Flt-1-dependent survival characterizes the epithelial-mesenchymal transition of colonic organoids.
Aberrant cell survival and resistance to apoptosis are hallmarks of tumor invasion and progression to metastatic disease, but the mechanisms involved are poorly understood. The epithelial-mesenchymal transition (EMT), a process that facilitates progression to invasive cancer, provides a superb model for studying such survival mechanisms. Here, we used a unique spheroid culture system that recapitulates the structure of the colonic epithelium and undergoes an EMT in response to cytokine stimulation to study this problem. Our data reveal that the EMT results in the increased expression of both VEGF and Flt-1, a tyrosine kinase VEGF receptor, and that the survival of these cells depends on a VEGF/Flt-1 autocrine pathway. Perturbation of Flt-1 function by either a blocking antibody or adenoviral expression of soluble Flt-1, which acts in a dominant-negative fashion, caused massive apoptosis only in cells that underwent EMT. This pathway was critical for the survival of other invasive colon carcinoma cell lines, and we observed a correlative upregulation of Flt-1 expression linked to in vivo human cancer progression. A role for Flt-1 in cell survival is unprecedented and has significant implications for Flt-1 function in tumor progression, as well as in other biological processes, including angiogenesis and development.
Bates
Richard C
RC
Division of Cancer Biology and Angiogenesis, Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA. rbates@caregroup.harvard.edu
Goldsmith
Jeffrey D
JD
Bachelder
Robin E
RE
Brown
Courtney
C
Shibuya
Masabumi
M
Oettgen
Peter
P
Mercurio
Arthur M
AM
D017209:Apoptosis / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D017931:DNA Primers; D004848:Epithelium / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005822:Genetic Vectors; D006801:Humans; D007150:Immunohistochemistry; D009940:Organoids / Q000254:growth & development* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D015398:Signal Transduction / Q000502:physiology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000502:physiology*; D040281:Vascular Endothelial Growth Factor Receptor-1; D042442:Vascular Endothelial Growth Factors / Q000378:metabolism*
D017931:DNA Primers; D016326:Extracellular Matrix Proteins; D042442:Vascular Endothelial Growth Factors; C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1