Silk fibroin, obtained from mulberry silkworm Bombyx mori, is used as scaffolds or hydrogels to support cancer cells growth . Off-of-shelf silk fibroin scaffolds are easy to fabricate. Further, the engineered fibroin scaffolds/matrices can be stored for a long time without losing the mechanical or physico-chemical properties. 3D in vitro cancer models are a useful tool to recapitulate the tumor microenvironment and perform drug screening assays . In this work, breast cancer cells and normal fibroblasts were seeded onto 3D silk scaffolds in order to fabricate a tool able to recapitulate the tumor microenvironment that can be used as screening platform for anti-cancer drugs. Alamar blue assay was used to monitor cell metabolism during the 14 days of culturing. The organizations of breast cancer cells and fibroblasts in the scaffolds are investigated by mean of histological staining and scansion electron microscopy imaging. Gene expression modulation concerning extracellular matrix markers is evaluated. Finally, 3D breast cancer models are challenged with different concentration of doxorubicin for the periods of 24, 48 and 72 hours. In order to validate the model as a drugs screening platform, the metabolic activity and cell proliferation are observed at each time point. This 3D in vitro breast cancer model can easily be scaled-up and translated to the preclinical testing of novel chemotherapeutics.
Acknowledgements: H2020 grant nr.668983 (FoReCaST) and FCT the grant PTDC/BTM-ORG/28168/2017 to VB and SCK.
 Kundu, B. et al Biomat. 2013; 34:9462-74.
 Rodrigues, T. et al. Pharmacol Ther. 2018;184:201–211.