The human tumour micro-environment modelled in in vitro biomatrices and applied to cancer drug discovery

The paracrine signalling pathways within a tumour micro-environment play an important role in the epithelial–mesenchymal transition (EMT) and metastasis. Cancer-associated fibroblasts (CAFs), in particular, have important roles in supporting these processes. Stromal–epithelial interactions have become a focus of cancer drug discovery but are not optimally modelled by xenograft systems. For example, transplanted human epithelial cells are infiltrated with murine stroma but within the hepatocyte growth factor (HGF)/C-met axis, an important paracrine signalling pathway, murine HGF from the stroma does not bind the human C-met receptor on human epithelial cells within xenografts. Therefore to replace the inappropriate use of xenografts to examine these paracrine interactions in drug discovery applications, we will model the tumour microenvironment in vitro, thereby aligning with the objectives of the NC3Rs. To test the utility of this approach we will model a colon liver metastasis niche using early-passage patient-derived epithelial cells and matched CAFs in a biomatrix that has been shown to support multiple cell types in co-culture, using a functional HGF/C-met pathway as a measure of success. We will apply the refinement of real-time fluorescent/bioluminescent reporters to assess expansion of the different cell-types within the culture and monitor environmental signals such as hypoxia, EMT and apoptotic potential concurrently, without the need to harvest the cells. These will be validated against fresh human colorectal liver metastasis samples. Furthermore replacement of CAFs with commercially-available human mesenchymal stem cells (MSCs) will also be assessed as use of these should enable broader application of this in vitro system to cells derived from different tumour types. The final assessment of drug response will be performed in a 96-well format to examine the utility of this in vitro approach to a higher through-put format maximising its uptake by the pharmaceutical industry in drug discovery applications. This refined in vitro system therefore has the potential to replace the need for animals in investigating the biology of the tumour micro-environment for both new target identification and lead optimisation.

• Further Funding: NC3Rs PhD Studentship, Application of a 3D hydrogel-based model to replace use of animals for passaging patient-derived xenografts, April 2017, £90,000
• Further Funding: NC3Rs Strategic Grant, Targeted, radiolabelled near-infrared quantum dots for high sensitivity and resolution, dual modality imaging of human tumours in mice, November 2014, £369,898 (Co-funded by EPSRC)