Cells shed from tumours show reduced clonogenicity, resistance to apoptosis, and in vivo tumorigenicity

The goal of this study was to compare growth characteristics of cells shed from a tumour with the native tumour cells. The human colon adenocarcinoma LS174T and its highly metastatic subline LS UM 6 were grown as tissue-isola ted tumours in nude mice and perfused to collect shed cells. The tumours we re then excised and prepared into single-cell suspensions. Clonogenicity in 0.3-0.9% agarose, apoptotic fraction, and in vivo tumorigenicity were dete rmined for each population. In both tumour lines, shed cells were less cion ogenic, more apoptotic and less tumorigenic than cells isolated directly fr om their native tissue. These findings suggest that shed cells have a low m etastatic potential compared to native tumour cells, most likely because th ey represent an apoptotic population. (C) 1999 Cancer Research Campaign.