Murine Cell Line Models for Vascular Mimicry: The Role of YAP/TAZ Signaling

Vascular mimicry (VM) refers to the formation of vessel-like structures by tumor cells independent of endothelial cells. These VM channels connect to the host's vascular network and are associated with aggressive tumors and poor patient prognosis. Most VM research has been conducted on melanoma, relying on patient-derived and mouse cell lines. In other solid tumors, VM studies rely on human cell lines, which have certain limitations for in vivo studies. Specifically, most in vivo VM research involving human cells uses subcutaneous mouse models that fail to recapitulate organ-specific tumor microenvironments. As the microenvironment is an essential driver of tumor vascularization, including VM, murine cell lines could facilitate VM investigations in syngeneic mouse models. Here, we present CT26 and KPC, well-characterized murine colorectal and pancreatic cancer cell lines, as cell models for VM investigations. Using in vitro cell-based assays, we demonstrate that CT26 and KPC undergo VM, a cell-intrinsic process that is enhanced by serum deprivation and exposure to hypoxia and is independent of tumor-secreted growth factors. Additionally, we demonstrate the importance of YAP/TAZ signaling in VM formation, as inhibition at non-cytotoxic concentrations attenuated VM formation. Remarkably, CA3, the most potent of the two inhibitors, significantly reduced cell proliferation in both cell lines at the IC₅₀ concentration. This reduction in cell proliferation was associated with the induction of apoptosis in CT26 cells and changes in the cell cycle in both CT26 and KPC cells. Finally, dual YAP/TAZ knockdown in both cell lines significantly abrogated VM formation, validating our initial findings using inhibitors. These results show that CT26 and KPC cells undergo VM, and given their extensive use in cancer research, can be used to investigate VM in vivo using syngeneic models.