Persistence of microscopic human cancers in mice: alterations in the angiogenic balance accompanies loss of tumor dormancy.
Some human tumor lines do not form visible tumors when inoculated into immunosuppressed mice. The fate of these human tumor lines was followed by transfecting them with green fluorescence protein before inoculating them into mice. Although the tumor lines failed to grow progressively, they formed small dormant microscopic foci maintained at constant mass by balanced proliferation and apoptosis. Transfecting the cells with either VEGF165 or activated c-Ha-ras induced loss of dormancy, which correlated with a shift in the angiogenic balance toward increased vascularity with reduced tumor cell apoptosis. These results support a model in which loss of dormancy is controlled in part by a switch to an angiogenic phenotype. These tumor lines may serve as models for investigating the cellular mechanisms controlling dormancy and identifying those factors that promote the loss of balanced proliferation and apoptosis. Finally, these models may prove useful in the design and testing of therapies directed toward eradicating dormant tumors and preventing tumor recurrence.
Udagawa
Taturo
T
Department of Surgery, Division of Surgical Research, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Fernandez
Antonio
A
Achilles
Eike-Gert
EG
Folkman
Judah
J
D'Amato
Robert J
RJ
D000818:Animals; D017209:Apoptosis; D002455:Cell Division; D049452:Green Fluorescent Proteins; D006801:Humans; D016867:Immunocompromised Host; D007202:Indicators and Reagents; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000097:blood* / Q000473:pathology*; D009389:Neovascularization, Pathologic; D014407:Tumor Cells, Cultured
D007202:Indicators and Reagents; D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins