Biology subjects

Juin, P. P.

Publications and source records attributed to Juin, P. P..

8 recordsLinked to original sources

bioRxiv2025

EGFR/TBK1-dependent mitochondrial quality control contributes to acquired resistance to temozolomide

Acquisition of secondary resistance to chemotherapy in cancer cells is an ill-characterized multi-step process. We conducted a non-supervised, global proteomic analysis of U251 glioma cells treated by temozolomide as they transit from drug-sensitive to tolerant and then resistant states. This unprecedented analysis revealed key mitochondrial evolutions throughout the process. Following an early stress substantiated by a transient peak of reactive oxygen species, mitochondrial quality control mechanisms enable emergence of the resistant population. We combined genome editing, targeted protein degradation via PROTAC, and pharmacologic inhibitors to investigate the mechanisms underlying stress resolution both at population and single cell scales (including microscopic evaluation and in-situ proximity ligation assays). These studies unravel a Src-activated EGFR and TBK1 axis that initiates autophagic recycling of mitochondria as a necessary step to the emergence of the resistant population.

cancer biology↗

bioRxiv2025

The Kinase CK1α coordinates Initiation and Termination of the cGAS-STING Pathway

The cGAS-STING pathway is an evolutionarily conserved antimicrobial defense mechanism that senses cytosolic DNA to trigger innate immune responses. cGAS and STING play dual roles in tumorigenesis, promoting antitumor immunity and cell death while fueling tumor growth and metastasis. However, the mechanisms fine-tuning this pathway remain elusive. Using proteomic approaches, we report that Casein Kinase 1 alpha (CK1) operates as a bimodal regulator of the cGAS-STING pathway. CK1 supports optimal DNA sensing by preventing the proteasomal degradation of cGAS driven by the cullin-RING ubiquitin ligase 3 (CRL3). Conversely, CK1 facilitates STING degradation and signaling termination in response to STING agonists, tempering IRF3 activation. Exploiting these counterposing functions, we show that selective degradation of CK1 with molecular-glue degraders impaired the survival of a triple-negative breast cancer cell line with chronic cGAS-STING activation and synergized with a STING agonist to kill acute myeloid leukemia cells. Thus, CK1s dual regulatory role in the cGAS-STING pathway presents a promising target for therapeutic development. TEASERThis study unveils CK1 as a bimodal regulator of the cGAS-STING pathway.

immunology↗

bioRxiv2025

MCL-1 as a molecular switch between myofibroblastic and pro-angiogenic features of breast cancer-associated fibroblasts

Breast cancer-associated fibroblasts (bCAFs) comprise inflammatory CAFs (iCAFs), characterized by the secretion of pro-inflammatory cytokines, and myofibroblastic CAFs (myCAFs), distinguished by their high production of extracellular matrix and their immunosuppressive properties. We previously showed that targeting the anti-apoptotic protein MCL-1 in primary culture of bCAF derived directly from human samples reduces their myofibroblastic characteristics. We herein show by single-cell RNA-sequencing analysis of bCAFs that MCL-1 knock down induces a phenotypic shift from wound-myCAF to IL-iCAF, characterized by the upregulation of genes associated with inflammation as well as angiogenesis-related genes. In vitro, genetic and pharmacologic MCL-1 inhibition increases VEGF secretion by bCAFs, enhancing endothelial cell tubulogenesis. In a chicken chorioallantoic membrane (CAM) model in ovo, co-engraftment of breast cancer cells and bCAFs with reduced MCL-1 expression leads to heightened peritumoral vascular density, driven by VEGF. Mechanistically, the pro-angiogenic phenotype revealed by MCL-1 inhibition is dependent on BAX-BAK activity. It results in NF-{kappa}B activation, inhibition of which by a IKK{beta} inhibitor suppresses the transcription of VEGF and pro-inflammatory factors triggered by MCL-1 inhibition in bCAFs. Chemotherapy induces a downregulation of MCL-1 in bCAFs and it promotes a pro-angiogenic phenotype, counteracted by overexpressed MCL-1. Overall, these findings uncover a novel regulatory function of MCL-1 in determining bCAF subpopulation differentiation and highlight its role in modulating their pro-angiogenic properties, in response to treatment in particular.

