here, we acquired and analysed multiplexed immunofluorescence images of human lung adenocarcinoma (LUAD) alongside tumour- stroma assembloids constructed with organoids and fibroblasts harvested from the leading edge (Tumour-Adjacent Fibroblasts;TAFs) or core (Tumour Core Fibroblasts;TCFs) of human LUAD. We introduce the concept of the "colocatome" as a spatial -omic dimension to catalogue all proximate and distant colocalisations between malignant and fibroblast subpopulations in both the assembloids and clinical specimens. The colocatome expands upon the colocalisation quotient (CLQ) through a nomalisation strategy that involves permutation analysis and thereby allows comparisons of CLQs under different conditions. Using colocatome analysis, we report that both TAFs and TCFs protected cancer cells from targeted oncogene treatment by uniquely reorganising the tumour-stroma cytoarchitecture, rather than by promoting cellular heterogeneity or selection. Moreover, we show that the assembloids colocatome recapitulates the tumour-stroma cytoarchitecture defining the tumour microenvironment of LUAD clinical samples and thereby can serve as a functional spatial readout to guide translational discoveries. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=190 SRC="FIGDIR/small/557278v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@a79aa3org.highwire.dtl.DTLVardef@199582forg.highwire.dtl.DTLVardef@6c7fb6org.highwire.dtl.DTLVardef@134a2aa_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2023

Innate immune receptor C5aR1 regulates cancer cell fate and can be targeted to improve radiotherapy in tumours with immunosuppressive microenvironments

An immunosuppressive microenvironment causes poor tumour T-cell infiltration and is associated with reduced patient overall survival in colorectal cancer. How to improve treatment responses in these tumours is still a challenge. Using an integrated screening approach to identify cancer-specific vulnerabilities, we identify complement receptor C5aR1 as a druggable target which when inhibited improves radiotherapy even in tumours displaying immunosuppressive features and poor CD8+ T-cell infiltration. While C5aR1 is well-known for its role in the immune compartment, we find that C5aR1 is also robustly expressed on malignant epithelial cells, highlighting potential tumour-cell specific functions. C5aR1 targeting results in increased NF-{kappa}B-dependent apoptosis specifically in tumours and not normal tissues; indicating that in malignant cells, C5aR1 primarily regulates cell fate. Collectively, these data reveal that increased complement gene expression is part of the stress response mounted by irradiated tumours and that targeting C5aR1 can improve radiotherapy even in tumours displaying immunosuppressive features.

cancer biology↗

bioRxiv2022

Hypoxia-mediated regulation of DDX5 through decreased chromatin accessibility and post-translational targeting restricts R-loop accumulation

Local hypoxia occurs in most solid tumors and is associated with aggressive disease and therapy resistance. Widespread changes in gene expression play a critical role in the biological response to hypoxia. However, most research has focused on hypoxia-inducible genes as opposed to those which are decreased in hypoxia. We demonstrate that chromatin accessibility is decreased in hypoxia, predominantly at gene promoters and specific pathways are impacted including DNA repair, splicing and the R-loop interactome. One of the genes with decreased chromatin accessibility in hypoxia was DDX5, encoding the RNA helicase, DDX5, which showed reduced expression in various cancer cell lines in hypoxic conditions, tumor xenografts and in patient samples with hypoxic tumors. Most interestingly, we found that when DDX5 is rescued in hypoxia, replication stress and R-loop levels accumulate further, demonstrating that hypoxia-mediated repression of DDX5 restricts R-loop accumulation. Together these data support the hypothesis that a critical part of the biological response to hypoxia is the repression of multiple R-loop processing factors, however, as shown for DDX5, their role is specific and distinct.

cancer biology↗

bioRxiv2021

Multi-Omics Analysis of Fibroblasts from the Invasive Tumor Edge Reveals that Tumor-Stroma Crosstalk Induces O-glycosylation of the CDK4-pRB Axis

The invasive leading edge represents a potential gateway for tumor invasion. We hypothesize that crosstalk between tumor and stromal cells within the tumor microenvironment (TME) results in the activation of key biological pathways depending on their location in the tumor (edge vs core). Here, we highlight phenotypic differences between Tumor-Adjacent-Fibroblasts (TAFs) from the invasive edge and Cancer-Associated Fibroblasts (CAFs) from the tumor core, established from human lung adenocarcinomas. We use an innovative multi-omics approach that includes genomics, proteomics and, O-glycoproteomics to characterize crosstalk between TAFs and cancer cells. Our analysis shows that O-glycosylation, an essential post-translational modification resulting from sugar metabolism, alters key biological pathways including the CDK4-pRB axis in the stroma, and indirectly modulates pro-invasive features of cancer cells. In summary, aside from improving the efficacy of CDK4 inhibitors anti-cancer agents, the O-glycoproteome poses a new consideration for important biological processes involved in tumor-stroma crosstalk.

cancer biology↗

bioRxiv2021

Aberrant BCMA Signaling Promotes Tumor Growth by Altering Protein Translation Machinery, a Therapeutic Target for the Treatment of Relapse/Refractory Multiple Myeloma

