Signal Transducers and Activators of Transcription Mediate Fibroblast Growth Factor-Induced Vascular Endothelial Morphogenesis

Department of Pathology, Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53792, USA.
Cancer Research (Impact Factor: 9.33). 02/2009; 69(4):1668-77. DOI: 10.1158/0008-5472.CAN-07-6385
Source: PubMed


The fibroblast growth factors (FGF) play diverse roles in development, wound healing, and angiogenesis. The intracellular signal transduction pathways, which mediate these pleiotropic activities, remain incompletely understood. We show here that the proangiogenic factors FGF2 and FGF8b can activate signal transducers and activators of transcription (STAT) in mouse microvascular endothelial cells (EC). Both FGF2 and FGF8b activate STAT5 and to a lesser extent STAT1, but not STAT3. The FGF2-dependent activation of endothelial STAT5 was confirmed in vivo with the Matrigel plug angiogenesis assay. In tissue samples of human gliomas, a tumor type wherein FGF-induced angiogenesis is important, STAT5 is detected in tumor vessel EC nuclei, consistent with STAT5 activation. By forced expression of constitutively active or dominant-negative mutant STAT5A in mouse brain ECs, we further show that STAT5 activation is both necessary and sufficient for FGF-induced cell migration, invasion, and tube formation, which are key events in vascular endothelial morphogenesis and angiogenesis. In contrast, STAT5 is not required for brain EC mitogenesis. The cytoplasmic tyrosine kinases Src and Janus kinase 2 (Jak2) both seem to be involved in the activation of STAT5, as their inhibition reduces FGF2- and FGF8b-induced STAT5 phosphorylation and EC tube formation. Constitutively active STAT5A partially restores tube formation in the presence of Src or Jak2 inhibitors. These observations show that FGFs use distinct signaling pathways to induce angiogenic phenotypes. Together, our findings implicate the FGF-Jak2/Src-STAT5 cascade as a critical angiogenic FGF signaling pathway.

