Magdeldin, T. | Search bioRxiv

bioRxiv2019

Cancer Associated Fibroblasts Mediate Cancer Progression and Remodel the Tumouroid Stroma

ObjectiveCancer associated fibroblasts (CAFs) are highly differentiated and heterogenous cancer stromal cells that promote tumour growth, angiogenesis and matrix remodelling. DesignWe utilised a novel 3D in vitro model of colorectal cancer, composed of a cancer mass and surrounding stromal compartment. We compared cancer invasion with an acellular stromal surround, a healthy or normal cellular stroma and a cancerous stroma. For the cancerous stroma we incorporated six patient-derived CAF samples to study their differential effects on cancer growth, vascular network formation, and remodelling. ResultsCAFs enhanced the distance and surface area of the invasive cancer mass whilst inhibiting vascular-like network formation. These processes were driven by the upregulation of hepatocyte growth factor (HFG), metallopeptidase inhibitor 1 (TIMP1) and fibulin 5 (FBLN5). Remodelling appeared to occur through the process of disruption of complex networks and was associated with the up upregulation of vascular endothelial growth factor (VEGFA) and down-regulation in vascular endothelial cadherin (VE-Cadherin). ConclusionThese results support, within a biomimetic 3D, in vitro framework, the direct role of CAFs in promoting cancer invasion and that CAFs are also key components in driving vasculogenesis and angiogenesis.

cancer biology↗

bioRxiv2019

Human induced pluripotent stem cell-derived neuroectodermal epithelial cells mistaken for blood-brain barrier-forming endothelial cells

Brain microvascular endothelial cells (BMECs) possess unique properties underlying the blood-brain-barrier (BBB), that are crucial for homeostatic brain functions and interactions with the immune system. Modulation of BBB function is essential for treatment of neurological diseases and effective tumor targeting. Studies to-date have been hampered by the lack of physiological models using cultivated human BMECs that sustain BBB properties. Recently, differentiation of induced pluripotent stem cells (iPSCs) into cells with BBB-like properties has been reported, providing a robust in vitro model for drug screening and mechanistic understanding of neurological diseases. However, the precise identity of these iBMECs remains unclear. Employing single-cell RNA sequencing, bioinformatic analysis and immunofluorescence for several pathways, transcription factors (TFs), and surface markers, we examined the molecular and functional properties of iBMECs differentiated either in the absence or presence of retinoic acid. We found that iBMECs lack both endothelial-lineage genes and ETS TFs that are essential for the establishment and maintenance of EC identity. Moreover, iBMECs fail to respond to angiogenic stimuli and form lumenized vessels in vivo. We demonstrate that human iBMECs are not barrier-forming ECs but rather EpCAM+ neuroectodermal epithelial cells (NE-EpiCs) that form tight junctions resembling those present in BBB-forming BMECs. Finally, overexpression of ETS TFs (ETV2, FLI1, and ERG) reprograms NE-EpiCs to become more like the BBB-forming ECs. Thus, although directed differentiation of human iBMECs primarily gives rise to epithelial cells, overexpression of several ETS TFs can divert them toward a vascular BBB in vitro.

cell biology↗