Biology subjects

Lun, X.

Publications and source records attributed to Lun, X..

5 recordsLinked to original sources

bioRxiv2026

High-plex protein imaging across thick tissue by synchronized amplification

High-plex protein imaging is essential for decoding complex tissue organization, yet it remains largely confined to thin sections. Current approaches in millimeter-thick samples suffer from poor signal penetration and depth-dependent, uneven signal amplification. Even with specialized instrumentation to facilitate probe diffusion, iterative millimeter-thick tissue workflows can take more than four days per staining round, and reported eleven-marker experiments extend beyond a month. We introduce Amplification by Cyclic Extension (ACE), a DNA-barcoded, synchronized in situ amplification strategy that uses thermally controlled cyclic extension to coordinate DNA concatemer growth across tissue depths. By synchronously activating and coordinating reaction progression throughout the sample, ACE enables controlled, uniform signal amplification across tissue depths. Using ACE, we demonstrate 63-plex protein and RNA imaging in thin sections, 22-plex protein imaging in 200 m mouse brain sections, and 16-plex protein imaging in 1 mm-thick brain tissue encompassing over three million cells. For millimeter-thick tissues, ACE reduces per-round target-switching time from multiple days to less than eight hours, shifting volumetric high-plex protein imaging from months to days. Together, these results establish ACE as a synchronized amplification strategy that enables scalable high-plex protein imaging in thick tissues.

bioengineering↗

bioRxiv2023

Spatiotemporal modeling reveals high-resolution invasion states in glioblastoma

Diffuse invasion of glioblastoma cells through normal brain tissue is a key contributor to tumor aggressiveness, resistance to conventional therapies, and dismal prognosis in patients. A deeper understanding of how components of the tumor microenvironment (TME) contribute to overall tumor organization and to programs of invasion may reveal opportunities for improved therapeutic strategies. Towards this goal, we applied a novel computational workflow to a spatiotemporally profiled GBM xenograft cohort, leveraging the ability to distinguish human tumor from mouse TME to overcome previous limitations in analysis of diffuse invasion. Our analytic approach, based on unsupervised deconvolution, performs reference-free discovery of cell types and cell activities within the complete GBM ecosystem. We present a comprehensive catalogue of 15 tumor cell programs set within the spatiotemporal context of 90 mouse brain and TME cell types, cell activities, and anatomic structures. Distinct tumor programs related to invasion were aligned with routes of perivascular, white matter, and parenchymal invasion. Furthermore, sub-modules of genes serving as program network hubs were highly prognostic in GBM patients. The compendium of programs presented here provides a basis for rational targeting of tumor and/or TME components. We anticipate that our approach will facilitate an ecosystem-level understanding of immediate and long-term consequences of such perturbations, including identification of compensatory programs that will inform improved combinatorial therapies.

cancer biology↗

bioRxiv2023

Impaired migration and metastatic spread of human melanoma by a novel small molecule targeting the transmembrane domain of death receptor p75NTR

Receptor transmembrane domains (TMDs) are crucially involved in relaying ligand information from extracellular to intracellular spaces and represent attractive targets for small molecule manipulation of receptor function. Screening a library of over 8,000 drug-like compounds with an assay based on the TMD of death receptor p75NTR, we identified a novel small molecule capable of inhibiting p75NTR-mediated migration of human melanoma cells. Employing medicinal chemistry, a more potent derivative termed Np75-4A22 was identified that blocks nerve growth factor (NGF)-mediated melanoma invasion at submicromolar concentrations. Mechanistically, Np75-4A22 was found, at least in part, to function by antagonizing NGF-mediated recruitment of the actin-bundling protein fascin to p75NTR and its association with the actin cytoskeleton. Importantly, preclinical assessment of Np75-4A22 showed high oral bioavailability, low toxicity, and significant inhibition of melanoma lung metastases in a highly metastatic mouse model. These results support further development of this approach as an alternative or complementary strategy for patients that do not respond to conventional chemotherapy or immune checkpoint inhibitors.

cancer biology↗

bioRxiv2021

macroH2A2 shapes chromatin accessibility at enhancer elements in glioblastoma to modulate a targetable self-renewal epigenetic network

Self-renewal is a crucial property of glioblastoma cells and is enabled by the choreographed function of chromatin regulators and transcription factors. Identifying targetable epigenetic mechanisms of self-renewal could represent an important step toward developing new and effective treatments for this universally lethal cancer. Here we uncover a targetable epigenetic axis of self-renewal mediated by the histone variant macroH2A2. Using patient-derived in vitro and in vivo models, we show that macroH2A2 has a direct role in shaping chromatin accessibility at enhancer elements to antagonize transcriptional programs of self-renewal. Pharmaceutical inhibition of the chromatin remodeler Menin increased macroH2A2 levels and repressed self- renewal. Our results reveal a targetable epigenetic mechanism of self-renewal controlled by macroH2A2 and suggest new treatment approaches for glioblastoma patients. SIGNIFICANCEGlioblastoma is an incurable brain cancer. Malignant self-renewing cells have been shown to drive tumor growth, to be refractory to current treatment approaches and to seed relapses, which ultimately prove lethal. Identifying new and targetable mechanisms associated with self-renewal could be a fundamental first step in designing effective therapies that slow or prevent glioblastoma relapses. Using patient-derived models of glioblastoma, we deployed epigenomic approaches and functional assays to define the role of the histone variant macroH2A2 in repressing self-renewal. We identified compounds that increase macroH2A2 levels and repress self-renewal, including a Menin inhibitor. As Menin inhibitors are being tested in clinical trials, these compounds could be used in new therapeutic paradigms to target self-renewing cell populations in glioblastoma.

cancer biology↗

bioRxiv2020

Multidimensional single-cell modeling of cellular signaling

Cell-to-cell differences in signaling components can lead to qualitatively different responses to stimuli. Understanding this heterogeneity in signaling response is limited by the inability of time-lapse methods to measure multiple pathway components simultaneously in situ. Here, we present Distribution-Independent Single-Cell ODE modeling (DISCO), a computational method for inference of continuous single-cell signaling dynamics from multiplexed snapshot data. We used DISCO to analyze signaling in the MAPK/ERK pathway of HEK293T cells stimulated with the growth factor EGF. Our model recapitulates known features of the ERK signaling response and enables the detection of hidden cell-to-cell variation in seemingly homogeneous samples. Further, DISCO analysis suggested that the MAPK/ERK pathway transmits signal duration rather than amplitude, and that cell-to-cell variation in MAPK/ERK signaling response depends primarily on initial cell states. Finally, we applied an extended version of DISCO to explain changes in signaling kinetics due to overexpression of a disease-relevant protein. Overall, DISCO enables a deeper understanding of how single-cell variation affects cellular responses in complex signaling systems.

systems biology↗