Authors: Indira Sigdel, Awurama Ofori-Kwafo, Earshed Al Mamun, Amit K. Tiwari, Yuan Tang
Source: Bioengineering and Translational Medicine
Published online: November 18, 2025.
Abstract:
Metastasis is the principal cause of mortality in breast cancer, but therapies specifically targeting metastatic mechanisms are scarce. In triple-negative breast cancer (TNBC), hypoxia within the tumor microenvironment (TME) promotes endothelial dysfunction, increasing vascular permeability and facilitating cancer cell intravasation. This study presents a microfluidic-based idealized microvascular on-chip (iMVoC) model utilizing human umbilical vein endothelial cells and TNBC cells (SUM159PTX) to model a hypoxic TME. This model mimicked dynamic flow perfusion, promoting endothelial alignment along the flow direction, while supporting 3D tumor structures exhibiting varying oxygen levels in the tissue compartment. The iMVoC model enabled cell–cell interactions and the exchange of media and nutrients between compartments. Hypoxia was confirmed by increased nuclear translocation of hypoxia inducible factors (HIF)-1α and HIF-2α in TNBC cells, indicating hypoxia-based signaling. Hypoxia-induced endothelial cell (EC) inflammation was validated through elevated permeability, upregulation of adhesion molecules, and increased reactive oxygen species (ROS) production, suggesting activation of the HIF-ROS pathway. Enhanced tumor cell intravasation was observed across inflamed endothelium, and cytokine profiling further confirmed EC activation through inflammatory signaling. Application of the protein kinase C delta (PKCδ) inhibitor (PKCδ-TAT) significantly mitigated these effects, shifting HIF localization from the nucleus to the cytoplasm, reducing ROS production, downregulating inflammatory cytokines, and lowering TNBC intravasation. These findings demonstrate PKCδ as a key mediator linking hypoxia to EC dysfunction and tumor dissemination. Protecting EC barrier integrity emerges as a promising strategy to mitigate hypoxia-driven TNBC metastasis, with the iMVoC platform offering a valuable tool for testing anti-cancer therapeutics or drug combinations involving PKCδ-TAT.