Biology subjects

Landais, Y.

Publications and source records attributed to Landais, Y..

4 recordsLinked to original sources

bioRxiv2025

A single-nucleus multimodal framework reveals epigenomic priming of chemoresistant states in ovarian cancer

Non-genetic intratumor heterogeneity (ITH) drives therapeutic failure in cancer, yet its clinical monitoring remains challenging. We develop a multimodal single-nucleus framework that simultaneously profiles transcriptional and histone modification landscapes from frozen biopsies. Applied to longitudinal samples from 16 patients with high-grade serous ovarian cancer (HGSOC), this approach reveals reproducible tumor evolution under chemotherapy: proliferative and interferon-responsive states are lost, while those associated with TNF- and epithelial-mesenchymal transition (EMT) expand. Chromatin profiling shows that these chemoresistant programs are epigenetically primed through H3K4me1 marks before treatment and nominates transcription-factor drivers, including ZBTB7A. Non-genetic baseline tumor composition predicts survival, and fibroblast remodeling parallels malignant adaptation. These findings establish a clinically scalable strategy for mapping functional ITH and identify epigenomic priming as a determinant of therapeutic failure. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=181 HEIGHT=200 SRC="FIGDIR/small/692102v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@432524org.highwire.dtl.DTLVardef@3b7843org.highwire.dtl.DTLVardef@54a2eforg.highwire.dtl.DTLVardef@95273d_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2024

PARP inhibitor counteracts Temozolomide Resistance in Glioblastoma Multiforme

BackgroundGlioblastoma multiforme (GBM) is the most common malignant primary brain tumour in adults and is invariably associated with poor prognosis. Resistance to Temozolomide (TMZ), the standard chemotherapeutic agent, remains a major clinical challenge, particularly due to DNA mismatch repair (MMR) deficiencies. The aim of this study was to determine whether combining TMZ with the poly(ADP-ribose) polymerase inhibitor Olaparib (OLA) could overcome TMZ resistance in GBM. MethodsWe conducted in vitro experiments using U251 cell-line, including a TMZ-resistant derivative, and primary GBM cultures derived from patient tumours. A CRISPR/Cas9 knockout screen was employed to identify genes involved in TMZ resistance. Cell viability, proliferation, and morphology were assessed following treatment with TMZ, OLA, or their combination. ResultsThe CRISPR screen identified inactivation of MMR pathway genes as key mediators of TMZ resistance. Co-treatment with OLA and TMZ demonstrated synergistic cytotoxicity in both parental and TMZ-resistant U251 cells, as well as in primary GBM cultures at diagnosis or relapse. Notably, OLA restored sensitivity to TMZ in MMR-deficient contexts and in tumours expressing O6-methylguanine-DNA-methyltransferase (MGMT). The combination treatment induced persistent DNA damage, cell cycle disruption, and cell death. ConclusionsThese findings provide strong preclinical evidence that combining TMZ with OLA can effectively overcome key mechanisms of TMZ resistance in GBM. This approach offers a promising therapeutic strategy warranting further clinical investigation. IMPORTANCE OF THE STUDYTemozolomide (TMZ) resistance remains a major therapeutic obstacle in glioblastoma (GBM), often driven by MMR deficiency or MGMT expression. While poly(ADP-ribose) polymerase (PARP) inhibitors have shown potential in other cancers, their role in overcoming TMZ resistance in GBM has remained unclear. In this study, a CRISPR screen identified MMR deficiency as a key driver of TMZ resistance. We further demonstrate that co-treatment with the PARP inhibitor Olaparib (OLA) restores TMZ sensitivity in both MMR-deficient and MGMT-expressing GBM cells and patient-derived cultures. These findings provide strong preclinical evidence supporting PARP inhibition as a promising therapeutic strategy to overcome chemoresistance in GBM and justify further clinical investigation. KEY POINTSO_LIPARP inhibitor Olaparib restores temozolomide sensitivity in resistant GBM cells C_LIO_LICombination therapy overcomes resistance driven by MMR deficiency or MGMT expression C_LIO_LIDual treatment induces persistent DNA damage and apoptosis in glioblastoma primary cultures C_LI

cancer biology↗

bioRxiv2024

Aging limits stemness and tumorigenesis in the lung by reprogramming iron homeostasis

Aging is associated with a decline in the number and fitness of adult stem cells1-4. Aging-associated loss of stemness is posited to suppress tumorigenesis5,6, but this hypothesis has not been tested in vivo. Here, using physiologically aged autochthonous genetically engineered mouse models and primary cells7,8, we demonstrate aging suppresses lung cancer initiation and progression by degrading stemness of the alveolar cell of origin. This phenotype is underpinned by aging-associated induction of the transcription factor NUPR1 and its downstream target lipocalin-2 in the cell of origin in mice and humans, leading to a functional iron insufficiency in the aged cells. Genetic inactivation of the NUPR1--lipocalin-2 axis or iron supplementation rescue stemness and promote tumorigenic potential of aged alveolar cells. Conversely, targeting the NUPR1-- lipocalin-2 axis is detrimental to young alveolar cells via induction of ferroptosis. We find that aging-associated DNA hypomethylation at specific enhancer sites associates with elevated NUPR1 expression, which is recapitulated in young alveolar cells by inhibition of DNA methylation. We uncover that aging drives a functional iron insufficiency, which leads to loss of stemness and tumorigenesis, but promotes resistance to ferroptosis. These findings have significant implications for the therapeutic modulation of cellular iron homeostasis in regenerative medicine and in cancer prevention. Furthermore, our findings are consistent with a model whereby most human cancers initiate in young individuals, revealing a critical window for such cancer prevention efforts.

cancer biology↗

bioRxiv2022

Multi-modal quantification of pathway activity with MAYA

Signaling pathways can be activated through various cascades of genes depending on cell identity and biological context. Single-cell atlases now provide the opportunity to inspect such complexity in health and disease. Yet, existing reference tools for pathway scoring resume activity of each pathway to one unique common metric across cell types. Here, we present MAYA a computational method that enables the automatic detection and scoring of the diverse modes of activation of biological pathways across cell populations. MAYA improves the granularity of pathway analysis by detecting subgroups of genes within reference pathways, each characteristic of a cell population and how it activates a pathway. Using multiple single-cell datasets, we demonstrate the biological relevance of identified modes of activation, the robustness of MAYA to noisy pathway lists and batch effect. MAYA can also predict cell types starting from lists of reference markers in a cluster-free manner. Finally, we show that MAYA reveals common modes of pathway activation in tumor cells across patients, opening the perspective to discover shared therapeutic vulnerabilities.

bioinformatics↗