Biology subjects

Longley, D.

Publications and source records attributed to Longley, D..

4 recordsLinked to original sources

bioRxiv2026

Spatiotemporal dynamics of Mcl-1 abundance and its influence on apoptosis susceptibility

The Bcl-2 protein family defines cellular competence for mitochondrial outer membrane permeabilization (MOMP) and apoptotic cell death. In proliferating cells, the Bcl-2 family member Mcl-1 accumulates across the cell cycle and confers trans-mitotic resistance to extrinsic apoptosis. We show here that Mcl-1, but not Bcl-xL, additionally undergoes a coordinated redistribution from the cytosol to mitochondria, concomitant with its over-proportional accumulation late in the cell cycle. Live-cell monitoring of Mcl-1 dynamics at single-cell resolution, combined with mathematical modelling, enabled us to quantify that Mcl-1 redistribution substantially contributes to elevating MOMP thresholds. Furthermore, we found that Mcl-1 accumulation and redistribution act concomitantly but independently to increase MOMP thresholds as cells approach mitosis and this elevated resistance is reset in daughter cells after division. Notably, heterogeneities in Mcl-1 abundance and subcellular distribution are pronounced even among isogenic cells within the same cell-cycle phase, and thus contribute to substantial cell-to-cell variability in MOMP susceptibility. Analysis of colorectal cancer tissue samples showed that variability in Mcl-1 expression and distribution is likewise prominent between cells in patient tumors and were predicted to drive intra-tumour heterogeneity in responses to treatments that induce MOMP. Overall, we demonstrate how changes in Mcl-1 amounts and localisation integrate with cell-cycle progression to modulate apoptotic susceptibility, thereby shaping cell-fate outcomes and contributing to cell-to-cell heterogeneities in death decision making.

cell biology↗

bioRxiv2024

Viral mimicry redirects immunosuppressed colorectal tumour landscapes towards a proinflammatory and CMS1-like regenerative state

In colorectal cancer (CRC), tumours classifier as consensus molecular subtype 4 (CMS4) have the worst prognosis and derive negligible benefit from chemotherapy. We previously described how repressed interferon-related signalling is associated with increased relapse in CMS4 tumours. Although the viral mimetic poly(I:C) can reduce liver metastasis in vivo, the initial phenotypic changes that underpin its anti-metastatic response remain poorly described, particularly in the immunosuppressed CMS4 tumour microenvironment. Here we characterise lineage-specific anti-metastatic responses induced by poly(I:C), including acute macrophage polarisation and a novel CMS1-like regenerative stem cell state, which drive pro-inflammatory microenvironmental changes in CRC. These insights enabled the development of tractable biomarkers that identify an "immune-warm" patient subset most likely to respond to poly(I:C), enriched for mismatch-repair proficient (pMMR), anti-inflammatory macrophages and CMS4-like features. The viral mimetic poly(I:C) offers a tailored treatment option for CMS4 tumours, by reprogramming stem cell states and activation of an innate-adaptive anti-metastatic response.

cancer biology↗

bioRxiv2023

Ribosome Quality Control Mechanism Mitigates the Cytotoxic Impacts of Ribosome Collisions Induced by 5-Fluorouracil

Translation of aberrant or damaged mRNAs results in ribosome stalling and collisions. The Ribosome Quality Control (RQC) mechanism detects collided ribosomes and removes aberrant mRNAs and nascent peptides, thus preventing their cytotoxic effects. Conversely, excessive or unresolved ribosome collisions can induce apoptosis. 5-Fluorouracil (5FU) forms the backbone of standard-of-care chemotherapeutic regimens for several types of cancer. Although best known for its incorporation into DNA and inhibition of thymidylate synthase, a major determinant of 5FUs anticancer activity is its incorporation into RNAs. Nevertheless, the mechanism(s) underlying RNA-dependent 5FU cytotoxicity and the cellular response to its impact on RNA metabolism remain unclear. Here, we report a key role for RQC in mitigating the cytotoxic effects of 5FU-induced dysregulation of mRNA translation. We show that acute 5FU treatment results in the rapid induction of the mTOR signalling pathway, an enhanced rate of mRNA translation initiation, and increased ribosome collisions that trigger RQC. We also found that RQC deficiency, caused by the depletion of ZNF598, results in increased 5FU-induced cell death, a phenotype that is reversed by inhibition of mTOR or repression of mRNA translation initiation. Importantly, 5FU treatment enhances the expression of key RQC factors, including ZNF598 and GIGYF2, via an mTOR-dependent post-translational regulation mechanism. This acute adaptation likely mitigates the cytotoxic consequences of increased ribosome collisions upon 5FU treatment. Overall, our data indicate a heretofore unknown mTOR-dependent mechanism that augments the RQC process, mitigating the cytotoxicity of 5FU and undermining its anticancer efficacy.

cell biology↗

bioRxiv2021

An atlas of inter- and intra-tumor heterogeneityof apoptosis competency in colorectal cancertissue at single cell resolution

Cancer cells ability to inhibit apoptosis is key to malignant transformation and limits response to therapy. Here, we performed multiplexed immunofluorescence analysis on tissue microarrays with 373 cores from 168 patients, segmentation of 2.4 million individual cells and quantification of 20 cell lineage and apoptosis proteins. Ordinary differential equation-based modelling of apoptosis sensitivity at single cell resolution was conducted and an atlas of inter- and intra-tumor heterogeneity in apoptosis susceptibility generated. We identified an enrichment for BCL2 in immune, and BAK, SMAC and XIAP in cancer cells. ODE-based modelling at single cell resolution identified an enhanced sensitivity of cancer cells to mitochondrial permeabilization and executioner caspase activation compared to immune and stromal cells, with significant inter- and intra-tumor heterogeneity. However, we did not find increased spatial heterogeneity of apoptosis signaling in cancer cells, suggesting that such heterogeneity is an intrinsic, non-genomic property not increased by the process of malignant transformation.

cancer biology↗