p53 modulation of anchorage independent growth and experimental metastasis
Nikiforov, M.A.; Hagen, K.; Ossovskaya, V.S.; Connor, T.M.; Lowe, S.W.; Deichman, G.I.; Gudkov, A.V.
Oncogene 13(8): 1709-1719
1996
ISSN/ISBN: 0950-9232 PMID: 8895517 Document Number: 458028
Death in circulation is one of the natural barriers preventing dissemination of tumor cells and formation of metastases. One of the negative factors acting in circulation is the loss of cell contact with natural substrate which can be imitated in vitro by the incubation of cells in suspension or in semi-solid media. Normal mouse fibroblasts (MEFs) stay viable in suspension and undergo p53-independent G-1 growth arrest. Transformation with Ela and ras oncogenes leads to the abrogation of this arrest and to the p53-dependent apoptosis occurring in G-1 phase of the cell cycle. Suppression of apoptosis by p53 gene knock-out, transduction of dominant negative p53 mutant or bcl-2 prevents death in suspension and greatly induces frequency of colony formation in semi-solid media. The ability of cells to undergo apoptosis does not correlate with their tumorigenicity in nude mice but does correlate with their ability to survive in lungs of intravenously injected mice and to form experimental metastases. We suggest that abrogation of a p53-mediated apoptosis facilitates experimental metastasis by promoting survival of tumor cells in circulation.