Biology subjects

Leung, H. Y.

Publications and source records attributed to Leung, H. Y..

10 recordsLinked to original sources

bioRxiv2026

Indole-3-propionic acid nano-prodrugs sustain increased lymphoid exposure and alleviate experimental autoimmune arthritis

Chronic inflammatory diseases, including rheumatoid arthritis (RA), currently require sustained control of inflammation. Although long-acting therapies can reduce dosing frequency, those that rely on systemic immunosuppression may still compromise protective immunity. Microbiota-derived metabolites offer a complementary starting point for immune modulation through naturally occurring host-microbe signals. Indole-3-propionic acid (IPA), a gut microbial tryptophan metabolite naturally present in human circulation, has newly recognized immunoregulatory activity, yet its effects across disease contexts and its potential for therapeutic use remain incompletely defined. Here, we developed polymeric IPA nano-prodrugs (pIPANP) by conjugating IPA to a methacrylamide polymer through ester linkages and formulating the polymer into injectable nanoparticles. Following subcutaneous administration of fluorescently-labeled pIPANP, injection-site fluorescence remained detectable for at least 35 days, with labeled material detected in multiple lymph nodes. LC-MS/MS confirmed higher lymph-node IPA concentrations in mice treated with the pIPANPs compared to free IPA control at every sampled time point over 14 days. In collagen antibody-induced arthritis (CAIA), pIPANPs reduced clinical disease severity and paw swelling under both prophylaxis and therapeutic administration. pIPANP treatment increased the relative representation of CD11cCD103CD11b- cells with a conventional dendritic cell (cDC)1-associated phenotype and reduced costimulatory-marker frequencies in both CD11cCD103 and CD11cCD11b populations, most prominently in hock-draining lymph nodes. These changes were accompanied by increased PD-1 and IFN-{gamma} frequencies among CD4 and CD8 T cells. Fluorescent nanoparticle tracking showed preferential association with several myeloid populations, while single-cell profiling revealed divergent interferon-response signatures across splenic populations. These findings reveal arthritis-associated immunomodulatory activity of polymeric IPA and support its further development as a microbiome-inspired, long-acting approach to inflammatory arthritis.

bioengineering↗

bioRxiv2025

Effect of Age on Xenobiotic-Induced Autoimmunity

Aging is associated with increased spontaneous autoantibody production and chronic inflammation, yet its impact on xenobiotic-induced autoimmunity remains unexplored. This study investigates the effect of age on mercury-induced autoimmunity (HgIA) in B10.S mice, a model of xenobiotic-induced autoimmunity characterized by anti-nucleolar autoantibodies (ANoA). Mature (3 months), adult (6 months), middle-aged (12 months), and old-age (24 months) mice were exposed to mercury (HgCl2) or phosphate-buffered saline (PBS) for 4-5 weeks. While spontaneous anti-nuclear antibodies (ANA) increased with age in PBS-treated mice (34% in middle-aged, 57% in old age mice), HgIA incidence declined in old age mice, with only 59% (26/44) developing significant ANoA titers compared to 91-100% in younger cohorts. Notably, 56% (10/18) of initially ANoA-negative old mice had detectable ANoA at a lower dilution, indicating a reduced but not absent response. ANoA negativity in old age mice was associated with lower immunoglobulin levels, reduced anti-chromatin antibodies, and diminished germinal center formation, suggestive of immunosenescence. Flow cytometry revealed age-related declines in CD4 T cells, with mercury exposure augmenting T-cell differentiation in younger but not old mice. These findings demonstrate that aging enhances spontaneous autoimmunity but impairs xenobiotic-induced autoimmunity, with a subset of old age mice retaining partial responsiveness at lower dilutions, highlighting the complex interplay between immunosenescence and environmental triggers.

immunology↗

bioRxiv2022

Spatial regulation of the glycocalyx component Podocalyxin is a switch for pro-metastatic function

The glycocalyx component and sialomucin Podocalyxin (PODXL) is required for normal tissue development by promoting apical membranes to form between cells, triggering lumen formation. Elevated PODXL expression is also associated with metastasis and poor clinical outcome in multiple tumour types. How PODXL presents this duality in effect remains unknown. We identify an unexpected function of PODXL as a decoy receptor for Galectin-3 (GAL3), whereby the PODXL-GAL3 interaction releases GAL3 repression of integrin-based invasion. Differential cortical targeting of PODXL, regulated by ubiquitination, is the molecular mechanism controlling alternate fates. Both PODXL high versus low surface levels occur in parallel subpopulations within cancer cells. Orthotopic intraprostatic xenograft of PODXL-manipulated cells or those with different surface levels of PODXL define that this axis controls metastasis in vivo. Clinically, interplay between PODXL-GAL3 stratifies prostate cancer patients with poor outcome. Our studies define the molecular mechanisms and context in which PODXL promotes invasion and metastasis.

