Abstract
BACKGROUND AND AIMS
Breast cancer is a leading cause of female mortality in the Western world. It is well established that
the spread of breast cancer, first locally and later distally, is the major factor in patient prognosis.
Experimental systems of breast cancer rely on cell lines usually derived from primary tumours or
pleural effusions. Two major obstacles hinder this research: (i) Some known sub-types of breast
cancers are not represented within current cell line collections; (ii) the influence of the tumour
microenvironment is not usually taken into account.
EXPERIMENTAL DESIGN
We developed a three-dimensional assay prepared from freshly harvested breast cancer tissue
embedded in soft rat collagen I cushions. Invasive behaviour and tumour response to tamoxifen
therapy was measured. Changes in proliferation, apoptosis and tumour volume in response to
tamoxifen treatment were quantified using image analysis software and optical projection
tomography. Further cell line based experiments and histopathological analysis of resection
specimens were subsequently investigated to investigate the role of EGFR signalling pathways in
driving invasion.
RESULTS
We demonstrate a technique to culture primary breast cancer specimens of all sub-types. Within 2-3
weeks, individual and collective invasion of epithelial cells into the surrounding collagen I was
observed using phase contrast light microscopy and histopathological methods. Addition of
tamoxifen to preparations derived from ER+ tumours demonstrated a range of response as
measured by proliferative and apoptotic markers and significant reduction in tumour volume not
seen in ER- specimens. Changes in tumour volume allowed stratification into responsive and
nonresponsive tumours. EGF within the culture medium appeared to drive a change in phenotype
from ER+ to triple negative phenotype and acted as a driver for epithelial invasiveness.
CONCLUSION
Here, we developed an assay to culture human breast tumours without sub-type bias and to
investigate and quantify the spread of these ex vivo. This method could be used to quantify drug
sensitivity in primary cancers under conditions closer to real life. This may provide a more predictive
model than currently used cell lines.