Background

The importance of the micro-environment in supporting tumour growth is becoming increasingly apparent. Classical murine models used to study tumour development may not mimic the human micro-environment well, since the tumours become infiltrated with mouse stromal cells; this may prevent modelling of certain key paracrine ligand-receptor interactions important for cancer development, such as HGF/c-met, since the human receptor does not recognise the mouse ligand.

Method

We have used novel 3-D cell-culture biomatrix models of human colorectal tumours such as those made by polyelectrolyte complexation (PEC) or cell suspension in basal membrane extract to develop authentic representations of tumour tissue. We have used fluorescent and bioluminescent reporter genes, in order to label and thus track specific tumour cell types such as epithelial cells and fibroblasts throughout formation and growth of these 3-D models.

Results

We have shown that these models are highly reproducible and that cells grown in this way behave more as they do in vivo than is the case for growth in standard 2-D plastic vessels, with regard to epithelial cell shape/polarity, cell-cell adhesions and molecular profile. In addition, 3-D models faithfully replicate tumour conditions such as hypoxia, epithelial-to-mesenchymal transition (EMT) and anti-cancer drug resistance.

Conclusion

Reporter genes driven by constitutive and inducible promoters enable tracking of individual cell populations and provide a real-time read-out for cell proliferation, hypoxia, EMT and apoptosis in complex 3D models. Ultimately, the models will provide systems for screening of new drugs that specifically target the tumour microenvironment.