cancer biology↗

bioRxiv2024

Antimitotic chemotherapy promotes tumor NF-kB secretory phenotype and immunosuppressive CXCR2+ neutrophils chemotaxis in triple-negative breast cancers

Integrated approaches that help understand how tumors, as immune-surveilled ecosystems, respond to chemotherapy are crucial for developing effective antitumor treatments. We previously showed, in immunodeficient context, that antimitotic chemotherapy induced cGAS/STING pathway amplifying antitumor response through a paracrine IFN-1 secretome. We herein studied tumor progression and response to treatment using an immunocompetent murine model. scRNAseq analysis revealed that paclitaxel treatment altered tumor cell phenotypes, favoring tumor cells with a gene expression signature indicative of active NF-{kappa}B pathway with secretory phenotype. Treatment coincidently reduced IFN-I signature cells during tumor progression. The resulting secretory shift correlated with neutrophil recruitment to the tumor, particularly CXCR2+ neutrophils, thereby contributing to an immunosuppressive microenvironment. Pharmacological inhibition of CXCR2 receptor by navarixin reactivated antitumor immunity, enhancing NK cell infiltration and tumor cytotoxicity. Navarixin combination with paclitaxel significantly reduced tumor volume and metastasis. Targeting the NF-{kappa}B-driven secretory phenotype, in particular through neutrophil modulation, holds promise for improving TNBC treatment outcomes.

cancer biology↗

bioRxiv2024

Allosteric regulation of BH3-in-groove interactions by tail anchors of BCL-xL complexes limits BH3 mimetic antagonism.

In briefThe C terminal tail anchors of BCL-2 family proteins exert allosteric influence over the interface crucial for BH3 binding and cell survival. This is regulated by additional features taking place at the mitochondria membrane such as recruitment of the death executioner BAX, which, in response to BH3 binding antagonism, contributes to protein complex disruption. SummaryBCL-xL exerts an essential cell survival function which relies on its hydrophobic groove binding to BH3 domain of BH3-only initiators and downstream BAX/BAK executioners. Combining resonance energy transfer assays and molecular dynamics simulations, we unravel that the C-terminal tail mediated subcellular membrane anchoring of BCL-xL selectively advantages binding to membrane-anchored PUMA initiator over BH3 mimetic ligands of the groove. This is due to the combined allosteric effect on BH3-in-groove binding of BCL-xL and PUMA tail anchors. Moreover, doubly anchored PUMA / BCL-xL complexes recruit endogenous BAX, which favors their antagonism by BH3 mimetics. BAXs C-terminal tail anchor alone is sufficient to enhance BH3 mimetics induced death in cells expressing PUMA / BCL-xL. Thus, the survival function of BCL-xL is regulated by a complex interplay between its tail anchor and those of its interacting partners. This enables both resistance to pharmacological inhibitors and modulation by BAX, which functions as a crucial feedback disruptor of the BCL-xL network. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/616265v1_ufig1.gif" ALT="Figure 1000"> View larger version (12K): org.highwire.dtl.DTLVardef@885687org.highwire.dtl.DTLVardef@e8eeaeorg.highwire.dtl.DTLVardef@8e09fborg.highwire.dtl.DTLVardef@1314d68_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsBH3 mimetic antagonism, and subsequent cell death, are limited when full length BCL-xL binds to some membrane-anchored BH3-only proteins such as PUMA. The BH3-in-groove interface is allosterically modulated by tail anchors of PUMA and BCL-xL. Binding to PUMA enriches BCL-xL interactome and recruits BAX. BAX counteracts the effects of tail anchors in BCL-xL complexes.

cell biology↗

bioRxiv2023

Cancer associated fibroblasts mitigate the efficacy of the combination treatment of chemotherapy and BCL-xL targeting in triple negative breast cancer cells