Recent T Cell therapies have been effective in the treatment of hematological cancers. However, immunotoxicity and treatment relapse pose significant clinical challenges. Here, we revealed distinctive requirement for neutralizing TNF receptor ligands APRIL and BAFF in MM and DLBCL. Furthermore, we investigated the use of BCMA decoy receptor (sBCMA-Fc) as a therapeutic inhibitor of ARPIL and BAFF. While wild-type sBCMA-Fc successfully blocked APRIL signaling with picomolar binding affinity, inhibiting tumor growth in MM models, it lacked efficacy in inhibiting DLBCL progression due to its weak binding for BAFF. To expand the therapeutic utility of sBCMA-Fc, using a protein engineering approach, we generated an affinity enhanced mutant sBCMA-Fc fusion molecule (sBCMA-Fc V3) with 4-folds and 500-folds enhancement in binding to APRIL and BAFF respectively. The sBCMA-Fc V3 clone significantly enhanced antitumor activity against both MM and DLBCL. Importantly, sBCMA-Fc V3 was proven to be a viable clinical candidate by showing adequate toxicity profile and on-target mechanism of action in nonhuman primates. SUMMARYThis study demonstrates the dichotomous function of APRIL and BAFF in MM and DLBCL, that can be safely targeted by an engineered fusion protein designed to trap APRIL and BAFF with ultra-high binding affinity.

cancer biology↗

bioRxiv2020

Targeting C5aR1 Increases the Therapeutic Window of Radiotherapy

Engaging innate immune pathways is emerging as a productive way of achieving durable anti-tumor responses. However, systemic administration of these therapies can result in toxicity, deemed to be particularly problematic when combined with current standard-of-care cytotoxic treatments such as radiotherapy. Increasing the therapeutic window of radiotherapy may be achieved by using targeted therapies, however, few pre-clinical studies investigate both tumor and normal tissue responses in detail. Here we show that targeting innate immune receptor C5aR1 improves tumor radiation response while reducing radiation-induced normal tissue toxicity, thereby increasing the therapeutic window. Genetically or pharmacologically targeting C5aR1 increases both IL-10 expression in the small intestine and IL-10 secretion by tumor cells. Increased IL-10 attenuates RelA phosphorylation and increases apoptosis in tumor cells, leading to improved radiation responses in murine models. Of note, these radiosensitizing effects are tumor-specific since, in the gastrointestinal tract, targeting C5aR1 instead results in decreased crypt cell apoptosis reduced signs of histological damage and improved survival following total abdominal irradiation in mice. Furthermore, the potent and orally active C5aR1 inhibitor, PMX205, improves tumor radiation responses even in a context of reduced/absent CD8+ T cell infiltration. These data indicate that PMX205 can modulate cancer-cell intrinsic functions to potentiate anti-tumor radiation responses even in tumors displaying features of T-cell deficiency or exclusion. Finally, using a preclinical murine model allowing the simultaneous assessment of tumor and normal tissue radiation responses, we show that PMX205 treatment reduces histological and functional markers of small-bowel toxicity while affording a positive tumor response. Our data, therefore, suggest that targeting C5aR1 could be a promising approach for increasing the therapeutic window of radiotherapy.

cancer biology↗

bioRxiv2020

Neutralizing PD-L1 and PD-L2 Enhances the Efficacy of Immune Checkpoint Inhibitors in Ovarian Cancer.

Immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway have improved for a number of solid tumors. Unfortunately, ovarian cancer represents a major clinical hurdle for immune checkpoint blockade (ICB) with reported low patient response rates. Using IHC staining, we find that PD-L2 is highly expressed in ovarian cancers and other malignancies with sub-optimal response to ICB, and is expressed at low levels in cancers responsive to ICB. Based on this observation, we hypothesized that the elevated expression of PD-L2 produced by both tumor and surrounding stromal cells contributes to immune-suppression. Since PD-L2 has been reported to have a 6- to10-fold higher native binding affinity to PD-1 compared with PD-L1, we hypothesized that high levels of PD-L2 can lead to insufficient blockade of the PD-1 signaling pathway. To overcome the immune repressive activity of PD-L2, we engineered a soluble PD-1 decoy molecule (sPD-1 mutant) that binds and neutralizes both PD-L1 and PD-L2 with a 10,000- and 200- fold improvement in binding affinity, respectively, when compared to wild-type binding to these same molecules. Such enhancement in binding affinity is facilitated by amino acid mutations both within and outside of the binding interface. Furthermore, this high affinity sPD-1 mutant molecule demonstrates superior in vivo efficacy in multiple cancer models including ovarian cancer where PD-L2 is highly expressed on the cell surface. One Sentence SummaryDual Inhibition of PD-L1 and PD-L2 using an affinity enhanced sPD-1 decoy molecule delivers superior antitumor activity when compared with PD-1 and PD-L1 antibodies in ovarian cancer.

cancer biology↗

bioRxiv2018

Joint single-cell DNA accessibility and protein epitope profiling reveals environmental regulation of epigenomic heterogeneity

Here we introduce Protein-indexed Assay of Transposase Accessible Chromatin with sequencing (Pi-ATAC) that combines single-cell chromatin and proteomic profiling. In conjunction with DNA transposition, the levels of multiple cell surface or intracellular protein epitopes are recorded by index flow cytometry and positions in arrayed microwells, and then subject to molecular barcoding for subsequent pooled analysis. Pi-ATAC simultaneously identifies the epigenomic and proteomic heterogeneity in individual cells. Pi-ATAC reveals a casual link between transcription factor abundance and DNA motif access, and deconvolute cell types and states in the tumor microenvironment in vivo. We identify a dominant role for hypoxia, marked by HIF1 protein, in the tumor microvenvironment for shaping the regulome in a subset of epithelial tumor cells.

genomics↗