One limitation in the breast cancer research field is that there are few in vitro models of breast cancer able to predict drug response and thus clinical patients’ outcome, mainly because the present models do not take account of the tumor heterogeneity. To address this issue, we developed an in vitro 3D organoid culture system using primary human breast cancer tissue that could be used to recapitulate in vivo organs. A major difficulty in the development of such models is to identify in vitro conditions that preserve the breast cancer phenotypes observed in vivo.
We isolated organoids from breast cancer patients and optimized the organoids growing conditions. By immunofluorescence assay we confirmed the receptor status, and the preservation of epithelial (E-cadherin) or the fibroblasts components included in the tissue microenvironment (TME) (alfa-SMA and FAP). Here we used organoids as mimic of tumor burden for drug penetration studies. In particular, we studied doxorubicin (DOX) penetration and biodistribution, by several means: immunofluorescence studies, caspase assay, and cell viability.
We demonstrated by IF studies, that miR-340, an oncosuppressor miR, was able to modulate DOX penetration. At the same time, miR-340 induced an increase in DOX sensitivity assessed by caspase-3 assay, PARP cleavage, as well as p38 phosphorylation. Breast cancer organoids have also been used to better understand the role of the TME in breast cancer response to therapy. We assessed drug sensitivity in the presence or absence of conditioned media obtained from cancer activated fibroblasts (CAFs). We found that organoids treated with conditioned media exhibit lower level of caspase 3 activation compared to the control upon palbociclib treatment, suggesting the importance role of TME in drug resistance.
Thus, organoids can be considered as a new tool for studying breast cancer and developing personalized medicine approaches and to test possible use of RNA therapeutics.
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All authors have declared no conflicts of interest.