Biology subjects

Blackhall, F.

Publications and source records attributed to Blackhall, F..

4 recordsLinked to original sources

bioRxiv2024

Circulating tumor cells shed large extracellular vesicles in capillary-sized bifurcations

Circulating tumor cells (CTCs) and their clusters are the drivers of metastasis, but we have an incomplete understanding of how they interact with capillary beds. Using microfluidic models mimicking human capillary bifurcations, we observed cell size- and bifurcation-dependent shedding of nuclei-free fragments by patient CTCs, CTC-derived explant cells and numerous cancer cell lines. Shedding reduced cell sizes up to 61%, facilitating their transit through bifurcations. We demonstrated that shed fragments were a novel subclass of large extracellular vesicles (LEVs), "shearosomes", that require shear stress for their biogenesis and whose proteome was associated with immune-related pathways. Shearosomes exhibited functions characteristic of previously identified EVs including cell-directed internalization by endothelial and immune cells, and intercellular communication abilities such as disruption of endothelial barrier integrity, polarization of monocytes into M2 tumor-promoting macrophages and interactions between endothelial and immune cells. Cumulatively, these findings suggest that CTCs shed shearosomes in capillary beds that drive key processes involved in the formation of pre-metastatic niches.

cancer biology↗

bioRxiv2024

Functional Characterisation of the ATOH1 Molecular Subtype Indicates a Pro-Metastatic Role in Small Cell Lung Cancer

Molecular subtypes of Small Cell Lung Cancer (SCLC) have been described based on differential expression of transcription factors (TFs) ASCL1, NEUROD1, POU2F3 and immune-related genes. We previously reported an additional subtype based on expression of the neurogenic TF ATOH1 within our SCLC Circulating tumour cell- Derived eXplant (CDX) model biobank. Here we show that ATOH1 protein was detected in 7/81 preclinical models and 16/102 clinical samples of SCLC. In CDX models, ATOH1 directly regulated neurogenesis and differentiation programs consistent with roles in normal tissues. In ex vivo cultures of ATOH1-positive CDX, ATOH1 was required for cell survival. In vivo, ATOH1 depletion slowed tumour growth and suppressed liver metastasis. Our data validate ATOH1 as a bona fide oncogenic driver of SCLC with tumour cell survival and pro-metastatic functions. Further investigation to explore ATOH1 driven vulnerabilities for targeted treatment with predictive biomarkers is warranted.

cancer biology↗

bioRxiv2023

The PI3K-AKT-mTOR axis persists as a therapeutic dependency in KRASG12D-driven non-small cell lung cancer

IntroductionKRASG12C and KRASG12D inhibitors represent a major translational breakthrough for non-small cell lung cancer (NSCLC) and cancer in general by directly targeting its most mutated oncoprotein. However, resistance to these small molecules has highlighted the need for rational combination partners necessitating a critical understanding of signaling downstream of KRAS mutant isoforms. MethodsWe contrasted tumor development between KrasG12Cand KrasG12D genetically engineered mouse models (GEMMs). To corroborate findings and determine mutant subtype-specific dependencies, isogenic models of KrasG12C and KrasG12D initiation and adaptation were profiled by RNA sequencing. We also employed cell line models of established KRAS mutant NSCLC and determined therapeutic vulnerabilities through pharmacological inhibition. We analysed differences in survival outcomes for patients affected by advanced KRASG12C or KRASG12D-mutant NSCLC. ResultsKRASG12D exhibited higher potency in vivo, manifesting as more rapid lung tumor formation and reduced survival of KRASG12D GEMMs compared to KRASG12C. This increased potency, recapitulated in an isogenic initiation model, was associated with enhanced PI3K-AKT-mTOR signaling. However, KRASG12C oncogenicity and downstream pathway activation were comparable with KRASG12D at later stages of tumorigenesis in vitro and in vivo, consistent with similar clinical outcomes in patients. Despite this, established KRASG12D NSCLC models depended more on the PI3K-AKT-mTOR pathway, while KRASG12C models on the MAPK pathway. Specifically, KRASG12D inhibition was synergistically enhanced by AKT inhibition. ConclusionsOur data highlight a unique combination treatment vulnerability and suggest that patient selection strategies for combination approaches using direct KRAS inhibitors should be i) contextualised to individual RAS mutants, and ii) tailored to their downstream signaling.

cancer biology↗

bioRxiv2022

Lineage plasticity in SCLC generates non-neuroendocrine cells primed for vasculogenic mimicry

IntroductionVasculogenic mimicry (VM), the process of tumor cell trans-differentiation to endow endothelial-like characteristics supporting de novo vessel formation, is associated with poor prognosis in several tumor types, including small cell lung cancer (SCLC). In genetically engineered mouse models (GEMMs) of SCLC, NOTCH and MYC co-operate to drive a neuroendocrine (NE) to non-NE phenotypic switch and co-operation between NE and non-NE cells is required for metastasis. Here, we define the phenotype of VM-competent cells and molecular mechanisms underpinning SCLC VM using circulating tumor cell-derived explant (CDX) models and GEMMs. MethodsWe analysed perfusion within VM vessels and their association with NE and non-NE phenotypes using multiplex immunohistochemistry in CDX and GEMMs. VM-proficient cell subpopulations in ex vivo cultures were molecularly profiled by RNA sequencing and mass spectrometry. We evaluated their 3D structure and defined collagen-integrin interactions. ResultsWe show that VM vessels are present in 23/25 CDX models and in 2 GEMMs. Perfused VM vessels support tumor growth and only Notch-active non-NE cells are VM-competent in vivo and ex vivo, expressing pseudohypoxia, blood vessel development and extracellular matrix (ECM) organization signatures. On Matrigel, VM-primed non-NE cells re-model ECM into hollow tubules in an integrin {beta}1-dependent process. ConclusionsWe identify VM as an exemplar of functional heterogeneity and plasticity in SCLC and these findings take significant steps towards understanding the molecular events that enable VM. These results support therapeutic co-targeting of both NE and non-NE cells to curtail SCLC progression and to improve SCLC patient outcomes in future.

cancer biology↗