Characterization of cancer cell adhesion on endothelial cells by super-resolution microscopy

Studies have highlighted that in cancer metastasis, the physical constraints caused by the capillaries’ size prompt stable adhesion in cell arrest at the distant organ sites. However, adhesion-mediated cell arrest also plays a significant role, and the mechanism behind it is yet to be understood. The vasculature wall is lined by endothelial cells, and a better understanding of their interaction with tumor cells is essential to go deep into cell arrest and extravasation in cancer metastasis. Using various in vitro experiments and microscopy techniques, we reveal (1) the primary adhesion site of tumor cells on an endothelial cell monolayer and (2) the role of tumor cell filopodia in adhesion and transendothelial migration. In fixed samples, more than 90% of tumor cells were localized on endothelial cell junctions. Live-cell imaging became essential to know whether the tumor cells directly adhere to the junction or migrate towards the junction after adhesion. Live-cell imaging data analysis is in progress with the help of ZeroCostDL4Mic based multiple deep-learning techniques. We also chose to use Airyscan super-resolution microscopy for live-cell imaging and structured illumination microscopy (SIM) for fixed samples to study the early adhesion and transendothelial migration. We discovered that the tumor cell filopodia plays a vital role in this event by bridging the first contact between tumor cells and endothelial cells. Starting from early adhesion, they actively contribute to adhesion maturation, extravasation site exploration, and extravasation