Figure 4.

Initial stages of experimental metastasis is independent of uPA/plasmin(ogen) activation system. (A) Arrest and initial extravasation of tumor cells is independent of mAb-112 and aprotinin. Day 12 embryos were injected with rhodamine-conjugated lectin. After 15 to 20 minutes, single-cell suspensions of CellTracker Green-labeled PC-lo/diss cells or PC-hi/diss cells, mixed with control IgG, mAb-112, or aprotinin, were directly injected into the allantoic vein. Ten minutes and 2 hours later, portions of the CAM were immediately imaged by immunofluorescence microscopy. Green fluorescent tumor cells were visualized still within the CAM vasculature at 10 minutes (top) or as initiating extravasation from the ectoderm capillary plexus at 2 hours after injection (bottom). No major morphologic differences were observed between PC-lo/diss and PC-hi/diss cells or between the control IgG- and mAb-112- or aprotinin-treated PC-hi/diss cells. Images were acquired at an original magnification of x 100. Scale bar, 50 µm. (B) Levels of CAM colonization were determined by Alu-qPCR 5 days after intravenous inoculation of PC-lo/diss or PC-hi/diss cellsmixed with indicated additives. Pooled data are presented from two (PC-lo/diss) to six (PC-hi/diss, aprotinin) individual experiments, using a total of 14 to 76 embryos per variant. Levels of colonization in individual embryos were determined as percent of PC-hi/diss control. Data are presented as mean ± SEM. ***P < .001.