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Updated: Aug 23, 2025
Quantifying the Brain Metastatic Tumor Micro-Environment using an Organ-On-A Chip 3D Model, Machine Learning, and Confocal Tomography
Published on: August 16, 2020
Mechanosensitive brain tumor cells construct blood-tumor barrier to mask chemosensitivity
Xin Chen1, Ali Momin2, Siyi Wanggou3
1Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada; Arthur and Sonia Labatt Brain Tumour Research Centre, The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
Abstract:
Major obstacles in brain cancer treatment include the blood-tumor barrier (BTB), which limits the access of most therapeutic agents, and quiescent tumor cells, which resist conventional chemotherapy. Here, we show that Sox2+ tumor cells project cellular processes to ensheathe capillaries in mouse medulloblastoma (MB), a process that depends on the mechanosensitive ion channel Piezo2. MB develops a tissue stiffness gradient as a function of distance to capillaries. Sox2+ tumor cells perceive substrate stiffness to sustain local intracellular calcium, actomyosin tension, and adhesion to promote cellular process growth and cell surface sequestration of β-catenin. Piezo2 knockout reverses WNT/β-catenin signaling states between Sox2+ tumor cells and endothelial cells, compromises the BTB, reduces the quiescence of Sox2+ tumor cells, and markedly enhances the MB response to chemotherapy. Our study reveals that mechanosensitive tumor cells construct the BTB to mask tumor chemosensitivity. Targeting Piezo2 addresses the BTB and tumor quiescence properties that underlie treatment failures in brain cancer.
Insights
Mechanosensitive tumor cells form the blood-tumor barrier (BTB) using Piezo2, hindering brain cancer treatment. Targeting Piezo2 disrupts the BTB and reduces tumor cell dormancy, improving chemotherapy effectiveness.
Area of Science:
- Neuroscience
- Cancer Biology
- Biophysics
Background:
- Brain cancer treatment faces challenges from the blood-tumor barrier (BTB) and quiescent tumor cells.
- Sox2-positive (Sox2+) tumor cells in medulloblastoma (MB) ensheathe capillaries via cellular processes.
Purpose of the Study:
- To investigate the role of mechanosensitive ion channels, specifically Piezo2, in BTB formation and brain tumor treatment resistance.
- To elucidate the mechanisms by which Sox2+ tumor cells interact with their microenvironment to promote tumor growth and therapeutic resistance.
Main Methods:
- Utilized mouse medulloblastoma models to study Sox2+ tumor cell behavior and BTB formation.
- Investigated the function of the mechanosensitive ion channel Piezo2 in cellular process extension, intracellular signaling (calcium, actomyosin tension), and cell adhesion.
- Analyzed the impact of Piezo2 knockout on BTB integrity, WNT/β-catenin signaling, tumor cell quiescence, and response to chemotherapy.
Main Results:
- Sox2+ tumor cells form cellular processes dependent on Piezo2, ensheathing capillaries and responding to tissue stiffness gradients.
- Perception of substrate stiffness by Sox2+ cells drives process growth, calcium signaling, actomyosin tension, and β-catenin sequestration.
- Piezo2 knockout disrupts BTB integrity, alters signaling between tumor and endothelial cells, reduces Sox2+ cell quiescence, and significantly improves chemotherapy response.
Conclusions:
- Mechanosensitive tumor cells actively construct the BTB to shield themselves from therapeutic agents and maintain quiescence.
- Targeting Piezo2 offers a novel therapeutic strategy to overcome BTB limitations and tumor dormancy in brain cancers.
- Understanding the mechanobiology of tumor cells is crucial for developing effective brain cancer treatments.
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