INTRODUCTION: Drug development is a high-costly process and may last 7-10 years with no guarantees for the final drug approval and efficacy particularly for cancer treatment. There is an urgent need to develop the new tools to be able to copycat the tumor microenvironment and more realistic drug-screening platform to predict the drug efficacy and toxicity. Biomaterials support the growth of cancer cells together with the other cellular and acellular players, which offer different options to recapitulate the tumor microenvironment. [1], [2] In this work, we develop a 3D in vitro cancer model based on naturally-derived silk protein fibroin biomaterial. Fibroin shows good biocompatibility, suitable mechanical properties, and tunable biodegradability. Silk fibroin-derived freeze-dried scaffolds are produced in order to recapitulate faithfully the tumor microenvironment.

METHODS: 2 % silk fibroin solution is used to fabricate the scaffolds.  The breast cancer cells (MCF-7) and normal mammary fibroblast are seeded or embedded on the scaffolds. The cell proliferation is monitored by means of Alamar blue assay at different time points for 14 days. 3D breast cancer model morphology is observed by confocal microscopy. The gene expression modulation concerning the extracellular matrix markers is evaluated by mean of qRT-PCR. Further, 3D bioengineered breast cancer models are treated with doxorubicin. The cell growth inhibition is assessed at 24, 48 and 72h post-treatments.

RESULTS: Silk fibroin scaffolds support the proliferation of the cancer cells and fibroblasts. The  growth of cells is enhanced when cancer cells and fibroblasts are seeded together (p<0.001). Histological staining shows 3D cell organization. MMP-1, MMP-2, MMP-3, Col-1 and fibronectin expressions are upregulated in co-culture (p<0.001). Doxorubicin treatment reduces the proliferation of cells proliferation. However, higher doxorubicin concentration is needed to kill the cancer cells when they are in co-culture with fibroblasts.

DISCUSSION & CONCLUSIONS: The platforms designed may represent promising model for understanding the crosstalk between cancer cells, fibroblasts and extracellular matrix. The developed 3D in vitro tumor tissue model is expected to be an appropriate platform for drug-screening.

ACKNOWLEDGEMENTS: Financial support was received from the European Union Framework Programme for Research and Innovation Horizon 2020 under ERA-Chair grant agreement nº 668983 — FoReCaST and the FCT project BREAST-IT (IF/028168/2017)

REFERENCES

[1] Caballero, D. et al. Biomat. 2017;149:98–115.

[2]        Rodrigues, T. et al. Pharmacol Ther. 2018;184:201–211.