Triple negative breast cancers (TNBC) present a poor prognosis primarily due to their resistance to chemotherapy. This resistance is understood to associate with elevated expression of certain antiapoptotic members within the proteins of the BCL-2 family (namely BCL-xL, MCL-1 and BCL-2). These regulate cell death by inhibiting pro-apoptotic protein activation through binding and sequestration and they can be selectively antagonized by BH3 mimetics. Yet the individual influences of BCL-xL, MCL-1, and BCL-2 on the sensitivity of TNBC cells to chemotherapy, and their regulation by cancer-associated fibroblasts (CAFs), major components of the tumor stroma and key contributors to therapy resistance remain to be delineated. By utilizing engineered TNBC cell line MDA-MB-231 deficient in BCL-2 family proteins and BH3 mimetics, we show that BCL-xL and MCL-1 promote cancer cell survival by compensatory mechanisms. This cell line shows limited sensitivity to chemotherapy, in line with the clinical resistance observed in TNBC patients. We elucidate that BCL-xL plays a pivotal role in therapy response, as its depletion or pharmacological inhibition heightened chemotherapy effectiveness. Moreover, BCL-xL expression is associated to chemotherapy resistance in patient-derived tumoroids where its pharmacological inhibition enhances ex vivo response to chemotherapy. In a co-culture model of cancer cells and CAFs, we observe that even in a context where BCL-xL inhibition renders cancer cells more susceptible to chemotherapy, those in contact with CAFs display reduced sensitivity to chemotherapy. Thus CAFs exert a profound pro-survival effect in breast cancer cells, even in a setting highly favoring cell death through combined chemotherapy and inhibition of the main actor of chemoresistance, BCL-xL.

cancer biology↗

bioRxiv2021

Targeting of MCL-1 in breast cancer associated fibroblasts reverses their myofibroblastic phenotype and pro-invasive properties

Cancer associated fibroblasts (CAF) are a major cellular component of epithelial tumors. In breast cancers in particular these stromal cells have numerous tumorigenic effects in part due to their acquisition of a myofibroblastic phenotype. Breast CAFs (bCAFS) typically express MCL-1. We show here that targeting this regulator of mitochondrial integrity using a specific BH-3 mimetic promotes fragmentation of these organelles without inducing cell death. MCL-1 antagonism in primary bCAFs directly derived from human samples mitigates myofibroblastic features and decreases expression of genes involved in actomyosin organization and contractility, associated with a cytoplasmic retention of the transcriptional regulator, Yes-Associated Protein (YAP). Such treatment decreases bCAFs ability to promote cancer cells invasion in 3D co-culture assays. These effects are counteracted by an inhibitor of the mitochondrial fission protein DRP-1, which interacts with MCL-1 upon BH3 mimetic treatment. Our findings underscore the usefulness of targeting MCL-1 in breast cancer ecosystems, not only to favor death of cancer cells but also to counteract the tumorigenic activation of fibroblasts with which they co-evolve. The authors declare no conflict of interest.

cancer biology↗

bioRxiv2020

Development of an absolute assignment predictor for triple-negative breast cancer subtyping using machine learning approaches

Triple-negative breast cancer (TNBC) heterogeneity represents one of the main impediment to precision medicine for this disease. Recent concordant transcriptomics studies have shown that TNBC could be splitted into at least three subtypes with potential therapeutic implications. Although, a few studies have been done to predict TNBC subtype by means of transcriptomics data, subtyping was partially sensitive and limited by batch effect and dependence to a given dataset, which may penalize the switch to routine diagnostic testing. Therefore, we sought to build an absolute predictor (i.e. intra-patient diagnosis) based on machine learning algorithm with a limited number of probes. To this end, we started by introducing probe binary comparison for each patient (indicators). We based predictive analysis on this transformed data. Probe selection was first performed by combining both filter and wrapper methods for variable selection using cross validation. We thus tested three prediction models (random forest, gradient boosting [GB] and extreme gradient boosting) using this optimal subset of indicators as inputs. Nested cross-validation allowed us to consistently choose the best model. Results showed that the 50 selected indicators highlighted biological characteristics associated with each TNBC subtype. The GB based on this subset of indicators has better performances as compared to the other models.

bioinformatics↗