Biology subjects

Bryant, D. M.

Publications and source records attributed to Bryant, D. M..

6 recordsLinked to original sources

bioRxiv2026

Glandular architecture and malignant behaviour in colorectal cancer is regulated by the sialomucin Podocalyxin.

Glandular architecture-the coordination of lumen-containing structures by an apical-basal polarised epithelium-is frequently maintained in colorectal cancer (CRC), yet whether it actively contributes to tumour progression or metastatic competence remains unclear. Here, we identify Podocalyxin (PODXL), a developmental regulator of epithelial lumen formation, as a key determinant of glandular tumour architecture in CRC. PODXL is upregulated in CRC, particularly in poor-prognosis Consensus Molecular Subtype 4 (CMS4) tumours, where high expression predicts reduced survival. Using genetically engineered mouse models, matched organoids, human cell lines and xenografts, we show that PODXL promotes organisation of CRC cells into gland-like, lumen-containing structures. Loss of PODXL disrupts glandular architecture in both primary tumours and liver metastases, reducing tumour growth and metastatic colonisation. Mechanistically, TGF-{beta} signalling drives PODXL upregulation. Together, these findings establish glandular architecture as an active determinant of CRC progression and identify PODXL as a functional contributor rather than merely a prognostic biomarker.

cancer biology↗

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

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

ECM dimensionality tunes actin tension to modulate the endoplasmic reticulum and spheroid phenotype

Primary tissue organoids and cell spheroids recapitulate tissue physiology with remarkable fidelity. We investigated how engagement with a three dimensional laminin-rich extracellular matrix supports the polarized, stress resilient spheroid phenotype of mammary epithelial cells. Cells within a three dimensional laminin-rich extracellular matrix decreased and redistributed the actin crosslinker filamin to reduce their cortical actin tension. Cells with low cortical actin tension had increased plasma membrane protrusions that promoted negative plasma membrane curvature and fostered protein associations with the plasma membrane, consistent with efficient protein secretion. By contrast, cells engaging a laminin-rich extracellular matrix in two dimensions had high filamin-dependent cortical actin tension, exhibited compromised endoplasmic reticulum function including increased expression of PKR-like Endoplasmic Reticulum Kinase signaling effectors, and had compromised protein secretion. Cells with low filamin-mediated cortical actin tension and reduced endoplasmic reticulum stress response signaling secreted, and assembled, a polarized endogenous basement membrane and survived better, and their spheroids were more resistant to exogenous stress. The findings implicate filamin-dependent cortical actin tension in endoplasmic reticulum function and highlight a role for mechanics in organoid homeostasis.

cell biology↗

bioRxiv2020

The MSP-RON axis stimulates cancer cell growth in models of triple negative breast cancer

Triple negative breast cancer is the most aggressive subtype of breast cancer with poor prognosis and high rates of relapse. The lack of actionable targets for TNBC has contributed to the high mortality rates of this disease, and new candidate molecules for potential manipulation are urgently required. Here, we show that macrophage-stimulating protein (MSP) and its tyrosine kinase receptor, RON, are potent drivers of cancer cell growth and tumor progression in a mouse model of TNBC driven by the loss of Trp53 and Brca1. After comparison of two genetically engineered mouse models of TNBC, we found that mammary tumors from K14-Cre;Brca1F/F;Trp53F/F (KB1P) mice exhibit high endogenous levels of MSP and RON expression. We show that MSP stimulates AKT and ERK1/2 activation as well as cancer cell growth in KB1P cell lines, while genetic and pharmacological inhibition of RON prevents these effects. Similarly, KB1P tumor progression in mice was robustly attenuated by treatment with a RON inhibitor with accompanied reduction in the proliferation marker, Ki-67. Our findings in a mouse model where MSP and RON expression are naturally increased provide evidence that this receptor and its ligand are viable candidate molecules for targeted treatment of TNBC.

cancer biology↗

bioRxiv2017

Fibroblast-derived HGF drives acinar lung cancer cell polarization through integrin-dependent RhoA-ROCK1 inhibition.

The formation of lumens in epithelial tissues requires apical-basal polarization of cells, and the co-ordination of this individual polarity collectively around a contiguous lumen. Signals from the Extracellular Matrix (ECM) instruct epithelia as to the orientation of where basal, and thus consequently apical, surfaces should be formed. We report that this pathway is normally absent in Calu-3 human lung adenocarcinoma cells in 3-Dimensional culture, but that paracrine signals from MRC5 lung fibroblasts can induce correct orientation of polarity and acinar morphogenesis. We identify HGF, acting through the c-Met receptor, as the key polarity-inducing morphogen, which acts to activate {beta}1-integrin-dependent adhesion. HGF and ECM-derived integrin signals co-operate via a c-Src-dependent inhibition of the RhoA-ROCK1 signalling pathway via p190A RhoGAP. This occurred via controlling localization of these signalling pathways to the ECM-abutting surface of cells in 3-Dimensional culture. Thus, stromal derived signals can influence morphogenesis in epithelial cells by controlling activation and localization of cell polarity pathways.

cell biology↗