Planque, C. | Search bioRxiv

bioRxiv2026

SPEAR: Spatial Epitranscriptomic Analysis by Mass Spectrometry Reveals Localized RNA Modification Remodeling During Glioma Progression

RNA modifications shape cell identity and disease, yet their spatial organization within tissues has remained largely inaccessible to existing technologies. NGS-based methods can map a limited number of individual modifications with spatial resolution, while liquid chromatography-tandem mass spectrometry (LC-MS/MS) provides comprehensive and quantitative coverage of the epitranscriptome from bulk, homogenized tissue. No current approach combines histological resolution, broad modification coverage, quantitative accuracy, and the sensitivity required for microscale clinical specimens. We present SPEAR (SPatial Epitranscriptomic Analysis by mass spectrometRy), a workflow coupling laser microdissection with a redesigned LC-MS/MS pipeline to enable quantitative epitranscriptomic profiling directly from formalin-fixed, paraffin-embedded (FFPE) tissue. This combination enables reproducible detection of dozens of RNA modifications from regions as small as 0.1 mm2, establishing a spatial scale previously inaccessible to mass spectrometry-based approaches. Applied to serial mouse brain sections, SPEAR resolved anatomically defined epitranscriptomic signatures across white and gray matter, establishing its spatial resolution and reproducibility in a controlled system. We then applied SPEAR to human diffuse gliomas containing, within individual specimens, both primary low-grade tumor regions and discrete foci undergoing transformation toward higher-grade malignancy. SPEAR resolved this transition directly, revealing a coordinated decrease in multiple methylated RNA modifications specifically within higher-grade regions, a spatially restricted signal that was masked by bulk analysis and reproducibly observed across patients despite underlying genetic heterogeneity. SPEAR establishes spatial epitranscriptomics as a tractable approach for molecular profiling of clinical tissue, providing a platform for biomarker discovery and molecular stratification based on the spatial organization of RNA modifications.

cancer biology↗

bioRxiv2022

The aminoglycoside streptomycin triggers ferroptosis in tumor initiating cells

Compelling evidence suggests that tumor initiating cells (TIC) are the roots of current shortcomings in advanced and metastatic cancer treatment. TIC represents a minor subpopulation of tumor cells endowed with self-renewal and multi-lineage differentiation capacity, which can disseminate and seed metastasis in distant organ. Our work identified Streptomycin (SM), a potent bactericidal antibiotic, as a new molecule capable of targeting non-adherent TIC from colon and breast cancer cell lines by inducing mitochondrial-dependent ferroptosis. SM-induced ferroptosis associates with profound alterations in mitochondrial morphology, such as swelling and cristae enlargement, coupled with hyperpolarization of mitochondrial membrane potential and production of mitochondrial ROS. The peculiar SM structure, and more particularly its aldehyde group, is essential for this mechanism. As such, the mere reduction of SM into dihydrostreptomycin abolishes its effect on TIC. This study reveals a new mechanism of action of SM that could help comprehend the molecular basis of TIC adaptation to inhospitable environments and pave the way for new treatment of advanced cancers.

cancer biology↗