cell biology↗

bioRxiv2022

HNRNPA2B1 controls an unfolded protein response-related prognostic gene signature in prostate cancer

HNRNPA2B1 is associated with prostate cancer (PC) disease aggressiveness and underlies pro-tumourigenic cellular stress responses. By analysing >500 PC transcriptomes, we reveal that HNRNPA2B1 over-expression is associated with poor patient prognosis and stress response pathways. These include the "protein processing in the endoplasmic reticulum" (ER) pathway, which incorporates the unfolded protein response (UPR). By RNA-sequencing of HNRNPA2B1-depleted cells PC cells, we identified HNRNPA2B1-mediated down-regulation of UPR genes including the master ER-stress sensor IRE1, which induces ER proteostasis. Consistent with IRE1 down-regulation in HNRNPA2B1-depleted cells, we observed reduced splicing of the IRE1-target and key UPR effector XBP1s. Furthermore, HNRNPA2B1 depletion up-regulates expression of the IRE1-dependent decay (RIDD) target gene BLOC1S1, which is degraded by activated IRE1. We identify a HNRNPA2B1-IRE1-XBP1-controlled four gene prognostic biomarker signature (HIX) which classifies a subgroup of primary PC patients at high risk of disease relapse. Pharmacological targeting of IRE1 attenuated HNRNAPA2-driven PC cell growth. Taken together, our data reveal a putative novel mechanism of UPR activation in PC by HNRNPA2B1, which may promote an IRE1-dependent yet potentially-targetable recurrent disease phenotype.

cancer biology↗

bioRxiv2022

The small GTPase ARF3 controls metastasis and invasion modality by regulating N-cadherin levels.

ARF GTPases are central regulators of membrane trafficking that act by controlling local membrane identity and remodelling to facilitate vesicle formation. Unravelling ARF GTPase function is complicated by the overlapping association of ARFs with guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and numerous interactors. The extent to which redundancy is a major factor in ARF function or whether individual ARF GTPases make unique contributions to cellular behaviour remains unclear. Through a functional genomic screen of 3-Dimensional (3D) prostate cancer cell behaviour we explore the contribution of all known ARF GTPases, GEFs, GAPs, and a large selection of interactors to collective morphogenesis. This revealed that the ARF3 GTPase regulates the modality of invasion, acting as a switch between leader cell-led chains of invasion or collective sheet movement. Functionally, the ability of ARF3 to control invasion modality is dependent on association and subsequent control of the junctional adhesion molecule N-cadherin. In vivo, ARF3 levels acted as a rheostat for metastasis from intraprostatic tumour transplants and ARF3:N-cadherin expression can be used to identify prostate cancer patients with metastatic, poor-outcome disease. Our analysis defines a unique function for the ARF3 GTPase in controlling how cells collectively organise during invasion and metastasis.

cell biology↗

bioRxiv2021

THEM6-mediated lipid remodelling sustains stress resistance in cancer

Despite the clinical benefit of androgen-deprivation therapy (ADT), the majority of patients with advanced prostate cancer (PCa) ultimately develop lethal castration-resistant prostate cancer (CRPC). In this study, we identified thioesterase superfamily member 6 (THEM6) as a marker of ADT resistance in PCa. In patients, THEM6 expression correlates with progressive disease and is associated with poor survival. THEM6 deletion reduces in vivo tumour growth and restores castration sensitivity in orthograft models of CRPC. Mechanistically, THEM6 is located at the endoplasmic reticulum (ER) membrane and controls lipid homeostasis by regulating intracellular levels of ether lipids. Consequently, THEM6 loss in CRPC cells significantly alters ER function, reducing de novo sterol biosynthesis and preventing lipid-mediated induction of ATF4. Finally, we show that THEM6 is required for the establishment of the MYC-induced stress response. Thus, similar to PCa, THEM6 loss significantly impairs tumorigenesis in the MYC-dependent subtype of triple negative breast cancer. Altogether, our results highlight THEM6 as a novel component of the treatment-induced stress response and a promising target for the treatment of CRPC and MYC-driven cancer.

cancer biology↗

bioRxiv2021

Cyclocreatine suppresses prostate tumorigenesis through dual effects on SAM and creatine metabolism