Full-text preview

Available from:
  • Source
    • "MEOX2 is also able to suppress EC activation through the downregulation of activity of the nuclear factor NF-í µí¼…B [86]. STAT5A was shown to mediate angiogenic activation of ECs through several mechanisms including Src/Jak2- dependent stimulatory signals from fibroblast growth factors FGF2 and FGF8b [87]. Prolactin family members such as proliferin and prolactin could mediate proangiogenic properties of the FGF/STAT5A activating axis through autocrine mechanism [88]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: A cluster of miR-221/222 is a key player in vascular biology through exhibiting its effects on vascular smooth muscle cells (VSMCs) and endothelial cells (ECs). These miRNAs contribute to vascular remodeling, an adaptive process involving phenotypic and behavioral changes in vascular cells in response to vascular injury. In proliferative vascular diseases such as atherosclerosis, pathological vascular remodeling plays a prominent role. The miR-221/222 cluster controls development and differentiation of ECs but inhibits their proangiogenic activation, proliferation, and migration. miR-221/222 are primarily implicated in maintaining endothelial integrity and supporting quiescent EC phenotype. Vascular expression of miR-221/222 is upregulated in initial atherogenic stages causing inhibition of angiogenic recruitment of ECs and increasing endothelial dysfunction and EC apoptosis. In contrast, these miRNAs stimulate VSMCs and switching from the VSMC "contractile" phenotype to the "synthetic" phenotype associated with induction of proliferation and motility. In atherosclerotic vessels, miR-221/222 drive neointima formation. Both miRNAs contribute to atherogenic calcification of VSMCs. In advanced plaques, chronic inflammation downregulates miR-221/222 expression in ECs that in turn could activate intralesion neoangiogenesis. In addition, both miRNAs could contribute to cardiovascular pathology through their effects on fat and glucose metabolism in nonvascular tissues such as adipose tissue, liver, and skeletal muscles.
    Full-text · Article · Jul 2015
  • Source
    • "The fact that JAKs and STATs are activated by multiple mitogens has encouraged researchers to develop strategies to target them in cancer treatments. There is limited, somewhat confusing, evidence for JAK/STAT signaling downstream of FGF-2 and its relevance is unclear [14], [15], [16]. We and others [17] have observed de-regulated JAK/STAT expression in a variety of lung carcinoma and sarcoma cell lines. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The development of resistance to chemotherapy is a major cause of cancer-related death. Elucidating the mechanisms of drug resistance should thus lead to novel therapeutic strategies. Fibroblast growth factor (FGF)-2 signaling induces the assembly of a multi-protein complex that provides tumor cells with the molecular machinery necessary for drug resistance. This complex, which involves protein kinase C (PKC) ε, v-raf murine sarcoma viral oncogene homolog B1 (B-RAF) and p70 S6 kinase β (S6K2), enhances the selective translation of anti-apoptotic proteins such as B-cell leukaemia/lymphoma-2 (BCL-2) and inhibitors of apoptosis protein (IAP) family members and these are able to protect multiple cancer cell types from chemotherapy-induced cell death. The Janus kinases (JAKs) are most noted for their critical roles in mediating cytokine signaling and immune responses. Here, we show that JAKs have novel functions that support their consideration as new targets in therapies aimed at reducing drug resistance. As an example, we show that the Janus kinase TYK2 is phosphorylated downstream of FGF-2 signaling and required for the full phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. Moreover, TYK2 is necessary for the induction of key anti-apoptotic proteins, such as BCL-2 and myeloid cell leukemia sequence (MCL) 1, and for the promotion of cell survival upon FGF-2. Silencing JAK1, JAK2 or TYK2 using RNA interference (RNAi) inhibits FGF2-mediated proliferation and results in the sensitization of tumor cells to chemotherapy-induced killing. These effects are independent of activation of signal transducer and activator of transcription (STAT) 1, STAT3 and STAT5A/B, the normal targets of JAK signaling. Instead, TYK2 associates with the other kinases previously implicated in FGF-2-mediated drug resistance. In light of these findings we hypothesize that TYK2 and other JAKs are important modulators of FGF-2-driven cell survival and that inhibitors of these kinases will likely improve the effectiveness of other cancer therapies.
    Full-text · Article · Oct 2011 · PLoS ONE
  • [Show abstract] [Hide abstract]
    ABSTRACT: Histone deacetylase was overexpressed in a variety of cancers and was closely correlated with oncogenic factors. The histone deacetylase inhibitor, trichostatin A (TSA) was shown to induce apoptosis in many cancer cells. However, the mechanism of TSA on induction of cancer cells apoptosis is poorly understood. This study was designed to characterize the global gene expression profiles before and after treatment of human leukemia cell line Molt-4 with TSA. Flow cytometry, MTT and DNA ladder were used to observe the effect of TSA on the apoptosis of MOLT-4 cells and normal human peripheral blood mononuclear cells (PBMC). Microarray, reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to detect the difference of gene and protein expressions of Molt-4 cells after incubation of the cells with TSA. The results showed that TSA could induce Molt-4 apoptosis in dose- and time-dependent manners but spared PBMCs. Microarray analysis showed that after incubation with TSA for 9 h, 310 genes were upregulated and 313 genes were deregulated. These genes regulate the growth, differentiation and survival of cells. Among these genes, STAT5A was down-regulated by 80.4% and MYC was down-regulated by 77.3%. It was concluded that TSA has definite growth-inhibiting and apoptosis-inducing effects on Molt-4 cells in time- and dose-dependent manners, with weak cytotoxic effects on PBMCs at the same time. The mechanism of TSA selectively inducing apoptosis and inhibiting growth may be ascribed to the changes of pro-proliferation genes and anti-apoptosis genes.
    No preview · Article · Sep 2009 · Journal of Huazhong University of Science and Technology
Show more