Democratised single cell proteomics uncovers tumor associated macrophage signature in CYLD cutaneous syndrome skin tumors

Abstract Single-cell proteomics (SCP) reveals cellular heterogeneity and biological insights inaccessible to bulk analysis. Existing limitations are cost, sample loss during processing, and accessibility to state-of-the-art instrumentation. We describe a label free SCP methodology in human tissue, combining fluorescence activated cell sorting (FACS), oil-immersion cell handling, mass-spectrometry, and neural-network derived spectral libraries which address these issues. We tested this methodology in a skin tumor syndrome, CYLD cutaneous syndrome (CCS), assessing tumor heterogeneity. Using a Bruker timsTOF HT platform we quantified > 4000 proteins, averaging ∼700 per cell, through a cost-effective pipeline without specialised liquid handling infrastructure. By utilising pre-existing bioinformatic tools from the scRNA-seq field we implemented a robust analysis methodology, discriminating between macrophages, dendritic cells and tumor keratinocytes, in an unbiased analysis of 419 CCS tumor cells. We validated the biological accuracy of cell annotations by cross referencing with each cell’s FACS markers. Furthermore, we identified a novel CCS tumor associated macrophage population which carried a tumor microenvironment remodelling signature. Our findings demonstrate an accessible SCP technology capable of yielding novel biological discoveries in clinical tissue. IMPORTANT Manuscripts submitted to Review Commons are peer reviewed in a journal-agnostic way. Upon transfer of the peer reviewed preprint to a journal, the referee reports will be available in full to the handling editor. The identity of the referees will NOT be communicated to the authors unless the reviewers choose to sign their report. The identity of the referee will be confidentially disclosed to any affiliate journals to which the manuscript is transferred. GUIDELINES For reviewers: https://www.reviewcommons.org/reviewers For authors: https://www.reviewcommons.org/authors CONTACT The Review Commons office can be contacted directly at: office{at}reviewcommons.org Footnotes Conflict of interest statement: “All authors declare no relevant conflicts of interest.”