Inhibition of Metastasis of Circulating Human Prostate Cancer Cells in the Chick Embryo by an Extracellular Matrix Produced by Foreskin Fibroblasts in Culture

We have previously demonstrated the increased metastatic potential of human prostate cancer circulating tumor cells (CTC), compared to their parental cells, in both orthotopic mouse models and the chick embryo model. In the current study, we asked whether an extracellular matrix (ECM), produced by human foreskin fibroblasts in culture, could inhibit PC-3 human prostate cancer CTC metastasis in the chick embryo model. The chorioallantoic membranes (CAM) of 18 chicken embryos were inoculated with either PC-3 human prostate cancer cells or PC-3 CTCs, both stably expressing green fluorescent protein (GFP). Embryos were divided into six groups: PC-3 parental-cell control; PC-3 plus soluble ECM; PC-3 parental cells plus semi-solid ECM; PC-3 CTC control; PC-3 CTC plus soluble ECM, and PC-3 CTC plus semi-solid ECM. Twelve hours following inoculation of the cells, a single dose of 100 μl of either soluble or semi-solid ECM was added to the appropriate group. Embryo brains were removed on day 8 post-inoculation, and were processed for cryosectioning. Imaging was performed on the cryosections using a scanning laser microscope in order to count metastatic foci. PC-3 controls had an average of 11.1 metastatic foci compared to 2.55 in the PC-3 plus soluble ECM group and 2.76 (p