title: VEGF drives cancer-initiating stem cells through VEGFR-2/Stat3 signaling to upregulate Myc and Sox2.
abstract: Vascular endothelial growth factor-A (VEGF), a potent angiogenic factor, is also implicated in self-renewal in several normal tissue types. VEGF has been shown to drive malignant stem cells but mechanisms thereof and tumor types affected are not fully characterized. Here, we show VEGF promotes breast and lung cancer stem cell (CSC) self-renewal via VEGF receptor-2 (VEGFR-2)/STAT3-mediated upregulation of Myc and Sox2. VEGF increased tumor spheres and aldehyde dehydrogenase activity, both proxies for stem cell function in vitro, in triple-negative breast cancer (TNBC) lines and dissociated primary cancers, and in lung cancer lines. VEGF exposure before injection increased breast cancer-initiating cell abundance in vivo yielding increased orthotopic tumors, and increased metastasis from orthotopic primaries and following tail vein injection without further VEGF treatment. VEGF rapidly stimulated VEGFR-2/JAK2/STAT3 binding and activated STAT3 to bind MYC and SOX2 promoters and induce their expression. VEGFR-2 knockdown or inhibition abrogated VEGF-mediated STAT3 activation, MYC and SOX2 induction and sphere formation. Notably, knockdown of either STAT3, MYC or SOX2 impaired VEGF-upregulation of pSTAT3, MYC and SOX2 expression and sphere formation. Each transcription factor, once upregulated, appears to promote sustained activation of the others, creating a feed-forward loop to drive self-renewal. Thus, in addition to angiogenic effects, VEGF promotes tumor-initiating cell self-renewal through VEGFR-2/STAT3 signaling. Analysis of primary breast and lung cancers (>1300 each) showed high VEGF expression, was prognostic of poor outcome and strongly associated with STAT3 and MYC expression, supporting the link between VEGF and CSC self-renewal. High-VEGF tumors may be most likely to escape anti-angiogenics by upregulating VEGF, driving CSC self-renewal to re-populate post-treatment. Our work highlights the need to better define VEGF-driven cancer subsets and supports further investigation of combined therapeutic blockade of VEGF or VEGFR-2 and JAK2/STAT3.
authors.affiliation: 1] Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA [2] Sheila and David Fuente Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: D
authors.initials: D
authors.lastname: Zhao
authors.affiliation: Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: C
authors.initials: C
authors.lastname: Pan
authors.affiliation: Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: J
authors.initials: J
authors.lastname: Sun
authors.affiliation: Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: C
authors.initials: C
authors.lastname: Gilbert
authors.affiliation: Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: K
authors.initials: K
authors.lastname: Drews-Elger
authors.affiliation: 1] Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA [2] Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Azzam
authors.affiliation: Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: M
authors.initials: M
authors.lastname: Picon-Ruiz
authors.affiliation: 1] Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA [2] Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: M
authors.initials: M
authors.lastname: Kim
authors.affiliation: Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: W
authors.initials: W
authors.lastname: Ullmer
authors.affiliation: 1] Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA [2] Sheila and David Fuente Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, Miami, FL, USA [3] Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: D
authors.initials: D
authors.lastname: El-Ashry
authors.affiliation: Division of Biostatistics, Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Creighton
authors.affiliation: 1] Braman Family Breast Cancer Institute at Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA [2] Sheila and David Fuente Graduate Program in Cancer Biology, University of Miami Miller School of Medicine, Miami, FL, USA [3] Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL, USA [4] Department of Medicine, University of Miami Miller School of Medicine, Miami, FL, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Slingerland
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000473:pathology*; D011485:Protein Binding / Q000187:drug effects; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics* / Q000378:metabolism; D055748:SOXB1 Transcription Factors / Q000235:genetics* / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*
chemical_list: C489427:MYC protein, human; D016271:Proto-Oncogene Proteins c-myc; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2