Biology subjects

Cassels, J.

Publications and source records attributed to Cassels, J..

3 recordsLinked to original sources

bioRxiv2026

CD180 identifies chemoresistant stem-like blasts and reveals a KMT2A-driven vulnerability in acute myeloid leukaemia

Relapse and chemoresistance remain major challenges in paediatric acute myeloid leukaemia (PAML), particularly in KMT2A-rearranged (KMT2A-r) subtypes where conventional markers such as CD34 are often absent, complicating measurable residual disease (MRD) detection. Leukaemia stem/regenerating cells (LSC/LRC) drive disease initiation, progression, and relapse, sharing stemness and chemoresistance properties that make them critical therapeutic targets. Using high-dimensional spectral flow cytometry, we identified CD180, a Toll-like receptor-like surface protein, as highly expressed on blasts and stem-like populations in KMT2A-r AML, while near absent on normal haematopoietic stem cells (HSCs). PAML KMT2A-r exhibits an unconventional immunophenotype dominated by CD34-CD180 populations. Integrated single-cell transcriptomics and functional profiling revealed CD180high clusters enriched for quiescence, oxidative phosphorylation, and KMT2A/LSC stemness signatures. CD180 cells demonstrated robust leukaemia-initiating capacity in xenograft models and persisted through therapy, re-emerging at relapse with phenotypic plasticity. Epigenomic analysis showed CD180 is a direct transcriptional target of the KMT2A::MLLT3 fusion complex, regulated by intragenic enhancers and downregulated by menin and BET inhibitors. Longitudinal single-cell analysis confirmed persistence and clonal evolution of CD180 populations during treatment and relapse, underscoring their mechanistic role in chemoresistance and disease progression. In summary, CD180 marks dynamic, relapse-driving populations in KMT2A-r PAML, persists through therapy, and importantly is near absent on normal HSCs, offering a selective therapeutic window. These findings position CD180 as a clinically actionable biomarker for MRD detection and a compelling therapeutic target for eradicating chemoresistant, stem-like cells in paediatric AML. Main PointsO_LICD180 marks chemoresistant, relapse-driving stem-like blasts in KMT2A-r paediatric AML, overcoming CD34-based MRD limitations. C_LIO_LIAbsent on normal HSCs, CD180 is a KMT2A::MLLT3 target and actionable for MRD, relapse prediction, and CD180-directed therapies. C_LI NoveltyThis study introduces CD180 as a novel biomarker and therapeutic target in AML, particularly KMT2A-rearranged subtypes where conventional markers are often absent. Unlike MRD strategies focused on bulk blasts, CD180 marks chemoresistant, stem-like populations driving relapse, critical reservoirs poorly defined in paediatric AML. This work fills a major gap in prognostic assessment and therapy by enabling precise detection of relapse-driving cells and offering a selective therapeutic window.

cancer biology↗

bioRxiv2024

The chemical chaperone 4-phenylbutyric acid rescues molecular cell defects of COL3A1 mutations that cause vascular Ehlers Danlos Syndrome

PurposeVascular Ehlers Danlos Syndrome (vEDS) is a connective tissue disorder caused by COL3A1 mutations for which there are no treatments due to a limited understanding of underlying mechanisms. We aimed to address this critical knowledge gap, focusing on collagen folding, to establish if targeting protein folding represents a potential therapeutic approach. MethodsWe performed a mechanistic analysis of two novel COL3A1 glycine mutations, G189S and G906R, using primary patient fibroblast cultures, and performed pre-clinical proof-of-concept treatments using FDA-approved chemical chaperones targeting protein folding and/or degradation. ResultsCOL3A1 mutations caused secretion of misfolded collagen III and intracellular collagen retention, leading to matrix defects and endoplasmic reticulum (ER) stress, with increased severity for the more C-terminal mutation. Promoting ER protein folding capacity through the chemical chaperone 4-phenylbutyric acid rescued the ER stress, thermostability of secreted collagen, matrix defects and apoptosis. Optimising treatment duration and dosage helped overcome allele-dependent treatment efficacy. In contrast, protein degradation alone or combined with targeting protein folding did not increase efficacy. ConclusionER stress is a molecular mechanism in vEDS that can be influenced by the position of COL3A1 mutation, and promoting protein folding is a putative mechanism-based therapeutic approach that can rescue intra- and extracellular defects.

genetics↗

bioRxiv2022

PKCβ facilitates leukemogenesis in chronic lymphocytic leukaemia by promoting constitutive BCR-mediated signaling

B cell antigen receptor (BCR) signaling competence is critical for pathogenesis of chronic lymphocytic leukemia (CLL). Defining key proteins that facilitate these networks aid in the identification of targets for therapeutic exploitation. We previously demonstrated that reduced PKC function in mouse hematopoietic stem/progenitor cells (HPSCs) resulted in PKC{beta}II upregulation and generation of a poor-prognostic CLL-like disease. Here, prkcb knockdown in HSPCs leads to reduced survival of PKC-KR-expressing CLL-like cells, concurrent with reduced expression of the leukemic markers CD5 and CD23. SP1 promotes elevated expression of prkcb in PKC-KR expressing cells enabling leukemogenesis. Global gene analysis revealed an upregulation of genes associated with B cell activation in PKC-KR expressing cells, coincident with upregulation of PKC{beta}II: supported by activation of key signaling hubs proximal to the BCR and elevated proliferation. Ibrutinib (BTK inhibitor) or enzastaurin (PKC{beta}II inhibitor) treatment of PKC-KR expressing cells and primary CLL cells showed similar patterns of Akt/mTOR pathway inhibition, supporting the role for PKC{beta}II in maintaining proliferative signals in our CLL mouse model. Ibrutinib or enzastaurin treatment also reduced PKC-KR-CLL cell migration towards CXCL12. Overall, we demonstrate that PKC{beta} expression facilitates leukemogenesis and identify that BCR-mediated signaling is a key driver of CLL development in the PKC-KR model. Statement of SignificancePKC{beta} facilitates leukemogenesis of CLL, driven through an SP1-regulated transcriptional program and promotes BCR signaling. Thus far, PKC{beta} is the only kinase within the BCR signaling pathway, a key pathway in driving CLL pathogenesis, implicated in the generation of neoplastic B lineage cells.

cancer biology↗