Prostate cancer is highly prevalent, being the second most common cause of cancer mortality in men worldwide. Applying a novel genetically engineered mouse model (GEMM) of aggressive prostate cancer driven by deficiency of PTEN and SPRY2 (Sprouty 2) tumour suppressors, we identified enhanced creatine metabolism within the phosphagen system in progressive disease. Altered creatine metabolism was validated in in vitro and in vivo prostate cancer models and in clinical cases. Upregulated creatine levels were due to increased uptake through the SLC6A8 creatine transporter and de novo synthesis, resulting in enhanced cellular basal respiration. Treatment with cyclocreatine (a creatine analogue that potently and specifically blocks the phosphagen system) dramatically reduces creatine and phosphocreatine levels. Blockade of creatine biosynthesis by cyclocreatine leads to cellular accumulation of S-adenosyl methionine (SAM), an intermediary of creatine biosynthesis, and suppresses prostate cancer growth in vitro. Furthermore, cyclocreatine treatment impairs cancer progression in our GEMM and in a xenograft liver metastasis model. Hence, by targeting the phosphagen system, cyclocreatine results in anti-tumourigenic effects from both SAM accumulation and suppressed phosphagen system.

cancer biology↗

bioRxiv2020

Schlafen family member 5 (SLFN5) regulates LAT1-mediated mTOR activation in castration-resistant prostate cancer

Androgen-deprivation therapy (ADT) is the standard of care for the treatment of non-resectable prostate cancer (PCa). Despite high treatment efficiency, most patients ultimately develop lethal castration-resistant prostate cancer (CRPC). In this study, we perform a comparative proteomic analysis of three in vivo, androgen receptor (AR)-driven, orthograft models of CRPC. Differential proteomic analysis reveals that distinct molecular mechanisms, including amino acid (AA) and fatty acid (FA) metabolism, are involved in the response to ADT between the different models. Despite this heterogeneity, we identify SLFN5 as an AR-regulated biomarker in CRPC. SLFN5 expression is high in CRPC tumours and correlates with poor patient outcome. In vivo, SLFN5 depletion strongly impairs tumour growth in castrated condition. Mechanistically, SLFN5 interacts with ATF4 and regulates the expression of LAT1, an essential AA transporter. Consequently, SLFN5 depletion in CRPC cells decreases intracellular levels of essential AA and impairs mTORC1 signalling in a LAT1-dependent manner.

cancer biology↗

bioRxiv2020

RUNX1 marks a luminal castration resistant lineage established at the onset of prostate development

The characterization of prostate epithelial hierarchy and lineage heterogeneity is critical to understand its regenerative properties and malignancies. Here, we report that the transcription factor RUNX1 marks a specific subpopulation of proximal luminal cells (PLCs), enriched in the periurethral region of the developing and adult mouse prostate, and distinct from the previously identified NKX3.1+ luminal castration resistant cells. Using scRNA-seq profiling and genetic lineage tracing, we show that RUNX1+ PLCs are unaffected by androgen deprivation, and do not contribute to the regeneration of the distal luminal compartments. Furthermore, we demonstrate that a transcriptionally similar RUNX1+ population emerges at the onset of embryonic prostate specification to populate the proximal region of the ducts. Collectively, our results reveal that RUNX1+ PLCs is an intrinsic castration-resistant and self-sustained lineage that emerges early during prostate development and provide new insights into the lineage relationships of the prostate epithelium.

developmental biology↗

bioRxiv2019

Spatial restriction of phosphoinositide metabolism is a molecular switch to promote metastasis.

The signalling pathways underpinning cell growth and invasion use overlapping components, yet how mutually exclusive cellular responses occur is unclear. We developed 3-Dimensional culture analyses to separately quantify growth and invasion. We identify that alternate variants of IQSEC1, an ARF GTPase Exchange Factor, act as switches to promote invasion over growth by spatially enriching cortical phosphoinositide metabolism. All IQSEC1 variants activate ARF5- and ARF6-dependent PIP5-kinase to promote PI(3,4,5)P3-AKT signalling and growth. In contrast, select pro-invasive IQSEC1 variants restrict PI(3,4,5)P3 production to discrete cortical domains to form invasion-driving protrusions. Inhibition of IQSEC1 attenuates invasion in vitro and metastasis in vivo. Induction of pro-invasive IQSEC1 variants and elevated IQSEC1 expression occurs in a number of tumour types and is associated with higher-grade metastatic cancer, activation of PIP3-signalling, and predicts long-term poor outcome across multiple cancers. Spatial enrichment of phosphoinositide metabolism therefore is a switch to induce invasion over growth in response to the same external signal. Targeting IQSEC1 as the central regulator of this switch may represent a therapeutic vulnerability to stop metastasis. HighlightsO_LISpatial enrichment of PI(3,4,5)P3 is a molecular switch to promote invasion. C_LIO_LIIQSEC1 is a GEF for ARF5/6, promoting PIP5K-dependent PI(3,4,5)P3 production downstream of the HGF receptor Met. C_LIO_LIPro-invasive IQSEC1 variants restrict cortical PI(3,4,5)P3 production to subdomains that convert into invasive protrusions. C_LIO_LIIQSEC1 inhibition attenuates in vitro invasion and metastasis in vivo. C_LIO_LIIQSEC1 module is associated with poor outcome across tumour types. C_LI

cancer biology↗